Griffiths Physics in an Ultracold Bose Gas

TL;DR

This paper experimentally investigates coupled quasi-2D ultracold Bose gas layers with disordered interlayer coupling, revealing Griffiths phases and phase crossovers relevant to disordered quantum systems.

Contribution

It demonstrates the realization of disordered interlayer coupling in ultracold Bose gases using advanced optical lattices, and identifies Griffiths phases in this system.

Findings

Identification of Griffiths phases between thermal and superfluid states

Implementation of disordered interlayer coupling with optical lattices

Observation of phase crossover regions in ultracold Bose gases

Abstract

Coupled XY model systems consisting of three-dimensional (3D) systems with disordered interlayer physics are of significant theoretical interest. We realize a set of coupled quasi-2D layers of $^{87}$Rb in the presence of disordered inter-layer coupling. This is achieved with our high bandwidth arbitrary optical lattice to obviate restrictions on the dimensionality of disorder with speckle-generated optical fields. We identify phase crossover regions compatible with the existence of a pair of intermediate Griffiths phases between a thermal state and the emergence of bulk 3D superfluidity.