Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session F49: Precision ManyBody Physics II: Topology and Strong CorrelationsFocus Recordings Available

Hide Abstracts 
Sponsoring Units: DCOMP DAMOP DCMP Chair: Ke Wang, University of Massachusetts, Amherst Room: McCormick Place W471B 
Tuesday, March 15, 2022 8:00AM  8:36AM 
F49.00001: Sounds and turbulence in a 2D Bose gas Invited Speaker: Zoran Hadzibabic I will discuss our recent experiments on driven boxtrapped 2D Bose gases. We have observed first and second sound in this system, which is the first such observation in a BerezinskiiKosterlitzThouless (BKT) superfluid. The measured speeds of the two sounds allow extraction of the superfluid density, which agrees with the expected universal jump at the critical point. I will also discuss our new results on strongly driven 2D gases in which a direct turbulent cascade emerges. 
Tuesday, March 15, 2022 8:36AM  8:48AM 
F49.00002: Precision ManyBody Study of the BKT Transition and TemperatureDependent Properties in the TwoDimensional Fermi Gas YuanYao He, Hao Shi, Shiwei Zhang We perform largescale, numerically exact Quantum Monte Carlo [1] calculations on the twodimensional interacting Fermi gas with a contact attraction. Reaching much larger lattice sizes and lower temperatures than previously possible, we determine systematically the finitetemperature phase diagram of the BerezinskiiKosterlitzThouless (BKT) transitions for interaction strengths ranging from BCS to crossover to BEC regimes. The evolutions of the pairing wavefunctions and the fermion and Cooper pair momentum distributions with temperature are accurately characterized. In the crossover regime, we find that the contact has a nonmonotonic temperature dependence, first increasing as temperature is lowered, and then showing a slight decline below the BKT transition temperature to approach the groundstate value [2] from above. We also compute the equation of state as a function of interaction strength for various temperatures. We expect that these results will serve as a useful guide for future experiments, and provide unbiased comparison and benchmark for the other analytical and computational studies. 
Tuesday, March 15, 2022 8:48AM  9:00AM 
F49.00003: Precision thermodynamics of the strongly interacting cold atomic Fermi gas in two spatial dimensions Shasta Ramachandran, Scott Jensen, Yoram Alhassid The twospecies Fermi gas in two spatial dimensions (2D) with an attractive short range interaction undergoes at zero temperature a crossover from a Bardeen CooperSchrieffer (BCS) condensate to a BoseEinstein condensate (BEC) as a function of the scattering length. This system exhibits features that are unique to two dimensions, including the presence of a bound state for an arbitrarily weak attractive interaction and the BerezinskiiKosterlitzThouless character of the phase transition to a superfluid below a critical temperature. Of particular interest is the strongly correlated regime which lies between the BCS and BEC limits. Using finitetemperature auxiliaryfield quantum Monte Carlo (AFMC) calculations, performed on discrete lattices and extrapolated to the continuum limit, we investigate the thermodynamic behavior of the 2D system across the strongly interacting regime. In particular, we discuss the extent of a pseudogap regime, in which pairing correlations survive above the critical temperature for superfluidity. We also discuss the calculation of dynamical observables, such as the singleparticle spectral function, through the use of numerical analytic continuation. 
Tuesday, March 15, 2022 9:00AM  9:12AM 
F49.00004: Operationally Accessible Entanglement in the 1D BoseHubbard Model Emanuel CasianoDiaz, Chris M Herdman, Adrian G Del Maestro Conserved quantities, such as the total particle number in a manybody system, may reduce the amount of entanglement that is operationally accessible as a resource for quantum information processing. This reduction can be quantified via the accessible or symmetryresolved entanglement entropies, which take these conservation laws into account. In this talk, we present quantum Monte Carlo results for the Rényi generalized accessible entanglement in the ground state of the BoseHubbard model accross the superfluidinsulator quantum phase transition in one dimension. We move beyond previous exact diagonalization studies and present results for the scaling with respect to the size of the spatial biparition at the critical point and discuss the role of particle number fluctuations in reducing the entanglement. 
