Publications by authors named "Andrey Gromov"

25 Publications

  • Page 1 of 1

Quench Dynamics of Collective Modes in Fractional Quantum Hall Bilayers.

Phys Rev Lett 2021 Feb;126(7):076604

Brown Theoretical Physics Center and Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA.

We introduce different types of quenches to probe the nonequilibrium dynamics and multiple collective modes of bilayer fractional quantum Hall states. We show that applying an electric field in one layer induces oscillations of a spin-1 degree of freedom, whose frequency matches the long-wavelength limit of the dipole mode. On the other hand, oscillations of the long-wavelength limit of the quadrupole mode, i.e., the spin-2 graviton, as well as the combination of two spin-1 states, can be activated by a sudden change of band mass anisotropy. We construct an effective field theory to describe the quench dynamics of these collective modes. In particular, we derive the dynamics for both the spin-2 and the spin-1 states and demonstrate their excellent agreement with numerics.
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http://dx.doi.org/10.1103/PhysRevLett.126.076604DOI Listing
February 2021

Collective Excitations at Filling Factor 5/2: The View from Superspace.

Phys Rev Lett 2020 Aug;125(7):077601

Kadanoff Center for Theoretical Physics, University of Chicago, Chicago, Illinois 60637, USA.

We present a microscopic theory of the neutral collective modes supported by the non-Abelian fractional quantum Hall states at filling factor 5/2. The theory is formulated in terms of the trial states describing the Girvin-MacDonald-Platzman mode and its fermionic counterpart. These modes are superpartners of each other in a concrete sense, which we elucidate.
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http://dx.doi.org/10.1103/PhysRevLett.125.077601DOI Listing
August 2020

Possible Differential Diagnosis of the Degrees of Rheological Disturbances in Patients with Type 2 Diabetes Mellitus by Dielectrophoresis of Erythrocytes.

J Pers Med 2020 Jul 5;10(3). Epub 2020 Jul 5.

Rzhanov Institute of Semiconductor Physics Siberian Branch of Russian Academy of Sciences, Lavrentiev Ave., 13, 630090 Novosibirsk, Russia.

Hemorheological disorders in structural and functional parameters of erythrocytes are involved in the pathological process in type 2 diabetes mellitus (DM).

Aim: to investigate the feasibility of differential diagnosis of the degrees of rheological disturbances in patients with type 2 DM by dielectrophoresis of erythrocytes.

Methods: 62 subjects (58.7 ± 1.6 years) with type 2 DM diagnosed according to the criteria of the ADA were subdivided into two groups: medium ( = 47) and high ( = 15) risk of microcirculatory disturbances (EASD, 2013). Electric and viscoelastic parameters of erythrocytes were determined by dielectrophoresis using an electric optical system of cell detection.

Results: the progression of rheological disturbances in the patients with type 2 DM was accompanied by significant decreases in deformation amplitude; dipole moment; polarizability; and membrane capacity; and increases in conductivity, viscosity, rigidity, hemolysis, and formation of aggregates ( < 0.05). Combined use of the parameters increased sensitivity (97.8%) and specificity (86.7%) for diagnosis of rheological disturbances in type 2 DM.

Conclusion: the proposed experimental approach possesses low invasiveness, high productivity, shorter duration, vividness of the results. The method allows to evaluate not only local (renal and ocular) but also systemic status of microcirculation using more than 20 parameters of erythrocytes.
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http://dx.doi.org/10.3390/jpm10030060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7565395PMC
July 2020

Anisotropic odd viscosity via a time-modulated drive.

Phys Rev E 2020 May;101(5-1):052606

The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.

At equilibrium, the structure and response of ordered phases are typically determined by the spontaneous breaking of spatial symmetries. Out of equilibrium, spatial order itself can become a dynamically emergent concept. In this article, we show that spatially anisotropic viscous coefficients and stresses can be designed in a far-from-equilibrium fluid by applying to its constituents a time-modulated drive. If the drive induces a rotation whose rate is slowed down when the constituents point along specific directions, then anisotropic structures and mechanical responses arise at long timescales. We demonstrate that the viscous response of such two-dimensional anisotropic driven fluids can acquire a tensorial, dissipationless component called anisotropic odd (or Hall) viscosity. Classical fluids with internal torques can display additional components of the odd viscosity neglected in previous studies of quantum Hall fluids that assumed angular momentum conservation. We show that, unlike their isotropic counterparts, these anisotropic and angular momentum-violating odd-viscosity coefficients can change even the bulk flow of an incompressible fluid by acting as a source of vorticity. In addition, shear distortions in the shape of an inclusion result in torques. We derive how the odd-viscous coefficients depend on the nonlinear, dissipative response of a fluid of rotating rods, i.e., odd viscosity is not simply given by angular momentum density.
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http://dx.doi.org/10.1103/PhysRevE.101.052606DOI Listing
May 2020

The formation of human populations in South and Central Asia.

