Macroscopic quantum fluctuations in the Josephson dynamics of two weakly linked Bose-Einstein condensates - art. no. 063601

We study analytically the quantum corrections to the Gross-Pitaevskii equat ion for two weakly linked Bose-Einstein condensates. The goals are (1) to i nvestigate dynamical regimes at the borderline between the classical and qu antum behavior of the bosonic field, and (2) to search macroscopic quantum coherence phenomena not observable with other superfluid/superconducting sy stems. Quantum fluctuations renormalize the classical Josephson oscillation frequencies. Large amplitude phase oscillations are modulated, exhibiting collapses and revivals. We describe an interwell oscillation mode with a va nishing (ensemble averaged) mean value of the observables, but with oscilla ting mean square fluctuations. We finally discuss the limit in which the cl assical Gross-Pitaevskii (Josephson) dynamics is recovered.