Freiburg 2019 – wissenschaftliches Programm
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FM: Fall Meeting
FM 24: Quantum Sensing: Entanglement and Beyond Shot Noise
FM 24.6: Talk
Montag, 23. September 2019, 17:45–18:00, 3044
Fundamental limits of the coherence in a two-component BEC — •Yifan Li1, Tilman Zibold1, Boris Décamps1, Matteo Fadel1, Paolo Colciaghi1, Krzysztof Pawlowsky2, and Philipp Treutlein1 — 1Department of Physics, University of Basel — 2Center for Theoretical Physics, Polish Academy of Sciences, Poland
We report experiments on the fundamental limits of coherence in two-component Bose-Einstein condensates (BECs) of 87Rb on an atom chip. We measure the increase of phase noise with time by performing Ramsey interferometry and find that the coherence of two-component BECs is mainly limited by interaction induced phase noise. This so-called clock-shift effect results in a dominant source of phase noise which depends on the fluctuations of total numbers of atoms and can be only partially canceled in data analysis due to the random nature of atom loss. To further understand the decoherence, we prepare nearly pure BECs in superpositions of hyperfine states and measure the rates of the dominant collisional loss processes. The decoherence process can be mitigated by relaxing the trapping potential and further suppressed by tuning the interactions with a state-dependent potential. Our experimental findings are relevant for compact atomic clocks realized in similar cold or ultracold atomic systems where atomic interactions are a limiting factor.