Phonon-polaritons in Bose-Einstein condensates induced by Casimir-Polder   interaction with graphene
  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. 
H. Ter\c{c}as, S. Ribeiro and J. T. Mendon\c{c}a
cond-mat.quant-gas