Science 2019 09;365(6457)

Earth Institute, University College Dublin, Dublin 4, Ireland.

By sequencing 523 ancient humans, we show that the primary source of ancestry in modern South Asians is a prehistoric genetic gradient between people related to early hunter-gatherers of Iran and Southeast Asia. After the Indus Valley Civilization's decline, its people mixed with individuals in the southeast to form one of the two main ancestral populations of South Asia, whose direct descendants live in southern India. Simultaneously, they mixed with descendants of Steppe pastoralists who, starting around 4000 years ago, spread via Central Asia to form the other main ancestral population. The Steppe ancestry in South Asia has the same profile as that in Bronze Age Eastern Europe, tracking a movement of people that affected both regions and that likely spread the distinctive features shared between Indo-Iranian and Balto-Slavic languages.
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http://dx.doi.org/10.1126/science.aat7487DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6822619PMC
September 2019

Chiral Topological Elasticity and Fracton Order.

Authors:
Andrey Gromov

Phys Rev Lett 2019 Feb;122(7):076403

Brown Theoretical Physics Center and Department of Physics, Brown University, Providence, Rhode Island 02912, USA.

We analyze the "higher rank" gauge theories that capture some of the phenomenology of the fracton order. It is shown that these theories lose gauge invariance when an arbitrarily weak and smooth curvature is introduced. We propose a resolution to this problem by introducing a theory invariant under area-preserving diffeomorphisms, which reduce to the higher rank gauge transformations upon linearization around a flat background. The proposed theory is geometric in nature and is interpreted as a theory of chiral topological elasticity. This theory exhibits some of the fracton phenomenology. We explore the conservation laws, topological excitations, linear response, various kinematical constraints, and canonical structure of the theory. Finally, we emphasize that the very structure of Riemann-Cartan geometry, which we use to formulate the theory, encodes some of the fracton phenomenology, suggesting that the fracton order itself is geometric in nature.
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http://dx.doi.org/10.1103/PhysRevLett.122.076403DOI Listing
February 2019

Electromagnetic and gravitational responses of photonic Landau levels.

Nature 2019 01 9;565(7738):173-179. Epub 2019 Jan 9.

James Franck Institute and the Department of Physics, University of Chicago, Chicago, IL, USA.

Topology has recently become a focus in condensed matter physics, arising in the context of the quantum Hall effect and topological insulators. In both of these cases, the topology of the system is defined through bulk properties ('topological invariants') but detected through surface properties. Here we measure three topological invariants of a quantum Hall material-photonic Landau levels in curved space-through local electromagnetic and gravitational responses of the bulk material. Viewing the material as a many-port circulator, the Chern number (a topological invariant) manifests as spatial winding of the phase of the circulator. The accumulation of particles near points of high spatial curvature and the moment of inertia of the resultant particle density distribution quantify two additional topological invariants-the mean orbital spin and the chiral central charge. We find that these invariants converge to their global values when probed over increasing length scales (several magnetic lengths), consistent with the intuition that the bulk and edges of a system are distinguishable only for sufficiently large samples (larger than roughly one magnetic length). Our experiments are enabled by applying quantum optics tools to synthetic topological matter (here twisted optical resonators). Combined with advances in Rydberg-mediated photon collisions, our work will enable precision characterization of topological matter in photon fluids.
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http://dx.doi.org/10.1038/s41586-018-0817-4DOI Listing
January 2019

Author Correction: 137 ancient human genomes from across the Eurasian steppes.

Nature 2018 11;563(7729):E16

Buketov Karaganda State University, Saryarka Archaeological Institute, Karaganda, Kazakhstan.

with In this Article, Angela M. Taravella and Melissa A. Wilson Sayres have been added to the author list (associated with: School of Life Sciences, Center for Evolution and Medicine, The Biodesign Institute, Arizona State University, Tempe, AZ, USA). The author list and Author Information section have been corrected online.
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http://dx.doi.org/10.1038/s41586-018-0488-1DOI Listing
November 2018

137 ancient human genomes from across the Eurasian steppes.

