Düsseldorf 2007 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 11: Quanteneffekte (QED)

Q 11.7: Talk

Monday, March 19, 2007, 15:45–16:00, 5E

Dynamical theory of Casimir-Polder forces — •Stefan Yoshi Buhmann and Dirk-Gunnar Welsch — Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena

The Casimir-Polder force experienced by a single atom in the presence of magnetoelectric bodies is a well-known consequence of QED. In contrast to the common static approaches often used to study forces on ground-state atoms, we employ a genuinely time-dependent approach in order to account for the nontrivial dynamics arising for initially excited atoms. Starting from the operator-valued Lorentz force, a general formula for the dynamical Casimir-Polder force is presented, which can be further evaluated by solving the coupled atom-field dynamics.

For weak coupling the Markov approximation can be used to show that the Casimir-Polder force on an initially excited atom can be written as a linear combination of components whose dynamics follows that of the associated atomic density-matrix elements. Strong atom-field coupling may arise if an atom near-resonantly interacts with a narrow quasimode of the body-assisted electromagnetic field, leading to a reversible exchange of excitation between the atom and the field mode. Assuming that the atom-mode system initially shares a single excitation, it is found that the resulting Casimir-Polder force undergoes damped Rabi oscillations, where both amplitude and mean value of the oscillations depend on the initial state.