The Dark Matter Galaxy Rotation Controversy Gets Personal

by Tommy on 1/11/2016

The MOND fanatics are not going down without a fight, apparently.

The last two sentences are the million dollar takeaway of this article.

This publication was made possible through the support of a grant from the John Templeton Foundation. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the John Templeton Foundation.

One law to rule them all. In other words, god did it. Stacy S. McGaugh credibility destroyed.

One Law To Rule Them All: The Radial Acceleration Relation of Galaxies, Federico Lelli, Stacy S. McGaugh, James M. Schombert and Marcel S. Pawlowski, Submitted to ApJ (31 October 2016)

We study the link between baryons and dark matter (DM) in 240 galaxies with spatially resolved kinematic data. Our sample spans 9 dex in stellar mass and includes all morphological types. We consider (i) 153 late-type galaxies (LTGs; spirals and irregulars) with gas rotation curves from the SPARC database; (ii) 25 early-type galaxies (ETGs; ellipticals and lenticulars) with stellar and HI data from ATLAS3D or X-ray data from Chandra; and (iii) 62 dwarf spheroidals (dSphs) with individual-star spectroscopy. We find that LTGs, ETGs, and “classical” dSphs follow the same radial acceleration relation: the observed acceleration gobs correlates with that expected from the distribution of baryons over 4 dex. Ultrafaint dSphs extend the relation by a further 2 dex and seem to trace a flattening at gobs ~ 10-11 m/s2. The radial acceleration relation exists for any plausible choice of the stellar mass-to-light ratio. For our fiducial values, the relation coincides with the 1:1 line (no DM) at high accelerations but systematically deviates from unity below a critical scale of ~10-10 m/s2. The observed scatter is remarkably small (~0.13 dex) and largely driven by observational uncertainties. The residuals show no correlations with other properties like radius, stellar surface density, or gas fraction. The radial acceleration relation is tantamount to a Natural Law: when the baryonic contribution is measured, the rotation curve follows, and vice versa. This local scaling law subsumes and generalizes several well-known dynamical properties of galaxies, like the Tully-Fisher and Faber-Jackson relations, the “baryon-halo” conspiracies, and Renzo’s rule.

A movie is available at this URL:

Jesus loves me, this I know, for the bible tells me so.

Mo money, mo money, mo money!

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Emergent Physics Found in Far From Equilibrium Systems

by Tommy on 1/11/2016

Editorial: Emergence in driven solid-state and cold-atom systems, Ludwig Mathey and Junichi Okamoto, Z. Naturforsch. A 71, 873 (13 October 2016), DOI:10.1515/zna-2016-0326

We briefly summarize the current status of driven solid-state and cold-atom systems, and introduce articles compiled in the Focus Section in Zeitschrift für Naturforschung A, Volume 71, Issue 10 (2016)

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Entanglement Equation of State Depends on Superfluid Density

by Tommy on 30/10/2016

This is as breathroughy as it gets. That’s my new favorite word – Breakthroughiness.

This goes along with the notion of truthiness in science, truth is always changing.

With a half dozen breakthroughs a day on the ArXiv, the shoe definitely fits here.

If this keeps up, I will not be able to continue covering these breakthroughs.

Entanglement area law in superfluid 4He, C. M. Herdman, P.-N. Roy, R. G. Melko and A. Del Maestro (26 October 2016)

Area laws were first discovered by Bekenstein and Hawking, who found that the entropy of a black hole grows proportional to its surface area, and not its volume. Entropy area laws have since become a fundamental part of modern physics, from the holographic principle in quantum gravity to ground state wavefunctions of quantum matter, where entanglement entropy is generically found to obey area law scaling. As no experiments are currently capable of directly probing the entanglement area law in naturally occurring many-body systems, evidence of its existence is based on studies of simplified theories. Using new exact microscopic numerical simulations of superfluid 4He, we demonstrate for the first time an area law scaling of entanglement entropy in a real quantum liquid in three dimensions. We validate the fundamental principles underlying its physical origin, and present an “entanglement equation of state” showing how it depends on the density of the superfluid.

I sense a bulk boundary correspondence here.

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21st Century Schizoid Mann

by Tommy on 30/10/2016

King Crimson – 21st Century Schizoid Man – BBC session (1969) HQ from ThinkFloyd61 on Vimeo.

Welcome to the 21st Century.

Happy Halloween!

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Mid Pleistocene 40-100 k.y. Glacial Cycle Transition Resolved

by Tommy on 27/10/2016

One less thing on my bucket list.

Breathing more deeply: Deep ocean carbon storage during the mid-Pleistocene climate transition, Caroline H. Lear, Katharina Billups, Rosalind E.M. Rickaby, Liselotte Diester-Haass, Elaine M. Mawbey and Sindia M. Sosdian, Geology, 44, 12, (20 October 2016), doi:10.1130/G38636.1

The ∼100 k.y. cyclicity of the late Pleistocene ice ages started during the mid-Pleistocene transition (MPT), as ice sheets became larger and persisted for longer. The climate system feedbacks responsible for introducing this nonlinear ice sheet response to orbital variations in insolation remain uncertain. Here we present benthic foraminiferal stable isotope (δ18O, δ13C) and trace metal records (Cd/Ca, B/Ca, U/Ca) from Deep Sea Drilling Project Site 607 in the North Atlantic. During the onset of the MPT, glacial-interglacial changes in δ13C values are associated with changes in nutrient content and carbonate saturation state, consistent with a change in water mass at our site from a nutrient-poor northern source during interglacial intervals to a nutrient-rich, corrosive southern source during glacial intervals. The respired carbon content of glacial Atlantic deep water increased across the MPT. Increased dominance of corrosive bottom waters during glacial intervals would have raised mean ocean alkalinity and lowered atmospheric pCO2. The amplitude of glacial-interglacial changes in δ13C increased across the MPT, but this was not mirrored by changes in nutrient content. We interpret this in terms of air-sea CO2 exchange effects, which changed the δ13C signature of dissolved inorganic carbon in the deep water mass source regions. Increased sea ice cover or ocean stratification during glacial times may have reduced CO2 outgassing in the Southern Ocean, providing an additional mechanism for reducing glacial atmospheric pCO2. Conversely, following the establishment of the ∼100 k.y. glacial cycles, δ13C of interglacial northern-sourced waters increased, perhaps reflecting reduced invasion of CO2 into the North Atlantic following the MPT.

And get this, it’s free, and on the internet!

I don’t even have to pound pavement.

Or travel to the Bahamas.

Or sleep in a bunk.

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Extraterrestrial Communications by Solar Spectral Modulation

by Tommy on 27/10/2016

This is not as crankish as it first appears.

Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars,
E. F. Borra and E. Trottier (10 October 2016)

A Fourier transform analysis of 2.5 million spectra in the Sloan Digital Sky Survey was carried out to detect periodic spectral modulations. Signals having the same period were found in only 234 stars overwhelmingly in the F2 to K1 spectral range. The signals cannot be caused by instrumental or data analysis effects because they are present in only a very small fraction of stars within a narrow spectral range and because signal to noise ratio considerations predict that the signal should mostly be detected in the brightest objects, while this is not the case. We consider several possibilities, such as rotational transitions in molecules, rapid pulsations, Fourier transform of spectral lines and signals generated by Extraterrestrial Intelligence (ETI). They cannot be generated by molecules or rapid pulsations. It is highly unlikely that they come from the Fourier transform of spectral lines because too many strong lines located at nearly periodic frequencies are needed. Finally we consider the possibility, predicted in a previous published paper, that the signals are caused by light pulses generated by Extraterrestrial Intelligence to makes us aware of their existence. We find that the detected signals have exactly the shape of an ETI signal predicted in the previous publication and are therefore in agreement with this hypothesis. The fact that they are only found in a very small fraction of stars within a narrow spectral range centered near the spectral type of the sun is also in agreement with the ETI hypothesis. However, at this stage, this hypothesis needs to be confirmed with further work. Although unlikely, there is also a possibility that the signals are due to highly peculiar chemical compositions in a small fraction of galactic halo stars.

Let me explain how this works. Assuming that humanity is able to subsequently and sequentially solve its reusable launch vehicle problems, space development and colonization problems, its global warming, ocean acidification carbon economy problems, its overpopulation problems, biodiversity loss problems and religious nuttery weaponization and nuclear weapons on ballistic missiles problems, and finally its asteroid tracking and deflection problems, then a sustainable solar system wide equilibrium civilization is inevitable. That means we’ll have a lot of time on our hands. What is a long lived humanoid civilization to do, besides being assimilated by the Borg?

Well, what we will do is build giant space based interferometer telescopes, where we will obtain extremely high resolution 3D holographic videos of nearby terrestrial planets and then we will spectrocopically analyze their emissions. Any other short or long live nearby civilizations will become immediately apparent. Absent axion based free energy and gravitational manipulation, the obvious thing to do is to attempt to communicate with these nearby long lived civilizations.

So here is the deal. Now that I have conclusively demonstrated that life is inevitable anywhere in this long lived stable universe where stable terrestrial planetary conditions exist (The Cosmic Evolution of Autobiogenesis), then I know that they are already observing us, they can see that we are developing technology, and thus they would already be signalling us. And the easiest way to do that reliably, is by Morse code, or some other spectral modulation of starlight. And given the distances involved and the angular dimensions required to build a modulator and/or emitter, the size and complexity of a deep space spectral modulator makes this an engineering exercise of relative simplicity. So as they say, that is that. Let humanity’s problem solving begin!

Oh … the humanity!

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Unparticles Revealed in the High Density Low Temperature Strongly Coupled Regime

by Tommy on 27/10/2016

There are two schools within the University of Illinois Urbana Champaign school of thought.

The Philip W. Phillips and the Robert G. Leigh/Taylor L. Hughes schools of thought.

Unparticles and D-Branes. I am leaning towards unparticles.

Strings and D-branes can’t be far behind.

Violation of f-sum Rule with Generalized Kinetic Energy, Kridsanaphong Limtragool and Philip W. Phillips (24 October 2016)

Motivated by the normal state of the cuprates in which the f-sum rule increases faster than a linear function of the particle density, we derive a conductivity sum rule for a system in which the kinetic energy operator in the Hamiltonian is a general function of the momentum squared. Such a kinetic energy arises in scale invariant theories and can be derived within the context of holography. Our derivation of the f-sum rule is based on the gauge couplings of a non-local Lagrangian in which the kinetic operator is a fractional Laplacian of order α. We find that the f-sum rule in this case deviates from the standard linear dependence on the particle density. We find two regimes. At high temperatures and low densities, the sum rule is proportional to nT(α−1)/αwhere T is the temperature. At low temperatures and high densities, the sum rule is proportional to n1+(2(α−1)/d) with d being the number of spatial dimensions. The result in the low temperature and high density limit, when α < 1, can be used to qualitatively explain the behavior of the effective number of charge carriers in the cuprates at various doping concentrations.

Unparticles! Whoever heard of such a thing.

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Mathematical and Physical Theory of Quantum Catastrophes

by Tommy on 27/10/2016

I studied René Thom extensively long ago, so this is particularly relevant to me.

Morphology of a quantum catastrophe, J. Mumford and D. H. J. O’Dell (25 October 2016)

Thom’s seven elementary catastrophes are the only structurally stable singularities in up to four dimensions (Thom 1975). Their stability against perturbations removes any symmetry requirement which accounts for their ubiquity in nature, e.g. – as caustics. Examples include rainbows (Nye 1999), the twinkling of starlight (Berry 1977), rogue waves at sea (Hohmann 2010) and structure formation in the universe (Zeldovich 1982). At large scales the intensity appears to diverge on a caustic, but at the scale of a wavelength interference smooths the singularity and produces characteristic diffraction patterns (Arnold 1975, Berry 1976, Trinkhaus 1977). At subwavelength scales wave catastrophes are organized by an underlying lattice of dislocations (nodes) around each of which the wave function circulates as a vortex (Pearcey 1946, Nye 1974). Here we study the morphology of a third generation beyond geometric and wave catastrophes, called quantum catastrophes, which are singularities of classical fields. They are regulated by quantizing the excitations, i.e. – second quantization (Leonhardt 2002, Berry 2004, Berry 2008, O’Dell 2012}, and live in Fock space which, being fundamentally discrete, leads to core-less discretized vortices. These are created or annihilated in pairs as the number of quanta is varied.

Fortunately last night’s ArXiv was far less breakthroughy than this stuff.

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High Pressure Superconductivity of BiTeI Verified

by Tommy on 27/10/2016

I’ve been watching this closely and it is moving along quickly.

Pressure-induced superconductivity in the giant Rashba system BiTeI, D. VanGennep, A. Linscheid, D. E. Jackson, S. T. Weir, Y. K. Vohra, H. Berger, G. R. Stewart, R. G. Hennig, P. J. Hirschfeld and J. J. Hamlin (25 October 2016)

At ambient pressure, BiTeI is the first material found to exhibit a giant Rashba splitting of the bulk electronic bands. At low pressures, BiTeI undergoes a transition from trivial insulator to topological insulator. At still higher pressures, two structural transitions are known to occur. We have carried out a series of electrical resistivity and AC magnetic susceptibility measurements on BiTeI at pressure up to ~ 40 GPa in an effort to characterize the properties of the high-pressure phases. A previous calculation found that the high-pressure orthorhombic P4/nmm structure BiTeI is a metal. We find that this structure is superconducting with Tc values as high as 6 K. AC magnetic susceptibility measurements support the bulk nature of the superconductivity. Using electronic structure and phonon calculations, we compute Tc and find that our data is consistent with phonon-mediated superconductivity.

So that, as they say, is that.

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Behavior of Dirac and Weyl Topological Semimetals Reviewed

by Tommy on 26/10/2016

Topological Semimetals, A. A. Burkov, Nature, 15, 1145 (25 October 2016)

Topological semimetals and metals have emerged as a new frontier in the field of quantum materials. Novel macroscopic quantum phenomena they exhibit are not only of fundamental interest, but may hold some potential for technological applications.

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Axion Crystals Proposed

by Tommy on 26/10/2016

It’s half a dozen super interesting papers a day now on the Arxiv. I predicted that.

Axion Crystals, Sho Ozaki and Naoki Yamamoto (25 October 2016)

The low-energy effective theories for gapped insulators are classified by three parameters: permittivity ϵ, permeability μ, and theta angle θ. Crystals with periodic ϵ are known as photonic crystals. We here study the band structure of photons in a new type of crystals with periodic θ (modulo 2π) in space, which we call the axion crystals. We find that the axion crystals have a number of new properties that the usual photonic crystals do not possess, such as the helicity-dependent photonic band gaps and the nonrelativistic gapless dispersion relation at small momentum. We briefly discuss possible realizations of axion crystals in condensed matter systems as well as high-energy physics.

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Dissipative Galaxy Halo Baryon Self Interactions Explains the Tully-Fisher Relation

by Tommy on 26/10/2016

The excitement over MOND theories was brief, apparently.

The Mass-Discrepancy Acceleration Relation: a Natural Outcome of Galaxy Formation in CDM halos, Aaron D. Ludlow, Alejandro Benitez-Llambay, Matthieu Schaller, Tom Theuns, Carlos S. Frenk, Richard Bower, Joop Schaye (Leiden), Robert A. Crain, Julio F. Navarro, Azadeh Fattahi and Kyle A. Oman (24 October 2016)

We analyze the total and baryonic acceleration profiles of a set of well-resolved galaxies identified in the EAGLE suite of hydrodynamic simulations. Our runs start from the same initial conditions but adopt different subgrid models for stellar and AGN feedback, resulting in diverse populations of galaxies by the present day. Some of them reproduce observed galaxy scaling relations, while others do not. However, regardless of the feedback implementation, all of our galaxies follow closely a simple relationship between the total and baryonic acceleration profiles, consistent with recent observations of rotationally supported galaxies. The relation has small scatter: different feedback processes — which produce different galaxy populations — mainly shift galaxies along the relation, rather than perpendicular to it. Furthermore, galaxies exhibit a single characteristic acceleration, g†, above which baryons dominate the mass budget, as observed. These observations have been hailed as evidence for modified Newtonian dynamics but can be accommodated within the standard cold dark matter paradigm.

See also:

La Fin du MOND? Λ CDM is Fully Consistent with SPARC Acceleration Law, B.W. Keller and J.W. Wadsley, Submitted to ApJ Letters (19 October 2016)

Recent analysis (McGaugh et al. 2016) of the SPARC galaxy sample found a surprisingly tight relation between the radial acceleration inferred from the rotation curves, and the acceleration due to the baryonic components of the disc. It has been suggested that this relation may be evidence for new physics, beyond ΛCDM . In this letter we show that the 18 galaxies from the MUGS2 match the SPARC acceleration relation. These cosmological simulations of star forming, rotationally supported discs were simulated with a WMAP3 ΛCDM cosmology, and match the SPARC acceleration relation with less scatter than the observational data. These results show that this acceleration law is a consequence of dissipative collapse of baryons, rather than being evidence for exotic dark-sector physics or new dynamical laws.

Forbes Starts with a Bang Article

You may now return to your task of looking for unusual low mass dark matter particles – axions.

There is still the dark energy controversy to chew on.

