On-demand single Cooper pair splitting in hybrid quantum dot systems*

Quantum dots have become ubiquitous in quantum processing applications to store quantum information and control the movement of charge. We report the implementation of a quantum dot device geometry in an InAs VLS nanowire that splits Cooper pairs on demand, detecting and retaining the resultant electrons. First, we identify the Cooper pair splitting charge transition using dispersive gate sensing at GHz frequencies. Second, we present results utilizing a quantum dot as an electron parity sensor without relying on external charge detectors. As part of a quadruple quantum dot system, we employ this sensor to detect parity changes resulting from electrons emerging from a superconducting island. Once augmented by spin manipulation capabilities, the measurement scheme presented enables conducting a Bell test on split Cooper pairs.