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

Schneider, Andre; Wolz, Tim; Pfirrmann, Marco; Spiecker, Martin; Rotzinger, Hannes; Ustinov, Alexey V.; Weides, Martin

Abstract (englisch):
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 $B=40\,\mathrm{mT}$, even without an optimized chip design or material combination of the qubit. The dephasing rate $\Gamma_\varphi$ 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.

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Verlagsausgabe §
DOI: 10.5445/IR/1000117440
Veröffentlicht am 27.02.2020
Originalveröffentlichung
DOI: 10.1103/PhysRevResearch.1.023003
Cover der Publikation
Zugehörige Institution(en) am KIT Physikalisches Institut (PHI)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 04.09.2019
Sprache Englisch
Identifikator ISSN: 2643-1564
KITopen-ID: 1000117440
Erschienen in Physical review research
Band 1
Heft 2
Seiten 023003
Schlagwörter qubit, quantum bit, quantum sensing
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