Deterministic non-local parity control and supercurrent-based detection in an Andreev molecule

TL;DR

This paper demonstrates deterministic non-local parity control in an Andreev molecule and introduces supercurrent-based detection as a sensor-free method, advancing scalable quantum architectures.

Contribution

It provides the first experimental demonstration of deterministic non-local parity control and supercurrent-based detection in an Andreev molecule, with a theoretical framework for parity engineering.

Findings

Successful non-local parity manipulation via electrical modulation.

Identification of universal parity transition rules.

Supercurrent as a direct, sensor-free parity probe.

Abstract

The ability to manipulate and detect the parity of quantum states in superconductor-semiconductor hybrid systems is pivotal to realizing the promise of topological quantum computation. However, as these architectures scale toward artificial Kitaev chains with phase-control loops, local accessibility becomes restricted, constraining conventional local parity control and detection. While Andreev molecules offer a platform for non-local intervention, deterministic protocols for parity manipulation have yet to be experimentally established. Here, we demonstrate deterministic non-local control over the parity configuration of a quantum dot (QD) by electrically modulating the coherent hybridization with a spatially adjacent QD within an Andreev molecule. By systematically investigating three distinct joint parity configuration regimes in the elastic co-tunneling limit, we experimentally uncover the operational conditions for this non-local control. In conjunction with theoretical simulations establishing a global phase diagram, we identify a set of universal selection rules governing parity transitions, dictated by the symmetry-imposed interplay between the joint parity configuration and the dominant inter-dot coupling mechanism (elastic co-tunneling vs. crossed Andreev reflection). Furthermore, we establish the supercurrent, directly signaled by zero-bias conductance peaks, as an intrinsic, sensor-free probe of the parity configuration, obviating the need for auxiliary charge sensors. Our results provide a validated physical framework for parity engineering, offering a key building block for scalable, multi-QD superconducting architectures.