Triplet-blockaded Josephson supercurrent in double quantum dots

TL;DR

This paper reports the direct measurement of supercurrent reversal in a double quantum dot system, demonstrating a spin to supercurrent conversion analogous to Pauli spin blockade, with potential applications in hybrid quantum devices.

Contribution

It provides the first experimental observation of supercurrent blockade linked to spin state transitions in double quantum dots, aligning with theoretical predictions.

Findings

Supercurrent reversal observed between charge states

Supercurrent blockade increases with magnetic field

Spin to supercurrent conversion demonstrated

Abstract

Serial double quantum dots created in semiconductor nanostructures provide a versatile platform for investigating two-electron spin quantum states, which can be tuned by electrostatic gating and an external magnetic field. In this work, we directly measure the supercurrent reversal between adjacent charge states of an InAs nanowire double quantum dot with superconducting leads, in good agreement with theoretical models. In the even charge parity sector, we observe a supercurrent blockade with increasing magnetic field, corresponding to the spin singlet to triplet transition. Our results demonstrate a direct spin to supercurrent conversion, the superconducting equivalent of the Pauli spin blockade. This effect can be exploited in hybrid quantum architectures coupling the quantum states of spin systems and superconducting circuits.