Fast Flux Entangling Gate for Fluxonium Circuits

TL;DR

This paper presents a high-fidelity two-qubit entangling gate for fluxonium superconducting qubits using fast flux pulses, optimized through simulations to achieve errors below 10^-4 despite flux noise and relaxation effects.

Contribution

It introduces a fast flux pulse method to implement a high-fidelity entangling gate on fluxonium qubits, with detailed simulation and noise analysis.

Findings

Gate error below 10^-4 with current flux noise levels.

Optimized flux pulse parameters for accurate entangling operation.

Robustness of the gate against flux noise and relaxation effects.

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.