Quantum Benchmarking of High-Fidelity Noise-Biased Operations on a Detuned Kerr-Cat Qubit

Authors

Bingcheng Qing, University of California, Berkeley
Ahmed Hajr, University of California, Berkeley
Ke Wang, University of California, Berkeley
Gerwin Koolstra, University of California, Berkeley
Long B. Nguyen, University of California, Berkeley
Jordan Hines, University of California, Berkeley
Irwin Huang, University of Rochester
Bibek Bhandari, Chapman University
Larry Chen, University of California, Berkeley
Ziqi Kang, University of California, Berkeley
Christian Jünger, University of California, Berkeley
Noah Goss, University of California, Berkeley
Nikitha Jain, University of California, Berkeley
Hyunseong Kim, University of California, Berkeley
Kan-Heng Lee, University of California, Berkeley
Akel Hashim, University of California, Berkeley
Nicholas E. Frattini, Yale University
Zahra Pedramrazi, University of California, Berkeley
Justin Dressel, Chapman UniversityFollow
Andrew N. Jordan, Chapman UniversityFollow
David I. Santiago, University of California, Berkeley
Irfan Siddiqi, University of California, Berkeley

Document Type

Article

Publication Date

1-30-2026

Abstract

Ubiquitous noise sources in quantum systems remain a key obstacle to building quantum computers, necessitating the use of quantum error correction codes. Recently, error-correcting codes tailored for noise-biased systems have been shown to offer high fault-tolerance thresholds and reduced hardware overhead, positioning noisebiased qubits as promising candidates for building universal quantum computers. However, quantum operations on these platforms remain challenging, and their noise structures have not yet been rigorously benchmarked to the same extent as those of conventional quantum hardware. In this work, we develop a comprehensive quantum control toolbox for a scalable noise-biased qubit, detuned Kerr-cat qubit, including initialization, universal single-qubit gates, and quantum nondemolition readout. We systematically characterize the noise structure of these operations using gate set tomography and dihedral randomized benchmarking, achieving high local gate fidelities, with F[Z(π=2)] = (99:18 ± 0:066)% and F[X(π=2)] = (92:5 ± 0:23)%. Notably, the noise bias of the detuned Kerr-cat qubit approaches 250 with a phaseflip time of 4 μs, which outperforms its resonant-Kerr-cat qubit counterparts as reported previously, representing a state-of-the-art performance benchmark for Kerrcat qubits. Moreover, our results reveal a critical overestimation of operational noise bias inferred from bit-flip and phase-flip times alone, highlighting the necessity of a precise and direct benchmarking for noise-biased qubit operations. Our work thus establishes a framework for systematically characterizing and validating the performance of quantum operations in structured-noise architectures, which lays the groundwork for implementing efficient quantum error correction in next-generation architectures.

Comments

This article was originally published in Proceedings of the National Academy of Sciences of the United States of America, volume 123, issue 5, in 2026. https://doi.org/10.1073/pnas.2520479123

Recommended Citation

B. Qing,A. Hajr,K. Wang,G. Koolstra,L.B. Nguyen,J. Hines,I. Huang,B. Bhandari,L. Chen,Z. Kang,C. Jünger,N. Goss,N. Jain,H. Kim,K. Lee,A. Hashim,N.E. Frattini,Z. Pedramrazi,J. Dressel,[...] & I. Siddiqi, Quantum benchmarking of high-fidelity noise-biased operations on a detuned Kerr-cat qubit, Proc. Natl. Acad. Sci. U.S.A. 123 (5) e2520479123, https://doi.org/10.1073/pnas.2520479123 (2026).

Peer Reviewed

1

Copyright

The authors

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.