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Blue Phophorene Oxide as a Tunable Quantum Simulator Device

by Tommy on 25/10/2016

Blue Phosphorene Oxide: Strain-tunable Quantum Phase Transitions and Novel 2D Emergent Fermions, Liyan Zhu, Shan-Shan Wang, Shan Guan, Ying Liu, Tingting Zhang, Guibin Chen and Shengyuan A. Yang, Nano Lett, 16 (10), 6548-6554 (20 September 2016), DOI:10.1021/acs.nanolett.6b03208

Tunable quantum phase transitions and novel emergent fermions in solid state materials are fascinating subjects of research. Here, we propose a new stable two-dimensional (2D) material, the blue phosphorene oxide (BPO), which exhibits both. Based on first-principles calculations, we show that its equilibrium state is a narrow-bandgap semiconductor with three bands at low energy. Remarkably, a moderate strain can drive a semiconductor-to-semimetal quantum phase transition in BPO. At the critical transition point, the three bands cross at a single point at Fermi level, around which the quasiparticles are a novel type of 2D pseudospin-1 fermions. Going beyond the transition, the system becomes a symmetry-protected semimetal, for which the conduction and valence bands touch quadratically at a single Fermi point that is protected by symmetry, and the low-energy quasiparticles become another novel type of 2D double Weyl fermions. We construct effective models characterizing the phase transition and these novel emergent fermions, and we point out several exotic effects, including super Klein tunneling, supercollimation, and universal optical absorbance. Our result reveals BPO as an intriguing platform for the exploration of fundamental properties of quantum phase transitions and novel emergent fermions, and also suggests its great potential in nanoscale device applications.

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Transport Near a Quantum Critical Point Model Analyzed

by Tommy on 25/10/2016

Nonperturbative functional renormalization-group approach to transport in the vicinity of a (2+1)-dimensional O(N)-symmetric quantum critical point, Félix Rose and Nicolas Dupuis (20 October 2016)

Nonperturbative functional renormalization-group approach to transport in the vicinity of a (2+1)-dimensional O(N)-symmetric quantum critical point, Using a nonperturbative functional renormalization-group approach to the two-dimensional quantum O(N) model, we compute the low-frequency limit ω → 0 of the zero-temperature conductivity in the vicinity of the quantum critical point. Our results are obtained from a derivative expansion to second order of a scale-dependent effective action in the presence of an external (i.e., non-dynamical) non-Abelian gauge field. While in the disordered phase the conductivity tensor σ(ω) is diagonal, in the ordered phase it is defined, when N ≥ 3, by two independent elements, σA(ω) and σB(ω), respectively associated to SO(N) rotations which do and do not change the direction of the order parameter. For N = 2, the conductivity in the ordered phase reduces to a single component σA(ω). We show that limω→0σ(ω,δ)σA(ω,−δ)/σ2q is a universal number which we compute as a function of N (δ measures the distance to the quantum critical point, q is the charge and σq = q2/h the quantum of conductance). On the other hand we argue that the ratio σB(ω→0)/σq is universal in the whole ordered phase, independent of N and, when N → ∞, equal to the universal conductivity σq at the quantum critical point.

This presentation is theoretically, mathematically and computationally … expansive.

And I imagine … expensive.

See also:

Critical region of the superfluid transition in the BCS-BEC crossover, T. Debelhoir and N. Dupuis, Phys. Rev. A 93, 023642 (24 February 2016), DOI:10.1103/PhysRevA.93.023642

We determine the size of the critical region of the superfluid transition in the BCS-BEC crossover of a three-dimensional fermion gas, using a renormalization-group approach to a bosonic theory of pairing fluctuations. For the unitary Fermi gas, we find a sizable critical region [TG,TG+], of order Tc, around the transition temperature Tc with a pronounced asymmetry: |TG+Tc| / |TGTc| ∼ 8. The critical region is strongly suppressed on the BCS side of the crossover but remains important on the BEC side.

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Structural Stability of Low Dimensional Materials Investigated

by Tommy on 25/10/2016

Existence Criterion of Low-Dimensional Materials, Jiapeng Chen, Biao Wang and Yangfan Hu (20 October 2016)

The discovery of graphene and other two-dimensional (2-D) materials has stimulated a general interest in low-dimensional (low-D) materials. Whereas long time ago, Peierls and Landau’s theoretical work had shown that any one- and two-dimensional materials could not exist in any temperature environment, the following two basic issues become the main concern for many researchers: why stable low-D materials can exist and what kind of low-D materials are stable. In this letter, we establish an energy stability criterion for low-D materials, which tries to provide a clear answer for these questions. We find that for any straight/planar low-D elemental materials, 1-D monatomic chains, 2-D honeycomb lattices, square lattices and triangular lattices are the only four permissible structures. For a specific kind of element, the stability of its low-D structure is determined by several derivatives of its interatomic potentials. We find that the stability of any straight/planar low-D structures can only be understood by assuming multi-body interatomic potentials. For reactive empirical bond-order (REBO) potential, the honeycomb structure is found to be the most stable one among all permissible planar 2-D structures. Using this criterion, the stable existence of graphene, silicene and germanene is explained.

Stability is easy to bork. Trust me on that.

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First Principles Calculation of the Thermal Conductivity of Solids

by Tommy on 25/10/2016

Ab initio Green-Kubo Approach for the Thermal Conductivity of Solids, Christian Carbogno, Rampi Ramprasad and Matthias Scheffler (20 October 2016)

We herein present a first-principles formulation of the Green-Kubo method that allows the accurate assessment of the non-radiative thermal conductivity of solid semiconductors and insulators in equilibrium ab initio molecular dynamics calculations. Using the virial for the nuclei, we propose a unique ab initio definition of the heat flux. Accurate size- and time convergence are achieved within moderate computational effort by a robust, asymptotically exact extrapolation scheme. We demonstrate the capabilities of the technique by investigating the thermal conductivity of extreme high and low heat conducting materials, namely diamond Si and tetragonal ZrO2.

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Electronic and Optical Correlations of Dense Excitons Probed

by Tommy on 22/10/2016

Last night’s ArXiv contained several landmark papers. Here’s one. Excitonic Mott transitions.

Negative activation energy and dielectric signatures of excitons and excitonic Mott transitions in quantum confined laser structures, Amit Bhunia, Kanika Bansal, Mohamed Henini, Marzook S. Alshammari and Shouvik Datta, Journal of Applied Physics, 120, 144304 (20 October 2016), DOI:10.1063/1.4964850

Mostly, optical spectroscopies are used to investigate the physics of excitons, whereas their electrical evidences are hardly explored. Here, we examined a forward bias activated differential capacitance response of GaInP-AlGaInP based multi-quantum well laser diodes to trace the presence of excitons using electrical measurements. Occurrence of negative activation energy after light emission is understood as thermodynamical signature of steady state excitonic population under intermediate range of carrier injections. Similar corroborative results are also observed in an InGaAs-GaAs quantum dot laser structure grown by molecular beam epitaxy. With increasing biases, the measured differential capacitance response slowly vanishes. This represents gradual Mott transition of an excitonic phase into an electron-hole plasma in a GaInP-AlGaInP laser diode. This is further substantiated by more and more exponentially looking shapes of high energy tails in electroluminescence spectra with increasing forward bias, which originates from a growing non-degenerate population of free electrons and holes. Such an experimental correlation between electrical and optical properties of excitons can be used to advance the next generation excitonic devices.

See also:

Observation of the exciton Mott transition in the photoluminescence of coupled quantum wells, Phys. Rev. B, 94, 155438 (21 October 2016)

Indirect excitons in coupled quantum wells have long radiative lifetimes and form a cold quasi-two-dimensional population suitable for studying collective quantum effects. Here we report the observation of the exciton Mott transition from an insulating (excitons) to a conducting (ionized electron-hole pairs) phase, which occurs gradually as a function of carrier density and temperature. The transition is inferred from spectral and time-resolved photoluminescence measurements around a carrier density of 2×1010cm−2 and temperatures of 12–16 K. An externally applied electric field is employed to tune the dynamics of the transition via the quantum-confined Stark effect. Our results provide evidence of a gradual nature of the exciton Mott transition.

They need to up the density.

Stay tuned. More to come.

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Five Dimensional Spacetime Appears in Topological Physics

by Tommy on 21/10/2016

This is another idea I’ve been fooling around with lately with respect to cosmogenesis.

Observation of a non-Abelian Yang Monopole: From New Chern Numbers to a Topological Transition, Seiji Sugawa, Francisco Salces-Carcoba, Abigail R. Perry, Yuchen Yue and Ian B. Spielman (19 October 2016)

Because global topological properties are robust against local perturbations, understanding and manipulating the topological properties of physical systems is essential in advancing quantum science and technology. For quantum computation, topologically protected qubit operations can increase computational robustness, and for metrology the quantized Hall effect directly defines the von Klitzing constant. Fundamentally, topological order is generated by singularities called topological defects in extended spaces, and is quantified in terms of Chern numbers, each of which measures different sorts of fields traversing surfaces enclosing these topological singularities. Here, inspired by high energy theories, we describe our synthesis and characterization of a singularity present in non-Abelian gauge theories – a Yang monopole – using atomic Bose-Einstein condensates in a five-dimensional space, and quantify the monopole in terms of Chern numbers measured on enclosing manifolds. While the well-known 1st Chern number vanished, the 2nd Chern number, measured for the first time in any physical settings, did not. By displacing the manifold, we then observed a phase transition from “topological” to “trivial” as the monopole left the manifold.

The general idea is that four dimensional space inflates in a time reversal invariant manner until the axion angle becomes infinitesimally small, and then the entire network of cosmic strings and domains start breaking up, and the particles and super axions are created, anti-annihilated, and the particles reheated in the resulting expanding four dimensional space time manifold. Since this process resembles an unzipping, the built in asymmetry results in the creation of matter.

In other words, matter over anti-matter is a result of the breaking of time reversal symmetry.

Regardless of my speculations and mathturbations, this is indeed a landmark paper.

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Cubic Diamond Hexagonal Lonsdaleite By Shock Compression

by Tommy on 21/10/2016

With this PETM result, even though the shards are largish, I was thinking about nanodiamods.

Nanosecond formation of diamond and lonsdaleite by shock compression of graphite, D. Kraus, A. Ravasio, M. Gauthier, D. O. Gericke, J. Vorberger, S. Frydrych, J. Helfrich, L. B. Fletcher, G. Schaumann, B. Nagler, B. Barbrel, B. Bachmann, E. J. Gamboa, S. Göde, E. Granados, G. Gregori, H. J. Lee, P. Neumayer, W. Schumaker, T. Döppner, R. W. Falcone, S. H. Glenzer and M. Roth, Nature Communications, 7, 10970 (14 March 2016), doi:10.1038/ncomms10970

The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery of microscopic diamonds in remnants of explosively driven graphite. Furthermore, shock synthesis of diamond and lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected to happen during violent meteor impacts. Here, we show unprecedented in situ X-ray diffraction measurements of diamond formation on nanosecond timescales by shock compression of pyrolytic as well as polycrystalline graphite to pressures from 19 GPa up to 228 GPa. While we observe the transition to diamond starting at 50 GPa for both pyrolytic and polycrystalline graphite, we also record the direct formation of lonsdaleite above 170 GPa for pyrolytic samples only. Our experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites.

Lonsdaleite is a real survivor!

Update: I thought I had already covered this earlier when it was published, and I was right.

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Are Black Holes Preferentially Sucking in Dark Matter?

by Tommy on 19/10/2016
Cosmic Dark Matter Black Hole Baryon String Void Structure

Cosmic Dark Matter Black Hole Baryon String Void Structure

I have been entertaining lots of conceptual dark matter cosmic evolution scenarios lately.

This is just one of many. Lots O’fun it is.

But not very productive as of yet.

Too many possibilities.

So much spacetime.

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Pressure Induced Superconductivity of Bismuth Telluride Iodide BeTeI

by Tommy on 19/10/2016

I’ve been keeping an eye on this for a while.

Topological quantum phase transition and superconductivity induced by pressure in the bismuth tellurohalide BiTeI, Yanpeng Qi, Wujun Shi, Pavel G. Naumov, Nitesh Kumar, Raman Sankar, Walter Schnelle, Chandra Shekhar, F. C. Chou, Claudia Felser, Binghai Yan and Sergey A. Medvedev (17 October 2016)

A pressure-induced topological quantum phase transition has been theoretically predicted for the semiconductor BiTeI with giant Rashba spin splitting. In this work, the evolution of the electrical transport properties in BiTeI and BiTeBr is investigated under high pressure. The pressure-dependent resistivity in a wide temperature range passes through a minimum at around 3 GPa, indicating the predicted transition in BiTeI. Superconductivity is observed in both BiTeI and BiTeBr while the resistivity at higher temperatures still exhibits semiconducting behavior. Theoretical calculations suggest that the superconductivity may develop from the multi-valley semiconductor phase. The superconducting transition temperature Tc increases with applied pressure and reaches a maximum value of 5.2 K at 23.5 GPa for BiTeI (4.8 K at 31.7 GPa for BiTeBr), followed by a slow decrease. Our results demonstrate that BiTeX (X = I, Br) compounds with non-trivial topology of electronic states display new ground states upon compression.

See also:

Pressure dependence of the band-gap energy in BiTeI, Sümeyra Güler-Kılıç and Çetin Kılıç, Phys. Rev. B, 94, 165203 (13 October 2016), DOI:10.1103/PhysRevB.94.165203

The evolution of the electronic structure of BiTeI, a layered semiconductor with a van der Waals gap, under compression is studied by employing semilocal and dispersion-corrected density-functional calculations. Comparative analysis of the results of these calculations shows that the band-gap energy of BiTeI decreases till it attains a minimum value of zero at a critical pressure, after which it increases again. The critical pressure corresponding to the closure of the band gap is calculated, at which BiTeI becomes a topological insulator. Comparison of the critical pressure to the pressure at which BiTeI undergoes a structural phase transition indicates that the closure of the band gap would not be hindered by a structural transformation. Moreover, the band-gap pressure coefficients of BiTeI are computed, and an expression of the critical pressure is devised in terms of these coefficients. Our findings indicate that the semilocal and dispersion-corrected approaches are in conflict about the compressibility of BiTeI, which result in overestimation and underestimation, respectively. Nevertheless, the effect of pressure on the atomic structure of BiTeI is found to be manifested primarily as the reduction of the width of the van der Waals gap according to both approaches, which also yield consistent predictions concerning the interlayer metallic bonding in BiTeI under compression. It is consequently shown that the calculated band-gap energies follow qualitatively and quantitatively the same trend within the two approximations employed here, and the transition to the zero-gap state occurs at the same critical width of the van der Waals gap.

This is more good evidence that we have a pretty good handle on these things by now.

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Tidal Disruption of Dark Matter Solves Missing Satellite Problem

by Tommy on 18/10/2016

This has also been out for a while. It’s still worth reading I guess. And it’s free!;

Tidal stirring of satellites with shallow density profiles prevents them from being too big to fail, Mihai Tomozeiu, Lucio Mayer and Thomas Quinn, The Astrophysical Journal Letters, 827, 1 (5 August 2016), doi:10.3847/2041-8205/827/1/L15

The “too big to fail” problem is revisited by studying the tidal evolution of populations of dwarf satellites with different density profiles. The high-resolution cosmological ΛCDM “ErisMod” set of simulations is used. These simulations can model both the stellar and dark matter components of the satellites, and their evolution under the action of the tides of a Milky Way (MW)-sized host halo at a force resolution better than 10 pc. The stronger tidal mass loss and re-shaping of the mass distribution induced in satellites with γ = 0.6 dark matter density distributions, as those resulting from the effect of feedback in hydrodynamical simulations of dwarf galaxy formation, are sufficient to bring the circular velocity profiles in agreement with the kinematics of MW’s dSphs. In contrast, in simulations in which the satellites retain cusps at z = 0 there are several “massive failures” with circular velocities in excess of the observational constraints. Various sources of deviations in the conventionally adopted relation between the circular velocity at the half-light radius and the one-dimensional line of sight velocity dispersions are found. Such deviations are caused by the response of circular velocity profiles to tidal effects, which also varies depending on the initially assumed inner density profile and by the complexity of the stellar kinematics, which include residual rotation and anisotropy. In addition, tidal effects naturally induce large deviations in the stellar mass–halo mass relation for halo masses below 109 M, preventing any reliable application of the abundance matching technique to dwarf galaxy satellites.

American Astronomical Society Press Release

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A Virtual Zoo of Quantum Topological States of Exotic Matter

by Tommy on 18/10/2016

From the inventor of the subject.

Zoo of quantum-topological phases of matter, Xiao-Gang Wen (13 October 2016)

What are topological phases of matter? First, they are phases of matter at zero temperature. Second, they have a non-zero energy gap. Third, they are more complicated and subtle than the familiar gapped zero temperature phases, such as insulating and magnetic phases. This paper will give a simple introduction and a brief survey of topological phases of matter. We will first discuss topological phases that have topological order. Then we will cover topological phases that have no topological order.

Breakthrough prizes all around. Maybe he’s already got one. I haven’t bothered to look.

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Static Charge Density Waves Stripe Order Found in 1/8 LBCO

by Tommy on 18/10/2016

In other words, CDW order is either cooperative, or competitive, or both. I get that.

This has been out for a while, but now that it has a bona fide press release, it’s official!

Remarkable Stability of Charge Density Wave Order in La1.875Ba0.125CuO4, X. M. Chen, V. Thampy, C. Mazzoli, A. M. Barbour, H. Miao, G. D. Gu, Y. Cao, J. M. Tranquada, M. P. M. Dean, and S. B. Wilkins, Phys. Rev. Lett. 117, 167001 (11 October 2016), doi:10.1103/PhysRevLett.117.167001

The occurrence of charge-density-wave (CDW) order in underdoped cuprates is now well established, although the precise nature of the CDW and its relationship with superconductivity is not. Theoretical proposals include contrasting ideas such as that pairing may be driven by CDW fluctuations or that static CDWs may intertwine with a spatially modulated superconducting wave function. We test the dynamics of CDW order in La1.875Ba0.125CuO4 by using x-ray photon correlation spectroscopy at the CDW wave vector, detected resonantly at the Cu L3 edge. We find that the CDW domains are strikingly static, with no evidence of significant fluctuations up to 2¾  h. We discuss the implications of these results for some of the competing theories.

