Proposal to measure the Casimir effect across the superconducting transition

The influence of the superconducting transition on the Casimir effect remains experimentally elusive. We propose an approach to address this challenge, exploiting the first-order superconducting transition induced in a thick film by a parallel magnetic field. Our calculations for a Au sphere opposite a Pb film, based on the Mattis-Bardeen theory, predict a jump in the Casimir force across the transition. By periodically modulating the magnetic field, we induce a corresponding modulation of the Casimir force that should be readily detectable with existing microtorsional oscillator technology, opening a promising pathway to finally observe the long-sought Casimir-superconductivity coupling. A successful measurement of this effect would provide crucial insights into the fundamental nature of the Casimir force and its interaction with macroscopic quantum phenomena.