Heidelberg 2015 – wissenschaftliches Programm
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 . 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.
 Yongqiang Li, Liang He, and Walter Hofstetter, Phys. Rev. A 87, 051604(R) (2013).