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Q: Fachverband Quantenoptik und Photonik

Q 56: Poster IV

Q 56.22: Poster

Donnerstag, 5. März 2009, 16:30–19:00, VMP 9 Poster

Blue-detuned evanescent field surface traps for neutral atoms based on mode interference in ultra-thin optical fibres — •Alex Baade, Guillem Sagué, and Arno Rauschenbeutel — Abteilung QUANTUM, Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz

We propose a novel concept for blue-detuned evanescent field surface traps for cold neutral atoms based on the interference of two transverse modes in an ultra-thin optical fibre. The resulting light-induced potential can be used to trap laser cooled Cs atoms at the positions of destructive interference in free space outside of the fibre. We discuss the trap created by the interference of the fundamental mode with one of the first higher order modes, yielding trapping sites at 100–200 nm from the fibre surface which, using a few tens of milliwatts of trapping laser power, have a depth on the order of 1 mK for caesium atoms and a trapping lifetime exceeding 100 s [1].

In order to experimentally investigate the mode interference in the evanescent field around an ultra-thin fibre we developed an experimental setup using a second tapered fibre as a near-field probe. The probe fibre is moved towards the tested fibre with a piezo actuator with an accuracy of a few nanometers. First measurements of the evanescent coupling between the two fibres as a function of distance are presented.

Financial support by the Volkswagen Foundation and the ESF is gratefully acknowledged.

[1] G. Sagué, A. Baade, and A. Rauschenbeutel, New J. Phys. 10, 113008 (2008).