Proposal for superconducting photodiode

We propose a concept of a superconducting (SC) photodiode—a device that transforms the energy and 'spin' of an external electromagnetic (EM) field into the rectified steady-state supercurrent and develop a microscopic theory describing its properties. For this, we consider a two-dimensional thin film cooled down below the temperature of SC transition with the injected dc supercurrent and exposed to an external EM field with a frequency smaller than the SC gap. As a result, we predict the emergence of a photoexcited quasiparticle current, and, as a consequence, oppositely oriented stationary flow of Cooper pairs. The strength and direction of this photoinduced supercurrent depend on (i) such material properties as the effective impurity scattering time and the nonequilibrium quasiparticles' energy relaxation time and (ii) such EM field properties as its frequency and polarization.