Scientists at the laboratory say that, for the first time, they along with their research partners have demonstrated a sustained, long-distance – 44 kilometers of fiber – teleportation of qubits of photons (quanta of light) with fidelity greater than 90%. The qubits were teleported over a fiber-optic network using state-of-the-art single-photon detectors and off-the-shelf equipment.
A detailed analytical model, including experimental imperfections, supports the results and indicates that a workable and high-fidelity quantum network using practical devices can be built, say the researchers.
“We’re thrilled by these results,” says Fermilab scientist Panagiotis Spentzouris, head of the Fermilab quantum science program and co-author of a paper on the research. “This is a key achievement on the way to building a technology that will redefine how we conduct global communication.”
Quantum teleportation is a “disembodied” transfer of quantum states from one location to another. The quantum teleportation of a qubit is achieved using quantum entanglement, in which two or more particles are inextricably linked to each other. If an entangled pair of particles is shared between two separate locations, no matter the distance between them, the encoded information is teleported.
For quantum networks, quantum teleportation and entanglement swapping are used to distribute quantum information between distant locations, allowing the realization of quantum cryptographic schemes or distributed quantum tasks, such as sensing or computing. Importantly, say the researchers, quantum teleportation is vital in order to extend the distance of quantum networks using quantum memories and quantum repeaters. This development will form part of a global quantum network: a so-called Quantum Internet.
The scientists – which included researchers at Fermilab, AT&T, Caltech, Harvard University, NASA Jet Propulsion Laboratory, and University of Calgary – successfully teleported qubits on two systems: the Caltech Quantum Network (CQNET), and the Fermilab Quantum Network (FQNET). The systems were designed, built, commissioned and deployed by Caltech’s public-private research program on Intelligent Quantum Networks and Technologies, or IN-Q-NET.
CQNET and FQNET, which feature near-autonomous data processing, are compatible both with existing telecommunication infrastructure and with emerging quantum processing and storage devices. Researchers are using them to improve the fidelity and rate of entanglement distribution, with an emphasis on complex quantum communication protocols and fundamental science.
“With this demonstration we’re beginning to lay the foundation for the construction of a Chicago-area metropolitan quantum network,” says Spentzouris.
The Chicagoland network, called the Illinois Express Quantum Network, is being designed by Fermilab in collaboration with Argonne National Laboratory, Caltech, Northwestern University and industry partners.
Fermilab Deputy Director of Research Joe Lykken adds, “The feat is a testament to success of collaboration across disciplines and institutions, which drives so much of what we accomplish in science. I commend the IN-Q-NET team and our partners in academia and industry on this first-of-its-kind achievement in quantum teleportation.”
For more, see “Teleportation Systems Toward a Quantum Internet.”
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