Transmon qubit in a magnetic field: evolution of coherence and transition frequency

Schneider, A., Wolz, T., Pfirrmann, M., Spiecker, M., Rotzinger, H., Ustinov, A. V. and Weides, M. (2019) Transmon qubit in a magnetic field: evolution of coherence and transition frequency. Physical Review Research, 1(2), 023003. (doi: 10.1103/PhysRevResearch.1.023003)

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Abstract

We report on spectroscopic and time-domain measurements on a fixed-frequency concentric transmon qubit in an applied in-plane magnetic field to explore its limits of magnetic field compatibility. We demonstrate quantum coherence of the qubit up to field values of B = 40 mT, even without an optimized chip design or material combination of the qubit. The dephasing rate ϕ is shown to be unaffected by the magnetic field in a broad range of the qubit transition frequency. For the evolution of the qubit transition frequency, we find the unintended second junction created in the shadow angle evaporation process to be non-negligible and deduce an analytic formula for the field-dependent qubit energies. We discuss the relevant field-dependent loss channels, which cannot be distinguished by our measurements, inviting further theoretical and experimental investigation. Using well-known and well-studied standard components of the superconducting quantum architecture, we are able to reach a field regime relevant for quantum sensing and hybrid applications of magnetic spins and spin systems.

Item Type:Articles
Additional Information:This work was supported by the European Research Council through Grant Agreement No. 648011, Deutsche Forschungsgemeinschaft through Projects No. WE4359/7-1 and No. INST 121384/138-1, and the Initiative and Networking Fund of the Helmholtz Association. We acknowledge financial support from the Carl-Zeiss-Foundation (A.S.) and the Helmholtz International Research School for Teratronics (T.W. and M.P.). A.V.U. acknowledges partial support from the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of the National University of Science and Technology MISIS (Contract No. K2-2017-081).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Weides, Professor Martin
Authors: Schneider, A., Wolz, T., Pfirrmann, M., Spiecker, M., Rotzinger, H., Ustinov, A. V., and Weides, M.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Physical Review Research
Publisher:American Physical Society
ISSN:2643-1564
ISSN (Online):2643-1564
Published Online:04 September 2019
Copyright Holders:Copyright © 2019 American Physical Society
First Published:First published in Physical Review Research 1(2):023003
Publisher Policy:Reproduced under a Creative Commons license
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