Non-equilibrium dynamics of fluctuations in an ultra-cold atomic mixture

TL;DR

This study explores the non-equilibrium behavior of spin fluctuations in an ultra-cold Bose gas mixture, revealing distinct dynamical regimes and reconstructing effective potentials through experimental and theoretical analysis.

Contribution

It provides the first detailed experimental and theoretical analysis of fluctuation dynamics in a spinor Bose gas mixture across various initial conditions.

Findings

Identification of three distinct dynamical regimes

Reconstruction of effective potentials for each regime

Observation of long-lived metastable states and rapid relaxation

Abstract

We investigate an ultra-cold mixture of Bose gases interacting via spin-changing collisions by studying the dynamics of spin fluctuations. The experimental implementation employs $^{23}$Na and $^{7}$Li atoms, which are prepared out of equilibrium across a wide range of initial conditions. We identify three regimes in the dynamics of the system for different initial states: a long-lived metastable regime, an instability range with strong growth of fluctuations, and a fast relaxing regime approaching thermal equilibrium. Theoretical modelling of the data allows us to reconstruct effective potentials which characterize the different dynamical regimes of the system.