Transmon-assisted high-fidelity controlled-Z gates for integer fluxonium qubits

J.-H. Wang; H. Xiong; J.-Z. Yang; H.-Y. Zhang; Y.-P. Song; L.-M. Duan

doi:10.1103/qmds-z7gb

← Back to search

Transmon-assisted high-fidelity controlled-Z gates for integer fluxonium qubits

J.-H. Wang, H. Xiong, J.-Z. Yang, H.-Y. Zhang, Y.-P. Song, L.-M. Duan

DOI 10.1103/qmds-z7gb · Physical Review Applied

T1

Active bibliographic source — not scientific approval

Bibliographic access preserves source history; it does not approve extracted materials or validate reported claims. Review warnings on each occurrence separately.

Abstract

Fluxoniums, as partially protected superconducting qubits, are promising to be employed in building high-performance large-scale quantum processor. The recently proposed “integer fluxonium” operates at zero external flux bias, with a frequency of approximately 3 GHz. Single-qubit gate fidelity has been demonstrated to exceed 99.9% [Mencia et al., PRX Quantum 5, 040318 (2024)], whereas two-qubit gate schemes and scalable architectures remain underexplored. In this work, we investigate a fluxonium-transmon-fluxonium (FTF) coupling architecture using integer fluxoniums. We first confirm suppression of ZZ interaction in the FTF system and then propose two high-fidelity controlled-Z (CZ) gate schemes utilizing the coupler control: a flux-activated adiabatic gate scheme and a microwave-activated nonadiabatic gate scheme. Both schemes are capable of achieving low coherent error of the order of 1×10−6 within gate durations of several tens of nanoseconds. In addition, we discuss a hybrid circuit system in which an integer fluxonium is coupled to a conventional fluxonium through a transmon coupler. Our proposal provides insights for future implementations of large-scale quantum circuits based on integer fluxonium devices.