Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session K19: Precision Many Body Physics VIIFocus
|
Hide Abstracts |
Sponsoring Units: DAMOP DCMP Chair: Ehsan Khatami, San Jose State University Room: BCEC 156C |
Wednesday, March 6, 2019 8:00AM - 8:36AM |
K19.00001: Monte Carlo Studies of Quantum Critical Metals Invited Speaker: Erez Berg Metallic quantum critical phenomena are believed to play a key role in many strongly correlated materials, including high temperature superconductors. Theoretically, the problem of quantum criticality in the presence of a Fermi surface has proven to be highly challenging. However, it has recently been realized that many models used to describe such systems are amenable to numerically exact solution by quantum Monte Carlo (QMC) techniques, without suffering from the fermion sign problem. I will review the status of the understanding of metallic quantum criticality, and the recent progress made by QMC simulations, focusing on the cases of spin density wave and Ising nematic criticality. The results obtained so far will be described, as well as their implications for superconductivity, non-Fermi liquid behavior, and transport in the vicinity of metallic quantum critical points. Some of the outstanding puzzles and future directions are highlighted. |
Wednesday, March 6, 2019 8:36AM - 8:48AM |
K19.00002: Real time Quantum Monte Carlo for out of equilibrium strongly correlated systems. Corentin Bertrand, Antoine Maillard, Serge Florens, Olivier Parcollet, Xavier Waintal
|
Wednesday, March 6, 2019 8:48AM - 9:00AM |
K19.00003: Infinite boundary conditions as a current source for impurity conductance in a quantum wire Adam Iaizzi, Chung-Yu Lo, Pochung Chen, Ying-Jer Kao Developing nanoelectronic devices requires a detailed understanding of conduction in quantum wires. Numerical methods based on the density matrix renormalization group (DRMG) are excellent tools for studying one-dimensional quantum systems, but studying finite biases and currents requires time-dependent simulations, which remain challenging. Here we consider the problem of conductance across an impurity (or quantum dot) connected to metallic leads. Previous studies1,2 have used a finite wire with open boundary conditions, which suffers from strong finite-size effects. We use a powerful numerical method incorporating infinite boundary conditions3 (obtained from infinite DMRG4) to simulate semi-infinite leads. We extract linear conductance from static correlation functions within a finite-size window that contains the impurity. Building on that, we use a time-dependent method to extract conductance in the presence of finite bias. |
Wednesday, March 6, 2019 9:00AM - 9:12AM |
K19.00004: Resonant Tunneling with Dissipation in a Spin-full Quantum Dot. Trevyn Larson, Gu Zhang, Chung-Ting Ke, Ming-Tso Wei, Harold U Baranger, Gleb Finkelstein We study resonant tunneling through a nanotube quantum dot subject to a dissipative environment. It has been previously shown that in the spin-less case, a quantum critical point is realized when the system is tuned on-resonance with symmetric coupling to the leads. At that point, conductance at low temperatures reaches e2/h and several scaling laws are observed. Here, we demonstrate a qualitatively different behavior in the case of a spin-full resonance. In particular, the positions of resonant peaks change in a non-trivial fashion as a function of temperature, which is attributed to the lack of the particle-hole symmetry; and the peak height is not quantized and varies with dissipation strength. We argue that these signatures indicate the presence of the intermediate fixed point. |
Wednesday, March 6, 2019 9:12AM - 9:24AM |
K19.00005: Quench dynamics of superconducting fluctuations and optical conductivity in a disordered system Aditi Mitra, Yonah S Lemonik There has been significant interest in the generation of very short-lived superconducting |
Wednesday, March 6, 2019 9:24AM - 9:36AM |
K19.00006: Many-body Dynamic Structure Factors with Phase Space methods Jonathan Wurtz, Anatoli S Polkovnikov Recently there has been much interest in describing the behavior of strongly-interacting quantum systems, especially equilibrium relaxation and hydrodynamic response. Intuitively, such behavior is classical, and should have an effective description with polynomial complexity as opposed to the exponential complexity of full quantum dynamics. This talk will detail work on one such semi-classical description, the Cluster Truncated Wigner Approximation, which approximates dynamics in a high-dimensional classical phase space. Via sampling in this phase space, the method precisely reproduces both short-time far-from-equilibrium quantum dynamics and long-time thermal dynamics. In particular, we will show how using this method one can accurately compute the spin diffusion constant with the dynamic structure factor. |
Wednesday, March 6, 2019 9:36AM - 9:48AM |
K19.00007: Berry's ansatz in Fock space: beyond random matrix theory for many-body quantum chaos Remy Dubertrand, Juan-Diego Urbina, Klaus Richter Berry's ansatz of random superposition of vector basis to mimic the statistical properties of quantum states in classically chaotic systems, has been highly successfull for one-body systems. It is at the heart of the original justification for the eigenstate thermalisation hypothesis (ETH) for many-body quantum systems. We detail its use in many-body Fock space using recent developments in many-body semiclassical techniques for Bose Hubbard models. Quantitative predicitions for 2-point correlations in Fock space are given, which agree very well with numerics. This study highlights how semiclassical techniques can be efficient for many-body chaos beyond the universal regime of random matrix theory. |
