Topological Phononics and Phonon Diodes Proposed

by Tommy on 28/06/2016

Topological Phononics and Phonon Diode, Yizhou Liu, Yong Xu, Shou-Cheng Zhang abd 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 Schr\”odinger-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 design of the ZT = 4 thermoelectric device.

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Topological Lifshitz Transitions By Grigory G. E. Volovik

by Tommy on 28/06/2016

Topological Lifshitz Transitions, G.E. Volovik (27 June 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)

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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!

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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 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

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.

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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.

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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?

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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!

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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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Fort McMurray, Alberta, Northern Canada is Feeling the Bern

by Tommy on 7/05/2016
Fort McMurray Convoy Wildfire Evacuation

Fort McMurray Convoy Wildfire Evacuation

I have no sympathy for these idiots. I will not shed a tear or contribute one cent for their welfare.

They richly deserve the punishment that nature is giving them.

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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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Future Higgs Portal into Electroweak Cosmology Discussed

by Tommy on 22/04/2016

The Higgs Portal and Cosmology, Ketevi Assamagan, Chien-Yi Chen, John Paul Chou, David Curtin, Michael A. Fedderke, Yuri Gershtein, Xiao-Gang He, Markus Klute, Jonathan Kozaczuk, Ashutosh Kotwal, Steven Lowette, Jose Miguel No, Tilman Plehn, Jianming Qian, Michael Ramsey-Musolf, Alexei Safonov, Jessie Shelton, Michael Spannowsky, Shufang Su, Devin G. E. Walker, Stephane Willocq and Peter Winslow, Summarization of the landscape of possibilities surveyed at the “Unlocking the Higgs Portal” Workshop held at the Amherst Center for Fundamental Interactions (ACFI) in May 2014, Report number ACFI-T16-10 (18 April 2016)

Higgs portal interactions provide a simple mechanism for addressing two open problems in cosmology: dark matter and the baryon asymmetry. In the latter instance, Higgs portal interactions may contain the ingredients for a strong first order electroweak phase transition as well as new CP-violating interactions as needed for electroweak baryogenesis. These interactions may also allow for a viable dark matter candidate. We survey the opportunities for probing the Higgs portal as it relates to these questions in cosmology at the LHC and possible future colliders.

More flailing around in the dark for the dark sector.

You gotta start somewhere.

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Some Ultralight Axion Like Particles Excluded by Observation

by Tommy on 22/04/2016

Search for Spectral Irregularities due to Photon–Axionlike-Particle Oscillations with the Fermi Large Area Telescope, M. Ajello et al. (The Fermi-LAT Collaboration), Phys. Rev. Lett., 116, 161101 (20 April 2016), DOI:10.1103/PhysRevLett.116.161101

We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5 × 10−12 GeV−1 for ALP masses 0.5 ≲ ma ≲ 5 neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe,

I haven’t read this paper, but this is a really poorly written abstract. We don’t know what ALPs are, we really don’t even know exactly what an axion is yet, and lattice QCD calculations already points to moderately heavy axions (not WIMP scale, ~ meV ~ keV ~), if they even exist at all.

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