Experimental Quantum Teleportation In Metropolitan Optical Fiber Networks

Quantum information science is a remarkable young and fast-developing research field,which has attracted not only physicists but also researchers from other disciplines,such as computer science,mathematics and electrical engineering.It has been demonstrated by numerous current developments that the characteristic quantum phenomena such as no-cloning theorem and quantum entanglement,which are incredible from the point of view of classical physics,may enable one to perform unconditional secure communication and parallel computing with exponential speed-up compared to the classical counterpart.Quantum network is predicted to be the platform for both of the application and fundamental research of quantum communication and distributed quantum computation.Mastering the techniques to transmit quantum information and distribute quantum entanglement between distant nodes in optical fibre networks by means of quantum teleportation and entanglement swapping is vital for future quantum network.The present dissertation is mainly about experimental study of quantum teleportation and entanglement swapping over an optical fibre network,including basic theoretical analysis and key technologies as well as experimental realizations.By developing techniques such as frequency uncorrelated telecommunication-wavelength photon-pair source and synchronization between independent pump lasers,we realize interference between photons generated by independent photon sources.With the these techniques and a number of experimental techniques to stabilize the system,we experimentally demonstrate quantum teleportation over 30-km optical fiber in Heifei network.In this work,we implement a scenario which well matches future quantum network by realizing prior entanglement distribution,independent quantum source and active feed-forward unitary operation in a single experiment.The result of this experiment is better than any previous quantum teleportation field tests.This work indicates that quantum teleportation across metropolitan distances is technical feasible.Then,by improving the experimental system,we demonstrate entanglement swapping with two independent entangled photon-pair sources separated by 12.5 km in the field,and entangle two photons which share no common history.By using the swapped entanglement,we realize a source independent quantum key distribution(QKD)with two-way classical communications,which is also immune to any attack against detection in measurement site.Moreover,we extend the distance of fiber entanglement swapping to 103 km by using 1-GHz clock entanglement sources.This work shows the technical feasibility of intercity entanglement swapping.Besides,by employing up-conversion single-photon detectors with high maximum count rate and low dark count rate,we experimentally demonstrate passive decoy-state QKD with spontaneous parametric down-conversion photon-pair source.The techniques developed in our research such as interference between independent photons,up-conversion single-photon detection and methods to stabilize the experimental setup,would dramatically facilitate research on quantum network and test of the foundation of quantum mechanics.