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A: Fachverband Atomphysik

A 18: Poster: Ultra-cold atoms, ions and BEC (with Q)

A 18.1: Poster

Dienstag, 24. März 2015, 17:00–19:00, C/Foyer

Interacting bosons in an optical cavity — •Dandan Su¹, Yongqiang Li², and Walter Hofstetter¹ — ¹Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany — ²Department of Physics, National University of Defense Technology, Changsha 410073, People's Republic of China

We numerically simulate strongly correlated ultracold bosons coupled to a high-finesse optical cavity. Assuming that a weak classical optical lattice is added in the cavity direction, we describe this system by a generalized Bose-Hubbard model, which is solved by means of bosonic dynamical mean-field theory. For a single-mode cavity, pumped by a laser beam in the transverse direction, the complete phase diagram is established, which contains two novel self-organized quantum phases, lattice supersolid and checkerboard solid, in addition to conventional phases such as superfluid and Mott insulator [1]. At finite but low temperature, thermal fluctuations are found to enhance the buildup of these self-organized phases. We demonstrate that cavity-mediated long-range interactions can give rise to stable lattice supersolid and checkerboard solid phases even in the regime of strong s-wave scattering. In the presence of a harmonic trap, we discuss the coexistence of these self-organized phases, as relevant to experiments. Furthermore, we investigate a system of bosons coupled to two crossed cavity modes, whose axes' angle is 60 degree. We study self-organization phenomena in the resulting hexagonal lattice.

[1] Yongqiang Li, Liang He, and Walter Hofstetter, Phys. Rev. A 87, 051604(R) (2013).