CNOT gates in inductively coupled multi-fluxonium systems

TL;DR

This paper investigates four inductively coupled fluxonium qubits to understand how spectator qubits affect CNOT gate fidelity, identifying frequency configurations that enable low-error, scalable quantum computing.

Contribution

It analyzes spectator qubit effects in multi-fluxonium systems and proposes configurations for low-error, scalable CNOT gates in larger quantum architectures.

Findings

Spectator qubits cause errors that are suppressed with sufficient frequency detuning.

Favorable frequency configurations achieve CNOT errors below 10^{-4}.

Results suggest scalability of fluxonium-based quantum processors.

Abstract

High-fidelity two-qubit gates have been demonstrated in systems of two fluxonium qubits; however, the realization of scalable quantum processors requires maintaining low error rates in substantially larger architectures. In this work, we analyze a system of four inductively coupled fluxonium qubits to determine the impact of spectator qubits on the performance of a \textsc{cnot} gate. Our results show that spectator-induced errors are strongly suppressed when the transition frequencies of the spectator qubits are sufficiently detuned from those of the active qubits. We identify favorable frequency configurations for the four-qubit chain that yield \textsc{cnot} gate errors below $10^{-4}$ for gate times shorter than 100 ns. Leveraging the locality of the nearest-neighbor coupling, we extrapolate our findings to longer fluxonium chains, suggesting a viable path toward scalable, low-error quantum information processing.