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arXiv · 2503.03867

Logical operations with a dynamical qubit in Floquet-Bacon-Shor code

Xuandong Sun·Longcheng Li·Zhiyi Wu·Zechen Guo·Peisheng Huang·Wenhui Huang·Qixian Li·Yongqi Liang·Yiting Liu·Daxiong Sun·Zilin Wang·Changrong Xie·Yuzhe Xiong·Xiaohan Yang·Jiajian Zhang·Jiawei Zhang·Libo Zhang·Zihao Zhang·Weijie Guo·Ji Jiang·Song Liu·Xiayu Linpeng·Jingjing Niu·Jiawei Qiu·Wenhui Ren·Ziyu Tao·Yuefeng Yuan·Yuxuan Zhou·Ji Chu·Youpeng Zhong·Xiaoming Sun·Dapeng Yu
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Abstract

Quantum error correction (QEC) protects quantum systems against inevitable noises and control inaccuracies, providing a pathway towards fault-tolerant (FT) quantum computation. Stabilizer codes, including surface code and color code, have long been the focus of research and have seen significant experimental progress in recent years. Recently proposed time-dynamical QEC, including Floquet codes and generalized time-dynamical code implementations, opens up new opportunities for FT quantum computation. By employing a periodic schedule of low-weight parity checks, Floquet codes can generate additional dynamical logical qubits, offering enhanced error correction capabilities and potentially higher code performance. Here, we experimentally implement the Floquet-Bacon-Shor code on a superconducting quantum processor. We encode a dynamical logical qubit within a $3\times 3$ lattice of data qubits, alongside a conventional static logical qubit. We demonstrate FT encoding and measurement of the two-qubit logical states, and stabilize these states using repeated error detection. We showcase universal single-qubit logical gates on the dynamical qubit. Furthermore, by implementing a logical CNOT gate, we entangle the dynamical and static logical qubits, generating an error-detected logical Bell state with a fidelity of 75.9\%. Our results highlight the potential of Floquet codes for resource-efficient FT quantum computation.

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Xuandong Sun, Longcheng Li, Zhiyi Wu, Zechen Guo, Peisheng Huang, Wenhui Huang, Qixian Li, Yongqi Liang, Yiting Liu, Daxiong Sun, Zilin Wang, Changrong Xie, Yuzhe Xiong, Xiaohan Yang, Jiajian Zhang, Jiawei Zhang, Libo Zhang, Zihao Zhang, Weijie Guo, Ji Jiang, Song Liu, Xiayu Linpeng, Jingjing Niu, Jiawei Qiu, Wenhui Ren, Ziyu Tao, Yuefeng Yuan, Yuxuan Zhou, Ji Chu, Youpeng Zhong, Xiaoming Sun, Dapeng Yu. 2025-03-05. Logical operations with a dynamical qubit in Floquet-Bacon-Shor code. https://doi.org/10.1103/425n-6k9s

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