Quantum teleportation using active feed-forward between two Canary Islands

摘要

Quantum teleportation [1] is a quintessential prerequisite of many quantuminformation processing protocols [2-4]. By using quantum teleportation, one cancircumvent the no-cloning theorem [5] and faithfully transfer unknown quantumstates to a party whose location is even unknown over arbitrary distances. Eversince the first experimental demonstrations of quantum teleportation ofindependent qubits [6] and of squeezed states [7], researchers haveprogressively extended the communication distance in teleportation, usuallywithout active feed-forward of the classical Bell-state measurement resultwhich is an essential ingredient in future applications such as communicationbetween quantum computers. Here we report the first long-distance quantumteleportation experiment with active feed-forward in real time. The experimentemployed two optical links, quantum and classical, over 143 km free spacebetween the two Canary Islands of La Palma and Tenerife. To achieve this, theexperiment had to employ novel techniques such as a frequency-uncorrelatedpolarization-entangled photon pair source, ultra-low-noise single-photondetectors, and entanglement-assisted clock synchronization. The averageteleported state fidelity was well beyond the classical limit of 2/3.Furthermore, we confirmed the quality of the quantum teleportation procedure(without feed-forward) by complete quantum process tomography. Our experimentconfirms the maturity and applicability of the involved technologies inreal-world scenarios, and is a milestone towards future satellite-based quantumteleportation.