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Fast CZ gate via energy-level engineering in superconducting qubits with a tunable coupler

Benzheng Yuan*, Chaojie Zhang, Chuanbing Han, Shuya Wang, Peng Xu, Huihui Sun, Qing Mu, Lixin Wang, Bo Zhao et al.

Weilong Wang† and Zheng Shan‡

  • Laboratory for Advanced Computing and Intelligence Engineering, Information Engineering University, Zhengzhou 450001, Henan, China

  • *Contact author: Benzhengyuan@outlook.com
  • †Contact author: wangwl19888@163.com
  • ‡Contact author: shanzhengzz@163.com
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Phys. Rev. A 113, 032426 – Published 13 March, 2026

DOI: https://doi.org/10.1103/kc8w-nvnn

Abstract

In superconducting quantum circuits, decoherence errors in qubits constitute a critical factor limiting quantum gate performance. To mitigate decoherence-induced gate infidelity, rapid implementation of quantum gates is essential. Here we propose a scheme for rapid controlled-Z (CZ) gate implementation through energy-level engineering, which leverages Rabi oscillations between the |11〉 state and the noncomputational state in a tunable-coupler architecture. Numerical simulations achieved a 22-ns nonadiabatic CZ gate with fidelity greater than 99.99%. We further investigated the performance of the CZ gate in the presence of anharmonicity offsets. The results demonstrate that a high-fidelity CZ gate with an error rate below 10−4 remains achievable even with finite anharmonicity variations. Furthermore, the detrimental impact of spectator qubits in different quantum states on the fidelity of the CZ gate is effectively suppressed by incorporating a tunable coupler. This scheme exhibits potential for extending the circuit execution depth constrained by coherence time limitations.

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Phys. Rev. A 113, 032426– Published 13 March, 2026
  • Received 4 June 2025
  • Accepted 23 February 2026
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