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HL: Fachverband Halbleiterphysik
HL 6: Semiconductor Qubits (joint session QI/HL)
HL 6.3: Talk
Monday, March 18, 2024, 10:15–10:30, HFT-FT 131
Counteracting decoherence induced by spin-valley coupling in single-qubit manipulation zones via quantum optimal control — •Akshay Menon Pazhedath1, Alessandro David1, Lars R. Schreiber2, Tommaso Calarco1, Matthias M. Müller1, Hendrik Bluhm2, and Felix Motzoi1 — 1Peter Grünberg Institute-Quantum Control (PGI-8), Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany — 2JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
Quantum bus architectures based on electron spin shuttling in a Si/SiGe heterostructure are promising candidates for scalable quantum computing. Electrically controlled single qubit gates are achieved with a carefully placed micro-magnet that provides a synthetic spin-orbit coupling in the designated manipulation zones [Künne et al. arXiv:2306.16348 (2023)]. The presence of spin-valley mediated decoherence hotspots at the vicinity of the micro-magnet can cause spin decoherence, limiting the capability to achieve fault tolerant gates. Using quantum optimal control techniques, we obtain new electron trajectories leading to significant improvements to the gate fidelity. The influence of valley splitting and the distance from decoherence hotspots are also investigated, based on statistical sampling of prototypical device configurations. For increasing values of spin-valley coupling, 99.12% of the samples converged below the required fault tolerant gate fidelity threshold, where all of the under- performing samples are due to a high value of spin-valley coupling.
Keywords: Spin-valley interaction; Single-qubit gates; Quantum optimal control; Electron shuttling; Spin dephasing