Berlin 2014 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 70: Quantum gases: Lattices IV

Q 70.6: Talk

Friday, March 21, 2014, 17:45–18:00, UDL HS2002

Exploring the driven-dissipative Dicke phase transition — •Renate Landig, Rafael Mottl, Lorenz Hruby, Ferdinand Brennecke, Tobias Donner, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zürich, Switzerland

We experimentally study the driven-dissipative Dicke quantum phase transition, realized by coupling the external degree of freedom of a Bose-Einstein condensate to the light field in a high-finesse optical cavity. By monitoring the cavity output field we are able to observe in real-time the diverging atomic density fluctuations while approaching the critical point. The observed critical behavior deviates from the expectation for the closed Dicke model and is in quantitative agreement with the enhanced fluctuation spectrum of the driven-dissipative system. Using a heterodyne detection setup, we spectroscopically resolve the cavity output field. This enables us to separately determine the quasiparticle excitation spectrum and its damping rate, and gives insight into the many-body state and its temperature.