Nature 2018 05 9;557(7705):369-374. Epub 2018 May 9.

Buketov Karaganda State University, Saryarka Archaeological Institute, Karaganda, Kazakhstan.

For thousands of years the Eurasian steppes have been a centre of human migrations and cultural change. Here we sequence the genomes of 137 ancient humans (about 1× average coverage), covering a period of 4,000 years, to understand the population history of the Eurasian steppes after the Bronze Age migrations. We find that the genetics of the Scythian groups that dominated the Eurasian steppes throughout the Iron Age were highly structured, with diverse origins comprising Late Bronze Age herders, European farmers and southern Siberian hunter-gatherers. Later, Scythians admixed with the eastern steppe nomads who formed the Xiongnu confederations, and moved westward in about the second or third century BC, forming the Hun traditions in the fourth-fifth century AD, and carrying with them plague that was basal to the Justinian plague. These nomads were further admixed with East Asian groups during several short-term khanates in the Medieval period. These historical events transformed the Eurasian steppes from being inhabited by Indo-European speakers of largely West Eurasian ancestry to the mostly Turkic-speaking groups of the present day, who are primarily of East Asian ancestry.
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http://dx.doi.org/10.1038/s41586-018-0094-2DOI Listing
May 2018

The first horse herders and the impact of early Bronze Age steppe expansions into Asia.

Science 2018 06 9;360(6396). Epub 2018 May 9.

Institute for the History of Material Culture, Russian Academy of Sciences, St. Petersburg, Russia.

The Yamnaya expansions from the western steppe into Europe and Asia during the Early Bronze Age (~3000 BCE) are believed to have brought with them Indo-European languages and possibly horse husbandry. We analyzed 74 ancient whole-genome sequences from across Inner Asia and Anatolia and show that the Botai people associated with the earliest horse husbandry derived from a hunter-gatherer population deeply diverged from the Yamnaya. Our results also suggest distinct migrations bringing West Eurasian ancestry into South Asia before and after, but not at the time of, Yamnaya culture. We find no evidence of steppe ancestry in Bronze Age Anatolia from when Indo-European languages are attested there. Thus, in contrast to Europe, Early Bronze Age Yamnaya-related migrations had limited direct genetic impact in Asia.
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http://dx.doi.org/10.1126/science.aar7711DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6748862PMC
June 2018

Publisher's Note: Particle-Hole Duality in the Lowest Landau Level [Phys. Rev. Lett. 118, 206602 (2017)].

Phys Rev Lett 2018 02;120(8):089903

This corrects the article DOI: 10.1103/PhysRevLett.118.206602.
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http://dx.doi.org/10.1103/PhysRevLett.120.089903DOI Listing
February 2018

Publisher's Note: Investigating Anisotropic Quantum Hall States with Bimetric Geometry [Phys. Rev. Lett. 119, 146602 (2017)].

Phys Rev Lett 2018 02;120(8):089902

This corrects the article DOI: 10.1103/PhysRevLett.119.146602.
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http://dx.doi.org/10.1103/PhysRevLett.120.089902DOI Listing
February 2018

Publisher's Note: Transport Signatures of the Hall Viscosity [Phys. Rev. Lett. 119, 226602 (2017)].

Phys Rev Lett 2018 Feb;120(7):079901

This corrects the article DOI: 10.1103/PhysRevLett.119.226602.
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http://dx.doi.org/10.1103/PhysRevLett.120.079901DOI Listing
February 2018

Transport Signatures of the Hall Viscosity.

Phys Rev Lett 2017 Dec 30;119(22):226602. Epub 2017 Nov 30.

Kadanoff Center for Theoretical Physics and Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA.

Hall viscosity is a nondissipative response function describing momentum transport in two-dimensional systems with broken parity. It is quantized in the quantum Hall regime, and contains information about the topological order of the quantum Hall state. Hall viscosity can distinguish different quantum Hall states with identical Hall conductances, but different topological order. To date, an experimentally accessible signature of Hall viscosity is lacking. We exploit the fact that Hall viscosity contributes to charge transport at finite wavelengths, and can therefore be extracted from nonlocal resistance measurements in inhomogeneous charge flows. We explain how to determine the Hall viscosity from such a transport experiment. In particular, we show that the profile of the electrochemical potential close to contacts where current is injected is sensitive to the value of the Hall viscosity.
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http://dx.doi.org/10.1103/PhysRevLett.119.226602DOI Listing
December 2017

Publisher's Note: Investigating Anisotropic Quantum Hall States with Bimetric Geometry [Phys. Rev. Lett. 119, 146602 (2017)].

