Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session F65: Topological Liquids: TheoryRecordings Available
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Sponsoring Units: DCMP Chair: Daniel Bulmash, University of Maryland Room: Hyatt Regency Hotel -Grant Park C |
Tuesday, March 15, 2022 8:00AM - 8:12AM |
F65.00001: Topological fluids in condensed matter systems Gustavo M Monteiro, Sriram Ganeshan The phenomenological Chern-Simons-Ginzburg-Landau (CSGL) model for fractional quantum Hall states gives rise to hydrodynamic-like equations of motion with a density-vorticity constraint. This constraint stems from the topological Chern-Simons term and encodes the macroscopic "quantum" effects. In this talk, we will discuss a reformulation of CSGL action in terms of a classical fluid Lagrangian with a topological term. Such a fluid action with a topological term was recently written to describe a fluid with a dense collection of vortices by Nair in arXiv:2008.11260. We discuss a systematic derivation of the topological fluid action starting from CSGL theory. We show that the role of the topological term in the fluid language is completely different from the Chern-Simons term of the CSGL action and the density vorticity constraint must be imposed using a Lagrange multiplier. In fact this connection is more general and allows us to express any charged bosonic condensate in terms of classical fluids with topological terms. Expressing condensed matter systems in terms of a fluid action with a topological term enables us to import the framework of linear and non-linear fluid dynamical phenomena within the ambit of topological orders studied in condensed matter systems. |
Tuesday, March 15, 2022 8:12AM - 8:24AM |
F65.00002: Thermal anyon interferometry in phonon-coupled Kitaev spin liquids Kai Klocke, Joel E Moore, Jason F Alicea, Gabor Halasz Recent theoretical studies inspired by experiments on the Kitaev magnet α-RuCl3 highlight the nontrivial impact of phonons on the thermal Hall conductivity of chiral topological phases. Here we introduce mixed mesoscopic-macroscopic devices that allow refined thermal-transport probes of non-Abelian spin liquids with Ising topological order. These devices feature a quantum-coherent mesoscopic region with quantized or negligible phonon conductance, flanked by macroscopic lobes that facilitate efficient thermalization between chiral Majorana edge modes and bulk phonons. We show that our devices enable (i) accurate determination of the quantized thermal Hall conductivity, (ii) identification of non-Abelian Ising anyons via the temperature dependence of the thermal conductance, and most interestingly (iii) single-anyon detection through heat-based anyon interferometry. Analogous results apply broadly to phonon-coupled chiral topological orders. |
Tuesday, March 15, 2022 8:24AM - 8:36AM |
F65.00003: Thermal Interferometry of Anyons in Spin Liquids Zezhu Wei, Dmitri E Feldman, Vesna F Mitrovic Aharonov-Bohm interferometry is the most direct probe of anyonic statistics in the quantum Hall effect. The technique involves oscillations of the electric current as a function of the magnetic field and is not applicable to Kitaev spin liquids and other systems without charged quasiparticles. Here, we establish a novel protocol, involving heat transport, for revealing fractional statistics even in the absence of charged excitations, as is the case in quantum spin liquids. Specifically, we demonstrate that heat transport in Kitaev spin liquids through two distinct interferometer's geometries, Fabry-Perot and Mach-Zehnder, exhibit drastically different behaviors. Therefore, we propose the use of heat transport interferometry as a probe of anyonic statistics in charge insulators. |
Tuesday, March 15, 2022 8:36AM - 8:48AM |
