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QI: Fachverband Quanteninformation
QI 20: Metrology and Sensing
QI 20.7: Vortrag
Freitag, 13. März 2026, 11:30–11:45, BEY/0137
Charge sensing back-action on spin qubit readout using a micromagnet — •Sudipto Das1, Domonkos Svastits1,2, Aritra Sen1, and Andras Palyi1,3 — 1Budapest University of Technology and Economics, Budapest, Hungary — 2Qutility @ Faulhorn Labs, Budapest, Hungary — 3HUN-REN-BME-BCE Quantum Technology Research Group, Budapest, Hungary
This work presents a theoretical framework for the charge-sensing readout of semiconductor spin qubits in double quantum dots. We explain the readout based on Pauli blockade spin-to-charge conversion and subsequent charge sensing via quantum point contact using the Qubit Measures Qubit model [1]. Our analysis focuses on n-type Silicon double quantum dots with micromagnets enabling resonant single-qubit control, explicitly accounting for the inhomogeneous micromagnet field and its modulation by charge-sensor shot noise.
Within this model, we quantify key readout errors-fidelity loss due to Zeeman-field modulation, mixedness of the post-measurement state, and leakage caused by perpendicular field fluctuations. We also incorporate the noise from charge sensors to understand its effect on readout. By studying their dependence on device parameters, including the orientation of the external magnetic field, we offer insights into readout performance optimization and readout sweet spots.
[1] D. Svastits, B. Hetényi, G. Széchenyi, J. Wootton, D. Loss, S. Bosco, and A. Pályi, Readout sweet spots for spin qubits with strong spin-orbit interaction, arXiv:2505.15878.
Keywords: Semiconductor Spin Qubits; Readout; Charge Sensing; Micromagnet; Quantum Point Contact