量子克隆

The quantum no-cloning theorem, which shows that two non-orthogonal.states cannot be cloned exactly, is one of the most important bases of the.quantum information theory. So one is interested in imperfect copies. Now there.are two kinds of imperfect cloning, one is universal cloning proposed by Hilley.et. al, the other is probabilistic quantum cloning presented by us. The purpose of.this project is to study these two kinds of quantum cloning in experiment. Based.on the properties of the signal photon having different degrees of freedom of.polarization and location, we design quantum logic circuits to perform the.probabilistic cloning and universal cloning via optical device. The experimental.results coincide with the theoretical predications

量子不可克隆原理是量子信息理论的重要基础，它给信息的提取设置.了不可逾越的障碍，因此研究量子信息的不精确克隆有着重要价值。美国.学者提出一类“普适克隆”原理，即对任意输入态克隆总成功，但保真度.小于1，例克隆两份输出的最大保真度为5/6，我们提出另一类“概率克隆”.原理，即对线性无关的量子态 输入，以某概率克隆出保真度为1 的输出。.本项目的主要研究目标是在实验上研制量子克隆机，我们利用单个光子具.有偏振和路径两个自由度的特性，设计出线性光学网络，它能将偏振自由.度的量子态克隆到路径自由度的量子态上，基于这个想法，我们研制成功.量子普适克隆机和量子概率克隆机，在实验上证实了我们概率克隆原理，.并验证了美国学者关于普适克隆的理论预言。