title: Enhanced coherence between condensates formed resonantly at different times.
abstract: We demonstrate coherence between exciton-polariton condensates created resonantly at different times. The coherence persists much longer than the individual particle dephasing time, and this persistence increases as the particle density increases. The observed coherence time exceeds that of the injecting laser pulse by more than an order of magnitude. We show that this significant coherence enhancement relies critically on the many-body particle interactions, as verified by its dependence on particle density, interaction strength, and bath temperature, whereas the mass of the particles plays no role in the condensation of resonantly injected polaritons. Furthermore, we observe a large nonlinear phase shift resulting from intra-condensate interaction energy. Our results provide a new approach for probing ultrafast dynamics of resonantly-created condensates and open new directions in the study of coherence in matter.
authors.forename: Alex
authors.initials: A
authors.lastname: Hayat
authors.forename: Christoph
authors.initials: C
authors.lastname: Lange
authors.forename: Lee A
authors.initials: LA
authors.lastname: Rozema
authors.forename: Rockson
authors.initials: R
authors.lastname: Chang
authors.forename: Shreyas
authors.initials: S
authors.lastname: Potnis
authors.forename: Henry M
authors.initials: HM
authors.lastname: van Driel
authors.forename: Aephraim M
authors.initials: AM
authors.lastname: Steinberg
authors.forename: Mark
authors.initials: M
authors.lastname: Steger
authors.forename: David W
authors.initials: DW
authors.lastname: Snoke
authors.forename: Loren N
authors.initials: LN
authors.lastname: Pfeiffer
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: West