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Q: Fachverband Quantenoptik und Photonik

Q 32: Poster: Quantum gases, ultracold atoms and molecules

Q 32.21: Poster

Mittwoch, 19. März 2014, 16:30–18:30, Spree-Palais

Measuring the dynamic structure factor of a dissipative quantum many-body system — •Renate Landig, Rafael Mottl, Lorenz Hruby, Ferdinand Brennecke, Tobias Donner, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zurich, Switzerland

A Bose-Einstein condensate whose motional degrees of freedom are coupled to a high-finesse optical cavity via a transverse pump beam constitutes a dissipative quantum many-body system with long range interactions. These interactions can induce a structural phase transition from a flat to a density-modulated state. The transverse pump field simultaneously represents a probe of the atomic density via cavity-enhanced Bragg scattering. By spectrally analysing the light field leaking out of the cavity, we measure non-destructively the dynamic structure factor of the fluctuating atomic density while the system undergoes the phase transition. An observed asymmetry in the dynamic structure factor is attributed to the coupling to dissipative baths. Critical exponents for both sides of the phase transition can be extracted from the data. We further present our progress in adding strong short-range interactions to this system, in order to explore Bose-Hubbard physics with cavity-mediated long-range interactions and self-organization in lower dimensions.