Decoherence and dephasing of strongly driven colliding Bose condensates

Bose-Einstein condensates (BEC) serve as a model system for the study of decoherence and dephasing processes. We denote ‘dephasing’ as the loss of overall common phase due to the coherent evo lution of the macroscopic wavefunction of the BEC. In contrast, ‘decoherence’ in this case is the coupling of the macroscopic wavefunction state to a continuum of initially unoccupied momentum excitations via collisions. Decoherence is driven by the fluctuations in th ese momentum modes and is irreversible on the timescales larger than the so -called ‘memory time’ of the continuum [1].