Regensburg 2022 – scientific programme
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QI: Fachverband Quanteninformation
QI 13: Implementations: Superconducting Qubits
QI 13.9: Talk
Friday, September 9, 2022, 12:00–12:15, H8
Magnetic field dependence of the quasiparticle parity lifetime in 3D transmons with thin-film Al−AlOx−Al Josephson junctions — •Jonas Krause1, Lucas Jannsen1, Christian Dickel1, Elmore Vaal1, Michel Vielmetter1, Jurek Frey2, Felix Motzoi3, Shai Machness2, Kelvin Loh4, Michiel Adriaan Rol4, Gianluigi Catelani5, and Yoichi Ando1 — 1Physics Institute II, University of Cologne — 2Quantum Computing Analytics (PGI 12), Forschungszentrum Jülich — 3Institute of Quantum Control (PGI-8), Forschungszentrum Jülich — 4Orange Quantum Systems — 5JARA Institute for Quantum Information (PGI-11), Forschungszentrum Jülich
Magnetic-field resilient superconducting circuits enable quantum sensing applications, hybrid quantum computing architectures, as well as studying flux noise and quasiparticle loss. Placing a thin-film aluminum transmon in a 3D copper cavity, we can measure its quasiparticle parity lifetime over a large range of magnetic fields, with in-plane fields approaching 1T. The magnetic field reduces the Josephson Energy EJ, while the charging energy EC is virtually unaffected. The transmon exhibits a parity-dependent frequency splitting. We are working on optimal control techniques for fast parity-selective gates which together with single-shot readout allow measuring the parity lifetime. The magnetic-field dependence of the parity lifetime is of interest for future topological qubits, which rely on combining superconductors with magnetic fields; additionally, it could improve the understanding quasiparticle loss in conventional superconducting qubits.