Phonon-polaritons in Bose-Einstein condensates induced by Casimir-Polder interaction with graphene

TL;DR

This paper demonstrates the formation of phonon-polaritons in a Bose-Einstein condensate coupled with graphene through Casimir-Polder interactions, revealing new hybrid excitations due to electromagnetic vacuum fluctuations.

Contribution

It introduces a self-consistent theoretical framework for phonon-polariton formation in BEC-graphene systems mediated by Casimir-Polder forces, a novel hybrid excitation mechanism.

Findings

Discovery of phonon-polaritons as hybrid excitations.

Derivation of self-consistent equations for coupled modes.

Identification of purely acoustic quasi-particles.

Abstract

We consider the mechanical coupling between a two-dimensional Bose-Einstein condensate with a graphene sheet via the vacuum fluctuations of the electromagnetic field which are at the origin of the so-called Casimir-Polder potential. By deriving a self-consistent set of equations governing the dynamics of the condensate and the flexural (out-of-plane) modes of the graphene, we can show the formation of a new type of purely acoustic quasi-particle excitation, a phonon-polariton resulting from the coherent superposition of quanta of flexural and Bogoliubov modes.