Research ArticlePHYSICS

Deterministic quantum teleportation through fiber channels

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Science Advances  19 Oct 2018:
Vol. 4, no. 10, eaas9401
DOI: 10.1126/sciadv.aas9401
  • Fig. 1 Experimental scheme of fiber-channel CV quantum teleportation.

    Two single-mode squeezed states generated by a pair of degenerate optical parametric amplifiers (DOPAs) are coupled to produce an EPR entangled state. The two sub-modes of the EPR entangled state are sent to Alice and Bob through two optical fiber channels, respectively. Then, Alice implements a joint measurement on the unknown input state and the sub-mode EPR1 and sends the measured results to Bob through classical channels. Bob implements a translation for EPR2 by coupling a coherent beam, which is modulated by two joint-measured classical signals, respectively, via an AM and a PM. Last, Victor accomplishes the verification for quantum teleportation. 98/2 BS, beam splitter with reflectivity of 98%; HR, mirror with a reflectivity larger than 99.9%; fiber coupler, used to couple optical modes into the fiber; BHD, balance homodyne detector.

  • Fig. 2 Fidelity of quantum teleportation versus the communication distance between Alice and Bob for different powers of the LO beam.

    The blue, red, yellow, and green curves express the calculated dependences of fidelities on the communication distance between Alice and Bob when the power of the LO beam is 0.25, 0.50, 1.00, and 2.50 mW, respectively. With the increasing power of the LO beam, the induced GAWBS extra noise gradually reduces the quantum entanglement between the sender (Alice) and the receiver (Bob). If the fidelity of quantum teleportation decreases below the classical limit of 1/2, then the process is unsuccessful. It can be seen that the fidelity drops quickly when the power of the LO beam is increased because the LO beam with higher power induces more GAWBS noise in the fiber channels. The squares mark the experimental results, which are in reasonable agreement with the theoretical values. Error bars represent the SE and are obtained from the statistics of the fidelity.

  • Fig. 3 Noise powers of the teleported state measured by Victor at 3.0 MHz.

    The measured noise power of the quantum teleported state over transmission distances of 2.0 km (A) and 6.0 km (B) between Alice and Bob. Curves (i), (ii), and (iii) are the corresponding QNLs of Victor’s detection, the noise power of the output state of quantum teleportation with EPR entanglement, and the noise power of teleportation without EPR entanglement (classical teleportation), respectively. The noise power of the quantum teleported output state is 1.99 ± 0.13 dB (1.30 ± 0.19 dB) below that of a classical teleported output state over a transmission distance of 2.0 km (6.0 km).

  • Fig. 4 Reconstructed Wigner functions of input and output states of quantum teleportation through a fiber channel.

    (A) Reconstructed Wigner function of the input coherent state. Reconstructed Wigner function of the quantum teleported state over transmission distances of 2.0 km (B) and 6.0 km (C).

  • Fig. 5 Fidelity of quantum teleportation versus the teleportation gain g for different communication lengths between Alice and Bob.

    In our experiment, the teleportation gains of amplitude quadrature and phase quadrature always take the same values (gx = gp = g) because the two quadrature components are symmetric. The blue and red curves express the dependences of calculated fidelities on the teleportation gain (g) when the transmission distance is 2.0 and 6.0 km, respectively. When g = 1 (0 dB) is selected in the experiment, the best fidelity can be obtained for both conditions. The squares mark the experimental results, which are in reasonable agreement with the theoretical values. Error bars represent the SE and are obtained from the statistics of the fidelity.

Supplementary Materials

  • Supplementary Materials

    This PDF file includes:

    • The method to reconstruct the Wigner function of the teleported state
    • Fig. S1. Experimental setup for fiber-channel CV quantum teleportation.

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