DOE/Brookhaven National Laboratory Press Release

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Ultra Cold Atoms Proposed as a Quantum Critical Simulator

by Tommy on 14/10/2016

Recall that Michael Kosterlitz, David Thouless and Duncan Haldane were recently awarded their Nobel Prizes in condensed matter physics. Recall also that I have recently proposed a bosonic superfluid dark matter and dark energy hypothesis, where the fundamental excitations of this bosonic quantum superfluid by high energy processes in ordinary and neutron stars, near black holes and other high density high energy exotic states of matter, connect the standard model to Einstein’s equation of gravitation and general relativity through ultra light super axions of some sort, in my rather lame and naive attempt to jump start a new quantum gravity and quantum cosmology unification. I have previously proposed that condensed matter and ultra cold atom trapping theories, experiments and numerical simulations are the ONLY way that we will be able to access this energy regime, and that already this has revolutionized our understanding of fundamental physics and its application to novel device physics. In fact, I have also already employed this strategy successfully on the origin of life problem. Therefore, I present here …

Quantitative Studies on the Quantum Critical Regime near Superfluid to Mott Insulator Transition, Hao Lee, Shiang Fang and Daw-Wei Wang (12 October 2016)

We investigate the critical behaviors of correlation length and critical exponents for strongly interacting bosons in a two-dimensional optical lattice via quantum Monte Carlo simulations. By comparing the full numerical results to those given by the effective theory, we quantitatively determine the critical regime where the universal scaling behaviors applies for both classical Berezinskii-Kosterlitz-Thouless transition at a finite temperature and quantum phase transition from superfluid to Mott insulator. Our results show that the critical regime can be as large as a few lattice sites in optical lattice and should be observable in present experimental conditions.

Quantum critical black hole collapse is on the horizon.

So is room temperature superconductivity.

I predict weirdness very soon now.

I could be wrong though.

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Gravitational Anomalies, Entanglement Entropy, Anomaly Inflow

by Tommy on 14/10/2016

This is another result from the University of Illinois – Urbana Champaign school of thought, that I have found to be extremely useful for my dark matter gravitational super duper axion hypothesis.

Entanglement Entropy & Anomaly Inflow, Taylor L. Hughes, Robert G. Leigh, Onkar Parrikar and Srinidhi T. Ramamurthy, Phys. Rev. D, 93, 065059 (30 March 2016)

We study entanglement entropy for parity-violating (time-reversal breaking) quantum field theories on R1,2 in the presence of a domain wall between two distinct parity-odd phases. The domain wall hosts a 1+1-dimensional conformal field theory (CFT) with non-trivial chiral central charge. Such a CFT possesses gravitational anomalies. It has been shown recently that, as a consequence, its intrinsic entanglement entropy is sensitive to Lorentz boosts around the entangling surface. Here, we show using various methods that the entanglement entropy of the three-dimensional bulk theory is also sensitive to such boosts owing to parity-violating effects, and that the bulk response to a Lorentz boost precisely cancels the contribution coming from the domain wall CFT. We argue that this can naturally be interpreted as entanglement inflow (i.e., inflow of entanglement entropy analogous to the familiar Callan-Harvey effect) between the bulk and the domain-wall, mediated by the low-lying states in the entanglement spectrum. These results can be generally applied to 2+1-d topological phases of matter that have edge theories with gravitational anomalies, and provide a precise connection between the gravitational anomaly of the physical edge theory and the low-lying spectrum of the entanglement Hamiltonian.

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Paleocene Eocene Thermal Maximum (PETM) Assigned to a Comet Impact

by Tommy on 14/10/2016

Impact ejecta at the Paleocene-Eocene boundary, Morgan F. Schaller, Megan K. Fung, James D. Wright, Miriam E. Katz and Dennis V. Kent, Science, 354, 6309, 225-229 (14 October 2016), DOI:10.1126/science.aaf5466

Extraterrestrial impacts have left a substantial imprint on the climate and evolutionary history of Earth. A rapid carbon cycle perturbation and global warming event about 56 million years ago at the Paleocene-Eocene (P-E) boundary (the Paleocene-Eocene Thermal Maximum) was accompanied by rapid expansions of mammals and terrestrial plants and extinctions of deep-sea benthic organisms. Here, we report the discovery of silicate glass spherules in a discrete stratigraphic layer from three marine P-E boundary sections on the Atlantic margin. Distinct characteristics identify the spherules as microtektites and microkrystites, indicating that an extraterrestrial impact occurred during the carbon isotope excursion at the P-E boundary.

My interests in these kinds of subjects started slowly and developed over a long period of time. Originally it started back in 1989, on the day of the Loma Prieta earthquake that occurred on October 17th, 1989. I was actually working in a foramanifera laboratory at the Caribbean Marine Research Center CMRC at Lee Stocking Island in the Exuma Cays in the Bahamas at that time.

I wasn’t doing that kind of research, but I was interested in it since it was occurring all around me, and I suddenly found myself surrounded by geologists and biologists, subjects which I knew little or nothing about. And we had a tide gauge. And I had an island. So by then I was totally keyed into the tides.

So on that day I was desperately trying to get back to the states, trying to negotiate a ride on Mr. and Mrs. Perry’s private plane, with them, the owners of the island on which the research center was located, who did not particularly like me and viewed everything I did with suspicion. That’s another story entirely. I was bumped off the flight the previous week, and their private flight was my only option. So I went home to cool my jets, and on my way back down to the cay to catch that ride, as I was walking down the hill to the dock, I ran into the highest tide I have ever EVER witnessed in all the years I had spent in the Bahamas. It was truly an awesome tide, it covered up jagged coral rocks that had never been covered before, rocks that can rip the bottom out of your boat if you don’t see them. It was a totally off the scale high tide. It was the only subject of discussion when I arrived at the lab, and that tide alone prompted a complete rebuild of the tide gauge column, and eventually a shift to digital tide gauges. Eventually later that day I did get my ride back to West Palm Beach, with Mr. and Mrs. Perry, a very quiet and silent ride indeed, and as I finally arrived in Tampa on my connection, in the airport lobby I was presented with a major earthquake on all of the television screens. Ding! Tides cause earthquakes. I was hooked.

So once the internet arrived on the scene I was ready. It was something that I was watching constantly. So over Christmas vacation 2004 when I was watching the USGS earthquake map and when there I saw an 8.1 major earthquake in the deep southern ocean near the Macquarie Islands, I noticed. I thought to myself that something is on the move down there, and if there is one, there should be another, and so for the next few days I was watching that map like a hawk, and when it happened, I saw it. I was on it. The Boxing Day Indonesian earthquake and tsunami.

Massive Quake Strikes Remote Macquarie Island In Antarctica

I was posting on sci.earthquake at the time, and I wish now I had said something earlier, not just after the fact. I felt that way when I was sitting in Grandma’s chair watching the Columbia space shuttle launch on its final mission, when I saw something fall off the rocket and shred into the exhaust plumes of the solid rocket boosters. I was so concerned about it that I ran out into the back yard thinking I would catch the explosion, but there it was, cleanly accelerating over the horizon and into space. So I thought all is well, when in fact all was not well, and I regret to this day not relaying my observations and thoughts to the space cadet community on the usenet.

Between those two incidents and all of my experiences in search and rescue in the Bahamas – I decided right then and there, on Boxing Day in 2004, if I see something then I am reporting it.

At that point I was seeing a lot of things I did not like. It was in the middle of the Bush years. So when I noticed that Ellen Thomas was coming to Eckerd College in St. Petersburg to speak on global warming and the PETM on February 16th, 2005, I went down there to see her, and after the talk, I spoke with her. At that time comet impacts were considered fringe, but she gave me some pointers and again, I was hooked. Ellen Prager was my boss for a year in 1995 and so I was already a catastrophist. And of course, catastrophe was a daily occurrence at the research lab and in the islands. Crisis management and science and problem solving was my way of life.

So when the Younger Dryas impact hypothesis arrived on the scene, of course I was interested, and when on Darwin’s Day in 2009, when I saw something in the Black Sturgeon River Basin south of Lake Nipigon in Ontario, Canada, of course, I reported it. On Valentines Day. February 14, 2009. So even when I am wrong, and I am mostly wrong nowadays, I don’t regret reporting what I see. That’s my story and I’m sticking with it. Until I see that I am wrong. I am a scientist.

This is my microphone.

Update: The takeaway is that big impacts can cause earthquakes, tsunamis and volcanoes.

Supervolcanoes and volcanism is well known to release large amounts of carbon dioxide.

Positive feedbacks in these phenomena could well include large methane releases.

Instantaneous effects of an impact are followed by long term effects.

Therefore I consider this problem now to be solved.

Update 2: Wow, I just realized this is a five way super catastrophe.

Cosmic impact, massive earthquake swarm, giant tsunami, super volcanism and then when the coal beds burned up in that mess, global warming. Life is great, no? I’m a catastrophist!

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Trillions and Trillions

by Tommy on 14/10/2016
Hubble Trillions Of Galaxies

Hubble Trillions Of Galaxies

The Evolution of Galaxy Number Density at z < 8 and its Implications, Christopher J. Conselice, Aaron Wilkinson, Kenneth Duncan and Alice Mortlock, Accepted to ApJ (9 October 2016)

The evolution of the number density of galaxies in the universe, and thus also the total number of galaxies, is a fundamental question with implications for a host of astrophysical problems including galaxy evolution and cosmology. However there has never been a detailed study of this important measurement, nor a clear path to answer it. To address this we use observed galaxy stellar mass functions up to z ∼ 8 to determine how the number densities of galaxies changes as a function of time and mass limit. We show that the increase in the total number density of galaxies (ϕT), more massive than M = 106 M, decreases as ϕTt−1, where t is the age of the universe. We further show that this evolution turns-over and rather increases with time at higher mass lower limits of M > 107 M. By using the M = 106 M lower limit we further show that the total number of galaxies in the universe up to z = 8 is 2.0+0.7−0.6 × 1012 (two trillion), almost a factor of ten higher than would be seen in an all sky survey at Hubble Ultra-Deep Field depth. We discuss the implications for these results for galaxy evolution, as well as compare our results with the latest models of galaxy formation. These results also reveal that the cosmic background light in the optical and near-infrared likely arise from these unobserved faint galaxies. We also show how these results solve the question of why the sky at night is dark, otherwise known as Olbers’ paradox.

Darkness seems to be winning in my universe.

And so I say – let there be light.

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Bismuth Topological Edge States Proposed for Thermoelectric ZT Efficiency Enhancements

by Tommy on 13/10/2016

Effects of topological edge states on the thermoelectric properties of Bi nanoribbons, L. Cheng, H. J. Liu, J. H. Liang, J. Zhang, J. Wei, P. H. Jiang and D. D. Fan (11 October 2016)

Using first-principles calculations combined with Boltzmann transport theory, we investigate the effects of topological edge states on the thermoelectric properties of Bi nanoribbons. It is found that there is a competition between the edge and bulk contributions to the Seebeck coefficients. However, the electronic transport of the system is dominated by the edge states because of its much larger electrical conductivity. As a consequence, a room temperature value exceeding 3.0 could be achieved for both p- and n-type systems when the relaxation time ratio between the edge and the bulk states is tuned to be 1000. Our theoretical study suggests that the utilization of topological edge states might be a promising approach to cross the threshold of the industrial application of thermoelectricity.

Eggimuffin. Yeah. Maybe.

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Time and Angle Resolved Photoemission Spectroscopy Probes Effects of Dirac Cone Warping on Transport and Structure of a Topological Superconductor – Bismuth Telluride – Bi2Te3

by Tommy on 12/10/2016

Observation of antiphase coherent phonons in the warped Dirac cone of Bi2Te3, E. Golias and J. Sánchez-Barriga, Phys. Rev. B 94, 161113R (11 October 2016), doi:PhysRevB.94.161113

In this Rapid Communication we investigate the coupling between excited electrons and phonons in the highly anisotropic electronic structure of the prototypical topological insulator Bi2Te3. Using time- and angle-resolved photoemission spectroscopy we are able to identify the emergence and ultrafast temporal evolution of the longitudinal-optical A1g coherent-phonon mode in Bi2Te3. We observe an antiphase behavior in the onset of the coherent-phonon oscillations between the ΓK¯ and the ΓM¯ high-symmetry directions that is consistent with warping. The qualitative agreement between our density-functional theory calculations and the experimental results reveals the critical role of the anisotropic coupling between Dirac fermions and phonon modes in the topological insulator Bi2Te3.

See also: Lightsources Article

Hot off the press.

Update: Bi2Te3 is actually the parent topological insulator of a topological superconductor.

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Bismuth Bi (111) and (110) Through Ultra Thin Nanowires

by Tommy on 12/10/2016

Electronic and structural properties of rhombohedral [111] and [110] oriented ultra-thin bismuth nanowires, Lida Ansari, Farzan Gity and James C. Greer (19 September 2016)

Structures and electronic properties of rhombohedral [111] and [110] bismuth nanowires are calculated with the use of density functional theory. The formation of an energy band gap from quantum confinement is studied and to improve estimates for the band gap the GW approximation is applied. The [111] oriented nanowires require surface bonds to be chemically saturated to avoid formation of metallic surface states whereas the surface of the [110] nanowires do not support metallic surface states. It is found that the onset of quantum confinement in the surface passivated [111] nanowires occurs at larger critical dimensions than for the [110] nanowires. For the [111] oriented nanowires it is predicted that a band gap of approximately 0.5 eV can be formed at a diameter of approximately 6 nm, whereas for the [110] oriented nanowires a diameter of approximately 3 nm is required to achieve a similar band gap energy. The GW correction is also applied to estimates of the electron affinity, ionisation potentials and work functions for both orientations of the nanowires for various diameters below 5 nm. The magnitude of the energy band gaps that arise in bismuth at critical dimensions of a few nanometers are of the same order as for conventional bulk semiconductors.

This is fairly brute force but the trends here are clearly distinguishable.

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Quantum Confinement Effect in Bismuth Multilayers Proposed for Conventional Electronics

by Tommy on 12/10/2016

Reinventing Solid State Electronics: Harnessing Quantum Confinement in Bismuth Thin Films, Farzan Gity, Lida Ansari, Martin Lanius, Peter Schüffelgen, Gregor Mussler, Detlev Grützmacher and James C. Greer (17 September 2016)

Solid state electronics relies on the intentional introduction of impurity atoms or dopants into a semiconductor crystal and/or the formation of junctions between different materials (heterojunctions) to create rectifiers, potential barriers, and conducting pathways. With these building blocks, switching and amplification of electrical currents and voltages is achieved. As miniaturization continues to ultra-scaled transistors with critical dimensions on the order of ten atomic lengths, the concept of doping to form rectifying junctions fails and heterojunction formation becomes extremely difficult. Here it is shown there is no need to introduce dopant atoms nor is the formation of a heterojunction required to achieve the fundamental electronic function of current rectification. Ideal diode behavior or rectification is achieved for the first time solely by manipulation of quantum confinement in approximately 2 nanometer thick films consisting of a single atomic element, the semimetal bismuth. Crucially for nanoelectronics, this new quantum approach enables room temperature operation.

I’m not exactly sure if diode electronics is the way to go with these things.

I have this terrible pain down my left side.

I’m feeling very depressed.

I might be paranoid.

I need positrons.

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New Detection Technique for Ultralight Dark Matter Axions

by Tommy on 11/10/2016

This is getting some press.

Broadband and Resonant Approaches to Axion Dark Matter Detection, Yonatan Kahn, Benjamin R. Safdi and Jesse Thaler, Phys. Rev. Lett. 117, 141801 (30 September 2016)

When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. We propose a new experiment to detect this axion effective current. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. We consider both resonant and broadband readout circuits and show that a broadband approach has advantages at small axion masses. We estimate the reach of this design, taking into account the irreducible sources of noise, and demonstrate potential sensitivity to axionlike dark matter with masses in the range of 10−14 − 10−6 eV. In particular, both the broadband and resonant strategies can probe the QCD axion with a GUT-scale decay constant.

This closes the gap with ADMX.

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Berry Curvature Induction in Lattice QCD Simulations Revealed

by Tommy on 11/10/2016

This has been extremely helpful to my dark matter axion program.

Lattice QCD simulation of the Berry curvature, Arata Yamamoto, Talk Given at 34th Annual International Symposium on Lattice Field Theory – Lattice 2016 (7 October 2016)

The Berry curvature is a fundamental concept describing topological order of quantum systems. While it can be analytically tractable in non-interacting systems, numerical simulations are necessary in interacting systems. We present a formulation to calculate the Berry curvature in lattice QCD.

See also:

Berry phase in lattice QCD, Arata Yamamoto, Phys. Rev. Lett. 117, 052001 (2016), DOI:10.1103/PhysRevLett.117.052001

We propose the lattice QCD calculation of the Berry phase which is defined by the ground state of a single fermion. We perform the ground-state projection of a single-fermion propagator, construct the Berry link variable on a momentum-space lattice, and calculate the Berry phase. As the first application, the first Chern number of the (2+1)-dimensional Wilson fermion is calculated by the Monte Carlo simulation.

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Current Induced Giant Diamagnetism in the Mott Insulator Calcium Ruthenate Ca2RuO4

by Tommy on 11/10/2016

When I see something this novel and interesting all I can do is repeat it verbatim.

Current Induced Giant Diamagnetism in the Mott Insulator Ca2RuO4, Chanchal Sow, Shingo Yonezawa, Sota Kitamura, Takashi Oka, Kazuhiko Kuroki, Fumihiko Nakamura and Yoshiteru Maeno (7 October 2016)

Mott insulators have surprised us many times by hosting new and diverse quantum phenomena when the frozen electrons are perturbed by various stimuli. Superconductivity, metal-insulator transition, and colossal magnetoresistance induced by element substitution, pressure, and magnetic field are prominent examples. Here we report a novel phenomenon, namely giant diamagnetism, in the Mott insulator Ca2RuO4 induced by electric current. With application of 1 A/cm2 current, the strongest diamagnetism among all nonsuperconducting materials is induced as the system is tuned to a semimetallic state. The origin lies in the emergence of indirect Dirac cones in the many-body spectrum and associated monopole-like anomaly in the momentum dependent susceptibility. This record-breaking and switchable diamagnetism is a new class of non-equilibrium quantum phenomena on the verge of Mott insulating states.

