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Main Authors: Huang, Eugene Y., Andersen, Christian Kraglund
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.17936
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author Huang, Eugene Y.
Andersen, Christian Kraglund
author_facet Huang, Eugene Y.
Andersen, Christian Kraglund
contents We study the cross-resonance effect in capacitively-coupled fluxonium qubits and devise a simple formula for their maximum ZX interaction strength. By going beyond the perturbative regime, we find that a CNOT gate can generally be realized in under 200 ns with residual ZZ limited to 50 kHz, for fluxonium qubits with frequencies below 1 GHz. Our analysis relies on a semi-analytical method: we first numerically diagonalize the Floquet Hamiltonian of the strongly-driven control qubit and then perturbatively incorporate the weak qubit-qubit coupling to obtain an effective Hamiltonian. We also derive frequency collision windows around harmful control-target and control-spectator transitions. For large fluxonium devices, we predict a collision-free yield that is considerably less sensitive to junction variability compared to transmons in the same layout. These results support the viability of an all-fluxonium cross-resonance architecture with only capacitive couplings.
format Preprint
id arxiv_https___arxiv_org_abs_2603_17936
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Exploration of Fluxonium Parameters for Capacitive Cross-Resonance Gates
Huang, Eugene Y.
Andersen, Christian Kraglund
Quantum Physics
We study the cross-resonance effect in capacitively-coupled fluxonium qubits and devise a simple formula for their maximum ZX interaction strength. By going beyond the perturbative regime, we find that a CNOT gate can generally be realized in under 200 ns with residual ZZ limited to 50 kHz, for fluxonium qubits with frequencies below 1 GHz. Our analysis relies on a semi-analytical method: we first numerically diagonalize the Floquet Hamiltonian of the strongly-driven control qubit and then perturbatively incorporate the weak qubit-qubit coupling to obtain an effective Hamiltonian. We also derive frequency collision windows around harmful control-target and control-spectator transitions. For large fluxonium devices, we predict a collision-free yield that is considerably less sensitive to junction variability compared to transmons in the same layout. These results support the viability of an all-fluxonium cross-resonance architecture with only capacitive couplings.
title Exploration of Fluxonium Parameters for Capacitive Cross-Resonance Gates
topic Quantum Physics
url https://arxiv.org/abs/2603.17936