通过自旋-光子混合纠缠远程制备单自旋态
Remote state preparation of a single-spin state via hybrid spin-photon entanglement
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中文总结 AI 辅助
提出一种利用自旋-光子混合纠缠远程制备电子自旋态的协议，通过相干态编码和辅助自旋测量规避非正交投影，实现高保真度远程态制备，并分析了损耗与退相干影响。
中文摘要 AI 辅助
远程态制备是一种基本的量子信息协议，它利用目标态的先验知识来减少量子态分发所需的通信资源。在这里，我们提出了一种针对静态电子自旋量子比特的远程态制备协议，该协议利用电子自旋与相干态光脉冲之间的混合纠缠，这种纠缠通过自旋腔系统中的自旋相关反射产生。与单光子编码不同，相干态编码天然容忍光子损失：损失通道会衰减相干态幅度，导致制备保真度逐渐降低，而不是概率性的协议失败。核心困难——在传统协议中需要对非正交相干态的叠加进行投影——通过将传输脉冲耦合到辅助自旋，然后进行零差检测和自旋投影测量来规避。因此，该协议避免了直接的相干态叠加测量和光子数分辨检测。在理想极限下，仅使用一位经典通信即可实现特定类别目标态的确定性制备。我们定量分析了相干态非正交性、光纤损耗和自旋退相干对制备保真度的影响。增加相干态幅度可提高态可区分性，从而提升制备保真度，但同时也增强了由光子损失引起的分支信息泄漏，导致在每个传输距离上存在最优幅度。对于实验相关参数，优化后的平均保真度在数十公里的距离上仍远高于经典基准。我们还讨论了使用金刚石氮-空位中心的可能实现方案。
英文摘要
Remote state preparation is a fundamental quantum-information protocol that exploits prior knowledge of a target state to reduce the communication resources required for quantum-state distribution. Here, we propose a remote-state-preparation protocol for a stationary electron-spin qubit using hybrid entanglement between the electron spin and a coherent-state light pulse, generated by spin-dependent reflection from a spin-cavity system. Unlike single-photon encodings, the coherent-state encoding is naturally tolerant of photon loss: a loss channel attenuates the coherent-state amplitude, leading to a gradual reduction in preparation fidelity rather than probabilistic protocol failure. The central difficulty---implementing the projection onto superpositions of nonorthogonal coherent states required in the conventional protocol---is circumvented by coupling the transmitted pulse to an auxiliary spin, followed by homodyne detection and a spin projective measurement. The protocol therefore avoids direct coherent-state-superposition measurements and photon-number-resolving detection. In the ideal limit, deterministic preparation of a particular class of target states can be achieved using only one bit of classical communication. We analytically quantify the effects of coherent-state nonorthogonality, fiber loss, and spin dephasing on the preparation fidelity. Increasing the coherent-state amplitude improves state distinguishability and hence the preparation fidelity, but also enhances which-branch information leakage caused by photon loss, resulting in an optimal amplitude at each transmission distance. For experimentally relevant parameters, the optimized average fidelity remains well above the classical benchmark over distances of tens of kilometers. We also discuss a possible implementation using diamond nitrogen-vacancy centers.
发表机构
- Wenzhou University（温州大学）
机构由 AI 辅助整理，请以论文原文为准。