See also:

Hallmarks of Hund’s coupling in the Mott insulator Ca2RuO4, D. Sutter, C.G. Fatuzzo, S. Moser, M. Kim, R. Fittipaldi, A. Vecchione, V. Granata, Y. Sassa, F. Cossalter, G. Gatti, M. Grioni, H.M. Ronnow, N.C. Plumb, C.E. Matt, M. Shi, M. Hoesch, T.K. Kim, T.R. Chang, H.T. Jeng, C. Jozwiak, A. Bostwick, E. Rotenberg, A. Georges, T. Neupert and J. Chang (10 October 2016)

A paradigmatic case of multi-band Mott physics including spin-orbit and Hund’s coupling is realised in Ca2RuO4. Progress in understanding the nature of this Mott insulating phase has been impeded by the lack of knowledge about the low-energy electronic structure. Here we provide — using angle-resolved photoemission electron spectroscopy – the band structure of the paramagnetic insulating phase of Ca2RuO4 and show how it features several distinct energy scales. Comparison to a simple analysis of atomic multiplets provides a quantitative estimate of the Hund’s coupling J = 0.4 eV. Furthermore, the experimental spectra are in good agreement with electronic structure calculations performed with Dynamical Mean-Field Theory. The crystal field stabilization of the dxy orbital due to c-axis contraction is shown to be important in explaining the nature of the insulating state. It is thus a combination of multiband physics, Coulomb interaction and Hund’s coupling that generates the Mott insulating state of Ca2RuO4. These results underscore the importance of Hund’s coupling in the ruthenates and related multiband materials.

I like where this is going.

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Electron Mass Enhanced Quantum Critical Material Proposed for Helium Free Cryogenic Refrigeration

by Tommy on 11/10/2016

Super-heavy electron material as metallic refrigerant for adiabatic demagnetization cooling, Yoshifumi Tokiwa, Boy Piening, Hirale S. Jeevan, Sergey L. Bud’ko, Paul C. Canfield and Philipp Gegenwart, Science Advances, 2, 9, e1600835 (9 September 2016), DOI:10.1126/sciadv.1600835

Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, because the investigations of fascinating quantum phenomena, such as superconductivity, superfluidity, and quantum criticality, often require refrigeration down to very low temperatures. Currently, cryogenic refrigerators with 3He gas are widely used for cooling below 1 K. However, usage of the gas has been increasingly difficult because of the current worldwide shortage. Therefore, it is important to consider alternative methods of refrigeration. We show that a new type of refrigerant, the super-heavy electron metal YbCo2Zn20, can be used for adiabatic demagnetization refrigeration, which does not require 3He gas. This method has a number of advantages, including much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb1−xScxCo2Zn20 by partial Sc substitution, with x ~ 0.19. The substitution induces chemical pressure that drives the materials to a zero-field quantum critical point. This leads to an additional enhancement of the magnetocaloric effect in low fields and low temperatures, enabling final temperatures well below 100 mK. This performance has, up to now, been restricted to insulators. For nearly a century, the same principle of using local magnetic moments has been applied for adiabatic demagnetization cooling. This study opens new possibilities of using itinerant magnetic moments for cryogen-free refrigeration.

This is yet another step in the right direction.

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Bismuth Oxy Iodide (BiOI) Proposed as Efficient Excitonic Water Electrolysis Photocatalyst

by Tommy on 11/10/2016

Spatial separation of photo-generated electron-hole pairs in BiOBr/BiOI bilayer to facilitate water splittingSpatial separation of photo-generated electron-hole pairs in BiOBr/BiOI bilayer to facilitate water splitting, Zhen-Kun Tang, Wen-Jin Yin, Le Zhang, Bo Wen, Deng-Yu Zhang, Li-Min Liu and Woon-Ming Lau, Scientific Reports 6, 32764 (2 September 2016), doi:10.1038/srep32764

The electronic structures and photocatalytic properties of bismuth oxyhalide bilayers (BiOX1/BiOX2, X1 and X2 are Cl, Br, I) are studied by density functional theory. Briefly, their compositionally tunable bandgaps range from 1.85 to 3.41 eV, suitable for sun-light absorption, and all bilayers have band-alignments good for photocatalytic water-splitting. Among them, heterogeneous BiOBr/BiOI bilayer is the best as it has the smallest bandgap. More importantly, photo-excitation of BiOBr/BiOI leads to electron supply to the conduction band minimum with localized states belonging mainly to bismuth of BiOBr where the H+/H2 half-reaction of water-splitting can be sustained. Meanwhile, holes generated by such photo-excitation are mainly derived from the iodine states of BiOI in the valence band maximum; thus, the O2/H2O half-reaction of water splitting is facilitated on BiOI. Detailed band-structure analysis also indicates that this intriguing spatial separation of photo-generated electron-hole pairs and the two half-reactions of water splitting are good for a wide photo-excitation spectrum from 2–5 eV; as such, BiOBr/BiOI bilayer can be an efficient photocatalyst for water-splitting, particularly with further optimization of its optical absorptivity.

I have heard something like this before somewhere.

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Spin Orbit Coupling (SOC) Applied to the BCS-BEC Transition

by Tommy on 3/10/2016

BCS-BEC transition in a Dilute Bose Gas with Spin-Orbit Coupling, Dekun Luo, Rong Li and Lan Yin (30 September 2016)

We study a two-component Bose gas with a symmetric spin-orbit coupling, and find that two atoms can form a bound state with any intra- or inter-species scattering length. Consequently, in the dilute limit, a stable condensation of diatomic molecules in the Bardeen-Cooper-Shrieffer (BCS) pairing state can be formed with weakly-attractive inter-species and repulsive intra-species interactions. This BCS paring state is energetically favored over Bose-Einstein condensation (BEC) of atoms at low densities, but as the density increases, there is a first-order transition from the BCS to BEC states.

Cool. When can we start?

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I’m Your Captain – Return Me My Ship

by Tommy on 1/10/2016

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Two Dimensional (2D) Time Reversal Symmetry (TRS) Breaking Topological Superconductivity Found in Bismuth Nickel Bilayers

by Tommy on 30/09/2016

This was the last thing I reported on here at the Blob almost a year ago, before I ran off the rails on my axion dark matter adventure. Now this subject has escalated into something that is very interesting, although possibly not p-wave topological superconductivity as was first suggested.

Time-Reversal-Symmetry-Breaking Superconductivity in Epitaxial Bismuth/Nickel Bilayers, Xinxin Gong, Mehdi Kargarian, Alex Stern, Di Yue, Hexin Zhou, Xiaofeng Jin, Victor M. Galitski, Victor M. Yakovenko and Jing Xia (27 September 2016)

Superconductivity that spontaneously breaks time-reversal symmetry (TRS) has been found, so far, only in a handful of 3D crystals with bulk inversion symmetry. Here we report an observation of spontaneous TRS breaking in a 2D superconducting system without inversion symmetry: the epitaxial bilayer films of bismuth and nickel. The evidence comes from the onset of the polar Kerr effect at the superconducting transition in the absence of an external magnetic field, detected by the ultrasensitive loop-less fiber-optic Sagnac interferometer. Because of strong spin-orbit interaction and lack of inversion symmetry in a Bi/Ni bilayer, superconducting pairing cannot be classified as singlet or triplet. We propose a theoretical model where magnetic fluctuations in Ni induce superconducting pairing of the dxy ± idx2 – y2 orbital symmetry between the electrons in Bi. This order parameter spontaneously breaks the TRS and has a non-zero phase winding number around the Fermi surface, thus making Bi/Ni a rare example of a 2D topological superconductor.

Supplementary Information:

See also:

Time reversal symmetry breaking superconductivity in topological materials, Yunsheng Qiu, Kyle Nocona Sanders, Jixia Dai, Julia E. Medvedeva, Weida Wu, Pouyan Ghaemi, Thomas Vojta and Yew San Hor (11 Decenber 2015)

Fascinating phenomena have been known to arise from the Dirac theory of relativistic quantum mechanics, which describes high energy particles having linear dispersion relations. Electrons in solids usually have non-relativistic dispersion relations but their quantum excitations can mimic relativistic effects. In topological insulators, electrons have both a linear dispersion relation, the Dirac behavior, on the surface and a non-relativistic energy dispersion in the bulk. Topological phases of matter have attracted much interest, particularly broken-symmetry phases in topological insulator materials. Here, we report by Nb doping that the topological insulator Bi2Se3 can be turned into a bulk type-II superconductor while the Dirac surface dispersion in the normal state is preserved. A macroscopic magnetic ordering appears below the superconducting critical temperature of 3.2 K indicating a spontaneous spin rotation symmetry breaking of the Nb magnetic moments. Even though such a magnetic order may appear at the edge of the superconductor, it is mediated by superconductivity and presents a novel phase of matter which gives rise to a zero-field Hall effect.

Next up, ARPES examination of this system.

This is gonna be big. Super big.

The adventure continues.

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Happy National Coffee Day – September 29, 2016

by Tommy on 29/09/2016
National Coffee Day

National Coffee Day

Say, pardon me but, could you help out a fellow American who’s down on his luck?

Humphrey Bogart Bugs Bunny

Humphrey Bogart Bugs Bunny

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Modified Gravity by Cosmic QCD Super Axion Boson Excitation

by Tommy on 27/09/2016

Here I clearly and officially state my gravitational cosmic QCD axion scaling hypothesis.

With this I bring fa down to a reasonable TeV Higgs scale level, depending upon density, etc. and solve numerous other cosmological conundrums, using geometry, topology and superfluidity in condensed matter physics systems as my guide. I’ve already solved the origin of life problem.

The Radial Acceleration Relation in Rotationally Supported Galaxies, Stacy McGaugh, Federico Lelli and Jim Schombert, Accepted for Publication in Physical Review Letters (19 September 2016)

We report a correlation between the radial acceleration traced by rotation curves and that predicted by the observed distribution of baryons. The same relation is followed by 2693 points in 153 galaxies with very different morphologies, masses, sizes, and gas fractions. The correlation persists even when dark matter dominates. Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxies.

No MACHOs or WIMPs and SUSY etc. lost into the black hole.

Mimicking dark matter in Horndeski gravity, Massimiliano Rinaldi (12 August 2016)

Since the rediscovery of Horndeski gravity, a lot of work has been devoted to the exploration of its properties, especially in the context of dark energy. However, one sector of this theory, namely the one containing the coupling of the Einstein tensor to the kinetic term of the scalar field, shows some surprising features in the construction of black holes and neutron stars. Motivated by these new results, I explore the possibility that this sector of Horndeski gravity can mimic cold dark matter at cosmological level and also explain the flattening of galactic rotation curves. I will show that it is possible to achieve both goals with a minimal set of assumptions.

If it mimics or simulates dark matter, then it IS dark matter.


Gauge Fields, Nonlinear Realizations, Supersymmetry, E.A. Ivanov, Physics of Particles and Nuclei (4 September 2016), DOI:10.1134/S1063779616040080

This is a brief survey of the all-years research activity in the Sector “Supersymmetry” (the former Markov Group) at the Bogoliubov Laboratory of Theoretical Physics. The focus is on the issues related to gauge fields, spontaneously broken symmetries in the nonlinear realizations approach, and diverse aspects of supersymmetry.

Ask an expert!

So if it’s not supersymmetry, then what is it?

The Inverse Higgs Phenomenon in Nonlinear Realizations, E. A. Ivanov and V. I. Ogievetsky, Teor. Mat. Fiz., 25, 164-177, Translated from Teoreticheskaya i Matematicheskaya Fizika

(27 February 1975), DOI:10.1007/BF01028947

Ok, so I’m gonna need a new axion. A super axion!

Coupled to gravitons and ordinary matter through the Higgs.

This is my special theory of gravity modification.

My working hypothesis of dark matter.

© 2016 Thomas Lee Elifritz

Now I just need a theory.

ITS gonna be weird.

Trust me on that.

Update 1: Alternatively you could push fa up to Planck scale, since it’s already a good fraction of the way there. What this does is make the mass of the axion more uncertain. But since I’m taking my clues from lattice QCD in a gravitationally flat environment, it probably doesn’t matter.

Update 2: Vera Rubin Passed Away on Christmas Day Evening on December 25th, 2016.

Update 3:

Gravitational Axions as Dark Matter

Update 4:

Gravitational Axions in Quantum Gravity and Cosmology

© 2017 Thomas Lee Elifritz

Double crackpot.

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The Beginning

by Tommy on 27/09/2016

The end is really just the beginning.

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The End

by Tommy on 25/08/2016

So it’s been almost but not quite two full years since I started this latest incarnation of the Blob.

Besides continually reminding myself that I’m a crackpot, I’ve come to the realization that I have no reason to continue doing this. My viewership is extremely limited, the subject matter here is arcane and bizarre, and I’ve solved most of the problems I set out to solve within my truncated intellectual and financial capabilities. The door has been opened, and it can’t be shut anymore.

So absent any external funding, it’s goodbye.

See ya on the other side.

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Novel Topological Insulator β-Bi4I4 Now Studied in Great Detail

by Tommy on 25/08/2016


I had blogged it earlier when it was still just an APS meeting abstract, now here it is.

A novel quasi-one-dimensional topological insulator in bismuth iodide β-Bi4I4, A novel quasi-one-dimensional topological insulator in bismuth iodide β-Bi4I4, Gabriel Autès, Anna Isaeva, Luca Moreschini, Jens C. Johannsen, Andrea Pisoni, Ryo Mori, Wentao Zhang, Taisia G. Filatova, Alexey N. Kuznetsov, László Forró, Wouter Van den Broek, Yeongkwan Kim, Keun Su Kim, Alessandra Lanzara, Jonathan D. Denlinger, Eli Rotenberg, Aaron Bostwick, Marco Grioni and Oleg V. Yazyev, Nature Materials, 15, 154–158 (14 December 2015), doi:10.1038/nmat4488

Recent progress in the field of topological states of matter has largely been initiated by the discovery of bismuth and antimony chalcogenide bulk topological insulators, followed by closely related ternary compounds and predictions of several weak TIs. However, both the conceptual richness of Z2 classification of TIs as well as their structural and compositional diversity are far from being fully exploited. Here, a new Z2 topological insulator is theoretically predicted and experimentally confirmed in the β-phase of quasi-one-dimensional bismuth iodide β-Bi4I4. The electronic structure of β-Bi4I4, characterized by Z2 invariants (1;110), is in proximity of both the weak TI phase (0;001) and the trivial insulator phase (0;000). Our angle-resolved photoemission spectroscopy measurements performed on the (001) surface reveal a highly anisotropic band-crossing feature located at the M point of the surface Brillouin zone and showing no dispersion with the photon energy, thus being fully consistent with the theoretical prediction.

See also:

Topological insulators: Quasi-1D topological insulators, Huaqing Huang and Wenhui Duan, Nature Materials, 15, 129–130 (22 January 2016), doi:10.1038/nmat4543

Bismuth iodide Bi4I4, composed of quasi-one-dimensional molecular chains, was theoretically predicted and now has been experimentally verified to be a novel strong topological insulator.

So it’s nice to see this subject taken to completion.

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Michael F. Siemion, Instructor, Wisconsin School of Electronics

by Tommy on 24/08/2016
Michael F. Siemion - Instructor - Wisconsin School of Electronics

Michael F. Siemion – Instructor – Wisconsin School of Electronics

I wasn’t old enough to get into the school. He tutored me privately.

Electronics and semiconductor physics – at a very early age.

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Condensed Matter Physics – Practical Cosmological Results

by Tommy on 24/08/2016

Surprises with Nonrelativistic Naturalness, Petr Horava, Int. J. Mod. Phys. D25, 1645007 (22 August 2016)

We explore the landscape of technical naturalness for nonrelativistic systems, finding surprises which challenge and enrich our relativistic intuition already in the simplest case of a single scalar field. While the immediate applications are expected in condensed matter and perhaps in cosmology, the study is motivated by the leading puzzles of fundamental physics involving gravity: The cosmological constant problem and the Higgs mass hierarchy problem.

Of course, nowadays, not all condensed matter physics is nonrelativistic.

That will be the game changer here.

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Cuprate Charge Density Modulations and Real Space Physics

by Tommy on 23/08/2016

Commensurate 4a0 period Charge Density Modulations throughout the Bi2Sr2CaCu2O8+x Pseudogap Regime, A. Mesaros, K. Fujita, S. D. Edkins, M. H. Hamidian, H. Eisaki, S. Uchida, J. C. Séamus Davis, M. J. Lawler and Eun-Ah Kim (22 August 2016)

Theories based upon strong real space (r-space) electron electron interactions have long predicted that unidirectional charge density modulations (CDM) with four unit cell (4a0) periodicity should occur in the hole doped cuprate Mott insulator (MI). Experimentally, however, increasing the hole density p is reported to cause the conventionally defined wavevector QA of the CDM to evolve continuously as if driven primarily by momentum space (k-space) effects. Here we introduce phase resolved electronic structure visualization for determination of the cuprate CDM wavevector. Remarkably, this new technique reveals a virtually doping independent locking of the local CDM wavevector at |Q0|=2π/4a0 throughout the underdoped phase diagram of the canonical cuprate Bi2Sr2CaCu2O8. These observations have significant fundamental consequences because they are orthogonal to a k-space (Fermi surface) based picture of the cuprate CDM but are consistent with strong coupling r-space based theories. Our findings imply that it is the latter that provide the intrinsic organizational principle for the cuprate CDM state.

Well it looks like we’ve come full circle again.

This is a carnival ride from hell.

