Single Andreev Bound State with Near-Perfect Transmission in an InAs Nanowire Josephson Junction*

The spectra of Andreev bound states (ABS) in superconductor-semiconductor nanowire hybrid systems have been studied extensively to elucidate the physics of proximity effect in spatially-confined systems and their potential applications. When the semiconductor nanowire is contacted by two superconducting leads, it forms a Josephson junction that has a phase-dependent ABS spectrum. The energy-phase dispersion leads to a periodic Josephson current-phase relation (CPR), which reveals physical properties of the ABS. Using a scanning SQUID (Superconducting QUantum Interference Device) microscope, we inductively probe the CPR of individual Al-InAs-Al Josephson junctions as a function of local gates. Through statistical analysis of a short junction model, we find CPR at particular gate voltages to be consistent with a single near-perfectly transmitting ABS. We also discuss CPR analysis with multiple modes. We will continue to investigate the properties of these states and their potential relation to Majorana zero modes.