title: BCS wave-function approach to the BEC-BCS crossover of exciton-polariton condensates.
abstract: The crossover between low and high density regimes of exciton-polariton condensates is examined using a BCS wave-function approach. Our approach is an extension of the BEC-BCS crossover theory for excitons, but includes a cavity photon field. The approach can describe both the low density limit, where the system can be described as a Bose-Einstein condensate (BEC) of exciton-polaritons, and the high density limit, where the system enters a photon-dominated regime. In contrast to the exciton BEC-BCS crossover where the system approaches an electron-hole plasma, the polariton high density limit has strongly correlated electron-hole pairs. At intermediate densities, there is a regime with BCS-like properties, with a peak at nonzero momentum of the singlet pair function. We calculate the expected photoluminescence and give several experimental signatures of the crossover.
authors.affiliation: National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan.
authors.forename: Tim
authors.initials: T
authors.lastname: Byrnes
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Horikiri
authors.forename: Natsuko
authors.initials: N
authors.lastname: Ishida
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Yamamoto