arXiv:1303.1642 · Journal of Statistical Mechanics Theory and Experiment
Phase transitions in three-dimensional bosonic systems in optical lattices
H Kleinert, Z Narzikulov, Abdulla Rakhimov
Abstract
We formulate the collective quantum field theory for three-dimensional bosonic optical lattices and evaluate its consequences in a mean-field approximation to two collective fields, proposed by Cooper et al (2011 Phys. Rev. A 83 053622), and in a lowest-order variational perturbation theory. It is shown that the present mean-field approximation predicts some essential features of the experimentally observed dependence of the critical temperature on the coupling strength and a second-order quantum phase transition. In contrast to a recent prediction for atomic gases given by Cooper et al , our finding indicates no superfluid state with zero condensate fraction.