A viable quantum internet – in which information stored in qubits is shared over long distances through entanglement – would transform the fields of communication, computing and data storage.

This month, scientists at Fermilab, a national laboratory operated by the U.S. Department of Energy, and their partners took a significant step towards realising that goal. The team has demonstrated, for the first time, sustained and long-distance (44 km) teleportation of qubits of photons (quanta of light) with fidelity greater than 90%. These qubits were teleported over a fibre-optic network using state-of-the-art single-photon detectors and off-the-shelf equipment. The new research appears in an open access paper in PRX Quantum.

"We're thrilled by these results," said Panagiotis Spentzouris, head of the Fermilab quantum science program and one of the paper's co-authors. "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 is shared between two locations, no matter the distance between them, the encoded information is teleported.

A quantum internet – in which these particle interactions replace traditional data processing and transfer – would therefore provide major advantages in terms of speed and security, with absolutely secure and ultra-fast connections.

For this new study, scientists performed quantum teleportation of time-bin (or time-of-arrival of) qubits of light at a wavelength of 1.5 microns. This approach is well-suited for photons that travel over low-loss fibre optics cables, the same used by the telecommunication industry today.

The joint team – which included researchers at Fermilab, AT&T, Caltech, Harvard University, NASA and the University of Calgary – successfully teleported qubits on two systems: the Caltech Quantum Network (CQNET), and the Fermilab Quantum Network (FQNET). Both systems feature near-autonomous data processing, and 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.

Credit: Fermilab

"We are very proud to have achieved this milestone on sustainable, high-performing and scalable quantum teleportation systems," said Maria Spiropulu, Professor of Physics at Caltech. "The results will be further improved with system upgrades we are expecting to complete by Q2 2021."

This breakthrough comes just a few months after the U.S. Department of Energy unveiled its blueprint for a national quantum internet, which is expected to see a prototype network constructed within the next decade. The Chicago region, which has become one of the leading global hubs for quantum research, is likely to play a central role in this emerging network.

"With this demonstration, we're beginning to lay the foundation for the construction of a Chicago-area metropolitan quantum network," said 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.

By FutureTimeLine