Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 34: Poster: Ultra-cold atoms, ions and BEC (with Q)

A 34.11: Poster

Wednesday, March 19, 2014, 16:30–18:30, Spree-Palais

Development of ultrahigh-finesse crossed cavities for a quantum gas experiment — •Moonjoo Lee, Julian Leonard, Andrea Morales, Thomas Karg, Tilman Esslinger, and Tobias Donner — Institute for Quantum Electronics, ETH Zürich, CH-8093 Zürich, Switzerland

Quantum gases coupled to an optical cavity opened a new field for exploring quantum many-body physics with long-range interactions. An additional cavity will provide various possibilities for both the atomic internal and external degrees of freedom based on the interference of two vacuum fields.

We fabricated two independent ultrahigh finesse cavities whose mode axes cross under an angle of 60 degrees. The supermirrors are modified to put them as close as possible in order to obtain the strongest coupling under the given spatial conditions. The machined mirror surfaces have 600 µm width and each cavity has a length of 1.7 mm with 0.5 million finesse. The resulting cavity parameters for a single rubidium atom are (g, κ, γ) / 2π = (2, 3, 0.15) MHz.

We discuss possible future experiments including the measurement of the eigenspectrum of a Bose-Einstein condensate coupled to the two crossed cavities, cavity-vacuum induced transparency, and slow light which might reveal the granular feature of the cavity photons. When the atoms are illuminated by a classical standing wave field, they can self-organize and scatter light from the pump field into both cavities. The emergent dynamical lattice potential will be hexagonal or triangular shape.