F65.00004: Enforced symmetry breaking by invertible topological phases Shang-Qiang Ning, Yang Qi, Zheng-Cheng Gu, Chenjie Wang It is well known that two-dimensional fermionic systems with a nonzero Chern number must break the time reversal symmetry, manifested by the appearance of chiral edge modes on an open boundary. Such an incompatibility between topology and symmetry can occur more generally. We will refer to this phenomenon as enforced symmetry breaking by topological orders. In this work, we systematically study enforced breaking of a general finite group $G_f$ by a class of topological orders, namely 0D, 1D and 2D fermionic invertible topological orders. Mathematically, the symmetry group $G_f$ is a central extension of a bosonic group $G$ by the fermion parity group $Z_2^f$, characterized by a 2-cocycle $\lambda\in H^2(G,Z_2)$. With some minor assumptions and for given $G$ and $\lambda$, we are able to obtain a series of criteria on the existence or non-existence of enforced symmetry breaking by the fermionic invertible topological orders. Using these criteria, we discover many examples that are not known previously. For 2D systems, we define the physical quantities to describe symmetry-enriched invertible topological orders and derive some obstruction functions using both fermionic and bosonic languages. In the latter case which is done via gauging the fermion parity, we find that some obstruction functions are consequences of \emph{conditional anomalies} of the bosonic symmetry-enriched topological states, with the conditions inherited from the original fermionic system. We also study enforced breaking of the continuous $SU_f(N)$ group by 2D invertible topological orders through a different argument. |
Tuesday, March 15, 2022 8:48AM - 9:00AM |
F65.00005: Detecting topological order from modular transformations of ground states on the torus Zhuan Li The ground states encode the information of the topological phases of a 2-dimensional system, which makes them crucial in determining the associated topological quantum field theory (TQFT). Most numerical methods for detecting the TQFT relied on the use of minimum entanglement states (MESs), extracting the anyon mutual statistics and self statistics via overlaps and/or the entanglement spectra. Here we show that there exist different TQFTs that cannot be distinguished solely by the overlap of MESs. These models share the same mutual statistics, and their self statistics differ by phase. We provide the upper limit of the information one may obtain from the overlap of MESs. Finally, we show that if the phase is enriched by rotational symmetry, there may be additional TQFT information that can be extracted from the overlap of MESs. |
Tuesday, March 15, 2022 9:00AM - 9:12AM |
F65.00006: Entanglement spectra of non-chiral topological (2+1)-dimensional phases with strong time-reversal breaking, and Li-Haldane state counting Mark J Arildsen, Norbert Schuch, Andreas W Ludwig The Li-Haldane correspondence [Li, Haldane, PRL 101, 010504 (2008)] is often used to help identify wave functions of (2+1)-D chiral topological phases, by studying low-lying entanglement spectra (ES) on long cylinders of finite circumference. Here we consider such ES of states (in fact, of wave functions of certain Projected Entangled Pair States [PEPS]) that are not chiral, but which strongly break time-reversal as well as reflection symmetry. This leads to ES which have branches of both right- and left-moving chiralities, but with vastly different velocities. For circumferences much smaller than the corresponding inverse entanglement gap scale, the low-lying ES appear chiral in some topological sectors, and precisely follow the Li-Haldane state counting of a corresponding truly chiral phase. On its face, this could lead one to mistakenly identify the phase as chiral. However, by considering the ES in all possible sectors, one can observe distinct differences from the chiral phase. We explore this phenomenon in the setting of an SU(3) spin liquid PEPS [Kurečić, Vanderstraeten, Schuch, PRB 99, 045116 (2019)]. Potential implications on the so-far unresolved question concerning interacting chiral PEPS wave functions will be discussed. |
Tuesday, March 15, 2022 9:12AM - 9:24AM |
F65.00007: Revealing divergent length scales in the Kitaev honeycomb model with quantum Fisher information James P Lambert, Erik S Sorensen Quantum spin liquid (QSL) phases of matter have proven extremely elusive from both experimental and theoretical perspectives. In the theoretical domain, examining the topological entanglement entropy has been a primary tool for diagnosing whether or not a model exhibits QSL physics in its groundstate. We study the Kitaev honeycomb model, a prototype of QSL physics in two dimensions, using the quantum Fisher information (QFI), which is both experimentally accessible and well defined at finite temperature. We explore he behaviour of the QFI in both the gapped and gapless phases and in the regions around the transition. |
