A Dielectric Superfluid of Polar Molecules

TL;DR

This paper demonstrates that a Bose-Einstein condensate of polar molecules can behave as a dielectric superfluid, exhibiting unique polarization modes and instabilities under realistic experimental conditions.

Contribution

It introduces a self-consistent mean-field framework linking condensate density to electric polarization, revealing dielectric properties in polar molecule BECs.

Findings

Polar BECs can exhibit dielectric behavior.

Coupled polarization and quasiparticle modes are identified.

A phonon-like instability emerges, akin to negative dielectric function materials.

Abstract

We show that, under achievable experimental conditions, a Bose-Einstein condensate (BEC) of polar molecules can exhibit dielectric character. In particular, we derive a set of self-consistent mean-field equations that couple the condensate density to its electric dipole field, leading to the emergence of polarization modes that are coupled to the rich quasiparticle spectrum of the condensate. While the usual roton instability is suppressed in this system, the coupling can give rise to a phonon-like instability that is characteristic of a dielectric material with a negative static dielectric function.