Two-dimensional dipolar bosons with weak disorder

TL;DR

This paper studies how weak disorder affects a two-dimensional dipolar bosonic gas, revealing a transition from superfluid to a non-trivial quantum phase as disorder increases, especially near roton-like excitations.

Contribution

It provides analytical and numerical insights into the effects of weak disorder on key properties of 2D dipolar bosons, including superfluidity and excitation spectrum.

Findings

Superfluidity vanishes below a critical disorder strength.

Disorder induces condensate depletion and modifies the ground state energy.

Roton-like excitations are crucial in the transition to the quantum regime.

Abstract

We consider two-dimensional dipolar bosonic gas with dipoles oriented perpendicularly to the plane in a weak random potential. We investigate analytically and numerically the condensate depletion, the one-body density-matrix, the ground state energy, the sound velocity and the superfluid fraction. Concentrating on the regime where a rotonlike excitation spectrum forms, our results show that the superfluidity disappears below a critical value of disorder strength yielding the transition to a non-trivial quantum regime.