Universal non-thermal fixed point for quasi-1D Bose gases

TL;DR

This study demonstrates that strongly interacting quasi-1D Bose gases exhibit universal non-thermal fixed point dynamics during relaxation, similar to weakly interacting systems, indicating a broad universality in far-from-equilibrium quantum gases.

Contribution

The paper provides experimental evidence for a universal non-thermal fixed point in strongly interacting quasi-1D Bose gases, extending the concept beyond weakly interacting systems.

Findings

Universal scaling dynamics observed in strongly interacting Bose gases.

Relaxation dynamics are independent of initial conditions and microscopic details.

Experimental results align with theoretical predictions of non-thermal fixed points.

Abstract

Spatio-temporal scaling dynamics connected to non-thermal fixed points has been suggested as a universal framework to describe the relaxation of isolated far-from-equilibrium systems. Experimental studies in weakly-interacting cold atom systems have found scaling dynamics connected to specific attractors. In our experiments, we study a quantum gas of strongly interacting $^6$Li$_2$ Feshbach molecules, brought far out of equilibrium by imprinting a white-noise phase profile. The observed relaxation follows the same universal dynamics as for the previously observed formation of the order parameter in a shock-cooled gas of weakly interacting $^{87}$Rb atoms. Our results point to a single universal fixed point with a large basin of attraction governing the relaxation of quasi-1D bosonic systems, independent of their specific initial conditions and microscopic details.