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arXiv · 2510.09461

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·Weilong Wang·Zheng Shan
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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 $\left|11\right\rangle$ state and the non-computational state in a tunable-coupler architecture. Numerical simulations achieved a $\mathrm{22~ns}$ nonadiabatic CZ gate with fidelity over $99.99\%$. 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 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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Benzheng Yuan, Chaojie Zhang, Chuanbing Han, Shuya Wang, Peng Xu, Huihui Sun, Qing Mu, Lixin Wang, Bo Zhao, Weilong Wang, Zheng Shan. 2026-03-09. Fast CZ Gate via Energy-Level Engineering in Superconducting Qubits with a Tunable Coupler. https://doi.org/10.1103/kc8w-nvnn

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