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Lattice QCD Calculations Applied To Axion Cosmology

by Tommy on 22/08/2016

Lattice QCD for Cosmology, Sz. Borsanyi, Z. Fodor, K. H. Kampert, S. D. Katz, T. Kawanai, T. G. Kovacs, S. W. Mages, A. Pasztor, F. Pittler, J. Redondo, A. Ringwald and K. K. Szabo (27 Jun 2016)

We present a full result for the equation of state (EoS) in 2+1+1 (up/down, strange and charm quarks are present) flavour lattice QCD. We extend this analysis and give the equation of state in 2+1+1+1 flavour QCD. In order to describe the evolution of the universe from temperatures several hundreds of GeV to several tens of MeV we also include the known effects of the electroweak theory and give the effective degree of freedoms. As another application of lattice QCD we calculate the topological susceptibility (chi) up to the few GeV temperature region. These two results, EoS and chi, can be used to predict the dark matter axion’s mass in the post-inflation scenario and/or give the relationship between the axion’s mass and the universal axionic angle, which acts as a initial condition of our universe.

Finally this is getting the treatment it deserves from the experts.

Fractions of an meV puts it at liquid helium temperatures.

Or alternatively, in the realm of the CMB.

See also:

Unifying inflation with the axion, dark matter, baryogenesis and the seesaw mechanism, Guillermo Ballesteros, Javier Redondo, Andreas Ringwald and Carlos Tamarit (18 August 2016)

A minimal extension of the Standard Model (SM) providing a complete and consistent picture of particle physics and cosmology up to the Planck scale is presented. We add to the SM three right-handed SM-singlet neutrinos, a new vector-like color triplet fermion and a complex SM singlet scalar σ whose vacuum expectation value at ∼1011 GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously. Primordial inflaton is produced by a combination of σ and the SM Higgs. Baryogenesis proceeds via thermal leptogenesis. At low energies, the model reduces to the SM, augmented by seesaw-generated neutrino masses, plus the axion, which solves the strong CP problem and accounts for the dark matter in the Universe. The model can be probed decisively by the next generation of cosmic microwave background and axion dark matter experiments.

But but but … gravitation!

Update: This article, or a variation of it, is now published in Nature.

Calculation of the axion mass based on high-temperature lattice quantum chromodynamics, S. Borsanyi, Z. Fodor, J. Guenther, K.-H. Kampert, S. D. Katz, T. Kawanai, T. G. Kovacs, S. W. Mages, A. Pasztor, F. Pittler, J. Redondo, A. Ringwald and K. K. Szabo, Nature, 539, 69–71 (03 November 2016), doi:10.1038/nature20115

And it is getting a lot of press.

The race is on.

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High Tc of Cuprates Attributed to Small Local Electronic Pairs

by Tommy on 22/08/2016

Dependence of the critical temperature in overdoped copper oxides on superfluid density, I. Božović, X. He, J. Wu and A. T. Bollinger, Nature, 536, 309–311 (18 August 2016), doi:10.1038/nature19061

The physics of underdoped copper oxide superconductors, including the pseudogap, spin and charge ordering and their relation to superconductivity is intensely debated. The overdoped copper oxides are perceived as simpler, with strongly correlated fermion physics evolving smoothly into the conventional Bardeen–Cooper–Schrieffer behaviour. Pioneering studies on a few overdoped samples indicated that the superfluid density was much lower than expected, but this was attributed to pair-breaking, disorder and phase separation. Here we report the way in which the magnetic penetration depth and the phase stiffness depend on temperature and doping by investigating the entire overdoped side of the La2−xSrxCuO4 phase diagram. We measured the absolute values of the magnetic penetration depth and the phase stiffness to an accuracy of one per cent in thousands of samples; the large statistics reveal clear trends and intrinsic properties. The films are homogeneous; variations in the critical superconducting temperature within a film are very small (less than one kelvin). At every level of doping the phase stiffness decreases linearly with temperature. The dependence of the zero-temperature phase stiffness on the critical superconducting temperature is generally linear, but with an offset; however, close to the origin this dependence becomes parabolic. This scaling law is incompatible with the standard Bardeen–Cooper–Schrieffer description.

I haven’t read the paper so I can’t comment other than to say … great.

It took them long enough.

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Composite Particle Theory and Fractional Axion Angles

by Tommy on 21/08/2016

As promised earlier, but never delivered, I finally got around to this.

Composite Particle Theory, Fractional Axion Angles, and Extrinsic Twist Defects in Three-Dimensional Gapped Fermionic Phases, Peng Ye, Taylor L. Hughes, Joseph Maciejko and Eduardo Fradkin (21 March 2016)

We study strongly fluctuating compact U(1) × U(1) gauge fields in a parton construction of gapped fermionic phases in three dimensions (3D). In the presence of a background electromagnetic field, the general framework of composite particle theory is proposed in analogy to Jain’s composite fermion theory of 2D fractional quantum Hall states. The resulting gapped phases are constructed by condensing two linearly independent bosonic composite particles, which consist of partons and U(1) × U(1) magnetic monopoles. Charge fractionalization is shown to result from a Debye-Huckel-like screening cloud formed by the condensed composite particles. Our general framework allows us to explore two symmetry-enrichment properties of 3D Abelian topological phases. First, we explore the time-reversal symmetry enrichment characterized by the axion angle Θ. Fractional topological insulators with Θ≠π and time-reversal symmetry are constructed in a concrete example. Second, we generalize the notion of anyonic symmetry of 2D Abelian topological phases to the notion of charge-loop excitation symmetry (Charles) in 3D Abelian topological phases. We propose that line twist defects can be utilized to realize Charles symmetry transformations. We study the non-Abelian fusion properties of such defects and the topological distinction between defect species. Several future directions are proposed.

See also:

Topological superconducting phases from inversion symmetry breaking order in spin-orbit-coupled systems, Yuxuan Wang, Gil Young Cho, Taylor L. Hughes and Eduardo Fradkin (28 April 2016), doi:10.1103/PhysRevB.93.134512

We analyze the superconducting instabilities in the vicinity of the quantum-critical point of an inversion symmetry breaking order. We first show that the fluctuations of the inversion symmetry breaking order lead to two degenerate superconducting (SC) instabilities, one in the s-wave channel, and the other in a time-reversal invariant odd-parity pairing channel (the simplest case being the same as the of 3He-B phase). Remarkably, we find that unlike many well-known examples, the selection of the pairing symmetry of the condensate is independent of the momentum-space structure of the collective mode that mediates the pairing interaction. We found that this degeneracy is a result of the existence of a conserved fermionic helicity, χ, and the two degenerate channels correspond to even and odd combinations of SC order parameters with χ = ± 1. As a result, the system has an enlarged symmetry U(1) × U(1), with each U(1) × U(1) corresponding to one value of the helicity χ. Because of the enlarged symmetry, this system admits exotic topological defects such as a fractional quantum vortex, which we show has a Majorana zero mode bound at its core. We discuss how the enlarged symmetry can be lifted by small perturbations, such as the Coulomb interaction or Fermi surface splitting in the presence of broken inversion symmetry, and we show that the resulting superconducting state can be topological or trivial depending on parameters. The U(1) × U(1) symmetry is restored at the phase boundary between the topological and trivial SC states, and allows for a transition between topologically distinct SC phases without the vanishing of the order parameter. We present a global phase diagram of the superconducting states and discuss possible experimental implications.

From the University of Illinois at Urbana-Champaign.

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Electronic and Mechanical Properties of Single, Bilayer and Multilayer Bismuthene Studied

by Tommy on 21/08/2016

Single and bilayer bismuthene: Stability at high temperature and mechanical and electronic properties, E. Aktürk, O. Üzengi Aktürk, and S. Ciraci, Phys. Rev. B 94, 014115 (20 July 2016), doi:10.1103/PhysRevB.94.014115

Based on first-principles phonon and finite temperature molecular dynamics calculations including spin-orbit coupling, we showed that free-standing single-layer phases of bismuth, namely buckled honeycomb and asymmetric washboard structures named as bismuthene, are stable at high temperature. We studied the atomic structure, mechanical, and electronic properties of these single-layer bismuthene phases and their bilayers. The spin-orbit coupling is found to be crucial in determining lattice constants, phonon frequencies, band gaps, and cohesion. In particular, phonons of 3D hexagonal crystal, as well as those of single-layer bismuthene phases, are softened with spin orbit coupling. By going from 3D hexagonal crystal to free-standing single-layer structures, 2D hexagonal lattice is compressed and semimetal is transformed to semiconductor as a result of confinement effect. On the contrary, by going from single-layer to bilayer bismuthenes, the lattice is slightly expanded and fundamental band gaps are narrowed. Our results reveals that interlayer coupling in multilayer and 3D Bi crystal is crucial for topologically trivial to nontrivial and semimetal to semiconductor transitions.

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Dark Matter Axion Landscape Potential Modeled and Explored

by Tommy on 20/08/2016

Dark Matter in Axion Landscape, Ryuji Daido, Takeshi Kobayashi and Fuminobu Takahashi (14 August 2016)

If there are a plethora of axions in nature, they may have a complicated potential and create an axion landscape. We study a possibility that one of the axions is so light that it is cosmologically stable, explaining the observed dark matter density. In particular we focus on a case in which two (or more) shift-symmetry breaking terms conspire to make the axion sufficiently light at the potential minimum. In this case the axion has a flat-bottomed potential. In contrast to the case in which a single cosine term dominates the potential, the axion abundance as well as its isocurvature perturbations are significantly suppressed. This allows an axion with a rather large mass to serve as dark matter without fine-tuning of the initial misalignment, and further makes higher-scale inflation to be consistent with the scenario.

Ok so here we go. I am now officially in over my head in axions and cosmogenesis.

Hey, that’s a new word! I like it already.

Update: Nope, I just looked it up, not only is it a word, it’s a nutty book and an album already!

There is hope, though, it’s not a feature length 3D film yet, available in virtual holography.

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The Graviton Condensation PhD Thesis of Sophia Zielinski

by Tommy on 14/08/2016

Spacetime geometry from graviton condensation: a new perspective on black holes, Sophia Zielinski, PhD Dissertation, Ludwig Maximilian University of München (Munich), Stefan Hofmann, Advisor (21 April 2016)

In this thesis we introduce a novel approach viewing spacetime geometry as an emergent phenomenon based on the condensation of a large number of quanta on a distinguished flat background. We advertise this idea with regard to investigations of spacetime singularities within a quantum field theoretical framework and semiclassical considerations of black holes. Given that in any physical theory apart from General Relativity the metric background is determined in advance, singularities are only associated with observables and can either be removed by renormalization techniques or are otherwise regarded as unphysical. The appearance of singularities in the spacetime structure itself, however, is pathological. The prediction of said singularities in the sense of geodesic incompleteness culminated in the famous singularity theorems established by Hawking and Penrose. Though these theorems are based on rather general assumptions we argue their physical relevance. Using the example of a black hole we show that any classical detector theory breaks down far before geodesic incompleteness can set in. Apart from that, we point out that the employment of point particles as diagnostic tools for spacetime anomalies is an oversimplification that is no longer valid in high curvature regimes. In view of these results the question arises to what extent quantum objects are affected by spacetime singularities. Based on the definition of geodesic incompleteness customized for quantum mechanical test particles we collect ideas for completeness concepts in dynamical spacetimes. As it turns out, a further development of these ideas has shown that Schwarzschild black holes, in particular, allow for a evolution of quantum probes that is well-defined all over. This fact, however, must not distract from such semiclassical considerations being accompanied by many so far unresolved paradoxes. We are therefore compelled to take steps towards a full quantum resolution of geometrical backgrounds. First steps towards such a microscopic description are made by means of a non-relativistic scalar toy model mimicking properties of General Relativity. In particular, we model black holes as quantum bound states of a large number N of soft quanta subject to a strong collective potential. Operating at the verge of a quantum phase transition perturbation theory naturally breaks down and a numerical analysis of the model becomes inevitable. Though indicating 1/N corrections as advertised in the underlying so-called Quantum-N portrait relevant for a possible purification of Hawking radiation and henceforth a resolution of the long-standing information paradox we recognize that such a non-relativistic model is simply not capable of capturing all relevant requirements of a proper black hole treatment. We therefore seek a relativistic framework mapping spacetime geometry to large-N quantum bound states. Given a non-trivial vacuum structure supporting graviton condensation this is achieved via in-medium modifications that can be linked to a collective binding potential. Viewing Minkowski spacetime as fundamental, the classical notion of any other spacetime geometry is recovered in the limit of an infinite constituent number of the corresponding bound state living on Minkowski. This construction works in analogy to the description of hadrons in quantum chromodynamics and, in particular, also uses non-perturbative methods like the auxiliary current description and the operator product expansion. Concentrating on black holes we develop a bound state description in accordance with the isometries of Schwarzschild spacetime. Subsequently, expressions for the constituent number density and the energy density are reviewed. With their help, it can be concluded that the mass of a black hole at parton level is proportional to its constituent number. Going beyond this level we then consider the scattering of a massless scalar particle off a black hole. Using previous results we can explicitly show that the constituent distribution represents an observable and therefore might ultimately be measured in experiments to confirm our approach. We furthermore suggest how the formation of black holes or Hawking radiation can be understood within this framework. After all, the gained insights, capable of depriving their mysteries, highlights the dubiety of treating black holes by means of classical tools. Since our setup allows to view other, non-black-hole geometries, as bound states as well, we point out that our formalism could also shed light on the cosmological constant problem by computing the vacuum energy in a de Sitter state. In addition, we point our that even quantum chromodynamics, and, in fact, any theory comprising bound states, can profit from our formalism. Apart from this, we discuss an alternative proposal describing classical solutions in terms of coherent states in the limit of an infinite occupation number of so-called corpuscles. Here, we will focus on the coherent state description of Anti-de Sitter spacetime. Since most parts of this thesis are directed to find a constituent description of black holes we will exclude this corpuscular description from the main part and introduce it in the appendix.

It’s always something. It’s never nothing.

Update: Clearly some new approaches are needed in the post LHC deserted universe, and this is one of them. Not too bad. I myself would recast this idea in momentum space. Clearly motion is dissipationless, right? Except when those leptons and baryons and guage bosons get in the way. Collisions and interactions are always unfortunate, you never know what might happen in an energetic long lived stable universe. You could accidentally produce assholes. Or politicians.

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Bismuthene Comes of Age

by Tommy on 11/08/2016

Bismuthene on a SiC Substrate: A Candidate for a New High-Temperature Quantum Spin Hall Paradigm, F. Reis, G. Li, L. Dudy, M. Bauernfeind, S. Glass, W. Hanke, R. Thomale, J. Schäfer and R. Claessen (2 August 2016)

Quantum spin Hall (QSH) materials promise revolutionary device applications based on dissipationless propagation of spin currents. They are two-dimensional (2D) representatives of the family of topological insulators, which exhibit conduction channels at their edges inherently protected against scattering. Initially predicted for graphene, and eventually realized in HgTe quantum wells, in the QSH systems realized so far, the decisive bottleneck preventing applications is the small bulk energy gap of less than 30 meV, requiring cryogenic operation temperatures in order to suppress detrimental bulk contributions to the edge conductance. Room-temperature functionalities, however, require much larger gaps. Here we show how this can be achieved by making use of a new QSH paradigm based on substrate-supported atomic monolayers of a high-Z element. Experimentally, the material is synthesized as honeycomb lattice of bismuth atoms, forming “bismuthene”, on top of the wide-gap substrate SiC(0001). Consistent with the theoretical expectations, the spectroscopic signatures in experiment display a huge gap of ~0.8 eV in bismuthene, as well as conductive edge states. The analysis of the layer-substrate orbitals arrives at a QSH phase, whose topological gap – as a hallmark mechanism – is driven directly by the atomic spin-orbit coupling (SOC). Our results demonstrate how strained artificial lattices of heavy atoms, in contact with an insulating substrate, can be utilized to evoke a novel topological wide-gap scenario, where the chemical potential is located well within the global system gap, ensuring pure edge state conductance. We anticipate future experiments on topological signatures, such as transport measurements that probe the QSH effect via quantized universal conductance, notably at room temperature.

All Hail The Probe!

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K-Theory Classification of Fermi Surfaces and Anomaly Inflows

by Tommy on 11/08/2016

Topology of Fermi Surfaces and Anomaly Inflows, Alejandro Adem, Omar Antolín Camarena, Gordon W. Semenoff and Daniel Sheinbaum (8 August 2016)

We derive a rigorous classification of topologically stable Fermi surfaces of non-interacting, discrete translation-invariant systems from electronic band theory, adiabatic evolution and their topological interpretations. For systems with Born-von Karman boundary conditions it is shown that there can only be topologically unstable Fermi surfaces. For systems on a half-space and with a gapped bulk, our derivation naturally yields a K-theory classification. Given the d−1-dimensional surface Brillouin zone Xs of a d-dimensional half-space, our result implies that different classes of globally stable Fermi surfaces belong in K−1(Xs) for systems with only discrete translation-invariance. This result has a chiral anomaly inflow interpretation, as it reduces to the spectral flow for d=2. Through equivariant homotopy methods we extend these results for symmetry classes AI, AII, C and D and discuss their corresponding anomaly inflow interpretation.

This works for me. I’m glad now I studied this stuff when I was younger.

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CERN LHC Large Hadron Collider – ATLAS and CMS Results

by Tommy on 5/08/2016

ATLAS and CMS show no beyond standard model BSM physics. No pseudo particles. Nothing.

Condensed matter physicists are thrilled. There are no accessible WIMPS, no SUSY and string theory is forever trapped in the spacetime foam of the black hole. What is happening is that the cosmic QCD axions and the Higgs field are remnants from the inflationary period where the complex topology of the spacetime singularity was transformed into a hot stable expanding universe filled with topological remnants, bosons and fermions, and widely spaced black holes.

Mostly widely spaced. Fortunately now we can observe them colliding. Axion Higgs physics to quantum critical black hole collapse, and a running cosmological constant coupled to axion excitation. Or something like that. At least that’s what condensed matter physics is telling me.

Ladies and gentlemen pick up your pencils and start designing your gonkulators. May the best quantum critical gravitational singularity simulating axion-Higgs gonkulator win. Hurry now!

Humanity needs you! And Mars Needs Women!

