Experimental investigation of supercurrent enhancement in S–N–S junctions by non-equilibrium injection into supercurrent-carrying bound Andreev states

We report measurements on three-terminal superconductor–semiconductor–superconductor injection devices demonstrating enhancement of the supercurrent by injection from a superconducting injector electrode. Two other electrodes were used to form the detector junction. Applying a small voltage to the injector electrode reduced the maximum supercurrent (the critical current) between the detector electrodes. When the injector voltage was increased further (upto the gap voltage Δ/ e), the critical current between the detector electrodes increased and approached a new maximum. This is evidence of enhancement of the supercurrent by non-equilibrium injection into bound supercurrent-carrying Andreev states. The effect persists to temperatures where the equilibrium supercurrent has vanished.