Experimental evidence of photoinduced vortex crossing in current carrying superconducting strips

Abstract

We report an experimental investigation that shows how magnetic vortices are generated and cross a current carrying superconducting strip when illuminated by a bright (\ensuremath{\sim}MeV) and fast (500 ps duration) infrared light pulse. The work has been carried out using a strike-and-probe electro-optic technique on a device consisting of a parallel superconducting strip configuration, with wide spacing between the strips to allow the interaction of the photons with a single strip. We find that photons hitting one strip induce a collective current redistribution in the parallel strips, which we can quantitatively account for in the framework of the London model by including the effect of generated and trapped magnetic vortices in the superconducting loops formed by the two adjacent slots. The amount of trapped vorticity and its dependence on increasing current density flowing in the illuminated strip is in good agreement with the photon-assisted unbinding of vortex-antivortex pairs. This work allows us to gain a deeper understanding of the interaction between photons and current carrying superconducting strips.