Update: The shit storm resulting from this has started, I see. The first crackpot to take the bait was Robert L. Oldershaw of Amherst College, of the infinite fractal universe infamy. He seems to think Hawking has all the answers. Zillions of MACHOs that we can’t see or detect, uh-huh.

Lubos Motl is in tatters of course. Sabine Hossenfelder isn’t taking it lying down. Ethan Siegal still thinks he has all the answers, and that will never change. He even looks like a Republican.

Meanwhile, the obvious seems to elude almost everyone except myself and John Baez.

Update 2: Peter Woit seems as calm as ever. Mathematicians are like that.

Update 3:

The Radial Acceleration Relation in Rotationally Supported Galaxies, Stacy McGaugh, Federico Lelli and Jim Schombert, Accepted for publication in Physical Review Letters (19 September 2016)

We report a correlation between the radial acceleration traced by rotation curves and that predicted by the observed distribution of baryons. The same relation is followed by 2693 points in 153 galaxies with very different morphologies, masses, sizes, and gas fractions. The correlation persists even when dark matter dominates. Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxies.

See also:

The universal rotation curve of dwarf disk galaxies, Ekaterina V. Karukes, Paolo Salucci, Submitted to MNRAS (22 September 2016)

Already MOND supporters are jumping all over this.

After consulting an expert, it’s clear I have a working hypothesis now. And it’s the last and only hypothesis standing. Maybe it’s time to reboot the Blob. How about ‘Dark Energy Matters’?

After all, the end is really just the beginning. I need to keep a record of the last two years.

I haven’t even invoked the magic © sign. The ‘crackpot’ sign.

No Comments

Autobiogenesis and the Origin of Life – Hydrothermal Vents and Hot Springs

by Tommy on 28/07/2016

The physiology and habitat of the last universal common ancestor, Madeline C. Weiss, Filipa L. Sousa, Natalia Mrnjavac, Sinje Neukirchen, Mayo Roettger, Shijulal Nelson-Sathi and William F. Martin, Nature Microbiology 1, Article number: 16116 (25 July 2016), doi:10.1038/nmicrobiol.2016.116

The concept of a last universal common ancestor of all cells (LUCA, or the progenote) is central to the study of early evolution and life’s origin, yet information about how and where LUCA lived is lacking. We investigated all clusters and phylogenetic trees for 6.1 million protein coding genes from sequenced prokaryotic genomes in order to reconstruct the microbial ecology of LUCA. Among 286,514 protein clusters, we identified 355 protein families (∼0.1%) that trace to LUCA by phylogenetic criteria. Because these proteins are not universally distributed, they can shed light on LUCA’s physiology. Their functions, properties and prosthetic groups depict LUCA as anaerobic, CO2-fixing, H2-dependent with a Wood–Ljungdahl pathway, N2-fixing and thermophilic. LUCA’s biochemistry was replete with FeS clusters and radical reaction mechanisms. Its cofactors reveal dependence upon transition metals, flavins, S-adenosyl methionine, coenzyme A, ferredoxin, molybdopterin, corrins and selenium. Its genetic code required nucleoside modifications and S-adenosyl methionine-dependent methylations. The 355 phylogenies identify clostridia and methanogens, whose modern lifestyles resemble that of LUCA, as basal among their respective domains. LUCA inhabited a geochemically active environment rich in H2, CO2 and iron. The data support the theory of an autotrophic origin of life involving the Wood–Ljungdahl pathway in a hydrothermal setting.

The Cosmic Evolution of Autobiogenesis

That’s a really hot cup of tea.

Godzillions of them.

No Comments

Halide Decorated Plumbene Monolayer is a Giant Gap Quantum Spin Hall Insulator

by Tommy on 23/07/2016

Unexpected Giant-Gap Quantum Spin Hall Insulator in Chemically Decorated Plumrbene Monolayer. Hui Zhao, Chang-wen Zhang, Wei-xiao Ji, Run-wu Zhang, Sheng-shi Li, Shi-shen Yan, Bao-min Zhang, Ping Li, and Pei-ji Wang, Sci Rep. 2016; 6: 20152 (2 February 2016), doi:10.1038/srep20152

Quantum spin Hall (QSH) effect of two-dimensional (2D) materials features edge states that are topologically protected from backscattering by time-reversal symmetry. However, the major obstacles to the application for QSH effect are the lack of suitable QSH insulators with a large bulk gap. Here, we predict a novel class of 2D QSH insulators in X-decorated plumbene monolayers (PbX; X = H, F, Cl, Br, I) with extraordinarily giant bulk gaps from 1.03 eV to a record value of 1.34 eV. The topological characteristic of PbX mainly originates from spx,y band inversion related to the lattice symmetry, while the effect of spin-orbital coupling (SOC) is only to open up a giant gap. Their QSH states are identified by nontrivial topological invariant Z2 = 1, as well as a single pair of topologically protected helical edge states locating inside the bulk gap. Noticeably, the QSH gaps of PbX are tunable and robust via external strain. We also propose high-dielectric-constant BN as an ideal substrate for the experimental realization of PbX, maintaining its nontrivial topology. These novel QSH insulators with giant gaps are a promising platform to enrich topological phenomena and expand potential applications at high temperature.

No Comments

The Witten Effect in Topological Superconductors

by Tommy on 22/07/2016

Josephson currents induced by the Witten effect, Flavio S. Nogueira, Zohar Nussinov and Jeroen van den Brink (14 July 2016)

We reveal the existence of a new type of topological Josephson effect involving type II superconductors and three-dimensional topological insulators as tunnel junctions. We predict that vortex lines induce an electromagnetic variant of the Witten effect that is the consequence of the axion electromagnetic response of the topological insulator. If an external magnetic field is applied perpendicular to the junction, the Witten effect induces an AC Josephson effect in absence of any external voltage. We derive a number of further experimental consequences and propose potential setups where these {quantized, flux induced, Witten} effects may be observed.

See also:

Duality of a compact topological superconductor model and the Witten effect. Flavio S. Nogueira, Zohar Nussinovand Jeroen van den Brink (21 July 2016)

We consider a compact abelian Higgs model in 3+1 dimensions with a topological axion term and construct its dual theories for both bulk and boundary at strong coupling. The model may be viewed as describing a superconductor with magnetic monopoles, which can also be interpreted as a field theory of a topological Mott insulator. We show that this model is dual to a non-compact topological field theory of particles and vortices. It has exactly the same form of a model for superconducting cosmic strings with an axion term. We consider the duality of the boundary field theory at strong coupling and show that in this case θ is quantized as −8πn/m where n and m are the quantum numbers associated to electric and magnetic charges. These topological states lack a non-interacting equivalent.

Finally something that looks like it might work in practice.

No Comments

Probing Photonic Lattices and Artificial Quantum Materials – Hamiltonian Tomography

by Tommy on 21/07/2016

Hamiltonian Tomography of Photonic Lattices, Ruichao Ma, Clai Owens, Aman LaChapelle, David I. Schuster, Jonathan Simon (18 July 2016)

In this letter we introduce a novel approach to Hamiltonian tomography of non-interacting tight-binding photonic lattices. To begin with, we prove that the matrix element of the low-energy effective Hamiltonian between sites i and j may be obtained directly from Sij(ω), the (suitably normalized) two-port measurement between sites i and j at frequency ω. This general result enables complete characterization of both on-site energies and tunneling matrix elements in arbitrary lattice networks by spectroscopy, and suggests that coupling between lattice sites is actually a topological property of the two-port spectrum. We further provide extensions of this technique for measurement of band-projectors in finite, disordered systems with good flatness ratios, and apply the tool to direct real-space measurement of the Chern number. Our approach demonstrates the extraordinary potential of microwave quantum circuits for exploration of exotic synthetic materials, providing a clear path to characterization and control of single-particle properties of Jaynes-Cummings-Hubbard lattices. More broadly, we provide a robust, unified method of spectroscopic characterization of linear networks from photonic crystals to microwave lattices and everything in-between.

Another great result from the University of Chicago.

I wonder if anyone at the ICHEP will figure it out?

No Comments

Lattice Gauge Theory Computational QCD Axion Cosmology

by Tommy on 14/07/2016

The topological susceptibility in finite temperature QCD and axion cosmology, Peter Petreczky, Hans-Peter Schadler and Sayantan Sharma (9 June 2016)

We study the topological susceptibility in 2+1 flavor QCD above the chiral crossover transition temperature using Highly Improved Staggered Quark action and several lattice spacings, corresponding to temporal extent of the lattice, Nτ = 6, 8, 10 and 12. We observe very distinct temperature dependencies of the topological susceptibility in the ranges above and below 250 MeV. While for temperatures above 250 MeV, the dependence is found to be consistent with dilute instanton gas approximation, at lower temperatures the fall-off of topological susceptibility is milder. We discuss the consequence of our results for cosmology wherein we estimate the bounds on the axion decay constant and the oscillation temperature if indeed the QCD axion is a possible dark matter candidate.

This is some followup exploratory work in this field that I blogged earlier.

It shouldn’t be too long now.

No Comments

The Younger Dryas Glacial Lake Agassiz Meltwater Discharge Masters Thesis of David J. Leydet at Oregon State University

by Tommy on 14/07/2016

Eastward Routing of Glacial Lake Agassiz Runoff caused the Younger Dryas Cold Event, David J. Leydet, Masters Thesis, College of Earth, Ocean and Atmospheric Sciences, Anders E. Carlson, Advisor, Oregon State University (3 May 2016)

The purpose of this thesis is to analyze an abrupt case of climate change in the past as a means to understand the mechanisms that force climate change. By looking to past analogs of climate change, we hopefully will gain an understanding of these events, which could be used to further our understanding of future climate change. In this light, I analyze the case of the Younger Dryas (YD), an abrupt cooling event that occurred from ~ 12.9 ka to ~ 11.7 ka. We investigate several hypotheses regarding the cause of the YD and attempt to determine the forcing mechanism for this abrupt cooling event. I use 10Be surface exposure dating as our method for dating retreat of the Laurentide Ice Sheet from the eastern outlets of glacial Lake Agassiz, a large pro-glacial lake that formed during the last deglaciation whose drainage into the North Atlantic is hypothesized to have caused the YD via a slowing of ocean overturning circulation. I find that the eastern outlets of glacial Lake Agassiz begin to deglaciate at 14.0 ± 0.3 ka with ice retreating from the key Lake Kaministikwia outlet at 13.0 ± 0.3 ka, concurrent with the onset of the YD. I also date retreat from the Steep Rock moraine at 13.8 ± 0.2 ka and retreat from the Marks moraine by 11.0 ± 0.4 ka. I use our chronology along with other terrestrial and marine proxies to reconstruct the meltwater routing history of Lake Agassiz. Specifically, the Gulf of St. Lawrence isotopic record indicates meltwater routing through Eastern Outlets, peaking at ~ 12.6 ka. Subsequently, the isotopic record of the Arctic Ocean near the mouth of the Mackenzie River indicates meltwater routing beginning at ~ 12.4 ka and peaking at 12.2 ka.

I argue that the timing of these meltwater pathways support the hypotheses that the YD was caused by freshwater forcing, weakening the Atlantic Meriodional Overturning Circulation, and thus cooling the climate of the Northern Hemisphere. The results demonstrate the importance of meltwater routing on the climate system and will be important in understanding the implications of future ice sheet-oceanclimate interactions in a climatically changing world.

This seems moderately definitive. I wonder how long it will last?

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Archimedes Space Architecture – Tsiolkovsky Launch Vehicle

by Tommy on 8/07/2016

These will be wrap up papers.

Archimedes Space Architecture (fixed)

Tsiolkovsky Reusable Launch Vehicles

Hopefully finished before September.

Yes, that’s a wrap, folks.

Update: I fixed the URL. This has taken so long I now need reading glasses.

I’m beginning to wonder if I will ever get to fly.

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Tabletop Simulation of Universe Cosmic Inflation Proposed

by Tommy on 8/07/2016

The universe on a table top: engineering quantum decay of a relativistic scalar field from a metastable vacuum, Oleksandr Fialko, Bogdan Opanchuk, Andrei I. Sidorov, Peter D. Drummond and Joachim Brand (6 July 2016)

The quantum decay of a relativistic scalar field from a metastable state (“false vacuum decay”) is a fundamental idea in quantum field theory and cosmology. This occurs via local formation of bubbles of true vacuum with their subsequent rapid expansion. It can be considered as a relativistic analog of a first-order phase transition in condensed matter. We propose an experimental test of false vacuum decay using an ultra-cold spinor Bose gas. A false vacuum for the relative phase of two spin components, serving as the unstable scalar field, is generated by means of a modulated linear coupling of the spin components. We analyze the system theoretically using the functional integral approach and show that various microscopic degrees of freedom in the system, albeit leading to dissipation in the relative phase sector, will not hamper the observation of the false vacuum decay in the laboratory. This is substantiated by numerical simulations, which demonstrate the spontaneous formation of true vacuum bubbles with realistic parameters and time-scales.

See also:;

Fate of the false vacuum: towards realization with ultra-cold atoms, O. Fialko, B. Opanchuk, A. I. Sidorov, P. D. Drummond and J. Brand, Europhys. Lett., 110, 56001 (22 June 2015), doi:10.1209/0295-5075/110/56001

Quantum decay of a relativistic scalar field from a false vacuum is a fundamental idea in quantum field theory. It is relevant to models of the early Universe, where the nucleation of bubbles gives rise to an inflationary universe and the creation of matter. Here we propose a laboratory test using an experimental model of an ultra-cold spinor Bose gas. A false vacuum for the relative phase of two spin components, serving as the unstable scalar field, is generated by means of a modulated radio-frequency coupling of the spin components. Numerical simulations demonstrate the spontaneous formation of true vacuum bubbles with realistic parameters and time-scales.

This sounds like a good start.

No Comments

Cuprate Thin Film Reveals a Nodeless High-Tc Pairing Gap

by Tommy on 8/07/2016

Nodeless pairing in superconducting copper-oxide monolayer films on Bi2Sr2CaCu2O8+δ, Yong Zhong, Yang Wang, Sha Han, Yan-Feng Lv, Wen-Lin Wang, Ding Zhang, Hao Ding, Yi-Min Zhang, Lili Wang, Ke He, Ruidan Zhong, John A. Schneeloch, Gen-Da Gu, Can-Li Song, Xu-Cun Ma and Qi-Kun Xue (7 July 2016)

The pairing mechanism of high-temperature superconductivity in cuprates remains the biggest unresolved mystery in condensed matter physics. To solve the problem, one of the most effective approaches is to investigate directly the superconducting CuO2 layers. Here, by growing CuO2 monolayer films on Bi2Sr2CaCu2O8+δ substrates, we identify two distinct and spatially separated energy gaps centered at the Fermi energy, a smaller U-like gap and a larger V-like gap on the films, and study their interactions with alien atoms by low-temperature scanning tunneling microscopy. The newly discovered U-like gap exhibits strong phase coherence and is immune to scattering by K, Cs and Ag atoms, suggesting its nature as a nodeless superconducting gap in the CuO2 layers, whereas the V-like gap agrees with the well-known pseudogap state in the underdoped regime. Our results support an s-wave superconductivity in Bi2Sr2CaCu2O8+δ, which, we propose, originates from the modulation-doping resultant two-dimensional hole liquid confined in the CuO2 layers.

Ok. Rodger Dodger. I read you fine. That’s affirmative. Over.

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Axion Higgs Quantum Critical Gravitational Black Hole Collapse

by Tommy on 2/07/2016
CERN LHC Cosmic Wormhole Portal Higher Dimensions

CERN LHC Cosmic Wormhole Portal

Or rather it’s the graviton – axion – Higgs. It doesn’t seem to be gravitons – Higgs – axions.

One would have to calculate when quantum critical black hole collapse would occur, using results from tabletop axion – Higgs simulators and cold atom modelling, and a thorough analysis of cosmological parameters. Certainly LIGOs are going to be super helpful here.

Offhand I would say under 100 TeV. Probably 1000 TeV would be doable.

Given the costs, guidance will be helpful.

Tread lightly my friends.

No Comments

Symmetry Protected Bosonic Thermal Heat Currents Explored

by Tommy on 30/06/2016

Topological Heat Transport and Symmetry-Protected Boson Currents, Ángel Rivas and Miguel A. Martin-Delgado (24 June 2016)

The study of non-equilibrium properties in topological systems is of practical and fundamental importance. Here, we analyze the stationary properties of a two-dimensional boson topological insulator coupled to two thermal baths in the quantum open-system formalism. Novel phenomena appear like chiral edge heat currents that are the out-of-equilibrium counterparts of the zero-temperature edge currents. We find the new set of discrete symmetries that protect these topological heat currents, differing from the zero-temperature limit. Remarkably, one of these currents flows opposite to the decreasing external temperature gradient. As the starting point, we consider the case of a single external reservoir showing prominent results like thermal erasure effects and topological thermal currents. Our results are experimentally accessible with platforms like photonics systems and optical lattices.

No Comments

Topological Phononics and Phonon Diodes Proposed

by Tommy on 28/06/2016

Topological Phononics and Phonon Diode, Yizhou Liu, Yong Xu, Shou-Cheng Zhang and Wenhui Duan (26 June 2016)

Generalizing the concept of topology from electrons to phonons could bring in an intriguing emerging field of “topological phononics”. For this purpose we propose a Schrödinger-like equation of phonons where topology-related quantities, time reversal symmetry (TRS) and its breaking can be naturally introduced. A Haldane model of phonons for a two-dimensional honeycomb lattice is then developed to describe the interplay of symmetry and quantum (anomalous) Hall-like phonon states. The nontrivial topological phase supports one-way gapless edge states within the bulk gap, which can conduct phonons without dissipation. Moreover, breaking inversion symmetry and TRS simultaneously is suggested to open a route for valley phononics and phonon diode. The findings could help design unprecedented new phononic devices.

This is exactly what I needed to complete the design of the ZT = 4 thermoelectric device.

