Quantum field effects in coupled atomic and molecular Bose-Einstein condensates - art. no. 053608

This paper examines the parameter regimes in which coupled atomic and molec ular Bose-Einstein condensates do not obey the Gross-Pitaevskii equation. S tochastic field equations for coupled atomic and molecular condensates are derived using the functional positive-P representation. These equations des cribe the full quantum state of the coupled condensates and include the com monly used Gross-Pitaevskii equation as the noiseless limit. The model incl udes all interactions between the particles. background gas losses, two-bod y losses, and the numerical simulations are performed in three dimensions. It is found that it is possible to differentiate the quantum and semiclassi cal behavior when the particle density is sufficiently low and the coupling is sufficiently strong.