Fast Flux Entangling Gate for Fluxonium Circuits

Abstract

We analyze a high-fidelity two-qubit gate using fast flux pulses on superconducting fluxonium qubits. The gate is realized by temporarily detuning magnetic flux through fluxonium loop away from the half flux quantum sweet spot. We simulate dynamics of two capacitively coupled fluxoniums during the flux pulses and optimize the pulse parameters to obtain a highly accurate $\sqrt{i\mathrm{swap}}$-like entangling gate. We also evaluate the effect of the flux noise and qubit relaxation on the gate fidelity. Our results demonstrate that the gate error remains below $10^{-4}$ for currently achievable magnitude of the flux noise and qubit relaxation time.

arXiv comment11 pages, 6 figures, new figure and new results added, comment on the effect of time-dependent external flux on circuit quantization added. Equation (4) is corrected from xx coupling to yy coupling

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• CNOT gates for fluxonium qubits via selective darkening of transitions
• Microwave-activated gates between a fluxonium and a transmon qubit
• Flux-pulse-assisted Readout of a Fluxonium Qubit
• Application of Optimal Control to Time-Resolution Protocol for Quantum Sensing