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Q: Fachverband Quantenoptik und Photonik
Q 38: Quantum Effects (QED) I
Q 38.6: Vortrag
Mittwoch, 11. März 2020, 15:15–15:30, f442
Appearance of a half-integer power in the small-distance expansion of the Casimir energy — •Benjamin Spreng1, Michael Hartmann1, Paulo Maia Neto2, and Gert-Ludwig Ingold1 — 1Institut für Physik, Universität Augsburg, Germany — 2Instituto de Física, Universidade Federal do Rio de Janeiro, Brazil
The proximity force approximation (PFA) is a widely used tool to study the Casimir interaction in experiments between for example a plane and a sphere. Within the PFA, the finite curvature of the sphere is accounted for by averaging the Casimir energy of parallel plates over the local distances of the two bodies. The approximation becomes valid when the ratio L/R is small where L is the distance of the sphere’s surface to the plane and R is the sphere’s radius.
At zero temperature, leading corrections beyond the PFA are linear in L/R and have been studied extensively. Here, we are interested in the expansion of the Casimir energy beyond the linear term. If applicable, the method of the derivative expansion suggests a correction quadratic in L/R. However, our numerically exact computation of the Casimir energy strongly suggests a correction of the form (L/R)3/2. This result is not limited to specific material classes and can also be found for other geometries such as for two spheres (with R replaced by the effective radius), and a cylinder opposite to a plane. A mechanism explaining the emergence of the half-integer power is provided.