Bonn 2025 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 11: QED and Cavity QED

Q 11.4: Talk

Monday, March 10, 2025, 17:45–18:00, HS Botanik

Three-Body Contributions to the Casimir Polder Force — •Emma Wünsche, Fabian Spallek, and Stefan Yoshi Buhmann — University Kassel, Germany

We study many-body contributions to the Casimir Polder (CP) force. Since for geometries of low symmetry or reduced symmetry no closed expressions for the CP potential are available, we employ a Born series for the Greens tensor and, relating the microscopic polarizability to the macroscopic permittivity, we derive a power series expansion of the CP potential in terms of the polarizabilities of the bodies' constituent atoms. The expansion can be interpreted as the sum of many-body Van-der-Waals contributions: the first term represents two-atom contributions, the second term three-atom interactions, and so on. For comparison, we reformulate existing results of macroscopic approaches for the CP potential and express them as a series in atomic polarizabilities. This allows us to validate the microscopic Van-der-Waals approach. We consider two different dielectric geometries: a small cylinder and an infinite half space, and find very good agreement for the two-atom contributions. While the three-atom contribution to the CP potential of an atom in front of an infinite plate can only be accessed numerically, for the cylinder-case, we find good agreement in the angular dependence of the three-atom contributions to the CP potential for the microscopic and macroscopic approaches.

Keywords: Casimir Polder force; Van der Waals potential; Casimir force; macroscopic QED