Frequency-Tunable Josephson Junction Resonator for Quantum Computing

摘要

We have fabricated and measured a high-Q Josephson junction resonator with atunable resonance frequency. A dc magnetic flux allows the resonance frequencyto be changed by over 10 %. Weak coupling to the environment allows a qualityfactor of $\thicksim$7000 when on average less than one photon is stored in theresonator. At large photon numbers, the nonlinearity of the Josephson junctioncreates two stable oscillation states. This resonator can be used as a tool forinvestigating the quality of Josephson junctions in qubits below the singlephoton limit, and can be used as a microwave qubit readout at high photonnumbers.