Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 58: Transport: Poster Session

TT 58.13: Poster

Mittwoch, 9. März 2016, 15:00–18:30, Poster D

Tuning decoherence in superconducting transmon qubits by mechanical strain — •Jan Brehm, Alexander Bilmes, Georg Weiss, Alexey Ustinov, and Juergen Lisenfeld — Karlsruher Institut fuer Technologie, Karlsruhe, Deutschland

Two-level tunneling systems (TLS) are formed by structural defects in disordered materials. They gained recent attention as an important decoherence source in superconducting qubits, where they appear on surface oxides and at film interfaces. Although the most advanced qubits do not show avoided level crossings arising from a strong coupling to individual TLS, they commonly display a pronounced frequency dependence of relaxation rates, with distinguishable peaks that may point towards weak resonant coupling to single TLS [1]. Previously, we have shown that TLS are tunable via an applied mechanical strain [2]. Here, we employ this method to test whether the characteristic decoherence spectrum of a transmon qubit sample responds to changes in the applied strain, as it can be expected when the decohering bath is formed of atomic TLS. In our experiment, we will employ a highly coherent X-mon qubit sample [1] and tune the strain by bending the qubit chip via a piezo actuator. Our latest results will be presented.
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