Coulomb blockade in open superconducting islands on InAs nanowires

TL;DR

This paper demonstrates Coulomb blockade oscillations in open superconducting InAs nanowire islands with tunable charge states, revealing mesoscopic effects influenced by magnetic fields and electron interference.

Contribution

It reports the observation of Coulomb blockade in an open superconducting island system, a phenomenon typically associated with closed systems, highlighting mesoscopic interference effects.

Findings

Coulomb blockade oscillations observed in open superconducting islands.

Oscillation periods switch between 2e and 1e depending on gate settings.

Magnetic field induces transition from 2e to 1e oscillations.

Abstract

Electrons in closed systems can exhibit Coulomb blockade (CB) oscillations due to charge quantization. Here, we report CB oscillations in aluminum superconducting islands on InAs nanowires in the open regime. The Al island is connected to the source/drain leads through two contacts: One is fully transmitting while the other is tuned into the tunneling regime. This device configuration is typical for tunneling spectroscopy where charging energy is generally considered negligible. The oscillation periods are 2$e$ or 1$e$, depending on the gate settings. A magnetic field can induce the 2$e$ to 1$e$ transition. Our result is reminiscent of the "mesoscopic Coulomb blockade" in open quantum dots caused by electron interference.