Tuesday, March 15, 2022 9:12AM  9:24AM 
F49.00005: Sensitivity of Quantum Information Measures to Local Bosonic Occupation Restrictions Hatem N Barghathi, Adrian G Del Maestro Discrete lattice models play an essential role in the understanding of quantum phenomena, but their exact numerical solution is hindered by the exponentially growing size of the underlying Hilbert space. Such difficulty is more pronounced in the case of bosons due to the lack of any occupation restrictions as opposed to fermionic or even spin models. Thus, a widely adopted approximation in exact diagonalization as well as in the Density Matrix Renormalization Group is to restrict the bosonic occupation numbers to only a few bosons per lattice site. While the corresponding relative errors under this approximation in many observables including the energy or local particle number fluctuations could be negligible, we report that imposing such restrictions could have drastic effects on quantum information measures such as particle and accessible (symmetry resolved) entanglement entropies. We find that in these cases, the error scales with the system size and thus could rapidly exceed 100%, as demonstrated in the ground state of the BoseHubbard model. 
Tuesday, March 15, 2022 9:24AM  9:36AM 
F49.00006: The threestate quantum Potts paramagnet protected by S_3 symmetry Tigran A Sedrakyan, Hrant Topchyan, Mkhitar Mirumyan, Shahane A Khachatryan, Tigran Hakobyan We report a realization of a threestate Potts paramagnet with gapless edge modes on a triangular lattice that is protected by Z_3 symmetry. We study various microscopic models for the gapless edge and discuss the corresponding conformal field theories and their central charges. These are the Z_3 analogs of free fermion XX model edge term obtained by Levin and Gu for the Z_2 Ising paramagnet. The obtained edge theories do not belong to the integrable set of FateevZamolodchikov models, and neither coincide with the chiral Potts model. 
Tuesday, March 15, 2022 9:36AM  9:48AM Withdrawn 
F49.00007: Emergent Kondo behavior from gauge fluctuations in spin liquids Rui Wang, Baigeng Wang, Y. X Zhao, yilin wang Kondo effect is a prominent quantum phenomenon describing the manybody screening of a local magnetic impurity. Here, we reveal a new type of nonmagnetic Kondo behavior generated by gauge fluctuations in stronglycorrelated baths. We show that a nonmagnetic bond defect not only introduces the potential scattering but also locally enhances the gauge fluctuations. The local gauge fluctuations further mediate a pseudospin exchange interaction that produces an asymmetric Kondo fixed point in lowenergy. The gaugefluctuationinduced Kondo phenomena do not exhibit the characteristic resistivity behavior of conventional Kondo effect, but display a nonmonotonous temperature dependence of thermal conductivity as well as an anisotropic pseudospin correlation. Moreover, with its origin from gauge fluctuations, the Kondo features can be regarded as promising indicators for identifying quantum spin liquids. Our work advances fundamental knowledge of novel Kondo phenomena in stronglycorrelated systems, which have no counterparts in thermal baths within the singleparticle description. 
Tuesday, March 15, 2022 9:48AM  10:00AM 
F49.00008: The fate of spincharge separation in the presence of longrange antiferromagnetism Luhang Yang, Phillip E Weinberg, Adrian E Feiguin We present a numerical study of competing orders in the 1D tJ model with long range RKKYlike staggered spin interactions. By circumventing the constraints imposed by MerminWagner's theorem, this Hamiltonian can realize longrange Néel order at and near halffilling. Upon doping, interactions induce a confining potential that binds holons and spinons forming full fledged polaronic quasiparticles. We determine the full phase diagram as a function of the exchange and density using the density matrix renormalization group (DMRG) method. We show that pairing is disfavored and the AFM insulator and polaronic metal phase are separated by a range of densities with phase segregation, while spincharge separation reemerges at low densities. In addition, we calculate the photoemission spectrum of the model, showing the emergence of a coherent polaronic band splitting away from the holonspinon continuum with a regime realizing hole pockets. 
Tuesday, March 15, 2022 10:00AM  10:12AM 
F49.00009: Multipoint Correlation Functions: Spectral Representation and Numerical Evaluation Jan Von Delft, Fabian B Kugler, SeungSup B Lee Oneparticle (or twopoint) correlation functions have a wellknown Lehmann representation, revealing the relation between their real and imaginaryfrequency variants, and can be computed by several means. For twoparticle (or fourpoint) functions, an analogous representation and nonperturbative numerical results were previously known for imaginary frequencies only, and results on the realfrequency axis largely remained elusive. Here, we present spectral representations for multipoint correlation functions for each of three widelyused formalisms: the zerotemperature, Matsubara, and Keldysh formalisms. The spectral representations separate information on the system's dynamics, encoded in universal partial spectral functions, from the correlators' analytical properties, encoded in formalismdependent convolution kernels. Using a novel numerical renormalization group scheme, we compute results for the fourpoint vertex of the Anderson impurity model. Starting with the Matsubara formalism, our approach allows us to obtain results at arbitrarily low temperatures. Continuing with the Keldysh formalism, we consider the dynamical meanfield solution of the Hubbard model and discuss the rich realfrequency structure of the vertex in the metalinsulator coexistence regime. 
