Readout sweet spots for spin qubits with strong spin-orbit interaction

Abstract:Qubit readout schemes often deviate from ideal projective measurements, introducing critical issues that limit quantum computing performance. In this work, we model charge-sensing-based readout for semiconductor spin qubits in double quantum dots, and identify key error mechanisms caused by the back-action of the charge sensor. We quantify how the charge noise of the sensor, residual tunneling, and $g$-tensor modulation degrade readout fidelity, induce a mixed post-measurement state, and cause leakage from the computational subspace. For state-of-the-art systems with strong spin-orbit interaction and electrically tunable $g$-tensors, we identify a readout sweet spot, that is, a special device configuration where readout is closest to projective. Our framework provides a foundation for developing effective readout error mitigation strategies, with broad applications for optimizing readout performance for a variety of charge-sensing techniques, advancing quantum protocols, and improving adaptive circuits for error correction.

Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

arXiv:2505.15878 [quant-ph]

(or arXiv:2505.15878v2 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2505.15878 Focus to learn more arXiv-issued DOI via DataCite

Phys. Rev. Lett. 136, 117001 (2026)

https://doi.org/10.1103/4x97-np1f Focus to learn more DOI(s) linking to related resources

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