Observation of Dynamical Super Efimovian Expansion in a Unitary Fermi Gas

TL;DR

This paper reports the experimental observation of a super Efimovian expansion in a strongly interacting Fermi gas, revealing universal scaling dynamics and double-log periodicity during expansion.

Contribution

It demonstrates the first observation of dynamical super Efimovian expansion in a quantum gas with engineered trap frequencies, highlighting universal scaling behavior.

Findings

Observation of double-log periodicity in cloud expansion

Verification of universal scaling in both non-interacting and unitarity limits

Identification of a new dynamical regime linked to super Efimov physics

Abstract

We report an observation of a dynamical super Efimovian expansion in a two-component strongly interacting Fermi gas by engineering time dependent external harmonic trap frequencies. When trap frequency is followed as $[1/4t^2+1/t^2\lambda\log(t/t_*)]^{1/2}$, where $t_*$ and $\lambda$ are two control parameters, and the change is faster than a critical value, the expansion of such the quantum gas shows a novel dynamics due to its spatial and dynamical scaling symmetry. A clear double-log periodicity, which is a hallmark of the super Efimov effect, is emergent for the cloud size in the expansion. The universality of such scaling dynamics is verified both in the non-interacting limit and in the unitarity limit. Observing super-Efmovian evolution represents a paradigm in probing universal properties and allows in a new way to study many-body nonequilibrium dynamics with experiments.