Quantum and thermal fluctuations in bosonic Josephson junctions

B. Juliá-Díaz; A. D. Gottlieb; J. Martorell; A. Polls

doi:10.1103/PhysRevA.88.033601

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Quantum and thermal fluctuations in bosonic Josephson junctions

B. Juliá-Díaz, A. D. Gottlieb, J. Martorell, A. Polls

DOI 10.1103/PhysRevA.88.033601 · Physical Review A

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Abstract

We use the Bose-Hubbard Hamiltonian to study quantum fluctuations in canonical equilibrium ensembles of bosonic Josephson junctions at relatively high temperatures, comparing the results for finite particle numbers N to the classical limit that is attained as N approaches infinity. We consider both attractive and repulsive atom-atom interactions, with special focus on the behavior near the T=0 quantum phase transition that occurs, for large enough N, when attractive interactions surpass a critical level. Differences between Bose-Hubbard results for small N and those of the classical limit are quite small even when N∼100, with deviations from the limit diminishing as 1/N.