Passive decoy-state quantum key distribution with practical light sources
Passive decoy-state quantum key distribution with practical light sources
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DOI：
10.1103/physreva.81.022310
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发表时间：
2010-02-01
影响因子：
2.9
通讯作者：
Moroder, Tobias
中科院分区：
文献类型：
--
作者：
Curty, Marcos;Ma, Xiongfeng;Moroder, Tobias
诱饵态已被证明是一种非常有用的方法，可以显着增强具有实用光源的量子密钥分配系统的性能。尽管原则上主动调制激光脉冲强度是准备诱饵态的有效方法，但实际上在某些情况下可能需要被动准备。典型的无源方案涉及参数下变频。最近，已经表明相位随机化弱相干脉冲（WCP）也可以用于相同的目的[M. Curty 等人，选项。莱特。 34, 3238 (2009).] 该提案仅需要线性光学器件和简单的阈值光子探测器，这表明了该方法的实际可行性。最重要的是，生成的密钥率与具有无限数量诱饵设置的主动诱饵状态设置所提供的密钥率相当。在本文中，我们扩展了这些结果，现在具体展示了对不同光源和光电探测器的其他实际场景的分析。特别是，我们考虑发射热态、相位随机 WCP 和强相干光的源与几种类型的光电探测器的结合，例如阈值光子探测器、光子数分辨探测器和经典光电探测器。我们的分析还包括当前阈值检测器显示的检测效率低下和暗计数形式的噪声可能对最终密钥率产生的影响。此外，我们还对有限数据大小导致的统计波动在实际实现中可能产生的影响进行了估计。
Decoy states have been proven to be a very useful method for significantly enhancing the performance of quantum key distribution systems with practical light sources. Although active modulation of the intensity of the laser pulses is an effective way of preparing decoy states in principle, in practice passive preparation might be desirable in some scenarios. Typical passive schemes involve parametric down-conversion. More recently, it has been shown that phase-randomized weak coherent pulses (WCP) can also be used for the same purpose [M. Curty et al., Opt. Lett. 34, 3238 (2009).] This proposal requires only linear optics together with a simple threshold photon detector, which shows the practical feasibility of the method. Most importantly, the resulting secret key rate is comparable to the one delivered by an active decoy-state setup with an infinite number of decoy settings. In this article we extend these results, now showing specifically the analysis for other practical scenarios with different light sources and photodetectors. In particular, we consider sources emitting thermal states, phase-randomized WCP, and strong coherent light in combination with several types of photodetectors, like, for instance, threshold photon detectors, photon number resolving detectors, and classical photodetectors. Our analysis includes as well the effect that detection inefficiencies and noise in the form of dark counts shown by current threshold detectors might have on the final secret key rate. Moreover, we provide estimations on the effects that statistical fluctuations due to a finite data size can have in practical implementations.