Calculation of the effects of a focused laser beam on the dynamic Josephson tunneling states

Perturbative calculations of the voltage response of constant-current biased Josephson tunnel junctions to a focused laser beam have been performed. The dependence of the voltage modification as a function of the laser beam position was calculated. The results were found to be qualitatively different for junctions biased on the first zero-field current step but with either vortex-mode or cavity-mode excitations. Therefore, the recently developed scanning focused laser beam technique operated in this mode can be a simple and effective method for probing the nature of the dynamic Josephson tunneling state