Fast Flux Entangling Gate for Fluxonium Circuits
Yinqi Chen, Konstantin Nesterov, Vladimir Manucharyan, Maxim Vavilov · Physical Review Applied · 2022
We analyze a high-fidelity two-qubit gate using fast flux pulses on superconducting fluxonium qubits. The gate is realized by temporarily detuning the magnetic flux through the 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 ${10}^{\ensuremath{-}4}$ for a currently achievable magnitude of the flux noise and qubit relaxation time.