中国物理B ›› 2026, Vol. 35 ›› Issue (4): 40308-040308.doi: 10.1088/1674-1056/ae13ea

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Generation of cross-cross resonance gates with two fluxonium qubits

Xinpeng Chen(陈鑫鹏)† and Zeliang Xiang(项泽亮)   

  1. School of Physics, Sun Yat-sen University, Guangzhou 510275, China
  • 收稿日期:2025-04-11 修回日期:2025-08-26 接受日期:2025-10-16 发布日期:2026-04-13
  • 通讯作者: Xinpeng Chen E-mail:1594729446@qq.com

Generation of cross-cross resonance gates with two fluxonium qubits

Xinpeng Chen(陈鑫鹏)† and Zeliang Xiang(项泽亮)   

  1. School of Physics, Sun Yat-sen University, Guangzhou 510275, China
  • Received:2025-04-11 Revised:2025-08-26 Accepted:2025-10-16 Published:2026-04-13
  • Contact: Xinpeng Chen E-mail:1594729446@qq.com

摘要: The cross-cross resonance (CCR) gate is an extension of the cross-resonance (CR) gate that has been theoretically implemented with transmon qubits. However, the weak anharmonicity of transmon qubits leads to decoherence and leakage errors, which reduce the fidelity of the gate operation. In this work, we propose employing fluxonium qubits to implement the CCR gate. With similar drive amplitudes, our scheme can achieve the required stronger $ZX$ and $XZ$ interactions compared to a transmon qubit system, resulting in shorter gate times. By combining the CCR gate with specific single-qubit gates, a $\sqrt{\text{iSWAP}}$ gate is realized, thereby enabling the construction of the iSWAP and SWAP gates. Moreover, through parameter optimization, these gates built on fluxonium qubits exhibit a significant reduction in operation time while simultaneously achieving higher fidelity. Our results provide valuable insights into achieving fast, low-error-rate swapping operations in superconducting circuits.

关键词: quantum computing, superconducting qubit, quantum gate

Abstract: The cross-cross resonance (CCR) gate is an extension of the cross-resonance (CR) gate that has been theoretically implemented with transmon qubits. However, the weak anharmonicity of transmon qubits leads to decoherence and leakage errors, which reduce the fidelity of the gate operation. In this work, we propose employing fluxonium qubits to implement the CCR gate. With similar drive amplitudes, our scheme can achieve the required stronger $ZX$ and $XZ$ interactions compared to a transmon qubit system, resulting in shorter gate times. By combining the CCR gate with specific single-qubit gates, a $\sqrt{\text{iSWAP}}$ gate is realized, thereby enabling the construction of the iSWAP and SWAP gates. Moreover, through parameter optimization, these gates built on fluxonium qubits exhibit a significant reduction in operation time while simultaneously achieving higher fidelity. Our results provide valuable insights into achieving fast, low-error-rate swapping operations in superconducting circuits.

Key words: quantum computing, superconducting qubit, quantum gate

中图分类号:  (Quantum computation architectures and implementations)

  • 03.67.Lx
03.65.Aa (Quantum systems with finite Hilbert space) 85.25.Am (Superconducting device characterization, design, and modeling)