Madjid F Hadi, Myers John M
Consultant, 82 Powers Road, Concord, MA 01742, USA.
Harvard School of Engineering and Applied Sciences, Cambridge, MA 02138, USA.
Entropy (Basel). 2020 Apr 11;22(4):434. doi: 10.3390/e22040434.
Entangled states of light exhibit measurable correlations between light detections at separated locations. These correlations are exploited in entangled-state quantum key distribution. To do so involves setting up and maintaining a rhythm of communication among clocks at separated locations. Here, we try to disentangle our thinking about clocks as used in actual experiments from theories of time, such as special relativity or general relativity, which already differ between each other. Special relativity intertwines the concept of time with a particular definition of the synchronization of clocks, which precludes synchronizing every clock to every other clock. General relativity imposes additional barriers to synchronization, barriers that invite seeking an alternative depending on any global concept of time. To this end, we focus on how clocks are actually used in some experimental situations. We show how working with clocks without worrying about time makes it possible to generalize some designs for quantum key distribution and also clarifies the need for alternatives to the special-relativistic definition of synchronization.
光的纠缠态在分离位置的光探测之间表现出可测量的相关性。这些相关性被用于纠缠态量子密钥分发。为此需要在分离位置的时钟之间建立并维持一种通信节奏。在这里，我们试图将实际实验中使用的时钟概念与时间理论（如狭义相对论或广义相对论，它们之间已经存在差异）区分开来。狭义相对论将时间概念与时钟同步的特定定义交织在一起，这排除了将每个时钟与其他每个时钟同步的可能性。广义相对论给同步带来了额外的障碍，这些障碍促使人们寻求一种依赖于任何全局时间概念的替代方法。为此，我们关注时钟在某些实验情况下的实际使用方式。我们展示了在不考虑时间的情况下使用时钟如何能够推广一些量子密钥分发的设计，同时也阐明了对狭义相对论同步定义替代方法的需求。
