  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.
