Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 8: Posters Transport

TT 8.42: Poster

Friday, March 4, 2005, 14:00–18:00, Poster TU C

Low temperature setup for characterization of superconducting qubits — •Karl Madek, Tobias Heimbeck, Heribert Knoglinger, Matteo Mariantoni, Christian Probst, Georg Wild, Achim Marx, and Rudolf Gross — Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany

In recent years interest in quantum computing has been continously growing. Because of the superconducting energy gap superconducting devices are promising candidates for quantum bits suggesting sufficiently large decoherence times. In order to experimentally investigate superconducting qubits well shielded low temperature measurement setups are required. We have established a dilution unit with several layers of mumetal and cryoperm shields and several stages of low pass filters at different temperatures in the biasing lines. A semirigid coaxial cable with thermally anchored attenuators is used for microwave spectroscopy on superconducting devices. Furthermore, the whole setup is placed in a shielded room. Measurements of the escape rate of Josephson junctions out of the zero voltage state using a current ramping technique serve to evaluate the quality of the shielding. The observation of a crossover from the quantum tunneling regime to the thermal regime shows the negligibility of noise. This work was supported by the Sonderforschungsbereich 631 of the Deutsche Forschungsgemeinschaft.