Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 40: Superconductivity: Qubits 1
TT 40.1: Vortrag
Mittwoch, 3. April 2019, 09:30–09:45, H48
Coherence of a transmon qubit under in-plane magnetic fields — •Andre Schneider1, Alexey V. Ustinov1,2, and Martin Weides1,3 — 1Karlsruhe Institute of Technology, Karlsruhe, Germany — 2National University of Science and Technology MISIS, Moscow, Russia — 3University of Glasgow, Glasgow, United Kingdom
Superconducting quantum circuits are versatile building elements for quantum technologies, with applications ranging from computing and simulation to sensing and metrology. The extreme sensitivity of SQUIDs to magnetic fields is used in many technological applications, and new quantum sensing schemes like the detection of amplitude and frequency of microwave signals by a superconducting transmon qubit [1] are being developed.
To identify possible fields of application, we investigate the environmental magnetic conditions for the usability of such a qubit.
By placing a transmon qubit in a magnetic field, we analyze its transition frequency and coherence properties.
We find that the transition frequency strongly depends on the flux penetrating the Al/AlOx/Al Josephson junction and can be modeled precisely as function of the in-plane magnetic field. We demonstrate quantum coherence up to field values of 40 mT with qubit lifetimes of T1 0.5 µ s and find corresponding T2 times
resulting in a constant pure dephasing rate at any field.
The possibility to operate superconducting qubits in magnetic fields far beyond the critical field of the bulk superconductor opens new avenues, for instance in quantum sensing and metrology.
A. Schneider et al., Phys. Rev. A 97, 062334 (2018)