Du Fang-Fang, Deng Fu-Guo, Long Gui-Lu
State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China.
Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China.
Sci Rep. 2016 Nov 2;6:35922. doi: 10.1038/srep35922.
Entanglement concentration protocol (ECP) is used to extract the maximally entangled states from less entangled pure states. Here we present a general hyperconcentration protocol for two-photon systems in partially hyperentangled Bell states that decay with the interrelation between the time-bin and the polarization degrees of freedom (DOFs), resorting to an input-output process with respect to diamond nitrogen-vacancy centers coupled to resonators. We show that the resource can be utilized sufficiently and the success probability is largely improved by iteration of the hyper-ECP process. Besides, our hyper-ECP can be directly extended to concentrate nonlocal partially hyperentangled N-photon Greenberger-Horne-Zeilinger states, and the success probability remains unchanged with the growth of the number of photons. Moreover, the time-bin entanglement is a useful DOF and it only requires one path for transmission, which means it not only economizes on a large amount of quantum resources but also relaxes from the path-length dispersion in long-distance quantum communication.
纠缠浓缩协议（ECP）用于从纠缠程度较低的纯态中提取最大纠缠态。在此，我们针对处于部分超纠缠贝尔态的双光子系统提出一种通用的超浓缩协议，这些贝尔态会随着时间-bin与偏振自由度（DOF）之间的相互关系而衰减，我们借助与谐振器耦合的金刚石氮空位中心的输入-输出过程来实现。我们表明，通过超ECP过程的迭代，可以充分利用资源并大幅提高成功概率。此外，我们的超ECP可以直接扩展到浓缩非局域部分超纠缠N光子格林伯格-霍恩-泽林格态，并且成功概率不会随着光子数的增加而改变。而且，时间-bin纠缠是一种有用的自由度，它只需要一条传输路径，这意味着它不仅节省了大量量子资源，还能缓解长距离量子通信中的路径长度色散问题。