Wednesday, March 6, 2019 9:48AM - 10:00AM |
K19.00008: Floquet behavior of correlated systems with light-matter coupling Mona Kalthoff, James Freericks, Goetz S Uhrig, Dante Kennes, Angel Rubio, Michael Sentef Periodically driven nonequilibrium many-body systems have a quasi-energy spectrum which can be tailored by external driving fields, known as Floquet engineering of desired system properties [Sentef et al., Nat. Comm. 6, 7047 (2015); Uhrig et al, arXiv:1808.10199 (2018)]. However, continuous periodic driving is not realizable in pump-probe experiments in solids. For instance it is not clear which criteria a pulse has to meet for a system exposed to a pulsed drive to approach the Floquet limit of a periodically driven system. However, there are analytical results for noninteracting band electrons in infinite dimensions [Kalthoff et al., Phys. Rev. B 98, 035138 (2018)]. Moreover we discuss t-DMRG results for interacting 1D chains in the charge density wave phase to study the emergence of Floquet behavior for realistic pulse shapes. This builds on the recently proposed Floquet engineering in quantum chains [Kennes et al., Phys. Rev. Lett. 120, 127601(2018)]. |
Wednesday, March 6, 2019 10:00AM - 10:12AM |
K19.00009: Ultrafast many-body correlations in an excitonic insulator out of equilibrium Riku Tuovinen, Denis Golez, Michael Schüler, Philipp Werner, Martin Eckstein, Michael Sentef A fast time propagation method for nonequilibrium Green's functions [1] based on the generalized Kadanoff-Baym Ansatz (GKBA) [2] is applied to a lattice system with a symmetry-broken equilibrium phase, namely an excitonic insulator [3]. The adiabatic preparation of a correlated symmetry-broken initial state from a Hartree-Fock wave function within GKBA is assessed by comparing with a solution of the imaginary-time Dyson equation [4]. We find that it is possible to reach a symmetry-broken correlated initial state with nonzero excitonic order parameter by the adiabatic switching procedure. We discuss under which circumstances this is possible in practice within reasonably short switching times. We further investigate the out-of-equilibrium dynamics of competing orders and how the balance between them could be controlled by laser driving [5]. |
Wednesday, March 6, 2019 10:12AM - 10:24AM |
K19.00010: Real-time quantum Monte Carlo for the spin-boson model Olga Goulko, Guy Cohen, Moshe Goldstein The spin–boson model consists of a two-state system coupled to a bath of non-interacting harmonic modes. This fundamental, yet non-trivial model describes dissipation in a quantum system and can be mapped to an impurity coupled to interacting electron leads. Using the inchworm Monte Carlo algorithm we are able to precisely compute various nonequilibrium properties of the spin-boson model, such as the real-time evolution of the population difference between the two states at different temperatures, different forms of the bosonic bath spectrum, and different values of the spin-bath coupling, including the strong coupling regime. We also discuss how to calculate the heat current through the system coupled to two baths at different temperatures using full counting statistics. |
Wednesday, March 6, 2019 10:24AM - 10:36AM |
K19.00011: Heating Dynamics in a Periodically Driven SYK-Model Clemens Kuhlenkamp, Simon Weidinger, Michael Knap Periodically driven quantum matter can realize exotic dynamical phases that do not even exist in equilibrium. In order to understand how ubiquitous and robust these phases are, it is important to understand the heating dynamics of generic interacting quantum systems. We study the thermalization and heating dynamics in a generalized SYK-model subjected to a periodic drive, which realize a Fermi-Liquid (FL) to Non-FL crossover at a certain energy scale. Using an exact field theoretic approach we determine two regimes in the heating dynamics. At energies above the crossover scale the system is efficiently thermalizing and heats up exponentially. This crossover in the heating dynamics may be experimentally studied by measuring the absorption of THz laser light that impinges an irregularly shaped graphene flake in a strong magnetic field, which has been proposed to realize exotic SYK physics. |
Wednesday, March 6, 2019 10:36AM - 10:48AM |
K19.00012: Entropy of the (1+1)-dimensional directed percolation Kenji Harada We investigate the informational aspect of a (1+1)-dimensional directed percolation which can be regarded as a reaction-diffusion process in a one-dimensional system and is a canonical model of a non-equilibrium continuous phase transition into an absorbing state. Using a tensor network scheme based on a mapping between a state probability distribution and a wave function, we can numerically calculate a time evolution of a state probability distribution. Although the density of active sites has no singular behavior, there is a new singular point in the conventional active phase at which the dynamical behavior of the entanglement entropy changes. The Rényi entropy has a cusp at the same point. The Rényi entropy also shows a universal relaxation at the critical point of the conventional absorbing phase transition. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit 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 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700