CaPS: Casimir Effect in the Plane-Sphere Geometry

Michael Hartmann, Gert-Ludwig Ingold
2020 Journal of Open Source Software  
CaPS is a package for the analysis of the Casimir effect in the plane-sphere geometry. The Casimir force arises due to quantum and thermal fluctuations of the electromagnetic field and is closely related to the van der Waals force (Bordag, Klimchitskaya, Mohideen, & Mostepanenko, 2009 ). It is the dominant force between neutral non-magnetic materials in the nanometer to micrometer range and plays an important role in colloidal systems. Of technological relevance are applications to micro-and
more » ... ons to micro-and nano-electromechanical systems where the Casimir force can lead to stiction and thus constitute a failure mechanism (Buks & Roukes, 2001; Chan, Aksyuk, Kleiman, Bishop, & Capasso, 2001 ). On a more fundamental level, the Casimir effect is linked to the zero-point energy and the cosmological constant problem (Martin, 2012) . A precise knowledge of the Casimir force is crucial for the search for possible deviations from Newton's law of gravitation that could arise from a fifth fundamental interaction (Antoniadis et al., 2011). CaPS allows one to compute the Casimir interaction in the plane-sphere geometry as shown in Fig. 1 . The plane-sphere geometry is most commonly used in precision measurements of the Casimir force. Specifically, CaPS allows one to compute the Casimir free energy and thus the Casimir force as a function of the sphere radius R, the minimal separation L between sphere and plane, the temperature T , and the material properties of plane and sphere. It is assumed that both objects are non-magnetic and placed in vacuum. In typical experiments the aspect ratio R/L is of the order of 1000. The main purpose of this package is to make aspect ratios as large as R/L ∼ 5000 accessible. Higher aspect ratios are usually well covered by the proximity force approximation. z R L Figure 1 : Geometry of the plane-sphere setup: A sphere with radius R is separated by the distance L from an infinitely extended plate. In typical experiments, the aspect ratio R/L is about three orders of magnitude larger than shown here.
doi:10.21105/joss.02011 fatcat:ebyqqb34ybhtbgeoyvm3t2ke4u