Fluxonium: an alternative qubit platform for high-fidelity operations

TL;DR

This paper demonstrates a fluxonium-based quantum processor with high coherence and gate fidelities, offering a promising alternative platform for fault-tolerant superconducting quantum computing.

Contribution

It introduces a fluxonium qubit system with fast, high-fidelity gates, showing competitive performance to transmon qubits for fault-tolerant quantum computing.

Findings

Single-qubit gate fidelity of 99.97%

Two-qubit gate fidelity of up to 99.72%

Achieved performance comparable to leading superconducting qubits

Abstract

Superconducting qubits provide a promising path toward building large-scale quantum computers. The simple and robust transmon qubit has been the leading platform, achieving multiple milestones. However, fault-tolerant quantum computing calls for qubit operations at error rates significantly lower than those exhibited in the state of the art. Consequently, alternative superconducting qubits with better error protection have attracted increasing interest. Among them, fluxonium is a particularly promising candidate, featuring large anharmonicity and long coherence times. Here, we engineer a fluxonium-based quantum processor that integrates high qubit-coherence, fast frequency-tunability, and individual-qubit addressability for reset, readout, and gates. With simple and fast gate schemes, we achieve an average single-qubit gate fidelity of 99.97% and a two-qubit gate fidelity of up to 99.72%. This performance is comparable to the highest values reported in the literature of superconducting circuits. Thus our work, for the first time within the realm of superconducting qubits, reveals an approach toward fault-tolerant quantum computing that is alternative and competitive to the transmon system.