Proposal for entangling gates on fluxonium qubits via a two-photon transition

TL;DR

This paper proposes microwave-activated entangling gates for fluxonium qubits that leverage two-photon transitions, achieving low error rates and fast operation suitable for scalable quantum computing.

Contribution

It introduces a novel gate scheme using two-photon transitions in fluxonium qubits, enabling high-fidelity entangling gates with tunable parameters and minimal leakage.

Findings

Gate error below 10^{-4} with <100 ns pulse duration

High coherence times (>1 ms) support scalable quantum processors

Flexible gate family equivalent to fermionic-simulation gates

Abstract

We propose a family of microwave-activated entangling gates on two capacitively coupled fluxonium qubits. A microwave pulse applied to either qubit at a frequency near the half-frequency of the $|00\rangle - |11\rangle$ transition induces two-photon Rabi oscillations with a negligible leakage outside the computational subspace, owing to the strong anharmonicity of fluxoniums. By adjusting the drive frequency, amplitude, and duration, we obtain the gate family that is locally equivalent to the fermionic-simulation gates such as $\sqrt{\rm SWAP}$-like and controlled-phase gates. The gate error can be tuned below $10^{-4}$ for a pulse duration under 100 ns without excessive circuit parameter matching. Given that the fluxonium coherence time can exceed 1 ms, our gate scheme is promising for large-scale quantum processors.