实用化连续变量量子隐形传态的实验研究

Quantum teleportation is one of the most important protocols in quantum information processing and it plays a pivotal role in the realization of quantum communication, quantum computing and the construction of quantum networks. Quantum teleportation has been achieved using a variety of different systems, including photonic qubits, nuclear magnetic resonance, optical modes, atomic ensembles, trapped atoms and solid-state systems. The distance of quantum teleportation is a crucial figure of merit determining its practical usage. Currently, hundred-kilometer discrete-variable quantum teleportation has been achieved, in free space and optical fiber, based on photonic polarization qubit and time-bin qubit, respectively. Compared with discrete-variable quantum teleportation, continuous-variable quantum teleportation has the advantages of deterministic Bell detection and high bandwidth. However, because continuous-variable quantum entangled state is senstive to propagation losses, it's a challenge to realize long-distance high-bandwidth practical continuous-variable quantum teleportation. We plan to experimentally investigate long-distance high-bandwidth continuous-variable quantum teleportation using continuous-variable quantum entangled state with high degree of entanglement at fiber telecommunication wavelength and optical fiber. We will also attempt to make use of noiseless linear amplification in the research of continuous-variable quantum teleportation. Our research will pave the way to the practical usage of continuous-variable quantum teleportation.

量子隐形传态是量子信息处理中最重要的协议之一，在实现量子通信和量子计算、构建量子网络等应用中起到了至关重要的作用。人们已经在光子比特、核磁共振、光学模式、原子系综、俘获原子以及固态系统等体系中实现了量子隐形传态。量子隐形传态的距离是决定其能否实用化的一个重要指标，目前人们已经分别在自由空间与光纤中实现了基于光子偏振比特与时间比特的百公里量级的分离变量量子隐形传态。与分离变量量子隐形传态相比，连续变量量子隐形传态具有决定性贝尔探测、高带宽等优势。然而，由于连续变量量子纠缠态对传输过程中损耗比较敏感，实现长距离、高带宽的实用化连续变量量子隐形传态是一个具有挑战性的课题。本项目拟采用光纤通信波段的高纠缠度连续变量量子纠缠光源作为量子资源，利用光纤进行长距离高带宽连续变量量子隐形传态的实验研究，并将无噪声线性放大应用于连续变量量子隐形传态进行探索性研究，推进连续变量量子隐形传态的实用化进程。

量子隐形传态是量子信息处理中最重要的协议之一，在实现量子通信和量子计算、构建量子网络等应用中起到了至关重要的作用。量子隐形传态的距离是决定其能否实用化的一个重要指标，目前人们已经分别在自由空间与光纤中实现了基于光子偏振比特与时间比特的百公里量级的分离变量量子隐形传态。与分离变量量子隐形传态相比，连续变量量子隐形传态具有决定性贝尔探测、高带宽等优势。然而，由于连续变量量子纠缠态对传输过程中损耗比较敏感，实现长距离、高带宽的实用化连续变量量子隐形传态是一个具有挑战性的课题。本项目采用光纤通信波段的高纠缠度连续变量量子纠缠光源作为量子资源，利用光纤作为量子通道进行了长距离连续变量量子隐形传态的实验与理论研究。我们实现了距离分别为2公里与6公里的连续变量量子隐形传态，其保真度分别为0.69与0.62，超过了0.5的经典极限。此外，我们通过量子层析重构了经过量子隐形传输之后的真空态的Wigner函数，同样证明了利用EPR纠缠态进行量子隐形传态的优势。我们首次实现了长距离连续变量量子态传输，信息传输比经典物理方法具有更高准确性。基于光学模确定性量子纠缠的连续变量量子隐形传态，可以用于高信噪比传输大数据信息流。因此，该工作为利用光纤实现量子信息网络及分布型量子计算提供了依据。