Phys Rev Lett 2017 Nov 31;119(18):189901. Epub 2017 Oct 31.

This corrects the article DOI: 10.1103/PhysRevLett.119.146602.
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http://dx.doi.org/10.1103/PhysRevLett.119.189901DOI Listing
November 2017

Investigating Anisotropic Quantum Hall States with Bimetric Geometry.

Phys Rev Lett 2017 Oct 5;119(14):146602. Epub 2017 Oct 5.

Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544, USA.

We construct a low energy effective theory of anisotropic fractional quantum Hall (FQH) states. We develop a formalism similar to that used in the bimetric approach to massive gravity, and apply it to describe Abelian anisotropic FQH states in the presence of external electromagnetic and geometric backgrounds. We derive a relationship between the shift, the Hall viscosity, and a new quantized coupling to anisotropy, which we term anisospin. We verify this relationship by numerically computing the Hall viscosity for a variety of anisotropic quantum Hall states using the density matrix renormalization group. Finally, we apply these techniques to the problem of nematic order and clarify certain disagreements that exist in the literature about the meaning of the coefficient of the Berry phase term in the nematic effective action.
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http://dx.doi.org/10.1103/PhysRevLett.119.146602DOI Listing
October 2017

Publisher's Note: Particle-Hole Duality in the Lowest Landau Level [Phys. Rev. Lett. 118, 206602 (2017)].

Phys Rev Lett 2017 Jun 27;118(26):269902. Epub 2017 Jun 27.

This corrects the article DOI: 10.1103/PhysRevLett.118.206602.
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http://dx.doi.org/10.1103/PhysRevLett.118.269902DOI Listing
June 2017

Particle-Hole Duality in the Lowest Landau Level.

Phys Rev Lett 2017 May 19;118(20):206602. Epub 2017 May 19.

Kadanoff Center for Theoretical Physics and Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA.

We derive a number of exact relations between response functions of holomorphic, chiral fractional quantum Hall states and their particle-hole (PH) conjugates. These exact relations allow one to calculate the Hall conductivity, Hall viscosity, various Berry phases, and the static structure factor of PH conjugate states from the corresponding properties of the original states. These relations establish a precise duality between chiral quantum Hall states and their PH conjugates. The key ingredient in the proof of the relations is a generalization of Girvin's construction of PH-conjugate states to inhomogeneous magnetic field and curvature. Finally, we make several nontrivial checks of the relations, including for the Jain states and their PH conjugates.
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http://dx.doi.org/10.1103/PhysRevLett.118.206602DOI Listing
May 2017

Synthetic Landau levels for photons.

Nature 2016 06 8;534(7609):671-5. Epub 2016 Jun 8.

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.
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http://dx.doi.org/10.1038/nature17943DOI Listing
June 2016

Boundary Effective Action for Quantum Hall States.

Phys Rev Lett 2016 Mar 21;116(12):126802. Epub 2016 Mar 21.

Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA.

We consider quantum Hall states on a space with boundary, focusing on the aspects of the edge physics which are completely determined by the symmetries of the problem. There are four distinct terms of Chern-Simons type that appear in the low-energy effective action of the state. Two of these protect gapless edge modes. They describe Hall conductance and, with some provisions, thermal Hall conductance. The remaining two, including the Wen-Zee term, which contributes to the Hall viscosity, do not protect gapless edge modes but are instead related to the local boundary response fixed by symmetries. We highlight some basic features of this response. It follows that the coefficient of the Wen-Zee term can change across an interface without closing a gap or breaking a symmetry.
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http://dx.doi.org/10.1103/PhysRevLett.116.126802DOI Listing
March 2016

Optimal Ancient DNA Yields from the Inner Ear Part of the Human Petrous Bone.

PLoS One 2015 18;10(6):e0129102. Epub 2015 Jun 18.

Institute for Biochemistry and Biology, Faculty for Mathematics and Natural Sciences, University of Potsdam, Karl-Liebknechtstr. 24-25, 14476 Potsdam Golm, Germany; Department of Biology, University of York, Wentworth Way, Heslington, York, United Kingdom.

