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arXiv · 1604.00865

Phase Transitions in a Bose-Hubbard Model with Cavity-Mediated Global-Range Interactions

N. Dogra·F. Brennecke·S. D. Huber·T. Donner
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Abstract

We study a system with competing short- and global-range interactions in the framework of the Bose-Hubbard model. Using a mean-field approximation we obtain the phase diagram of the system and observe four different phases: a superfluid, a supersolid, a Mott insulator and a charge density wave, where the transitions between the various phases can be either of first or second order. We qualitatively support these results using Monte-Carlo simulations. An analysis of the low-energy excitations shows that the second-order phase transition from the charge density wave to the supersolid is associated with the softening of particle- and hole-like excitations which give rise to a gapless mode and an amplitude Higgs mode in the supersolid phase. This amplitude Higgs mode is further transformed into a roton mode which softens at the supersolid to superfluid phase transition.

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N. Dogra, F. Brennecke, S. D. Huber, T. Donner. 2016-04-04. Phase Transitions in a Bose-Hubbard Model with Cavity-Mediated Global-Range Interactions. https://doi.org/10.1103/physreva.94.023632

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