title: Ideal mean-field transition in a modulated cold atom system.
abstract: We show that an atomic system in a periodically modulated optical trap displays an ideal mean-field symmetry-breaking transition. The symmetry is broken with respect to time translation by the modulation period. We describe experimental observations and develop a full microscopic theory of the observed critical phenomena. The transition is explained as resulting from the interplay of the long-range interatomic interaction and nonequilibrium fluctuations in the strongly modulated system. The observations, including anomalous fluctuations in the symmetry broken phase, are fully described by the theory.
authors.affiliation: Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
authors.forename: Myoung-Sun
authors.initials: MS
authors.lastname: Heo
authors.forename: Yonghee
authors.initials: Y
authors.lastname: Kim
authors.forename: Kihwan
authors.initials: K
authors.lastname: Kim
authors.forename: Geol
authors.initials: G
authors.lastname: Moon
authors.forename: Junhyun
authors.initials: J
authors.lastname: Lee
authors.forename: Heung-Ryoul
authors.initials: HR
authors.lastname: Noh
authors.forename: M I
authors.initials: MI
authors.lastname: Dykman
authors.forename: Wonho
authors.initials: W
authors.lastname: Jhe