TY - JOUR

T1 - First-principles quantum simulations of dissociation of molecular condensates

T2 - Atom correlations in momentum space

AU - Savage, C. M.

AU - Schwenn, P. E.

AU - Kheruntsyan, K. V.

PY - 2006

Y1 - 2006

N2 - We investigate the quantum many-body dynamics of dissociation of a Bose-Einstein condensate of molecular dimers into pairs of constituent bosonic atoms and analyze the resulting atom-atom correlations. The quantum fields of both the molecules and atoms are simulated from first principles in three dimensions using the positive- P representation method. This allows us to provide an exact treatment of the molecular field depletion and s -wave scattering interactions between the particles, as well as to extend the analysis to nonuniform systems. In the simplest uniform case, we find that the major source of atom-atom decorrelation is atom-atom recombination which produces molecules outside the initially occupied condensate mode. The unwanted molecules are formed from dissociated atom pairs with nonopposite momenta. The net effect of this processâ€"which becomes increasingly significant for dissociation durations corresponding to more than about 40% conversionâ€"is to reduce the atom-atom correlations. In addition, for nonuniform systems we find that mode mixing due to inhomogeneity can result in further degradation of the correlation signal. We characterize the correlation strength via the degree of squeezing of particle number-difference fluctuations in a certain momentum-space volume and show that the correlation strength can be increased if the signals are binned into larger counting volumes.

AB - We investigate the quantum many-body dynamics of dissociation of a Bose-Einstein condensate of molecular dimers into pairs of constituent bosonic atoms and analyze the resulting atom-atom correlations. The quantum fields of both the molecules and atoms are simulated from first principles in three dimensions using the positive- P representation method. This allows us to provide an exact treatment of the molecular field depletion and s -wave scattering interactions between the particles, as well as to extend the analysis to nonuniform systems. In the simplest uniform case, we find that the major source of atom-atom decorrelation is atom-atom recombination which produces molecules outside the initially occupied condensate mode. The unwanted molecules are formed from dissociated atom pairs with nonopposite momenta. The net effect of this processâ€"which becomes increasingly significant for dissociation durations corresponding to more than about 40% conversionâ€"is to reduce the atom-atom correlations. In addition, for nonuniform systems we find that mode mixing due to inhomogeneity can result in further degradation of the correlation signal. We characterize the correlation strength via the degree of squeezing of particle number-difference fluctuations in a certain momentum-space volume and show that the correlation strength can be increased if the signals are binned into larger counting volumes.

UR - http://www.scopus.com/inward/record.url?scp=33749160352&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.74.033620

DO - 10.1103/PhysRevA.74.033620

M3 - Article

SN - 1050-2947

VL - 74

JO - Physical Review A - Atomic, Molecular, and Optical Physics

JF - Physical Review A - Atomic, Molecular, and Optical Physics

IS - 3

M1 - 033620

ER -