Propagation of electromagnetic waves in Bose-Einstein condensate of atoms with dipole moments

TL;DR

This paper investigates how electromagnetic waves propagate in a Bose-Einstein condensate of atoms with dipole moments, considering different spectral interactions and the effects of dipole-dipole interactions on wave behavior.

Contribution

It introduces a modified Gross--Pitaevskii equation accounting for dipole moments and electromagnetic interactions, analyzing wave propagation in different spectral crossing scenarios.

Findings

Electromagnetic and condensate excitation spectra can either cross or hybridize.

Propagation of sound can be accompanied by electromagnetic oscillations.

Dipole-dipole interactions significantly influence wave propagation characteristics.

Abstract

We study the propagation of electromagnetic waves in the Bose-Einstein condensate of atoms with both intrinsic dipole moments and those induced by the electric field. The modified Gross--Pitaevskii equation is used, which takes into account relaxation and interaction with the electromagnetic field. Two cases are considered: 1) when the dispersion curves of the electromagnetic wave and of the condensate excitations do not intercross and 2) when the condensate excitations' spectrum has a gap and the two dispersion curves do intercross. In the second case the two branches hybridize. It is shown that propagation of sound waves can be accompanied by oscillation of the electromagnetic field. The impact is studied of the dipole-dipole interaction on the character of electromagnetic and acoustic waves' propagation in the Bose-Einstein condensate.