Conditions for quantum violent relaxation

Year: 2025

Authors: Giachetti G., Defenu N.

Autors Affiliation: CY Paris Univ, 2 Adolphe Chauvin, F-95302 Pontoise, France; ENS, Ecole Normale Super, Lab Phys, F-75005 Paris, France; PSL Univ, F-75005 Paris, France; Swiss Fed Inst Technol, Inst Theoret Phys, Wolfgang Pauli Str 27, Zurich, Switzerland; CNR INO, Area Sci Pk, I-34149 Trieste, Italy.

Abstract: While the dynamics of fully connected systems is dominated by mean-field effect, in the classical limit the single-particle observables are observed to relax toward a nonthermal stationary value. This phenomenon is known as violent relaxation and it is generally absent at the quantum-mechanical level, where single-particle observables exhibits long-lived oscillations. In this paper we explain this discrepancy by determining some very restrictive conditions that quantum single-site Hamiltonians should meet in order for the system to undergo relaxation. We thus check them by introducing a new model (the so-called w model) which can exhibit dynamical phase transition among thermal behavior, persistent excitations, and violent relaxation. We also propose a way to implement it within light-matter coupling. We finally explain how the classical limit restore this behavior, thus showing that, even if the mean-field dynamics of quantum models is usually thought to be classical, quantum effects still play an important role in it.

Journal/Review: PHYSICAL REVIEW B

Volume: 111 (21)      Pages from: 214301-1  to: 214301-11

More Information: We acknowledge funding by the Swiss National Science Foundation (SNSF) under project funding ID 200021 207537 and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy EXC2181/1-390900948 (the Heidelberg STRUCTURES Excellence Cluster) and by the European Union under GA No. 101077500-QLR-Net. This research was supported in part by Grant No. NSF PHY-230935 to the Kavli Institute for Theoretical Physics (KITP) .
KeyWords: Statistical-mechanics; Range; Equilibrium; Systems; Distributions; Model
DOI: 10.1103/PhysRevB.111.214301