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A: Fachverband Atomphysik

A 41: Poster Session IIIa

A 41.23: Poster

Donnerstag, 8. März 2018, 16:15–18:15, Orangerie

Mean-field phase diagram of ultracold bosons inside a cavity — •Lukas Himbert, Rebecca Kraus, Shraddha Sharma, Astrid Elisa Niederle, and Giovanna Morigi — Theoretische Physik, Universität des Saarlandes, D-66123 Saarbrücken, Germany

We study a system of ultracold atoms confined by a 2-dimensional optical lattice within a cavity and optomechanically coupled with the cavity mode of the same wavelength as the lattice. The dynamics is described by an extended Bose-Hubbard Hamiltonian with global-range interactions between the atoms. By applying a mean-field approximation, we numerically determine the ground state phase diagram in the grand canonical ensemble. We reproduce the phase diagram presented by Dogra et al. [PRA 94, 023632 (2016)] and identify a Mott insulator, a superfluid, a charge density wave, and a supersolid phase; the latter two exhibit checkerboard order favoured by the global interaction. Moreover, regions separating the superfluid and the supersolid phase exhibit discontinuous jumps of the density as a function of the chemical potential, suggesting a first-order transition. We then consider the inhomogeinity of a harmonic trap and determine its influence on the phase diagram.