Improved qubit bifurcation readout in the straddling regime of circuit QED

Abstract

We study bifurcation measurement of a multi-level superconducting qubit using a nonlinear resonator biased in the straddling regime, where the resonator frequency sits between two qubit transition frequencies. We find that high-fidelity bifurcation measurements are possible because of the enhanced qubit-state-dependent pull of the resonator frequency, the behavior of qubit-induced nonlinearities and the reduced Purcell decay rate of the qubit that can be realized in this regime. Numerical simulations find up to a threefold improvement in qubit readout fidelity when operating in, rather than outside of, the straddling regime. High-fidelity measurements can be obtained at much smaller qubit-resonator couplings than current typical experimental realizations, reducing spectral crowding and potentially simplifying the implementation of multi-qubit devices.

9 pages, 6 figures

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Cited by in corpus (6)

• Large Dispersive Shift of Cavity Resonance Induced by a Superconducting Flux Qubit in the Straddling Regime
• Stückelberg interference in a superconducting qubit under periodic latching modulation
• Tunable-Cavity QED with Phase Qubits
• Photon blockade and the quantum-to-classical transition in the driven-dissipative Josephson pendulum coupled to a resonator
• Photon-noise-tolerant dispersive readout of a superconducting qubit using a nonlinear Purcell filter
• Quantum Acoustics with Superconducting Qubits in the Multimode Transition-Coupling Regime