# Waves in a Bose-Einstein condensate of atoms with a dipole moment

## TL;DR

This paper investigates how hybridization of electromagnetic and sound waves in a dipolar Bose-Einstein condensate affects wave propagation, highlighting the role of dipole interactions and dissipation effects on the spectrum.

## Contribution

It introduces a modified Gross-Pitaevskii framework to analyze wave hybridization and the impact of dipole-dipole interactions in a BEC with intrinsic dipole moments.

## Key findings

- Hybridization creates two excitation branches with electromagnetic and sound oscillations.
- Dipole-dipole interactions significantly increase repulsion between spectral branches.
- Dissipative effects alter the dispersion curves of the waves.

## Abstract

Based on the modified Gross-Pitaevskii equation for atoms with intrinsic dipole moments which accounts for the relaxation of a condensate, the dipole-dipole interaction and the interaction of atoms with the electromagnetic field, the propagation of the sound and electromagnetic waves in a Bose-Einstein condensate is studied. Owing to hybridization of the electromagnetic and sound waves near the resonance frequency of an atom, there arise the two branches of excitations in which the electromagnetic oscillations transform into the sound oscillations and vice versa. It is shown that under hybridization the crucial role is played by the dipole-dipole interaction, which leads to a substantial increase of the repulsion between the branches of the spectrum. The influence of the dissipative effects connected with the relaxation of the macroscopic wave function of the condensate and the imaginary part of the polarizability of an atom on the form of the dispersion curves is investigated.