Depletion of a Bose-Einstein condensate by laser-iduced dipole-dipole interactions

TL;DR

This paper investigates how laser-induced dipole-dipole interactions affect a Bose-Einstein condensate, revealing increased depletion and a roton dip in the excitation spectrum, with effects amplified at higher temperatures.

Contribution

It introduces a theoretical analysis of laser-induced dipole interactions in BECs using Hartree-Fock-Bogoliubov theory, highlighting novel temperature-dependent phenomena.

Findings

Increased depletion at specific momenta due to dipolar interactions

Emergence of a roton dip in the excitation spectrum

Enhanced effects at temperatures above absolute zero

Abstract

We study a gaseous Bose-Einstein condensate with laser-induced dipole-dipole interactions using the Hartree-Fock-Bogoliubov theory within the Popov approximation. The dipolar interactions introduce long-range atom-atom correlations, which manifest themselves as increased depletion at momenta similar to that of the laser wavelength, as well as a "roton" dip in the excitation spectrum. Surprisingly, the roton dip and the corresponding peak in the depletion are enhanced by raising the temperature above absolute zero.