Fast readout of quantum dot spin qubits via Andreev spins

TL;DR

This paper introduces a fast, high-fidelity measurement protocol for quantum dot spin qubits using tunable coupling with Andreev spin qubits, enabling rapid readout and scalability in quantum computing.

Contribution

It proposes an electrically-tunable coupling scheme for quantum dot and Andreev spin qubits, allowing fast, high-fidelity measurements with minimized crosstalk, compatible with germanium devices.

Findings

Achieves sub-microsecond readout times.

Provides a switchable coupling to reduce back-action.

Compatible with scalable quantum architectures.

Abstract

Spin qubits in semiconducting quantum dots are currently limited by slow readout processes, which are orders of magnitude slower than gate operations. In contrast, Andreev spin qubits benefit from fast measurement schemes enabled by the large resonator couplings of superconducting qubits but suffer from reduced coherence during qubit operations. Here, we propose fast and high-fidelity measurement protocols based on an electrically-tunable coupling between quantum dot and Andreev spin qubits. In realistic devices, this coupling can be made sufficiently strong to enable high-fidelity readout well below microseconds, potentially enabling mid-circuit measurements. Crucially, the electrical tunability of our coupler permits to switch it off during idle periods, minimizing crosstalk and measurement back-action. Our approach is fully compatible with germanium-based devices and paves the way for scalable quantum computing architectures by leveraging the advantages of heterogeneous qubit implementations.