Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 58: Transport: Poster Session
TT 58.24: Poster
Mittwoch, 9. März 2016, 15:00–18:30, Poster D
Interacting two-level defects as sources of fluctuating high-frequency noise in superconducting circuits — •Clemens Müller1, Jürgen Lisenfeld2, Alexander Shnirman3,4, and Stefano Poletto5 — 1ARC Centre of Excellence for Engineered Quantum Systems, The University of Queensland, Brisbane, Austrlalia — 2Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany — 3Institut für Theory der Kondensierten Materie, Karlsruhe Institute of Technology, Karlsruhe, Germany — 4LD Landau Institute for Theoretical Physics, Moscow, Russia — 5IBM TJ Watson Research Centre, Yorktown Heights, USA
Since the very first experiments, superconducting circuits have suffered from strong coupling to environmental noise, destroying quantum coherence and degrading performance. In state-of-the-art experiments, it is found that the relaxation time of superconducting qubits fluctuates as a function of time. We present measurements of such fluctuations in a 3D-transmon circuit and develop a qualitative model based on interactions within a bath of background two-level systems (TLS) which emerge from defects in the device material. In our model, the time-dependent noise density acting on the qubit emerges from its near-resonant coupling to high-frequency TLS which experience energy fluctuations due to their interaction with thermally fluctuating TLS at low frequencies. We support the model by providing experimental evidence of such energy fluctuations observed in a single TLS in a phase qubit circuit.