Quantum teleportation with independent sources and prior entanglement distribution over a network

Journal name:
Nature Photonics
Volume:
10,
Pages:
671–675
Year published:
DOI:
doi:10.1038/nphoton.2016.179
Received
Accepted
Published online

Quantum teleportation1 faithfully transfers a quantum state between distant nodes in a network, which enables revolutionary information-processing applications2, 3, 4. This has motivated a tremendous amount of research activity5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24. 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. We take the challenge and report the construction of a 30 km optical-fibre-based quantum network distributed over a 12.5 km area. This network is robust against noise in the real world with active stabilization strategies, which allows us to realize quantum teleportation with all the ingredients simultaneously. Both the quantum-state and process-tomography measurements and an independent statistical hypothesis test confirm the quantum nature of the quantum teleportation over this network. Our experiment marks a critical step towards the realization of a global ‘quantum internet’ in the real world.

At a glance

Figures

  1. Schematics of a quantum network with a star-topology structure.
    Figure 1: Schematics of a quantum network with a star-topology structure.

    The central node hosts a quantum processor and shares entanglement with the relay nodes. The end users access the central quantum processor by teleporting the quantum states to the central node via the relay nodes. The relay nodes perform a BSM, and feedforward the measurement outcomes to the central processor.

  2. Quantum teleportation in a Hefei optical fibre network.
    Figure 2: Quantum teleportation in a Hefei optical fibre network.

    a, Bird's-eye view of the experiment. Alice prepares the quantum state, |ψin, on a heralded single photon (HSP) and sends it to Charlie, who shares an EPR pair with Bob beforehand. Each photon of the EPR pair is stored in a 15 km coiled fibre (CF). Charlie implements a BSM on his photon and the received HSP and then sends the feedforward signal to Bob, who performs a unitary correction operation (U) and state analysis. The quantum signals are transmitted in the optical fibre denoted by the solid line, whereas the classical signals are sent in another optical fibre denoted by the dashed line. b, Experimental set-up. Both Alice and Charlie generate photon pairs through the FWM process in the DSF. The MZIs are used in the state preparation and measurement (Methods). The microwave generator (MG) serves as master clock. To synchronize (Sync) the HSP source and EPR source, Charlie sends a portion of his pulse laser beam to Alice through an optical fibre channel, and Alice detects them by using a 45 GHz PD to generate driving pulses for an EOM. The heralding signals are converted into a laser pulses with a laser diode (LD) and transmitted to Charlie through the same optical fibre. Two optical circulators are used to achieve the bi-direction signal transmission. The feedforward signal (FF) and clock signals (C1, 10 MHz clock signal and C2, 200 MHz clock signal) generated by the arbitrary function generator (AFG) are carried by laser pulses with different wavelengths, which are launched into an optical fibre by a DWDM filter and sent to Bob. After being separated by another DWDM, the feedforward signal and 10 MHz clock are converted into electrical signals and fed to a time-to-digital converter (TDC). The feedforward signal is also used to trigger a short PG module to generate the driving pulse for the phase modulator (PM) to perform the unitary correction operation. Electronic-controlled polarization controllers (EPC) are used to compensate automatically the polarization drift caused by the optical fibre. Map data: Google. CNES/Astrium. DigitalGlobe.

  3. State fidelities of quantum teleportation with four different input states: |t0〉,  |t1〉,  |D〉 and |R〉.
    Figure 3: State fidelities of quantum teleportation with four different input states: |t0〉,  |t1〉,  |D〉 and |R〉.

    The observed state fidelities without and with active feedforward operation are denoted by the colours cyan and blue, respectively. The error bars represent one standard deviation. All the observed state fidelities significantly exceed the classical fidelity limit of 2/3, represented by the red horizontal line.

  4. Quantum-process tomography of quantum teleportation.
    Figure 4: Quantum-process tomography of quantum teleportation.

    ad, Process matrices for quantum teleportation without (a,b) and with (c,d) active feedforward operation, respectively.

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Author information

Affiliations

  1. National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, Shanghai Branch, University of Science and Technology of China, Shanghai 201315, China

    • Qi-Chao Sun,
    • Ya-Li Mao,
    • Yang-Fan Jiang,
    • Xiao Jiang,
    • Teng-Yun Chen,
    • Jing-Yun Fan,
    • Qiang Zhang &
    • Jian-Wei Pan
  2. CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, Shanghai Branch, University of Science and Technology of China, Shanghai 201315, China

    • Qi-Chao Sun,
    • Ya-Li Mao,
    • Yang-Fan Jiang,
    • Xiao Jiang,
    • Teng-Yun Chen,
    • Jing-Yun Fan,
    • Qiang Zhang &
    • Jian-Wei Pan
  3. Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China

    • Qi-Chao Sun &
    • Xian-Feng Chen
  4. State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China

    • Si-Jing Chen,
    • Wei-Jun Zhang,
    • Li-Xing You &
    • Zhen Wang
  5. Tsinghua National Laboratory for Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

    • Wei Zhang
  6. Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

    • Yan-Bao Zhang
  7. Advanced ICT Research Institute, National Institute of Information and Communications Technology, 588-2, Iwaoka, Nishi-ku, Kobe, Hyogo 651-2492, Japan

    • Shigehito Miki,
    • Taro Yamashita &
    • Hirotaka Terai

Contributions

Q.Z. and J.-W.P. conceived and designed the experiments, S.-J.C., W.-J.Z., S.M., T.Y., H.T., L.-X.Y. and Z.W. fabricated and characterized the SNSPDs, Q.-C.S. and W.Z. designed and characterized the photon sources, Q.-C.S., Y.-L.M. and Y.-F.J. carried out the field test, X.J.,T.-Y.C. and X.-F.C. provided experimental assistance, Q.-C.S., Y.-B.Z. and J.-Y.F. analysed the data, Q.-C.S., X.-F.C., J.-Y.F., Q.Z. and J.-W.P. wrote the manuscript with input from all authors and Q.Z. and J.-W.P. supervised the whole project.

Competing financial interests

The authors declare no competing financial interests.

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