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Q: Fachverband Quantenoptik und Photonik

Q 23: Quantum Effects: Light Scattering and Propagation II / QED I

Q 23.3: Vortrag

Mittwoch, 10. März 2010, 11:15–11:30, A 320

Direct Measurement of intermediate-range Casimir-Polder potentials — •Helmar Bender, Phillippe Courteille, Carsten Marzok, Christian Stehle, Claus Zimmermann, and Sebastian Slama — Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen

The zero-point vacuum fluctuations of the electromagnetic field are a result of fundamental importance in quantum electrodynamics (QED). One of its few measurable effects is the force between a groundstate atom and a solid surface. Measurements of the corresponding Casimir-Polder (CP) potential exist for both, the short distance regime and the long distance regime where retardation has to be taken into account.

We present the first direct measurement of the CP-potential in the intermediate regime at distances of about 150-250 nm where retardation slowly comes into play. The measurement is based on the reflection of ultracold Rb-atoms from evanescent wave barriers. With this method we are able to deduce the CP-potential as a function of the distance without making any prior assumptions on its shape.

The results are compared to the analytical expressions existent for the long- and the short range regime as well as to a full QED-calculation. The full QED-calculation agrees best with our data.