In this paper we consider a scheme for cryptographic key distribution based on a variation of continuous variable quantum key distribution called central broadcast. In the continuous variable central broadcast scheme, security arises from discord present in the Hanbury Brown and Twiss effect from a thermal source. The benefit of this scheme is that it expands the range of frequencies into the microwave regime. Longer wavelengths—where the thermal photon number is higher and correlations remain robust over long distances—may even be preferable to optical wavelengths. Assuming that Alice controls the source but not the distribution of the light (e.g. satellite broadcasts), then we demonstrate that the central broadcast scheme is robust to an entangling cloner attack. We establish the security of the protocol both experimentally and theoretically.

中文翻译：

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热态下的量子保密II

在本文中，我们考虑一种基于连续变量量子密钥分布的变化（称为中央广播）的加密密钥分布方案。在连续可变中央广播方案中，安全性是由存在于Hanbury Brown中的不和谐和来自热源的Twiss效应引起的。这种方案的好处是它将频率范围扩展到微波范围。更长的波长（其中热光子数更高，并且在长距离上相关性仍然很强）甚至可能比光学波长更好。假设爱丽丝控制着光源而不是光的分布（例如卫星广播），那么我们证明了中央广播方案对于缠结的克隆攻击是鲁棒的。我们在实验和理论上都建立了协议的安全性。