Fast Measurement of a Tunable Superconducting Flux Qubit via a Driven Nonlinear Resonator with Applications in Quantum Annealing*

Development of readout schemes of flux qubits in the persistent current basis is important for quantum annealing applications. High fidelity detection, controlled backaction on the qubit, as well as rapid acquisition, are all relevant for flexible quantum annealing. In order to accommodate these requirements, we develop a readout based on the use of metastable oscillation states in a nonlinear oscillator detection circuit specifically tailored for capacitively shunted flux qubits. In this work, we discuss the design as well as preliminary results for a device specifically designed for tunable capacitively shunted flux qubits specifically designed for use in quantum annealers.