Two-dimensional quantum droplets in dipolar Bose gases

TL;DR

This paper analytically investigates quantum and thermal fluctuation effects in a dilute quasi-two-dimensional dipolar Bose gas, revealing conditions for droplet formation and stability influenced by temperature and interactions.

Contribution

It provides the first analytical calculation of fluctuation corrections in 2D dipolar Bose gases, explaining droplet formation and stability beyond mean field theory.

Findings

Quantum fluctuations can turn repulsion into attraction in the density-temperature plane.

Droplet stability is limited to ultralow temperatures due to thermal fluctuations.

Equilibrium density depends strongly on temperature and confinement strength.

Abstract

We calculate analytically the quantum and thermal fluctuations corrections of a dilute quasi-two-dimensional Bose-condensed dipolar gas. We show that these fluctuations may change their character from repulsion to attraction in the density-temperature plane owing to the striking momentum dependence of the dipole-dipole interactions. The dipolar instability is halted by such unconventional beyond mean field corrections leading to the formation of a droplet phase. The equilibrium features and coherence properties exhibited by such droplets are deeply discussed. At finite temperature, we find that the equilibrium density crucially depends on the temperature and on the confinement strength and thus, a stable droplet can exist only at ultralow temperature due to the strong thermal fluctuations.