2e-periodic switching current in nanowire-based single-Cooper-pair transistors

We report on measurements of the switching current of mesoscopic superconducting islands in hybrid InAs/Al core/shell nanowires. We find a switching current which is 2e periodic in the island gate charge in several devices for a wide range of temperatures and tunnel barrier conductances. Such 2e periodicity is evidence of a low quasiparticle poisoning rate and represents an important starting point for implementing theoretical proposals to investigate Majorana fusion channels in hybrid semiconductor-superconductor nanowires. In addition, our measurements demonstrate that the devices can be tuned between Coulomb-dominated and Josephson-dominated regimes. Taken together, our results indicate these systems are promising candidates for fusion experiments, and we discuss the path forward.