Post-quench dynamics and pre-thermalization in a resonant Bose gas

TL;DR

This paper investigates the non-equilibrium dynamics of a resonant Bose gas after a strong interaction quench, revealing a pre-thermalized state with characteristic momentum distribution and experimental agreement.

Contribution

It introduces a self-consistent dynamic field approach to describe post-quench behavior and identifies the emergence of a pre-thermalized state with specific observable features.

Findings

Observation of Rabi-like oscillations between condensate and quasiparticles

Identification of a pre-thermalized steady state with power-law momentum tail

Qualitative agreement with recent experimental results

Abstract

We explore the dynamics of a resonant Bose gas following its quench to a strongly interacting regime near a Feshbach resonance. For such deep quenches, we utilize a self-consistent dynamic field approximation and find that after an initial regime of many-body Rabi-like oscillations between the condensate and finite-momentum quasiparticle pairs, at long times, the gas reaches a pre-thermalized nonequilibrium steady state. We explore the resulting state through its broad stationary momentum distribution function, that exhibits a power-law high momentum tail. We study the dynamics and steady-state form of the associated enhanced depletion, quench-rate dependent excitation energy, Tan's contact, structure function and radio frequency spectroscopy. We find these predictions to be in a qualitative agreement with recent experiments.