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A: Fachverband Atomphysik
A 7: Ultracold atoms I: Traps and cooling (with Q)
A 7.7: Talk
Tuesday, March 3, 2009, 12:00–12:15, Audi-B
Trapping neutral Cs-atoms using ultra-thin optical fibres — •Eugen Vetsch, Daniel Reitz, Guillem Sagué, Regine Schmidt, and Arno Rauschenbeutel — Abteilung QUANTUM, Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz
We present our recent results on trapping cold neutral Caesium atoms close to the surface of an ultra-thin optical fibre. The atoms are captured by a two-colour trap which is based on light-induced dipole forces exerted on the atoms by a blue- and red-detuned evanescent light field, created by launching two co-propagating laser beams through the fibre. This results in a cylindrically symmetric trap around the fibre that exhibits a trapping minimum about two hundred nanometres above the surface. By launching an additional, counter-propagating red-detuned laser beam through the fibre, a red-detuned standing wave is realized, confining the atoms in all three dimensions.
We are currently able to trap more than 103 atoms with a lifetime of about 50 ms. We probe the atoms by measuring the absorption of a weak resonant probe field which is sent through the fibre and which couples to the atoms via the evanescent field. Remarkably, the atomic ensemble is optically dense for this probe field. This opens the route towards non-linear optics applications like electromagnetically induced transparency, slow and stopped light processes, deterministic single photon sources, and quantum memories with fibre-coupled atomic ensembles.
Financial support by the Volkswagen Foundation and the ESF is gratefully acknowledged.