Intrinsic decoherence in an ultracold Bose gas confined in a double-well potential

We address the intrinsic decoherence of an N-body interacting bosonic quantum fluid confined in a double-well potential in one dimension, and its effect on the transition from coherent oscillations to self-trapping regimes as a function of the interparticle interaction. Performing a full quantum approach to the N-particle system, we study the transition and the observed decoherence through the analysis of the one-particle reduced density matrix. The results are obtained by following the time evolution of such a matrix. For large systems and because of the interparticle interactions, the system reaches stationary states which can be characterized both by the vanishing of the off-diagonal matrix elements, in what one may call the preferred basis, and by the value of its associated von Neumman entropy. The present results could be useful in analysing experimental realizations, such as those by Albiez et al (2005 Phys. Rev. Lett. 95 010402).