title: Bose-Einstein condensation with an entangled order parameter.
abstract: We propose a practically accessible non-mean-field ground state of Bose-Einstein condensation, which occurs in an interspecies two-particle entangled state, and is thus described by an entangled order parameter. A suitably defined entanglement entropy is used as the characterization of the non-mean-field nature, and is found to persist in a wide parameter regime. The interspecies entanglement leads to novel interference terms in the dynamical equations governing the single-particle orbital wave function. Experimental feasibility and several methods of probe are discussed. We urge the study of multichannel scattering between different species of atoms.
authors.affiliation: Department Physics, Fudan University, Shanghai 200433, China. yushi@fudan.edu.cn
authors.forename: Yu
authors.initials: Y
authors.lastname: Shi
authors.forename: Qian
authors.initials: Q
authors.lastname: Niu