High-Fidelity Controlled-Phase Gate for Binomial Codes via Geometric Phase Engineering
Authors
Yifang Xu
Yilong Zhou
Lida Sun
Hongwei Huang
Zi-Jie Chen
Lintao Xiao
Bo Zhang
Chuanlong Ma
Ziyue Hua
Weiting Wang
Guangming Xue
Haifeng Yu
Weizhou Cai
Chang-Ling Zou
Luyan Sun
Abstract
High-fidelity two-logical-qubit gates are essential for realizing fault-tolerant quantum computation with bosonic codes, yet experimentally reported fidelities have rarely exceeded 90\%. Here, we propose a geometric phase engineering approach for implementing controlled-phase gates for binomially encoded logical qubits. This method leverages the structural simplicity of geometric drives to reduce the numerical optimization dimensionality while fully incorporating system nonlinearities, enabling fast and high-fidelity logical operations. As an example, we experimentally demonstrate a process fidelity of 97.4$\pm$0.8\% for a controlled-Z gate between two binomial codes, surpassing all previously reported two-logical-qubit gates in bosonic codes. This work demonstrates that geometric phase engineering provides an effective and experimentally feasible route to fast, high-fidelity logical operations in bosonic quantum processors.
