Atomic Bose and Anderson glasses in optical lattices

TL;DR

This paper demonstrates how ultracold atomic Bose gases in optical lattices can be used to study disordered Bose systems, revealing phase transitions from superfluid to Bose-glass or Anderson-glass phases induced by controlled disorder.

Contribution

It introduces a method to control disorder in optical lattices and explores the resulting phase transitions in Bose gases under different interaction regimes.

Findings

Disorder induces a transition from superfluid to Bose-glass phase in strong interactions.

Weak interactions show a transition from superfluid to Anderson-glass phase.

Low-intensity disorder significantly reduces superfluid fraction.

Abstract

An ultra cold atomic Bose gas in an optical lattice is shown to provide an ideal system for the controlled analysis of disordered Bose lattice gases. This goal may be easily achieved under the current experimental conditions, by introducing a pseudo-random potential created by a second additional lattice or, alternatively, by placing a speckle pattern on the main lattice. We show that for a non commensurable filling factor, in the strong interaction limit, a controlled growing of the disorder drives a dynamical transition from superfluid to Bose-glass phase. Similarly, in the weak interaction limit, a dynamical transition from superfluid to Anderson-glass phase may be observed. In both regimes, we show that even very low-intensity disorder-inducing lasers cause large modifications of the superfluid fraction of the system.