Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 38: Poster: Quantum Optics and Photonics I

Q 38.8: Poster

Tuesday, March 6, 2018, 16:15–18:15, Orangerie

Self organisation of a BEC in two crossed cavities across an atomic resonance — •Davide Dreon, Andrea Morales, Philip Zupancic, Xiangliang Li, Tobias Donner, and Tilman Esslinger — ETH, Zürich, Switzerland

The interaction of a Bose-Einstein condensate (BEC) with the electromagnetic field of an optical cavity is known to exhibit a superradiant phase transition to a self-organized phase. In our experiment, a ⁸⁷Rb BEC is placed at the mode crossing of two optical cavities. The BEC is illuminated with a ’pump’ laser beam whose detuning from the D₂ atomic line determines the interaction regime. We recently explored different red detunings, where the system reduces its potential energy spontaneously forming an attractive lattice in the cavity mode. Here, we have observed a supersolid phase [1,2] and a phase with intertwined order [3]. In contrast, in the blue detuned case the energy of the atoms is increased by the presence of an optical lattice and therefore spontaneous superradiant scattering in the cavity should be inhibited.

I will report on our most recent experimental results on the blue side of the atomic resonance, where we observe, surprisingly, that self-organization is still possible. We measure the phase diagram of the system and explain our findings with simple energy arguments. In addition to the steady state regime typical of red detunings, dynamical instabilities leading to limit cycles of the cavity field amplitude or chaotic behaviors are expected [4].

[1] Nature, 543, 87-90 (2017), [2] arXiv:1704.05803 (to appear in Science), [3] arXiv:1711.07988, [4] PRL 115, 163601 (2015)