Hannover 2016 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 58: Poster: Quantum Optics and Photonics IV

Q 58.85: Poster

Donnerstag, 3. März 2016, 16:30–19:00, Empore Lichthof

Development of a digital phase lock for optical lattices — •Dominik Vogel, Nick Fläschner, Matthias Tarnowski, Benno Rem, Christof Weitenberg, and Klaus Sengstock — Universität Hamburg, Germany

Non-separable optical lattices feature new physics as for example Dirac cones and Berry phases in the case of the hexagonal lattice, which is formed by three interfering beams. Usually, the lattice beams pass through optical fibers for optimal beam profiles and therefore pick up independent phases, which translate the lattice potential and thus couple acoustic noise to the ensemble of ultra cold atoms, leading to heating.

In this poster, we present a digital phase locked loop that fixes those phases by controlling the laser frequencies via AOMs. The loop features a 800 kS/s bipolar analog to digital converter, a real time processor and a DDS frequency source. Our setup enables a total feeback signal delay under 2 micro seconds, while providing the high linewidth quality of a DDS-source, which is superior to conventional analog phase locks. In closed loop, we achieve a significant reduction of the phase noise, which is expected to increase the atomic life time in the optical lattice and thus provides access to new temperature regimes.