Quantum teleportation using active feed-forward between two Canary Islands

TL;DR

This paper demonstrates the first long-distance quantum teleportation with active feed-forward over 143 km between Canary Islands, using advanced techniques to achieve high fidelity and confirming the feasibility for satellite-based quantum communication.

Contribution

It presents the first real-time active feed-forward quantum teleportation over a 143 km free-space link, advancing practical quantum communication technology.

Findings

Average teleportation fidelity exceeded classical limit

Successful quantum process tomography confirmed procedure quality

Technologies demonstrated are suitable for satellite-based quantum teleportation

Abstract

Quantum teleportation [1] is a quintessential prerequisite of many quantum information processing protocols [2-4]. By using quantum teleportation, one can circumvent the no-cloning theorem [5] and faithfully transfer unknown quantum states to a party whose location is even unknown over arbitrary distances. Ever since the first experimental demonstrations of quantum teleportation of independent qubits [6] and of squeezed states [7], researchers have progressively extended the communication distance in teleportation, usually without active feed-forward of the classical Bell-state measurement result which is an essential ingredient in future applications such as communication between quantum computers. Here we report the first long-distance quantum teleportation experiment with active feed-forward in real time. The experiment employed two optical links, quantum and classical, over 143 km free space between the two Canary Islands of La Palma and Tenerife. To achieve this, the experiment had to employ novel techniques such as a frequency-uncorrelated polarization-entangled photon pair source, ultra-low-noise single-photon detectors, and entanglement-assisted clock synchronization. The average teleported 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 experiment confirms the maturity and applicability of the involved technologies in real-world scenarios, and is a milestone towards future satellite-based quantum teleportation.