No Comments

Topological Lifshitz Transitions By Grigory G. E. Volovik

by Tommy on 28/06/2016

Topological Lifshitz Transitions, G. E. Volovik, Accepted for the Issue of Journal of Low Temperatures Devoted to Centenary of I. M. Lifshitz (20 October 2016)

Different types of Lifshitz transitions are governed by topology in momentum space. They involve the topological transitions with the change of topology of Fermi surfaces, Weyl and Dirac points, nodal ines, and also the transitions between the fully gapped states.

The future has most definitely arrived.

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A Basic Review of the Quantum Hall Effect

by Tommy on 23/06/2016

Lectures on the Quantum Hall Effect, David Tong (21 June 2016)

The purpose of these lectures is to describe the basic theoretical structures underlying the rich and beautiful physics of the quantum Hall effect. The focus is on the interplay between microscopic wavefunctions, long-distance effective Chern-Simons theories, and the modes which live on the boundary. The notes are aimed at graduate students in any discipline where ℏ = 1. A working knowledge of quantum field theory is assumed.


1. The Basics (Landau levels and Berry phase).
2. The Integer Quantum Hall Effect.
3. The Fractional Quantum Hall Effect.
4. Non-Abelian Quantum Hall States.
5. Chern-Simons Theories.
6. Edge Modes.

These lectures were given at TIFR, Mumbai. Individual chapters can be downloaded from this http URL. The notes on the course webpage will be updated more frequently than those on the arXiv.

David Tong: Lectures on the Quantum Hall Effect (With Web and ArXiv References)

No Comments

Abram Steiner – The Universal Hydroponic Nutrient Solution

by Tommy on 23/06/2016
Abram Steiner Hydroponics

Abram Steiner Hydroponics

Vale, Bram Steiner, Soilless culture pioneer Abram Steiner, 1920-2016

Rock Donnan, Practical Hydroponics and Greenhouses, No. 166 (April 2016)

This was the first real science project that I did, besides the mathematics. I had hit the ground running (hobbling in crutches as I recall) in 1978, after finally making the move to the farm, and was easily doing these calculations in first year first semester general chemistry class, By 1979 I had it all worked out, and quickly verified it all by flame photospectroscopy. It soon went awry.

I only recently reviewed the idea in this short little essay.

Which led directly to the GroX.

Mars GroX will be lighter. (fixed)

Nutrient Solutions for Hydroponic Systems, Libia I. Trejo-Téllez and Fernando C. Gómez-Merino, Hydroponics – A Standard Methodology for Plant Biological Researches, Dr. Toshiki Asao (Ed.) (23 March 2012)

Finally it’s all back on track.

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CERN LHC ATLAS CMS Rumor – 750 GeV Bump Not Seen

by Tommy on 22/06/2016

I can only assess these rumors a rumor credibility index of one unit Motl. It doesn’t look good.

That’s ok with me, as I originally stated that I don’t need this pseudo particle for what I propose.

This is already a done deal. Up next for me?

I am open to job offers.

D.C., Seattle, Denver.




In that order.

Anywhere but Wisconsin.

Update: Get your job offers in before I sign Kermit the Frog’s rich and famous contract!

Update 2: Miss Piggy has been leaving a lot of messages on my voice mail, so hurry up!

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Large Nearby Resonant Quasi Satellite Asteroid Near Earth

by Tommy on 17/06/2016
Asteroid Earth Quasi Satellite 2016 HO3

Asteroid Earth Quasi Satellite 2016 HO3

2016 HO3. As large as 100 meters in diameter. As close as 9 million miles. Perfect.

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The Gravimetrics Era Has Begun – Gravonomy Has Arrived

by Tommy on 15/06/2016

Hmmmmm Bleep. Don’t blink, or you’ll miss it.

Update: Gravinomics – the economics of black holes. Gravology!

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Schrödinger’s Rocket is Dead

by Tommy on 15/06/2016

It’s official, Elon Musk looked inside the box.

Deimos 2 ASDS Barge Smoking Remains

Deimos 2 ASDS Barge Smoking Remains

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Photonic Quantum Geometry and Topology Simulator Created

by Tommy on 13/06/2016

Synthetic Landau levels for photons, Nathan Schine, Albert Ryou, Andrey Gromov, Ariel Sommer and Jonathan Simon, Nature (8 June 2016), doi:10.1038/nature17943

Synthetic photonic materials are an emerging platform for exploring the interface between microscopic quantum dynamics and macroscopic material properties. Photons experiencing a Lorentz force develop handedness, providing opportunities to study quantum Hall physics and topological quantum science. Here we present an experimental realization of a magnetic field for continuum photons. We trap optical photons in a multimode ring resonator to make a two-dimensional gas of massive bosons, and then employ a non-planar geometry to induce an image rotation on each round-trip. This results in photonic Coriolis/Lorentz and centrifugal forces and so realizes the Fock–Darwin Hamiltonian for photons in a magnetic field and harmonic trap. Using spatial- and energy-resolved spectroscopy, we track the resulting photonic eigenstates as radial trapping is reduced, finally observing a photonic Landau level at degeneracy. To circumvent the challenge of trap instability at the centrifugal limit, we constrain the photons to move on a cone. Spectroscopic probes demonstrate flat space (zero curvature) away from the cone tip. At the cone tip, we observe that spatial curvature increases the local density of states, and we measure fractional state number excess consistent with the Wen–Zee theory, providing an experimental test of this theory of electrons in both a magnetic field and curved space. This work opens the door to exploration of the interplay of geometry and topology, and in conjunction with Rydberg electromagnetically induced transparency, enables studies of photonic fractional quantum Hall fluids and direct detection of anyons.

Ok, that was quick. Let the quantum gravity cosmic singularity simulation era begin!

University of Chicago Press Release

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We Live in a Spacetime Quantum Field Theory Pseudogap

by Tommy on 9/06/2016

The Cosmic Evolution of Autobiogenesis

We are the weirdness in the spacetime pseudogap.

Pandora’s box is open. The cat is out of the bag.

Do you know any other good euphemisms?

I’m afraid I’m fresh out of them.

Pop Goes The Weasel

All around the mulberry bush,
The monkey chased the weasel.
The monkey stopped to pull up his sock,
Pop! goes the weasel.

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CERN LHC Finds Baby Falcon Mascot For SpaceX Elon Musk

by Tommy on 9/06/2016


Photo Credit: Sophia Bennett/CERN

I hope this works out for him.

Her. The CERN chick.

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Simulating Holographic Quantum Gravity With Ultracold Gases

by Tommy on 9/06/2016

Creating and probing the Sachdev-Ye-Kitaev model with ultracold gases: Towards experimental studies of quantum gravity, Ippei Danshita, Masanori Hanada and Masaki Tezuka (8 June 2016)

We suggest that the holographic principle, combined with recent technological advances in atomic, molecular, and optical physics, can lead to experimental studies of quantum gravity. As a specific example, we consider the Sachdev-Ye-Kitaev (SYK) model, which consists of spin-polarized fermions with an all-to-all random two-body hopping and has been conjectured to be dual to a certain quantum gravitational system. We propose that the SYK model can be engineered by confining ultracold fermionic atoms into optical lattices and coupling two atoms with molecular states via photo-association lasers. Achieving low-temperature states of the SYK model is interpreted as a realization of a stringy black hole, provided that the holographic duality is true. We also show how to measure out-of-time-order correlation functions of the SYK model, which allow for identifying the maximally chaotic property of the black hole.

Wasn’t I just talking about this in my cosmic evolution essay? Sure I was. This morning!

I’m glad this is all decided now.

No Comments

Space Based Gravitational Wave Detectors Easily Possible

by Tommy on 8/06/2016

Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results, M. Armano et al., Phys. Rev. Lett. 116, 231101 (7 June 2016), doi:10.1103/PhysRevLett.116.231101

We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 ± 0.1 fm s−2/√Hz, or (0.54 ± 0.01) × 10−15g/√Hz, with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 ± 0.3) fm/√Hz, about 2 orders of magnitude better than requirements. At f ≤ 0.5  mHz we observe a low-frequency tail that stays below 12 fm s−2/√Hz down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

APS Commentary

ESA Press Release

This entire field has wildly exceeded my expectations.

Gravitational manipulation is coming.

No Comments

Local Value of Hubble Constant Measured More Precisely

by Tommy on 3/06/2016

A 2.4% Determination of the Local Value of the Hubble Constant, Adam G. Riess, Lucas M. Macri, Samantha L. Hoffmann, Dan Scolnic, Stefano Casertano, Alexei V. Filippenko, Brad E. Tucker, Mark J. Reid, David O. Jones, Jeffrey M. Silverman, Ryan Chornock, Peter Challis, Wenlong Yuan, Peter J. Brown and Ryan J. Foley, Accepted ApJ (17 May 2016)

We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to reduce the uncertainty in the local value of the Hubble constant (H_0) from 3.3% to 2.4%. Improvements come from new, near-infrared observations of Cepheid variables in 11 new hosts of recent SNe~Ia, more than doubling the sample of SNe~Ia having a Cepheid-calibrated distance for a total of 19; these leverage the magnitude-z relation based on 300 SNe~Ia at z < 0.15. All 19 hosts and the megamaser system NGC4258 were observed with WFC3, thus nullifying cross-instrument zeropoint errors. Other improvements include a 33% reduction in the systematic uncertainty in the maser distance to NGC4258, more Cepheids and a more robust distance to the LMC from late-type DEBs, HST observations of Cepheids in M31, and new HST-based trigonometric parallaxes for Milky Way (MW) Cepheids. We consider four geometric distance calibrations of Cepheids: (i) megamasers in NGC4258, (ii) 8 DEBs in the LMC, (iii) 15 MW Cepheids with parallaxes, and (iv) 2 DEBs in M31. H0 from each is 72.02 +/- 2.51, 71.82 +/- 2.67, 75.91 +/- 2.37, and 74.31 +/- 3.27 km/sec/Mpc, respectively. Our best estimate of 73.00 +/- 1.75 km/sec/Mpc combines the anchors NGC4258, MW, and LMC, and includes systematic errors for a final uncertainty of 2.4%. This value is 3.3 sigma higher than 66.93 +/- 0.62 km/sec/Mpc predicted by LambdaCDM with 3 neutrinos with mass 0.06 eV and the Planck data, but reduces to 2.0 sigma relative to the prediction of 69.3 +/- 0.7 km/sec/Mpc with the combination of WMAP + ACT + SPT + BAO, suggesting systematic uncertainties in CMB measurements may play a role in the tension. If we take the conflict between Planck and H0 at face value, one plausible explanation could involve an additional source of dark radiation in the early Universe in the range of Delta Neff = 0.4 – 1. We anticipate significant improvements in H0 from upcoming parallax measurements.

Anybody remember Universe – The Infinite Frontier?

That was probably the best introductory astronomy series ever. I practically earned a BS degree at the St. Petersburg Community college watching that over and over again, endlessly taping it onto extended (six hour) play VHS cassettes on my VCR.

Obviously my preferred hypthesis is a quantum critical Higgs leading to quantum critical black hole collapse, with only the standard model remaining at the electroweak scale, along with a bunch of axions and gravitons of varying mass, hopefully at the eV scale and the low TeV scale.

Gravitational manipulation via bosonic axion fields and axion excitation anyone?

No Comments

Earth Water Provided By Carbonaceous Asteroid Bombardment

by Tommy on 1/06/2016

An asteroidal origin for water in the Moon, Jessica J. Barnes, David A. Kring, Romain Tartèse, Ian A. Franchi, Mahesh Anand and Sara S. Russell, Nature Communications, 7, 11684 (31 May 2016), doi:10.1038/ncomms11684

The Apollo-derived tenet of an anhydrous Moon has been contested following measurement of water in several lunar samples that require water to be present in the lunar interior. However, significant uncertainties exist regarding the flux, sources and timing of water delivery to the Moon. Here we address those fundamental issues by constraining the mass of water accreted to the Moon and modelling the relative proportions of asteroidal and cometary sources for water that are consistent with measured isotopic compositions of lunar samples. We determine that a combination of carbonaceous chondrite-type materials were responsible for the majority of water (and nitrogen) delivered to the Earth–Moon system. Crucially, we conclude that comets containing water enriched in deuterium contributed significantly < 20% of the water in the Moon. Therefore, our work places important constraints on the types of objects impacting the Moon ~ 4.5 – 4.3 billion years ago and on the origin of water in the inner Solar System.

I’ll take that drink on the rocks!

No Comments

Engineered Van der Waals Multilayer Heterojunction Excitons

by Tommy on 16/05/2016

Near-Unity Absorption in Van der Waals Semiconductors for Ultrathin Photovoltaics, Deep Jariwala, Artur R. Davoyan, Giulia Tagliabue, Michelle C. Sherrott, Joeson Wong and Harry A. Atwater (13 May 2016)

Key criteria for high efficiency photovoltaics include achieving high radiative efficiency, maximizing above-bandgap semiconductor absorption, and enabling carrier-selective charge collection at the cell operating point that exploits the full quasi-Fermi level separation for the carriers. High efficiency inorganic photovoltaic materials (e.g., Si, GaAs and GaInP) can achieve these criteria, but thin film photovoltaic absorbers have lacked the ability to fulfill one or more of these criteria, often due to surface and interface recombination effects. In contrast, Van der Waals semiconductors have naturally passivated surfaces with electronically active edges that allows retention of high electronic quality down-to the atomically thin limit and recent reports suggest that Van der Waals semiconductors can achieve the first criterion of high radiative efficiency. Here, we report that the second criteria for high efficiency of near-unity light absorption is possible in extremely thin (< 15 nm) Van der Waals semiconductor structures by coupling to strongly damped optical modes of semiconductor/metal heterostructures. We demonstrate near unity, broadband absorbing photovoltaic devices using sub-15 nm thick transition metal dichalcogenides (TMDCs) as van der Waals semiconductor active layers. Our TMDC devices show a short circuit current density > 10 mA/cm2 at ~ 20 Suns and exhibits spectral response that parallels the spectral absorption over the above bandgap region. Our work addresses one of the key criteria to enable TMDCs to achieve high photovoltaic efficiency.

See also:

Engineering and Manipulating Structured Excitons, Xiaoning Zang, Simone Montangero, Lincoln D. Carr and Mark T. Lusk (13 May 2016)

When a semiconductor absorbs light, the resulting electron-hole superposition amounts to a uncontrolled quantum ripple that eventually degenerates into diffusion (Frenkel 1931, Wannier 1937, Lanzani 2012). If the conformation of these excitonic superpositions could be engineered, though, they would constitute a new means of transporting information and energy. We show that properly designed laser pulses can be used to create such structured excitons. They can be formed with a prescribed speed, direction and spectral make-up that allows them to be selectively passed, rejected or even dissociated using superlattices. Their coherence also provides a handle for manipulation using active, external controls. Energy and information can be conveniently processed and subsequently removed at a distant site by reversing the original procedure to produce a stimulated emission. The ability to create, manage and remove structured excitons comprises the foundation for opto-excitonic circuits with application to a wide range of quantum information, energy and light-flow technologies. The paradigm is demonstrated using both tight-binding and Time-Domain Density Functional Theory simulations.

I don’t quite understand what the hold up with this could be.

Commercial capital, or government funding?

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Superconductors as (Very) Light Axion Dark Matter Absorbers

by Tommy on 16/05/2016

Detecting Ultralight Bosonic Dark Matter via Absorption in Superconductors, Yonit Hochberg, Tongyan Lin and Kathryn M. Zurek (22 April 2016)

Superconducting targets have recently been proposed for the direct detection of dark matter as light as a keV, via elastic scattering off conduction electrons in Cooper pairs. Detecting such light dark matter requires sensitivity to energies as small as the superconducting gap of O(meV). Here we show that these same superconducting devices can detect much lighter DM, of meV to eV mass, via dark matter absorption on a conduction electron, followed by emission of an athermal phonon. We demonstrate the power of this setup for relic kinetically mixed hidden photons, pseudoscalars, and scalars, showing the reach can exceed current astrophysical and terrestrial constraints with only a moderate exposure.

See also:

Superconducting Detectors for Super Light Dark Matter, Yonit Hochberg, Yue Zhao and Kathryn M. Zurek, Phys. Rev. Lett. 116, 011301 (7 January 2016), doi:10.1103/PhysRevLett.116.011301

We propose and study a new class of superconducting detectors which are sensitive to O(meV) electron recoils from dark matter-electron scattering. Such devices could detect dark matter as light as the warm dark matter limit, mX > keV. We compute the rate of dark matter scattering off of free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with terrestrial and cosmological/astrophysical constraints could be detected by such detectors with a moderate size exposure.

With topological superconductors I can detect fluctuating dynamical axion fields as well.

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Sulfur Isotopes Date Great Atmospheric Oxygen Inversion Event

by Tommy on 14/05/2016

Rapid oxygenation of Earth’s atmosphere 2.33 billion years ago, Genming Luo, Shuhei Ono, Nicolas J. Beukes, David T. Wang, Shucheng Xie and Roger E. Summons, Science Advances 2, 5, e1600134 (6 May 2016), doi:10.1126/sciadv.1600134

Molecular oxygen (O2) is, and has been, a primary driver of biological evolution and shapes the contemporary landscape of Earth’s biogeochemical cycles. Although “whiffs” of oxygen have been documented in the Archean atmosphere, substantial O2 did not accumulate irreversibly until the Early Paleoproterozoic, during what has been termed the Great Oxygenation Event (GOE). The timing of the GOE and the rate at which this oxygenation took place have been poorly constrained until now. We report the transition (that is, from being mass-independent to becoming mass-dependent) in multiple sulfur isotope signals of diagenetic pyrite in a continuous sedimentary sequence in three coeval drill cores in the Transvaal Supergroup, South Africa. These data precisely constrain the GOE to 2.33 billion years ago. The new data suggest that the oxygenation occurred rapidly—within 1 to 10 million years—and was followed by a slower rise in the ocean sulfate inventory. Our data indicate that a climate perturbation predated the GOE, whereas the relationships among GOE, “Snowball Earth” glaciation, and biogeochemical cycling will require further stratigraphic correlation supported with precise chronologies and paleolatitude reconstructions.

