Controlling symmetry and localization with an artificial gauge field in a disordered quantum system

TL;DR

This study experimentally demonstrates how an artificial gauge field can control symmetry properties and localization phenomena in a disordered Floquet quantum system, revealing universal scaling behavior.

Contribution

It introduces a method to tune symmetry in a disordered quantum system using an artificial gauge field and observes symmetry-sensitive localization signatures.

Findings

Observation of coherent backscattering and forward scattering as signatures of localization

Demonstration of the universality of the $eta(g)$ scaling function across symmetry classes

Control of localization properties via artificial gauge field in a Floquet system

Abstract

Anderson localization, the absence of diffusion in disordered media, draws its origins from the destructive interference between multiple scattering paths. The localization properties of disordered systems are expected to be dramatically sensitive to their symmetry characteristics. So far however, this question has been little explored experimentally. Here, we investigate the realization of an artificial gauge field in a synthetic (temporal) dimension of a disordered, periodically-driven (Floquet) quantum system. Tuning the strength of this gauge field allows us to control the time-reversal symmetry properties of the system, which we probe through the experimental observation of three symmetry-sensitive `smoking-gun' signatures of localization. The first two are the coherent backscattering, marker of weak localization, and the coherent forward scattering, genuine interferential signature of Anderson localization, observed here for the first time. The third is the direct measurement of the $\beta(g)$ scaling function in two different symmetry classes, allowing to demonstrate its universality and the one-parameter scaling hypothesis.