Superfluidity with disorder in a quantum gas thin film

TL;DR

This study explores how disorder affects superfluidity in a quasi-two-dimensional quantum gas film of lithium molecules, revealing a transition from superfluid to glass-like states as disorder increases.

Contribution

It provides experimental insights into the disorder-induced superfluid to insulator transition in a strongly interacting quantum gas in two dimensions.

Findings

Superfluid state exists at low disorder levels.

Transition to a poorly conducting, glass-like phase occurs at high disorder.

Conduction properties change abruptly at the percolation threshold.

Abstract

We investigate the properties of a strongly interacting, superfluid gas of 6Li2 Feshbach molecules forming a thin film confined in a quasi two-dimensional channel with a tunable random potential, creating a microscopic disorder. We measure the atomic current and extract the resistance of the film in a two-terminal configuration, and identify a superfluid state at low disorder strength, which evolves into a normal, poorly conducting state for strong disorder. The transition takes place when the chemical potential reaches the percolation threshold of the disorder. The evolution of the conduction properties contrasts with the smooth behavior of the density and compressibility across the transition, measured in-situ at equilibrium. These features suggest the emergence of a glass-like phase at strong disorder.