Thermodynamics of a two-dimensional dipolar Bose gas with correlated disorder in the roton regime

TL;DR

This paper investigates how weak correlated disorder affects the thermodynamic properties of a 2D dipolar Bose gas, revealing significant modifications near the roton instability and potential quantum phase transition.

Contribution

It provides analytical expressions for key thermodynamic quantities of a 2D dipolar Bose gas with correlated disorder in the roton regime, extending Bogoliubov theory.

Findings

Condensate depletion and anomalous density are comparable.

Structure factor and superfluid fraction are significantly altered near the roton instability.

Transition to an unusual quantum state occurs as the roton approaches zero.

Abstract

We sudy the impact of a weak random potential with a Gaussian correlation function on the thermodynamics of a two-dimensional (2D) dipolar bosonic gas. Analytical expressions for the quantum depletion, anomalous density, the ground state energy, the equation of state and the sound velocity are derived in the roton regime within the framework of the Bogoliubov theory. Surprisingly, we find that the condensate depletion and the anomalous density are comparable. The structure factor and the superfluid fraction are also obtained analytically and numerically. We show that these quantities acquire dramatically modified profiles when the roton is close to zero yielding the transition to an unusual quantum state.