Tuesday, March 15, 2022 9:24AM - 9:36AM |
F65.00008: A simple analog of black hole information paradox in quantum Hall interfaces Kwok Wai Ma, Kun Yang The black hole information paradox has been hotly debated for the last few decades, without full resolution. This makes it desirable to find analogs of this paradox in simple and experimentally accessible systems, whose resolutions may shed light on this long-standing and fundamental problem. Here we identify and resolve an apparent "information paradox" in a quantum Hall interface between the Halperin-331 and Pfaffian states. Information carried by pseudospin degree of freedom of the Abelian 331 quasiparticles gets scrambled when they cross the interface to enter non-Abelian Pfaffian state, and becomes inaccessible to local measurements; in this sense the Pfaffian region is an analog of black hole interior while the interface plays a role similar to its horizon. We demonstrate that the "lost" information gets recovered once the "black hole" evaporates and the quasiparticles return to the 331 region, albeit in a highly entangled form. Such recovery is quantified by the Page curve of the entropy carried by these quasiparticles, which are analogs of Hawking radiation. |
Tuesday, March 15, 2022 9:36AM - 9:48AM |
F65.00009: Realization of Supersymmetry and Its Spontaneous Breaking in Quantum Hall Edges Kwok Wai Ma, Ruojun Wang, Kun Yang Supersymmetry (SUSY) relating bosons and fermions plays an important role in unifying different fundamental interactions in particle physics. Since no superpartners of elementary particles have been observed, SUSY, if present, must be broken at low-energy. This makes it important to understand how SUSY is realized and broken, and study their consequences. We show that an N=(1,0) SUSY, arguably the simplest type, can be realized at the edge of the Moore-Read quantum Hall state. Depending on the absence or presence of edge reconstruction, both SUSY-preserving and SUSY broken phases can be realized in the same system, allowing for their unified description. The significance of the gapless fermionic Goldstino mode in the SUSY broken phase is discussed. |
Tuesday, March 15, 2022 9:48AM - 10:00AM |
F65.00010: Volume-preserving diffeomorphism as nonabelian higher-rank gauge symmetry Yi-Hsien Du, Umang B Mehta, Dung X Nguyen, Dam T Son Higher-rank gauge theories have been drawing attention in condensed matter physics in recent years. The physical motivation of such theories is thought to be associated with a new class of topological matter so-called "fractons," quasiparticles with restricted mobility. We demonstrate a nonlinear version of the higher rank gauge symmetry in 2+1D and 3+1D with volume-preserving diffeomorphism as the symmetry group. We show that various condensed matter systems, including fractional quantum Hall effect and ferromagnetism, possess this symmetry, which exhibits fractonic behavior of the excitations in these systems. |
Tuesday, March 15, 2022 10:00AM - 10:12AM |
F65.00011: Noncommutative gauge symmetry in fractional quantum Hall states Umang B Mehta, Dam T Son, Yi-Hsien Du We show how to couple the lowest Landau level to a probe field in a way that the whole theory is invariant under a noncommutative U(1) gauge symmetry. While the time component of the probe field couples to the projected density operator, the spatial components are best interpreted as quantum displacements. In order to resolve the conflict between particle-hole symmetry at half filling and the presence of a mixed Chern-Simons term, and the ability to write down a fully noncommutative field theory on the lowest Landau level, we develop a map from the noncommutative U(1) gauge symmetry to a simpler, "baby noncommutative" gauge symmetry which is isomorphic to the group of volume preserving diffeomorphisms of flat space. |
Tuesday, March 15, 2022 10:12AM - 10:24AM |
