Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session X32: Computational approaches for farfromequilibrium quantum systemsInvited

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Sponsoring Units: DCOMP DCMP Chair: Fabian HeidrichMeisner, Ludwig Max Univ Muenchen Room: LACC 408A 
Friday, March 9, 2018 8:00AM  8:36AM 
X32.00001: Numerical Linked Cluster Expansions for Quantum Quenches in the Thermodynamic Limit Invited Speaker: Marcos Rigol Studies of the quantum dynamics of isolated systems are providing fundamental insights into how statistical mechanics emerges under unitary time evolution. Thermalization seems ubiquitous, but experiments with ultracold gases have shown that it need not always occur. Unfortunately, computational studies of generic (quantum chaotic) models are limited to small systems, for which arbitrarily long times can be calculated, or short times, for which large or infinite system sizes can be solved. Consequently, what happens in the thermodynamic limit after long times has been inaccessible to theoretical studies. In this talk, we introduce a linkedcluster based computational approach that allows one to address the latter question in lattice systems. We use this approach to probe thermalization in quantum chaotic models and its breakdown at integrability [1,2], as well as to study quantum quenches and generalized thermalization in the integrable XXZ chain [3,4]. 
Friday, March 9, 2018 8:36AM  9:12AM 
X32.00002: Nonequilibrium Dynamical Mean Field Theory Invited Speaker: Philipp Werner A widely used approximate method for studying the equilibrium properties of correlated lattice systems and materials is the dynamical mean field theory (DMFT) [1]. This formalism, which is based on the assumption of local interactions and local selfenergies, can be generalized to nonequilibrium problems [2,3]. I will discuss the nonequilibrium DMFT simulation of photoexcited Mott insulating systems, with a focus on recent extensions of the formalism, which capture the effects of timeperiodic driving, nonlocal correlations, and multiorbital interactions. In particular, I will consider the highharmonic generation in Mott insulators [4], the cooling of photodoped carriers by local and nonlocal spin [5,6] and charge [7] excitations, and the nontrivial effect of photocarriers on the pairing susceptibility in strongly correlated multiorbital systems [8]. 
Friday, March 9, 2018 9:12AM  9:48AM 
X32.00003: Diagrammatic Monte Carlo for realtime propagation Invited Speaker: Emanuel Gull We present a general introduction to Monte Carlo algorithms for solving impurity problems exposed to strong timedependent variation of their parameters. We show several numerical approaches to Keldysh diagrammatics and present results for voltage quenches, interaction quenches, and timedependent external fields. With these methods, nonequilibrium Monte Carlo methods are now at the point that they can be used as impurity solvers for dynamical mean field theory impurity problems, and we will show several applications of this method for equilibrium and nonequilibrium problems. 
Friday, March 9, 2018 9:48AM  10:24AM 
X32.00004: Studies of the Loschmidt Echo and Entanglement Spreading in Two Dimensional Anisotropic Spin Systems Invited Speaker: Robert Konik We describe a method for simulating the real time evolution of 
Friday, March 9, 2018 10:24AM  11:00AM 
X32.00005: Efficient Simulation of Quantum Thermalization Dynamics Invited Speaker: Frank Pollmann The past decade has seen a great interest in the question about whether and how quantum manybody system locally thermalize. It has been driven by theoretical findings involving the long sought demonstration that manybody localization (MBL) exists as well as the derivation of exact bounds on chaos. In my talk, I will introduce matrixproduct state (MPS) based methods that allow for an efficient numerical simulation of the quantum thermalization dynamics. Firstly, I will show that, contrary to the common belief that the rapid growth of entanglement restricts simulations to short times, the long time limit of local observables can be well captured using the MPS based timedependent variational principle. Secondly, I will discuss how mixed states can be represented using dynamically disentangled purified states. These novel methods allow to extract transport coefficients efficiently. 
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