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Figueroa-Romero P, Modi K, Pollock FA. Equilibration on average in quantum processes with finite temporal resolution. Phys Rev E 2020; 102:032144. [PMID: 33075897 DOI: 10.1103/physreve.102.032144] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 09/15/2020] [Indexed: 11/07/2022]
Abstract
We characterize the conditions under which a multitime quantum process with a finite temporal resolution can be approximately described by an equilibrium one. By providing a generalization of the notion of equilibration on average, where a system remains closed to a fixed equilibrium for most times, to one which can be operationally assessed at multiple times, we place an upper-bound on a new observable distinguishability measure comparing a multitime process with a finite temporal resolution against a fixed equilibrium one. While the same conditions on single-time equilibration, such as a large occupation of energy levels in the initial state remain necessary, we obtain genuine multitime contributions depending on the temporal resolution of the process and the amount of disturbance of the observer's operations on it.
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Affiliation(s)
| | - Kavan Modi
- School of Physics & Astronomy, Monash University, Victoria 3800, Australia
| | - Felix A Pollock
- School of Physics & Astronomy, Monash University, Victoria 3800, Australia
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Kaplan HB, Guo L, Tan WL, De A, Marquardt F, Pagano G, Monroe C. Many-Body Dephasing in a Trapped-Ion Quantum Simulator. PHYSICAL REVIEW LETTERS 2020; 125:120605. [PMID: 33016720 DOI: 10.1103/physrevlett.125.120605] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 08/20/2020] [Indexed: 06/11/2023]
Abstract
How a closed interacting quantum many-body system relaxes and dephases as a function of time is a fundamental question in thermodynamic and statistical physics. In this Letter, we analyze and observe the persistent temporal fluctuations after a quantum quench of a tunable long-range interacting transverse-field Ising Hamiltonian realized with a trapped-ion quantum simulator. We measure the temporal fluctuations in the average magnetization of a finite-size system of spin-1/2 particles. We experiment in a regime where the properties of the system are closely related to the integrable Hamiltonian with global spin-spin coupling, which enables analytical predictions for the long-time nonintegrable dynamics. The analytical expression for the temporal fluctuations predicts the exponential suppression of temporal fluctuations with increasing system size. Our measurement data is consistent with our theory predicting the regime of many-body dephasing.
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Affiliation(s)
- Harvey B Kaplan
- Joint Quantum Institute, Department of Physics and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
| | - Lingzhen Guo
- Max Planck Institute for the Science of Light, Staudtstrasse 2, 91058 Erlangen, Germany
| | - Wen Lin Tan
- Joint Quantum Institute, Department of Physics and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
| | - Arinjoy De
- Joint Quantum Institute, Department of Physics and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
| | - Florian Marquardt
- Max Planck Institute for the Science of Light, Staudtstrasse 2, 91058 Erlangen, Germany
- Physics Department, University of Erlangen-Nuremberg, Staudtstrasse 5, 91058 Erlangen, Germany
| | - Guido Pagano
- Joint Quantum Institute, Department of Physics and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
- Department of Physics and Astronomy, Rice University, 6100 Main Street, Houston, Texas 77005, USA
| | - Christopher Monroe
- Joint Quantum Institute, Department of Physics and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
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Kiendl T, Marquardt F. Many-Particle Dephasing after a Quench. PHYSICAL REVIEW LETTERS 2017; 118:130601. [PMID: 28409976 DOI: 10.1103/physrevlett.118.130601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Indexed: 06/07/2023]
Abstract
After a quench in a quantum many-body system, expectation values tend to relax towards long-time averages. However, temporal fluctuations remain in the long-time limit, and it is crucial to study the suppression of these fluctuations with increasing system size. The particularly important case of nonintegrable models has been addressed so far only by numerics and conjectures based on analytical bounds. In this work, we are able to derive analytical predictions for the temporal fluctuations in a nonintegrable model (the transverse Ising chain with extra terms). Our results are based on identifying a dynamical regime of "many-particle dephasing," where quasiparticles do not yet relax but fluctuations are nonetheless suppressed exponentially by weak integrability breaking.
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Affiliation(s)
- Thomas Kiendl
- Dahlem Center for Complex Quantum Systems and Institut für Theoretische Physik, Freie Universität Berlin, 14195, Berlin, Germany
- Institute for Theoretical Physics, Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen, Germany
| | - Florian Marquardt
- Institute for Theoretical Physics, Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen, Germany
- Max Planck Institute for the Science of Light, Günther-Scharowsky-Straße 1/Bau 24, D-91058 Erlangen, Germany
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