F65.00012: Bridging three-dimensional coupled-wire models and cellular topological states: Solvable models for topological and fracton orders Yohei Fuji, Akira Furusaki Three-dimensional (3d) gapped topological phases with fractional excitations are divided into two subclasses: One has topological order with point-like and loop-like excitations fully mobile in the 3d space, and the other has fracton order with point-like excitations constrained in lower-dimensional subspaces. While these exotic phases are often studied by exactly solvable Hamiltonians made of commuting projectors, they are not capable of describing those with chiral gapless surface states. Based on cellular construction recently proposed for 3d topological phases, we introduce a systematic way to produce another type of exactly solvable models in terms of coupled quantum wires with given inputs of cellular structure, two-dimensional Abelian topological order, and their gapped interfaces. We show that they can describe both 3d topological and fracton orders and even their hybrid and study their universal features such as quasiparticle statistics and topological ground-state degeneracy. As a byproduct, we apply this construction to two-dimensional coupled-wire models with ordinary topological orders and translation symmetry enriched topological orders. We believe that our results pave the way to investigate effective quantum field descriptions or microscopic model realizations of fracton orders with chiral gapless surface states. |
Tuesday, March 15, 2022 10:24AM - 10:36AM |
F65.00013: Higher-spin non-relativistic geometry in the fractional quantum Hall effect Patricio Salgado-Rebolledo Motivated by recent progress in the formulation of geometric modls for the fractional quantum Hall states, we propose a novel non-relativistic geometric model for Laughlin states based on an extension of the Nappi-Witten algebra. We show that, staring from a single Chern-Simons theory with a gauge connection that takes values in the extended Nappi-Witten algebra, that the U(1) gauge sector responsible for the fractional Hall conductance, the gravitational Chern-Simons action and Wen-Zee term associated to the Hall viscosity can be derived in a unified way. When considering the Wess-Zumino-Witten model induced at the boundary, we reproduce the Florianini-Jackiw chiral boson action associated to gapless edge states. By means of a contaction procedure applied to the sl(3,R) algebra, two different higher-spin extension of the Nappi-Witten symmetry are defined. The corresponding Chern-Simons actions extend the previous results to include higher spin fields. The relation between these higher spin exitations and the W-infinity symmetry of quantum incompressible fluids previously considered in the literature by A. Capelli is studied. Generalisation of there results to include non-topological terms in the action are also considered. |
Tuesday, March 15, 2022 10:36AM - 10:48AM Withdrawn |
F65.00014: Non-Relativistic Supergeometry in the Moore-Read Fractional Quantum Hall State Giandomenico Palumbo, Patricio Salgado-Rebolledo The Moore-Read state is one the most well known non-Abelian fractional quantum Hall states. It supports non-Abelian Ising anyons in the bulk and a chiral boson and a chiral Majorana mode on the boundary. It has been recently conjectured that these two boundary modes are superpartners of each other and described by a supersymmetric conformal field theory. |
Tuesday, March 15, 2022 10:48AM - 11:00AM |
F65.00015: Anomalous dimensions of monopole operators at the transitions between Dirac and topological spin liquids Rufus Boyack, Eric Dupuis, William Witczak-Krempa The quantum phase transitions between a Dirac spin liquid and two types of topological spin liquids (chiral and Z_{2} spin liquids) are considered. The transitions are described by conformal field theories (CFTs) consisting of quantum electrodynamics in 2+1 dimensions with 2N flavors of two-component massless Dirac fermions and a four-fermion interaction. For the transition to a chiral spin liquid, it is the Gross-Neveu interaction (QED_{3}-GN), while for the transition to the Z_{2} spin liquid it is a superconducting pairing term (QED_{3}-Z_{2}GN). We study monopole operators at these quantum critical points using a large-N expansion to subleading order in 1/N. The scaling dimension of a QED_{3}-GN monopole with minimal charge is found to be very close to the scaling dimensions of other operators predicted to be equal by a conjectured duality between QED_{3}-GN with 2N=2 flavors and the bosonic CP^{1} model. By studying the large-charge asymptotics of the scaling dimensions in both QED_{3}-GN and QED_{3}-Z_{2}GN, we verify that the coefficient of the constant term precisely matches the universal prediction for CFTs with a global U(1) symmetry. |
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