Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 12: Poster Session Superconductivity

TT 12.8: Poster

Montag, 11. März 2013, 15:00–19:00, Poster D

Towards long lived tunable transmon qubit in microstrip geometry — •Jochen Braumüller, Lucas Radtke, Hannes Rotzinger, Martin Weides, and Alexey V. Ustinov — Karlsruhe Institute of Technology (KIT), Physikalisches Institut, 76131 Karlsruhe, Germany

Qubits constitute the main building blocks of a prospective quantum computer. One main challenge is given by short decoherence times. In this work we investigate a transmon qubit based on a superconducting charge qubit with reduced sensitivity to charge noise. This is achieved by operating the qubit at a Josephson to charging energy ratio of about 100. At the same time, a sufficiently large anharmonicity of the energy levels is preserved. The qubit is realized in a 2D geometry based on large capacitor pads being connected by two Josephson junctions in parallel. This split Josephson junction allows the qubit to be tunable in Josephson energy and therefore in resonance frequency. The large area capacitor pads mainly coupled through the substrate and a backside metalization reduce the surface loss contribution. Manipulation and readout of the qubit is mediated by a microstrip resonator coupled to a feedline. We will present resonator and qubit designs together with respective microwave simulations. Preliminary results on circuit fabrication and low temperature measurements will also be discussed.