Tuesday, March 15, 2022 10:12AM  10:24AM 
F49.00010: Unfolding the spectral function of SrMoO_{3} Alexander Hampel, Edoardo Cappelli, Cyrus E Dreyer, Anna Tamai, Felix Baumberger, Antoine Georges The electronic spectral function obtained from angularresolved photoelectron spectroscopy (ARPES) often provides the most detailed picture of the electronic structure of a material that can be obtained experimentally. This can be directly compared with ab initio calculations, e.g., based on density functional theory plus dynamical mean field (DFT+DMFT). Here we showcase a high precision comparison between theory and experiment using the distorted perovskite oxide SrMoO_{3} as an example. First, the DMFT equations are solved directly on the real frequency axis with the Fork TensorProduct States (FTPS) method. Then, the resulting spectral function is unfolded into the highersymmetry cubic unit cell, showing that structural properties play a crucial role in correctly interpreting the ARPES spectra. Finally, the analysis of the spectral function is performed utilizing a newly developed WebApp: "FermiSee", which makes the analysis of spectral properties of Wannierlike Hamiltonians easily accessible. We demonstrate how this WebApp enables straightforward analysis of spectral properties of correlated models and realistic materials alike. For the case of SrMoO_{3}, this analysis reveals no indications of plasmonic features at lower binding energies, resolving a long standing controversy between theory and experiment for this specific material. 
Tuesday, March 15, 2022 10:24AM  10:36AM 
F49.00011: Quantum manybody scars from infinite temperature thermofielddouble states in bilayer systems Julia S Wildeboer, Christopher M Langlett, Zhicheng Yang, Alexey V Gorshkov, Thomas Iadecola, Shenglong Xu Recently, a new class of quantum manybody scar (QMBS) states called rainbow scars was introduced in arXiv:2107.03416. In this work, we explore a closely related construction of QMBS based on infinitetemperature thermofielddouble (TFD) states, which we dub TFD scars. The construction naturally applies to bilayer systems, including both spatial bilayers (with two spatially separated layers) and ``internal'' bilayers where the two layers correspond to different internal degrees of freedom (e.g., electron spins). Like the rainbow scar states, the TFD scars exhibit extensive bipartite entanglement entropy between the two layers despite having a simple entanglement structure. We explicitly investigate several bilayer systems with different kinds of degrees of freedom, e.g. spins, bosons, fermions, and quantum dimers with constrained Hilbert spaces. Some of the examples we consider subsume previously known examples of quantum manybody scars, including the spin1 XY model and the $\eta$pairing states in FermiHubbardlike models. Furthermore, the construction also leads to new examples of QMBS, including in BoseHubbard and quantum dimer models. Building on recent experimental advances, we discuss potential relations to systems that can be engineered in a laboratory setting. 
Tuesday, March 15, 2022 10:36AM  10:48AM 
F49.00012: Equilibrium Spectral Functions from Finitetemperature RealTime Oneparticle Green's Functions for Realistic Systems Thomas J Blommel, Emanuel C Gull Equilibrium spectral functions are of central importance in condensed matter physics, providing information about the states available to the electrons in a system. Realfrequency spectral functions are typically calculated by analytically continuing imaginarytime equilibrium Green's functions. In this work, we obtain finitetemperature realtime selfconsistent Green's Functions within the secondorder selfenergy approximation by solving the equilibrium KadanoffBaym equations. We then obtain realfrequency spectral functions from the Fourier transform of this data. Results for molecular systems are discussed and compared to current state of the art calculations. 
Tuesday, March 15, 2022 10:48AM  11:00AM 
F49.00013: Modeling polymer systems in the presence of nontrivial topological relations: a combined analyticalnumerical approach Franco Ferrari The news that will be delivered in this talk is that field theories are back to the realm of polymer physics and may be effectively used in order to understand the statistical behavior of knotted and concatenated polymer rings in a melt or in solution. This is a good news because for a long time analytical models of polymer rings subjected to topological constraints have been considered as mathematically intractable. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2024 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700