Heidelberg 2015 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 49: Quantum Effects: Cavity QED I

Q 49.2: Vortrag

Donnerstag, 26. März 2015, 11:30–11:45, B/gHS

Atom-cavity physics with a Bose-Einstein condensate in an ultra-narrow band resonator — •Hans Keßler, Jens Klinder, and Andreas Hemmerich — ILP, Uni Hamburg

A Bose-Einstein condensate (BEC) is prepared inside an optical resonator with an ultra-narrow band width on the order of the single photon recoil energy. For transverse pumping with a traveling wave, matter wave superradiance is observed [1]: above a critical intensity superradiant light pulses are emitted into the cavity and the atoms are collectively scattered into coherent superpositions of discrete momentum states, which can be precisely controlled by adjusting the effective cavity-pump detuning δ_eff. For transverse pumping with a standing wave the physics encountered depends on the sign of δ_eff: at positive δ_eff>0, matter wave superradiance is found, similarly as for traveling wave pumping. At negative δ_eff<0, the Hepp-Lieb-Dicke phase transition is observed: a stationary intra-cavity field emerges, which confines the BEC in a self-organized lattice potential. Due to the narrow cavity bandwidth we operate in a regime where a sweep across the phase boundary on a ms time scale leads to significant hysteresis with an enclosed loop area showing power law scaling with respect to the transition time [2].