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arXiv · 1511.03833

Topological Superfluids and BEC-BCS Crossover in Attractive Haldane-Hubbard Model

Yi-Cai Zhang·Zhihao Xu·Shizhong Zhang
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Abstract

Motivated by the recent realization of the Haldane model in shaking optical lattice, we investigate the effects of attractive interaction and BEC-BCS crossover in this model at and away from half filling. We show that, contrary to the usual s-wave BEC-BCS crossover in the lattice, a topological superfluid with Chern number C=2 appears in an extended region of phase space for intermediate strength of the attractive interaction in the interaction-density plane. When inversion symmetry is broken, a new gapless topological state is realized. We also investigate the fluctuations in these superfluid phases and show that the Anderson-Bogoliubov mode is quadratic due to time-reversal symmetry breaking and the existence of an undamped Leggett mode in the strong coupling limit.

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Yi-Cai Zhang, Zhihao Xu, Shizhong Zhang. 2015-11-12. Topological Superfluids and BEC-BCS Crossover in Attractive Haldane-Hubbard Model. https://doi.org/10.1103/physreva.95.043640

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