It’s quite possible the oxygen was there all along in the upper atmosphere and the climate perturbation initiated a great atmospheric oxygen inversion layer collapse to the surface, resulting in geologically instantaneous oxygenation. That’s my crackpot theory at this point.

This will take a while to sort out.

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Early Earth Achaean Atmosphere Was Chemically Differentiated

by Tommy on 12/05/2016

Ancient micrometeorites suggestive of an oxygen-rich Archaean upper atmosphere, Andrew G. Tomkins, Lara Bowlt, Matthew Genge, Siobhan A. Wilson, Helen E. A. Brand and Jeremy L. Wykes, Nature, 533, 235–238 (11 May 2016), doi:10.1038/nature17678

It is widely accepted that Earth’s early atmosphere contained less than 0.001 per cent of the present-day atmospheric oxygen (O2) level, until the Great Oxidation Event resulted in a major rise in O2 concentration about 2.4 billion years ago. There are multiple lines of evidence for low O2 concentrations on early Earth, but all previous observations relate to the composition of the lower atmosphere in the Archaean era; to date no method has been developed to sample the Archaean upper atmosphere. We have extracted fossil micrometeorites from limestone sedimentary rock that had accumulated slowly 2.7 billion years ago before being preserved in Australia’s Pilbara region. We propose that these micrometeorites formed when sand-sized particles entered Earth’s atmosphere and melted at altitudes of about 75 to 90 kilometres (given an atmospheric density similar to that of today). Here we show that the FeNi metal in the resulting cosmic spherules was oxidized while molten, and quench-crystallized to form spheres of interlocking dendritic crystals primarily of magnetite (Fe3O4), with wüstite (FeO)+metal preserved in a few particles. Our model of atmospheric micrometeorite oxidation suggests that Archaean upper-atmosphere oxygen concentrations may have been close to those of the present-day Earth, and that the ratio of oxygen to carbon monoxide was sufficiently high to prevent noticeable inhibition of oxidation by carbon monoxide. The anomalous sulfur isotope (Δ33S) signature of pyrite (FeS2) in seafloor sediments from this period, which requires an anoxic surface environment, implies that there may have been minimal mixing between the upper and lower atmosphere during the Archaean.

I suppose this would be the greenhouse gas and oxygen companion to the previous article.

They told me when I was a young child that I would not start to know the answers to some of these questions before the second decade of the next century, and I now remember how disappointed I was that there would be no flat screen TVs and Dick Tracy watches any time soon. But here it is already now, the 2nd decade of the 21st century, and they were right!

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This is Your Only Planet Earth on Carbon Dioxide Steroids

by Tommy on 12/05/2016
Planet Earth Average Global Surface Temperature Anomaly

Planet Earth Average Global Surface Temperature Anomaly

Fort McMurray citizens can now get back to their important task of profiting from destruction.

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Monolayer Arsenene and Antimonene Allotropes Studied

by Tommy on 10/05/2016

First-principle calculations of phononic, electronic and optical properties of monolayer arsenene and antimonene allotropes, Yuanfeng Xu, Bo Peng, Hao Zhang, Hezhu Shao, Rongjun Zhang, Hongliang Lu, David Wei Zhang and Heyuan Zhu (12 April 2016)

Recently a stable monolayer of antimony in buckled honeycomb structure called antimonene was successfully grown on 3D topological insulator Bi2Te3 and Sb2Te3, which displays semiconducting properties. By first principle calculations, we systematically investigate the phononic, electronic and optical properties of α− and β− allotropes of monolayer arsenene/antimonene. We investigate the dynamical stabilities of these four materials by considering the phonon dispersions. The obtained electronic structures reveal the direct band gap of monolayer α−As/Sb and indirect band gap of β−As/Sb. Significant absorption is observed in α−Sb, which can be used as a broad saturable absorber.

See also:

Atomically Thin Group V Elemental Films: Theoretical Investigations of Antimonene Allotropes, Gaoxue Wang, Ravindra Pandey and Shashi P. Karna, ACS Appl. Mater. Interfaces, 2015, 7 (21), pp 11490–11496 (8 May, 2015), DOI:10.1021/acsami.5b02441

Group V elemental monolayers including phosphorene are emerging as promising 2D materials with semiconducting electronic properties. Here, we present the results of first-principles calculations on stability, mechanical and electronic properties of 2D antimony (Sb), antimonene. Our calculations show that free-standing α and β allotropes of antimonene are stable and semiconducting. The α-Sb has a puckered structure with two atomic sublayers and β-Sb has a buckled hexagonal lattice. The calculated Raman spectra and STM images have distinct features thus facilitating characterization of both allotropes. The β-Sb has nearly isotropic mechanical properties, whereas α-Sb shows strongly anisotropic characteristics. An indirect–direct band gap transition is expected with moderate tensile strains applied to the monolayers, which opens up the possibility of their applications in optoelectronics.

I’m not quite sure if I covered this earlier or not.

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Early Archaean Earth Atmosphere Less Than Half of Today’s

by Tommy on 10/05/2016

Earth’s air pressure 2.7 billion years ago constrained to less than half of modern levels, Sanjoy M. Som, Roger Buick, James W. Hagadorn, Tim S. Blake, John M. Perreault, Jelte P. Harnmeijer and David C. Catling, Nature Geoscience (9 May 2016), doi:10.1038/ngeo2713

How the Earth stayed warm several billion years ago when the Sun was considerably fainter is the long-standing problem of the ‘faint young Sun paradox’. Because of negligible O2 and only moderate CO2 levels in the Archaean atmosphere, methane has been invoked as an auxiliary greenhouse gas. Alternatively, pressure broadening in a thicker atmosphere with a N2 partial pressure around 1.6–2.4 bar could have enhanced the greenhouse effect. But fossilized raindrop imprints indicate that air pressure 2.7 billion years ago (Gyr) was below twice modern levels and probably below 1.1 bar, precluding such pressure enhancement. This result is supported by nitrogen and argon isotope studies of fluid inclusions in 3.0 – 3.5 Gyr rocks. Here, we calculate absolute Archaean barometric pressure using the size distribution of gas bubbles in basaltic lava flows that solidified at sea level ~ 2.7 Gyr in the Pilbara Craton, Australia. Our data indicate a surprisingly low surface atmospheric pressure of Patm = 0.23 ± 0.23 (2σ) bar, and combined with previous studies suggests ~ 0.5 bar as an upper limit to late Archaean Patm. The result implies that the thin atmosphere was rich in auxiliary greenhouse gases and that Patm fluctuated over geologic time to a previously unrecognized extent.

The origin and evolution of the nitrogen component of Earth’s atmosphere has been high on my unsolved problems list since I was a very young child. It’s nice to finally see even subtle hints of some of the answers here. The same goes for Mars. It starts with big early planetoid impacts.

Update: And big close planetoid flybys too, apparently.

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Atomic Quantum Simulation of 3D U(1) Gauge Higgs Model

by Tommy on 10/05/2016

Atomic quantum simulation of a three-dimensional U(1) gauge-Higgs model, Yoshihito Kuno, Shinya Sakane, Kenichi Kasamatsu, Ikuo Ichinose and Tetsuo Matsui (9 May 2016)

In this paper, we study atomic quantum simulations of a U(1) gauge-Higgs model on a three-dimensional (3D) spatial lattice. We start from an extended 3D Bose-Hubbard model with nearest-neighbor repulsions and show that it can simulate a U(1) gauge-Higgs model with next nearest-neighbor Higgs couplings. Here the phase of the boson variable on each site of the optical lattice describes the vector potential on each link of the gauge-model lattice. To determine the phase diagram of the gauge-Higgs model at a zero temperature, we perform Monte-Carlo simulations of the corresponding 3+1-dimensional U(1) gauge-Higgs model, and obtain the three phases, i.e., the confinement, Coulomb and Higgs phases. To investigate the dynamical properties of the gauge-Higgs model, we apply the Gross-Pitaevskii equations to the extended Bose-Hubbard model. We simulate the time-evolution of an electric flux initially put on a straight line connecting two external point charges. We also calculate the potential energy between this pair of charges and obtain the string tension in the confinement phase. Finally, we propose a feasible experimental setup for the atomic simulations of this quantum gauge-Higgs model in the 3D optical lattice.

This is going straight into my autobiogenesis essay.

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Binary Group V – V Monolayer Bonding Compounds Sought

by Tommy on 10/05/2016

Atomically thin binary V-V compound semiconductor: a first-principles study, Weiyang Yu, Zhili Zhu, Chun-Yao Niu, Xiaolin Cai and Wei-Bing Zhang (6 April 2016)

Searching the novel 2D semiconductor is crucial to develop the next-generation low-dimensional electronic device. Using first-principles calculations, we propose a class of unexplored binary V-V compound semiconductor (PN, AsN, SbN, AsP, SbP and SbAs) with monolayer black phosphorene (α) and blue phosphorene (β) structure. Our phonon spectra and room-temperature molecular dynamics (MD) calculations indicate that all compounds are very stable. Moreover, most of compounds are found to present a moderate energy gap in the visible frequency range, which can be tuned gradually by in-plane strain. Especially, α-phase V-V compounds have a direct gap while β-SbN, AsN, SbP, and SbAs may be promising candidates of 2D solar cell materials due to a wide gap separating acoustic and optical phonon modes. Furthermore, vertical heterostructures can be also built using lattice matched α(β)-SbN and phosphorene, and both vdW heterostructures are found to have intriguing direct band gap. The present investigation not only broads the scope of layered group V semiconductors but also provides an unprecedented route for the potential applications of 2D V-V families in optoelectronic and nanoelectronic semiconductor devices.

Moving onwards inexorably, as if drawn by a magnet.

Or as Mothra to Godzilla.

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Dirac Monopoles from Weyl Hamiltonian by Green’s Functions

by Tommy on 4/05/2016

Topological Numbers and the Weyl Semimetal, Mahmut Elbistan (3 May 2016)

Generalized Dirac monopoles in momentum space are constructed in even d+1 dimensions from the Weyl Hamiltonian in terms of Green’s functions. In 3+1 spacetime dimensions, the (unit) charge of the monopole is equal to both the winding number and the Chern number, expressed as the integral of the Berry curvature. Based on the equivalence of the Chern and winding numbers, a chirally coupled field theory action is proposed for the Weyl semimetal phase. At the one loop order, the effective action yields both the chiral magnetic effect and the anomalous Hall effect. The Chern number appears as a coefficient in the conductivity, thus emphasizes the role of topology. The anomalous contribution of chiral fermions to transport phenomena is reflected as the gauge anomaly with the topological term E . B. Relevance of monopoles and Chern numbers for the semiclassical chiral kinetic theory is also discussed.

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Kibble – Zurek Mechanism Simulated in Cold Atom Systems

by Tommy on 4/05/2016

Universal space-time scaling symmetry in the dynamics of bosons across a quantum phase transition, Logan W. Clark, Lei Feng and Cheng Chin (3 May 2016)

The dynamics of many-body systems spanning condensed matter, cosmology, and beyond is hypothesized to be universal when the systems cross continuous phase transitions. The universal dynamics is expected to satisfy a scaling symmetry of space and time with the crossing rate, inspired by the Kibble-Zurek mechanism. We test this symmetry based on Bose condensates in a shaken optical lattice. Shaking the lattice drives condensates across an effectively ferromagnetic quantum phase transition. After crossing the critical point, the condensates manifest delayed growth of spin fluctuations and develop anti-ferromagnetic spatial correlations resulting from sub-Poisson generation of topological defects. The characteristic times and lengths scale as power-laws of the crossing rate, yielding the temporal exponent 0.50(2) and the spatial exponent 0.26(2), consistent with theory. Furthermore, the fluctuations and correlations are invariant in scaled space-time coordinates, in support of the scaling symmetry of quantum critical dynamics.

To Infinity, And Beyond!

Update: Tom Kibble passed away.

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I, Tommy – I’m Naming the SI Unit of Momentum After Myself

by Tommy on 30/04/2016
Higgs Particle Collision

Higgs Particle Collision

Ok, after inventing the scientific domain of engineering science, and then going on to invent the subdomain of ‘quantum astrophysics’, what do I do for an encore? Well, I did this quite a while ago during the era of the static ISP website, simple javascripts and AJAX, on my fundamental physical and chemical units, symbols and constants pages and then in my infamous AJAXified interactive periodic table of the elements. The SI unit of momentum is mine! I’m claiming it. Me.

SI Unit of Momentum

Symbol : I (Impulse)

Name : Fritz

Units : kg m s-1

You heard it here first. I can’t remember if I ever posted this to the usenet.

I dare you to out crackpot this.

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Growth, Transport Properties – Bismuth on Potassium Chloride

by Tommy on 29/04/2016

Semiconductor- to metallic-like behavior in Bi thin films on KCl substrate, Thanh Nhan Bui, Jean-Pierre Raskin and Benoit Hackens, J. Appl. Phys. 119, 135304 (5 April 2016); DOI:10.1063/1.4945036

Bi thin films, with a thickness of 100 nm, are deposited by electron-beam evaporation on a freshly cleaved (100) KCl substrate. The substrate temperature during film growth (Tdep) ranges from room temperature up to 170 °C. Films deposited at room temperature exhibit a maze-like microstructure typical of the rhombohedral (110) texture, as confirmed by X-ray diffraction. For Tdep above 80 °C, a different microstructure appears, characterized by concentric triangular shapes corresponding to the trigonal (111) texture. Temperature dependence of the resistivity shows a transition from a semiconductor-like behavior for films deposited at room temperature to a metallic-like behavior for Tdep above 80 °C. From magnetoresistance measurements between room temperature and 1.6 K, we extract the electron and hole mobilities, concentrations, and mean free paths, which allow to draw a complete picture of the transport properties of both types of films.

Ok, back to the grind.

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CDW Phase Diagram of the Cuprates Further Refined Yet Again

by Tommy on 28/04/2016
Dynamic Fluctuating CDW Cuprate Phase Diagram

Dynamic Fluctuating CDW Cuprate Phase Diagram

Dynamical charge density waves rule the phase diagram of cuprates, S. Caprara, C. Di Castro, G. Seibold and M. Grilli (26 April 2016)

In the last few years charge density waves (CDWs) have been ubiquitously observed in cuprates and are now the most investigated among the competing orders in the longstanding (but still hot) debate on high-temperature superconducting cuprates. Different dome-shaped CDW onset lines in the temperature vs. doping phase diagram are detected by experiments with probes having different characteristic timescales. These lines are extrapolated at zero temperature to different quantum critical points (QCPs) in agreement with the long-standing theoretical result that CDW’s are present in these systems and disappear with a QCP by increasing doping. This QCP is buried underneath the superconducting dome, in the optimal doping region (i.e., where the superconducting critical temperature Tc is highest). A wealth of new experimental data raise fundamental issues that challenge the various theoretical proposals. Here, we reproduce the complex experimental phase diagram and provide a coherent solution to all these problems based on the occurrence of dynamically fluctuating CDWs.

Who did not see this coming?

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Optimum Performance of Thermoelectric Energy Conversion

by Tommy on 28/04/2016

Thermoelectric energy converters under a trade-off figure of merit with broken time-reversal symmetry, I. Iyyappan and M. Ponmurugan (26 April 2016)

We study the optimum performance of the thermoelectric energy converters such as heat engines and refrigerators with broken time-reversal symmetry by applying unified trade-off figure of merit Ω˙, which takes the account of best compromise between the maximum work extraction and the minimum work loss. We find that the maximum Ω˙ criterion provide the significantly high performance of the thermoelectric energy converter if the system possess reasonably large value of the asymmetric parameter as compared to the maximum χ criterion. However, the maximum χ criterion provide the better performance than the maximum Ω˙ criterion for low value of the asymmetric parameter. Our results can be useful to design high efficient real thermoelectric heat engines and refrigerators with broken time-reversal symmetry.

These kinds of in depth analyses are extremely insightful and helpful.

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Quantum Proton Tunneling of Water Molecules Trapped in Beryl

by Tommy on 26/04/2016

Quantum Tunneling of Water in Beryl: A New State of the Water Molecule, Alexander I. Kolesnikov, George F. Reiter, Narayani Choudhury, Timothy R. Prisk, Eugene Mamontov, Andrey Podlesnyak, George Ehlers, Andrew G. Seel, David J. Wesolowski and Lawrence M. Anovitz, Phys. Rev. Lett., 116, 167802 (22 April 2016), DOI:10.1103/PhysRevLett.116.167802

Using neutron scattering and ab initio simulations, we document the discovery of a new “quantum tunneling state” of the water molecule confined in 5 Å channels in the mineral beryl, characterized by extended proton and electron delocalization. We observed a number of peaks in the inelastic neutron scattering spectra that were uniquely assigned to water quantum tunneling. In addition, the water proton momentum distribution was measured with deep inelastic neutron scattering, which directly revealed coherent delocalization of the protons in the ground state.

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Boron 11B Nuclear Isotopes Constrain CO2 Climate Forcing

by Tommy on 26/04/2016

Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate, Eleni Anagnostou, Eleanor H. John, Kirsty M. Edgar, Gavin L. Foster, Andy Ridgwell, Gordon N. Inglis, Richard D. Pancost, Daniel J. Lunt and Paul N. Pearson, Nature (25 April 2016), doi:10.1038/nature17423

The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500 – 3,000 parts per million, and in the absence of tighter constraints carbon–climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ11B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty percent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 percent confidence), which is similar to the canonical range (1.5 to 4.5 degrees Celsius), indicating that a large fraction of the warmth of the early Eocene greenhouse was driven by increased CO2 concentrations, and that climate sensitivity was relatively constant throughout this period.

Now you know you be fucked. It’s official. I’m just not seeing those electric cars on the road.

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