Stable Position of a Micro Torsion Balance under the Casimir Force

Abstract

The Casimir interaction between a torsion balance and flat plate is considered using proximity force approximation (PFA) and geometric optics approximation (GOA). Both approximations predict that the parallel configuration becomes unstable as the distance between a torsion balance and flat plate decreases. However, the dependence of the tilt angle at the stable position on the separation is significantly different. The tilt angle obtained by PFA continuously changes over the entire range; however, the discontinuous transition is predicted in GOA. [DOI: 10.1380/ejssnt.2013.60]