title: Complex chemical potential: signature of decay in a bose-einstein condensate.
abstract: We explore the zero-temperature statics of an atomic Bose-Einstein condensate in which a Feshbach resonance creates a coupling to a second condensate component of quasibound molecules. Using a variational procedure to find the equation of state, the appearance of this binding is manifest in a collapsing ground state, where only the molecular condensate is present up to some critical density. Further, an excited state is seen to reproduce the usual low-density atomic condensate behavior in this system, but the molecular component is found to produce a coherent, many-body decay, quantified by the imaginary part of the chemical potential. Most importantly, the unique decay rate dependencies on density (approximately rho (3/2)) and on scattering length (approximately (5/2)) can be measured in experimental tests of this result.
authors.affiliation: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, 02139, USA.
authors.forename: George E
authors.initials: GE
authors.lastname: Cragg
authors.forename: Arthur K
authors.initials: AK
authors.lastname: Kerman