Dresden 2026 – scientific programme
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QI: Fachverband Quanteninformation
QI 6: Implementations II
QI 6.4: Talk
Tuesday, March 10, 2026, 10:30–10:45, BEY/0245
Modelling readout of spin qubits using a single electron transistor — •Domonkos Svastits1,2, Sudipto Das1, Aritra Sen1, and András Pályi1,3 — 1Budapest University of Technology and Economics, Budapest, Hungary — 2Qutility @ Faulhornlabs, Budapest, Hungary — 3HUN-REN-BME-BCE Quantum Technology Research Group, Budapest, Hungary
Spin qubits in semiconductor quantum dots are a promising platform for scalable quantum computing. However, current qubit operations remain too noisy for practical applications, with qubit readout often being the noisiest operation. Readout typically uses Pauli blockade spin-to-charge conversion combined with charge sensing. In this work, we present a microscopic model of charge sensing implemented by a single-electron transistor (SET), intended to guide improvements in spin-qubit readout, focusing on an n-type Silicon double quantum dot equipped with a micromagnet. Our model provides a microscopic, dynamical description of the measurement process. We show the measurement induces unwanted back-action in the form of incoherent transitions between qubit energy eigenstates, similar to predictions for a QPC (D. Svastits et al., arXiv:2505.15878 [quant-ph]). We also calculate how the measurement rate, i.e. the speed of the measurement, depends on the qubit Hamiltonian. We find that the parameter dependence of readout infidelity, post-measurement state mixedness and leakage are well explained by the transition rates and the measurement rate. Finally, we propose experimentally practical strategies to increase the measurement rate while suppressing the transition rates.
Keywords: measurement; back-action; single-electron transistor; post-measurement state