The invention and development of next or second generation sequencing methods has resulted in a dramatic transformation of ancient DNA research and allowed shotgun sequencing of entire genomes from fossil specimens. However, although there are exceptions, most fossil specimens contain only low (~ 1% or less) percentages of endogenous DNA. The only skeletal element for which a systematically higher endogenous DNA content compared to other skeletal elements has been shown is the petrous part of the temporal bone. In this study we investigate whether (a) different parts of the petrous bone of archaeological human specimens give different percentages of endogenous DNA yields, (b) there are significant differences in average DNA read lengths, damage patterns and total DNA concentration, and (c) it is possible to obtain endogenous ancient DNA from petrous bones from hot environments. We carried out intra-petrous comparisons for ten petrous bones from specimens from Holocene archaeological contexts across Eurasia dated between 10,000-1,800 calibrated years before present (cal. BP). We obtained shotgun DNA sequences from three distinct areas within the petrous: a spongy part of trabecular bone (part A), the dense part of cortical bone encircling the osseous inner ear, or otic capsule (part B), and the dense part within the otic capsule (part C). Our results confirm that dense bone parts of the petrous bone can provide high endogenous aDNA yields and indicate that endogenous DNA fractions for part C can exceed those obtained for part B by up to 65-fold and those from part A by up to 177-fold, while total endogenous DNA concentrations are up to 126-fold and 109-fold higher for these comparisons. Our results also show that while endogenous yields from part C were lower than 1% for samples from hot (both arid and humid) parts, the DNA damage patterns indicate that at least some of the reads originate from ancient DNA molecules, potentially enabling ancient DNA analyses of samples from hot regions that are otherwise not amenable to ancient DNA analyses.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0129102PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4472748PMC
April 2016

Population genomics of Bronze Age Eurasia.

Nature 2015 Jun;522(7555):167-72

The Archaeological Museum of Wrocław, 50-077 Wrocław, Poland.

The Bronze Age of Eurasia (around 3000-1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought.
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http://dx.doi.org/10.1038/nature14507DOI Listing
June 2015

Framing anomaly in the effective theory of the fractional quantum Hall effect.

Phys Rev Lett 2015 Jan 7;114(1):016805. Epub 2015 Jan 7.

Department of Physics and Institute for Condensed Matter Theory, University of Illinois, 1110 W. Green St., Urbana, Illinois 61801-3080, USA and Kavli Institute for Theoretical Physics, University of California Santa Barbara, California 93106-4030, USA.

We consider the geometric part of the effective action for the fractional quantum Hall effect (FQHE). It is shown that accounting for the framing anomaly of the quantum Chern-Simons theory is essential to obtain the correct gravitational linear response functions. In the lowest order in gradients, the linear response generating functional includes Chern-Simons, Wen-Zee, and gravitational Chern-Simons terms. The latter term has a contribution from the framing anomaly which fixes the value of thermal Hall conductivity and contributes to the Hall viscosity of the FQH states on a sphere. We also discuss the effects of the framing anomaly on linear responses for non-Abelian FQH states.
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http://dx.doi.org/10.1103/PhysRevLett.114.016805DOI Listing
January 2015

Thermal Hall effect and geometry with torsion.

Phys Rev Lett 2015 Jan 6;114(1):016802. Epub 2015 Jan 6.

Department of Physics and Astronomy and Simons Center for Geometry and Physics, Stony Brook University, Stony Brook, New York 11794, USA.

We formulate a geometric framework that allows us to study momentum and energy transport in nonrelativistic systems. It amounts to a coupling of the nonrelativistic system to the Newton-Cartan (NC) geometry with torsion. The approach generalizes the classic Luttinger's formulation of thermal transport. In particular, we clarify the geometric meaning of the fields conjugated to energy and energy current. These fields describe the geometric background with nonvanishing temporal torsion. We use the developed formalism to construct the equilibrium partition function of a nonrelativistic system coupled to the NC geometry in 2+1 dimensions and to derive various thermodynamic relations.
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http://dx.doi.org/10.1103/PhysRevLett.114.016802DOI Listing
January 2015

Density-curvature response and gravitational anomaly.

Phys Rev Lett 2014 Dec 22;113(26):266802. Epub 2014 Dec 22.

Department of Physics and Astronomy and Simons Center for Geometry and Physics, Stony Brook University, Stony Brook, New York 11794, USA.

We study constraints imposed by the Galilean invariance on linear electromagnetic and elastic responses of two-dimensional gapped systems in a background magnetic field. Exact relations between response functions following from the Ward identities are derived. In addition to the viscosity-conductivity relations known in the literature, we find new relations between the density-curvature response and the thermal Hall response.
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http://dx.doi.org/10.1103/PhysRevLett.113.266802DOI Listing
December 2014