A tunable rf SQUID manipulated as flux and phase qubit

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.

Proceedings of Nobel Symposium "Qubits for future quantum computers", Goeteborg, Sweden, May 25-28, 2009; to appear in Physica Scripta

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Cited by in corpus (7)

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• Superconducting qubit manipulated by fast pulses: experimental observation of distinct decoherence regimes
• Deep-well ultrafast manipulation of a SQUID flux qubit
• Real-time simulation of flux qubits used for quantum annealing
• Optimization of Junction and Bias Parameters in readout of Phase Qubit
• Flux Qubit Readout in the Persistent Current Basis at arbitrary Bias Points
• Two-photon coupling via Josephson element I: Breaking the symmetry with magnetic fields