Hannover 2010 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 65: Quantum Gases : Lattices III

Q 65.5: Talk

Friday, March 12, 2010, 15:15–15:30, E 001

The Dicke Quantum Phase Transition in a Superfluid Gas Coupled to an Optical Cavity — •Kristian Baumann, Christine Guerlin, Ferdinand Brennecke, Silvan Leinss, Rafael Mottl, and Tilman Esslinger — IQE, ETH Zürich, Switzerland

A fundamental concept to describe the collective matter-light interaction is the Dicke model which has been predicted to how an intriguing quantum phase transition. We have realize d the Dicke quantum phase transition in an open system formed by a Bose-Einstein condensate coupled to an optical cavity, and observed the emergence of a self-organized supersolid phase. The phase transition is driven by infinitely long-ranged interactions between the condensed atoms. We show that the phase transition is described by the Dicke Hamiltonian, including counter-rotating coupling terms, and that the supersolid phase is associated with a spontaneously broken spatial symmetry. The boundary of the phase transition is mapped out in quantitative agreement with the Dicke model.