Heidelberg 2015 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 27: Quantum Gases: Bosons IV

Q 27.6: Talk

Tuesday, March 24, 2015, 15:45–16:00, P/H2

Measurements of phase coherence and excitation in finite temperature Bose-Einstein condensates — •Matteo Fadel, Baptiste Allard, Roman Schmied, and Philipp Treutlein — Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland

Atomic Bose-Einstein condensates (BECs) are highly controllable isolated quantum systems with long coherence times, and offer applications in metrology and quantum information processing. We experimentally prepare finite-temperature BECs, and measure their decoherence dynamics and excitation spectrum.

Our system consists of a two-component Rubidium-87 Bose-Einstein condensate, consisting of a few hundred atoms, created on an atom-chip [1]. We modulate the trap position and frequency to prepare condensates at different temperatures, and use sideband Rabi spectroscopy to probe the excitation spectrum.

In finite-temperature BECs, interactions with the non-condensed fraction are predicted to limit the phase coherence [2]. We experimentally study these fundamental limits by performing Ramsey spectroscopy with BECs of different temperatures and densities.

[1] P. Boehi, et al., Nature Physics 5, 592 (2009).

[2] A. Sinatra, Y. Castin, and E. Witkowska, Phys. Rev. A 80, 033614 (2009).