Glassy features of a Bose Glass

TL;DR

This paper investigates the Bose glass phase in a disordered two-dimensional Bose-Hubbard model, revealing numerous metastable states with similar energies but random phases, which may explain experimental coherence loss.

Contribution

It uncovers the existence of many low-energy metastable configurations with complex local order and random phases, advancing understanding of Bose glass properties.

Findings

Multiple metastable states with similar energies

Local order patterns resemble the ground state

Random phases in different coherent islands

Abstract

We study a two-dimensional Bose-Hubbard model at a zero temperature with random local potentials in the presence of either uniform or binary disorder. Many low-energy metastable configurations are found with virtually the same energy as the ground state. These are characterized by the same blotchy pattern of the, in principle, complex nonzero local order parameter as the ground state. Yet, unlike the ground state, each island exhibits an overall random independent phase. The different phases in different coherent islands could provide a further explanation for the lack of coherence observed in experiments on Bose glasses.