title: Holographic storage of multiple coherence gratings in a Bose-Einstein condensate.
abstract: We demonstrate superradiant conversion between a two-mode collective atomic state and a single-mode light field in an elongated cloud of Bose-condensed atoms. Two off-resonant write beams induce superradiant Raman scattering, producing two independent coherence gratings with different wave vectors in the cloud. By applying phase-matched read beams after a controllable delay, the gratings can be selectively converted into the light field also in a superradiant way. Because of the large optical density and the small velocity width of the condensate, a high conversion efficiency of >70% and a long storage time of >120 micros were achieved.
authors.affiliation: Institute of Physics, University of Tokyo, 3-8-1, Komaba, Tokyo 153-8902, Japan. yutaka@phys.c.u-tokyo.ac.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yoshikawa
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Nakayama
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Torii
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kuga