GKP与纠缠猫态的近最优贝尔非局域性

中文摘要 AI 辅助

Gottesman-Kitaev-Preskill (GKP)态作为一种玻色子编码，因其可通过综合征测量识别并纠正小的位移误差，而被广泛研究用于容错量子计算。然而，容错操作所需的GKP压缩度远超当前光学平台所能提供的水平。因此，识别可由有限压缩GKP态实现的量子信息任务至关重要。在此，我们研究了在实验驱动的测量约束下，有限能量GKP贝尔态中的贝尔非局域性。尽管有限能量GKP贝尔态即使在低压缩下也支持贝尔非局域性，但仅靠逻辑泡利测量无法揭示它。要获得该态所支持的最大CHSH违规，通常需要逻辑非克利福德旋转。我们转而证明，所需的非高斯资源可以存在于测量本身。光子数分辨探测结合高斯预处理和自适应前馈，无需实现逻辑非克利福德门即可接近CHSH贝尔不等式的最大违规。相同的测量原理也显著增强了猫码贝尔对和纠缠相干态的贝尔违规，表明其效用超越了GKP晶格。我们的结果将非高斯测量确定为揭示有限能量玻色子态中贝尔非局域性的实用途径。

英文摘要

Gottesman-Kitaev-Preskill (GKP) states are widely studied as a bosonic encoding for fault-tolerant quantum computing because small displacement errors can be identified and corrected through syndrome measurements. However, fault-tolerant operation requires substantially greater GKP squeezing than is currently available in optical platforms. It is therefore important to identify quantum-information tasks that can be realised with finite-squeezing GKP states. Here, we study Bell nonlocality in finite-energy GKP Bell states under experimentally motivated measurement constraints. Although finite-energy GKP Bell states support Bell nonlocality even at low squeezing, logical Pauli measurements alone cannot reveal it. Accessing the maximum CHSH violation supported by the state generally requires logical non-Clifford rotations. We instead show that the required non-Gaussian resource can reside in the measurement itself. Photon-number-resolving detection combined with Gaussian preprocessing and adaptive feed-forward closely approaches the maximum violation of the CHSH Bell inequality without implementing logical non-Clifford gates. The same measurement principle strongly enhances Bell violations for cat-code Bell pairs and entangled coherent states, demonstrating that its usefulness extends beyond the GKP lattice. Our results identify non-Gaussian measurements as a practical route to revealing Bell nonlocality in finite-energy bosonic states.

发表机构

• University of Technology Sydney（悉尼科技大学）
• Centre for Quantum Software and Information, University of Technology Sydney（悉尼科技大学量子软件与信息研究中心）
• Centre of Excellence for Quantum Computation and Communication Technology, School of Mathematics and Physics, University of Queensland（昆士兰大学数学与物理学院量子计算与通信技术卓越中心）
• University of Queensland（昆士兰大学）

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