Quan Quan, Zhao Ming-Jing, Fei Shao-Ming, Fan Heng, Yang Wen-Li, Long Gui-Lu
State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China.
Institute of Modern Physics, Northwest University, Xi'an, 710069, China.
Sci Rep. 2018 Sep 18;8(1):13960. doi: 10.1038/s41598-018-31918-0.
We investigate two-copy scenario of quantum teleportation based on Bell measurements. The detailed protocol is presented and the general expression of the corresponding optimal teleportation fidelity is derived, which is given by the two-copy fully entangled fraction that is invariant under local unitary transformations. We prove that under a specific case of the protocol, which is significant for improving the optimal fidelity, the set of states with their two-copy fully entangled fractions bounded by a threshold value that required for useful two-copy teleportation is convex and compact. Hence the witness operators exist to separate states that are useful for two-copy teleportation from the rest ones. Moreover, we show that the optimal fidelity of two-copy teleportation surpasses that of the original one copy teleportation.
我们研究了基于贝尔测量的量子隐形传态的双拷贝方案。给出了详细的协议，并推导了相应最优隐形传态保真度的一般表达式，该表达式由在局域酉变换下不变的双拷贝完全纠缠分数给出。我们证明，在该协议的一个特定情形下（这对于提高最优保真度很重要），其双拷贝完全纠缠分数由有用双拷贝隐形传态所需的阈值界定的态集合是凸的且紧致的。因此，存在见证算符来区分对双拷贝隐形传态有用的态和其余的态。此外，我们表明双拷贝隐形传态的最优保真度超过了原始单拷贝隐形传态的最优保真度。
