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  • Letter
  • Open Access

Generalized cross-resonance scheme for maximally entangling two-qutrit gates

Yash Saxena1,2,*, Tharrmashastha SAPV2,3,†, Sagnik Chatterjee2,3,4,‡, and Ray-Kuang Lee1,5,6,§

  • 1Department of Physics, National Tsing Hua University, Hsinchu City 300013, Taiwan
  • 2Center for Quantum Technologies, IIIT-Delhi, New Delhi 110020, India
  • 3Department of Computer Science, IIIT-Delhi, New Delhi 110020, India
  • 4School of Technology and Computer Science, TIFR, Mumbai 400005, India
  • 5Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan
  • 6Center for Quantum Science and Technology, Hsinchu 30013, Taiwan

  • *Contact author: ysaxena@gapp.nthu.edu.tw
  • †Contact author: tharrmashasthav@iiitd.ac.in
  • ‡Contact author: sagnikc@iiitd.ac.in
  • §Contact author: rklee@ee.nthu.edu.tw
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Phys. Rev. Research 8, L032023 – Published 12 August, 2026

DOI: https://doi.org/10.1103/qqtg-x6jg

Abstract

To utilize higher-dimensional quantum systems, in this Letter we derive a generalized cross-resonance scheme for realizing maximally entangling two-qutrit gates on fixed-frequency transmons beyond the 0–1 subspace. Our two-qutrit gates, namely, UCR01 and UCR12, acting on the 0–1 and 1–2 energy transitions of transmons, respectively, directly allow for entanglement on the 1–2 levels. Unlike the known works, our gate is parametric in nature, enabling us to construct multiple entangling gates of interest. By performing simulations in Qiskit, we demonstrate two-qutrit generalized controlled-X (UCX01 and UCX12) and controlled-H (UCH01 and UCH12) gates, which are instances of the proposed UCR gates, with reported gate fidelities of 93.17%(99.73%),91.47%(97.88%),96.06%(99.39%), and 95.68%(98.99%), respectively, with (and without) noise. We also reveal a two-qutrit Bell state with a fidelity of 87.54%(99.06%), with a complete Bell state preparation in an ∼514ns pulse sequence, which is less than the gate time of the known scheme by cross-Kerr-based entangling gates.

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Phys. Rev. Research 8, L032023– Published 12 August, 2026
  • Received 10 June 2025
  • Accepted 25 June 2026
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