Quantum teleportation faithfully transfers a quantum state between distant nodes in a network, which enables revolutionary information-processing applications. However, in the past not a single quantum-teleportation experiment has been realized with independent quantum sources, entanglement distribution prior to the Bell-state measurement (BSM) and feedforward operation simultaneously, even in the laboratory environment.
Recently a solution to this predicament has been found by a research team led by Prof. PAN Jianwei and Prof. ZHANG Qiang from the University of Science and Technology of China (USTC). In the testing quantum communication network at Hefei, they achieved quantum teleportation with independent sources and prior entanglement distribution, which is a critical step towards Global ‘Quantum Internet’ in the real world. This work was published in Nature Photonics on 19th of September.
In a quantum teleportation, distant sender and receiver of the message must first share a pair of entangled particles. Then the sender will conduct BSM both to the quantumized particle to be transmitted and to the entangled particle. Later the receiver will get the result of the BSM, who will perform unitary operations accordingly.
To achieve quantum teleportation, PAN’s team developed time phase entangled photon source that is suit for optical fiber network transmission in the first place. In the hope of solving the problem of synchronization and interference between two independent photon sources, they developed long-range optical synchronization technology at the level of picosecond and applied fiber Bragg grating for narrow band filtering. An active feedback system was later put forward to deal with the delay and polarization fluctuation of distant fiber transmission. After all these work, they finally achieved quantum teleportation over the construction of a 30 km optical-fibre-based quantum network distributed over a 12.5 km area. The network is robust against noise in the real world with active stabilization strategies, which allows the scientists to realize quantum teleportation with all the ingredients simultaneously. Both the quantum-state and process-tomography measurements and an independent statistical hypothesis test confirmed the quantum nature of the quantum teleportation over the network.
This work has proved the practicability of quantum teleporatation at city scale. The achievement was highly appraised by the reviewer as ‘significantly advances the field’ and ‘blueprints for future quantum technologies’. It is believed that this work may inspire many quantum science experiments in the future and will serve as the base of a global quantum internet.
This study entitled “Quantum teleportation with independent sources and prior entanglement distribution over a network” online in Nature Photonics. And it was done by USTC in cooperation with the Laboratory of Information Technologies and Microsystem of Chinese Academy of Sciences (CAS) in Shanghai, Tsinghua University, Shanghai Jiao Tong University and several other research institutions. This work was supported by the National Fundamental Research Program, the National Natural Science Foundation of China, the Chinese Academy of Science.
The link of the paper: http://www.nature.com/nphoton/journal/v10/n10/full/nphoton.2016.179.html
Prof. PAN Jianwei
Prof. ZHANG Qiang