Hannover 2010 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 16: Quantum Gases: Interaction Effects I
Q 16.1: Gruppenbericht
Dienstag, 9. März 2010, 14:00–14:30, E 001
Giant coherence times in trapped atomic gases — Christian Deutsch1, Fernando Ramirez-Martinez2, Clement Lacroute2, Friedemann Reinhard1, Tobias Schneider1, Jean-Noel Fuchs3, Frederic Piechon3, Franck Laloe3, Jakob Reichel1, and •Peter Rosenbusch2 — 1LKB, Ecole Normale Supérieure, Paris — 2LNE-SYRTE, Observatoire de Paris — 3LPS, Université Paris-Sud, Orsay
We present an atom chip experiment designed to operate a microwave clock using magnetically trapped atoms. The project builds on the demonstration experiment [Phys. Rev. Lett., vol. 92, 203005 (2004)] but aims at an improved clock stability of 10−13 at 1 s, 10 times better than commercial clocks. We give results on the contrast of Ramsey fringes recorded in the thermal regime, where atoms can be treated as independent particles following different trajectories. The predicted dephasing time for 105 atoms, based on the known collisional shift, the second order Zeeman shift and their partial compensation is around 1.5 s [Appl. Phys. B, vol. 95, 227 (2009)]. Here we present experimental data where the fringe contrast remains bigger than 75% up to 5 s of Ramsey free evolution time, equivalent to a 15 s 1/e-time, which is 10 times longer than predicted. This, to our knowledge is a new record in neutral atom experiments. First simulations indicate that the identical spin rotation effect, known to be at the origin of spin waves [Phys. Rev. Lett., vol. 102, 215301 (2009)], here leads to a synchronisation of the atom phases.