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arXiv · 0910.4562

A tunable rf SQUID manipulated as flux and phase qubit

S Poletto·F Chiarello·M G Castellano·J Lisenfeld·A Lukashenko·P Carelli·A V Ustinov
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Abstract

We report on two different manipulation procedures of a tunable rf SQUID. First, we operate this system as a flux qubit, where the coherent evolution between the two flux states is induced by a rapid change of the energy potential, turning it from a double well into a single well. The measured coherent Larmor-like oscillation of the retrapping probability in one of the wells has a frequency ranging from 6 to 20 GHz, with a theoretically expected upper limit of 40 GHz. Furthermore, here we also report a manipulation of the same device as a phase qubit. In the phase regime, the manipulation of the energy states is realized by applying a resonant microwave drive. In spite of the conceptual difference between these two manipulation procedures, the measured decay times of Larmor oscillation and microwave-driven Rabi oscillation are rather similar. Due to the higher frequency of the Larmor oscillations, the microwave-free qubit manipulation allows for much faster coherent operations.

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S Poletto, F Chiarello, M G Castellano, J Lisenfeld, A Lukashenko, P Carelli, A V Ustinov. 2009-10-23. A tunable rf SQUID manipulated as flux and phase qubit. https://doi.org/10.1088/0031-8949%2F2009%2Ft137%2F014011

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