Switching dynamics in Al/InAs nanowire-based gate-controlled superconducting switch.

The observation of the gate-controlled supercurrent (GCS) effect in superconducting nanostructures increased the hopes for realizing a superconducting equivalent of semiconductor field-effect transistors. However, recent works attribute this effect to various leakage-based scenarios, giving rise to a debate on its origin. A proper understanding of the microscopic process underlying the GCS effect and the relevant time scales would be beneficial to evaluate the possible applications. In this work, we observed gate-induced two-level fluctuations between the superconducting state and normal state in Al/InAs nanowires (NWs). Noise correlation measurements show a strong correlation with leakage current fluctuations. The time-domain measurements show that these fluctuations have Poissonian statistics. Our detailed analysis of the leakage current measurements reveals that it is consistent with the stress-induced leakage current (SILC), in which inelastic tunneling with phonon generation is the predominant transport mechanism. Our findings shed light on the microscopic origin of the GCS effect and give deeper insight into the switching dynamics of the superconducting NW under the influence of the strong gate voltage. It was recently shown that a voltage could be used to control a supercurrent in superconducting nanostructures, much like a transistor, however, the exact origin of this effect has been debated. Here Elalaily et al. show via noise measurements that the suppression of the supercurrent in the superconducting device arises due to excitation emission by inelastic tunneling of the electrons through the trap states created by stressing the oxide layer between the gate and the NW under a high electric field. [ABSTRACT FROM AUTHOR]