Multi-state discrimination below the quantum noise limit at the single-photon level
Multi-state discrimination below the quantum noise limit at the single-photon level
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DOI：
10.1038/s41534-017-0042-2
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发表时间：
2017-10-16
影响因子：
7.6
通讯作者：
Becerra, F. E.
中科院分区：
文献类型：
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作者：
Ferdinand, A. R.;DiMario, M. T.;Becerra, F. E.
接近灵敏度极限量子极限的测量是量子信息处理、量子计量和通信的核心。在单光子水平上区分多个状态的量子测量对于优化低功耗光通信和量子通信中的信息传输至关重要，并且可以增强许多量子信息协议的功能。在这里，我们从理论上研究并通过实验证明了在实际损耗和噪声条件下，基于通过单光子计数和位移操作实现全局优化自适应测量的策略，在单光子水平上区分灵敏度超过量子噪声极限（QNL）的光的多个相干态。这些辨别策略可以提供现实的优势来增强低功率下的信息传输，并且与光子数分辨检测兼容，从而提供高功率下的鲁棒性，从而允许在现实条件下在任意输入功率水平上超越 QNL。
Measurements approaching the ultimate quantum limits of sensitivity are central in quantum information processing, quantum metrology, and communication. Quantum measurements to discriminate multiple states at the single-photon level are essential for optimizing information transfer in low-power optical communications and quantum communications, and can enhance the capabilities of many quantum information protocols. Here, we theoretically investigate and experimentally demonstrate the discrimination of multiple coherent states of light with sensitivities surpassing the quantum noise limit (QNL) at the single-photon level under realistic conditions of loss and noise based on strategies implementing globally-optimized adaptive measurements with single photon counting and displacement operations. These discrimination strategies can provide realistic advantages to enhance information transfer at low powers, and are compatible with photon number resolving detection, which provides robustness at high powers, thus allowing for surpassing the QNL at arbitrary input power levels under realistic conditions.