Charge noise and overdrive errors in reflectometry-based charge, spin and Majorana qubit readout

• Published in: arXiv.org
• Main Authors: Vahid Derakhshan Maman, Gonzalez-Zalba, M F, Pályi, András
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 22.06.2020
• Subjects: Accuracy; Physics - Mesoscale and Nanoscale Physics; Physics - Quantum Physics; Quantum dots; Qubits (quantum computing); Reflectometry
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2006.12391

Solid-state qubits incorporating quantum dots can be read out by gate reflectometry. Here, we theoretically describe physical mechanisms that render such reflectometry-based readout schemes imperfect. We discuss charge qubits, singlet-triplet spin qubits, and Majorana qubits. In our model, we account for readout errors due to slow charge noise, and due to overdriving, when a too strong probe is causing errors. A key result is that for charge and spin qubits, the readout fidelity saturates at large probe strengths, whereas for Majorana qubits, there is an optimal probe strength which provides a maximized readout fidelity. We also point out the existence of severe readout errors appearing in a resonance-like fashion as the pulse strength is increased, and show that these errors are related to probe-induced multi-photon transitions. Besides providing practical guidelines toward optimized readout, our study might also inspire ways to use gate reflectometry for device characterization.