From many-body oscillations to thermalization in an isolated spinor gas

TL;DR

This paper investigates how an isolated spinor gas transitions from reversible oscillations to thermalization, revealing the roles of spectrum linearity, non-linearity, and chaos in many-body dynamics through experiments and simulations.

Contribution

It demonstrates experimentally and numerically how a spinor gas exhibits a spectrum-dependent transition from oscillations to thermalization, highlighting the emergence of chaos and irreversibility.

Findings

Linear spectrum causes undamped oscillations

Non-linear spectrum leads to irreversibility

Chaotic dynamics induce thermalization

Abstract

The dynamics of a many-body system can take many forms, from a purely reversible evolution to fast thermalization. Here we show experimentally and numerically that an assembly of spin 1 atoms all in the same spatial mode allows one to explore this wide variety of behaviors. When the system can be described by a Bogoliubov analysis, the relevant energy spectrum is linear and leads to undamped oscillations of many-body observables. Outside this regime, the non-linearity of the spectrum leads to irreversibity, characterized by a universal behavior. When the integrability of the Hamiltonian is broken, a chaotic dynamics emerges and leads to thermalization, in agreement with the Eigenstate Thermalization Hypothesis paradigm.