Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 58: Transport: Poster Session
TT 58.12: Poster
Mittwoch, 9. März 2016, 15:00–18:30, Poster D
Characterization of 3D-transmons and rectangular waveguides for transmission experiments — •Lukas Grünhaupt1, Marcel Langer1, Jochen Braumüller1, Andre Schneider1, Hannes Rotzinger1, Alexander Averkin2, Alexey V. Ustinov1,2, and Martin Weides1,3 — 1Institute of Physics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany — 2National University of Science and Technology MISIS, Moscow 119049, Russia — 3Material Science in Mainz, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
We report on experiments with 3D-transmon qubits designed and fabricated at KIT. Time domain measurements of our first sample in a 3D aluminum cavity show a lifetime T1 = 1.6 μs and dephasing time T2 = 2.0 μs. By improving the cavity design, we could increase the coherence times by one order of magnitude to T1 = 16 μs and T2 = 13 μs (spin echo dephasing time T2* = 30 μs).
Our goal is to advance the 3D*concept by performing transmission experiments in a rectangular hollow core waveguide, therefore having the superconducting qubit in a truly three-dimensional environment. Consequently, we designed and fabricated a copper waveguide compatible with our cryogenic measurement setup, paying special attention to the impedance matching sections between the coaxial microwave line and the waveguide. We show preliminary transmission measurements at mK temperatures and present the challenges associated with measuring a transmon in a hollow core waveguide.