Quantum teleportation is essential for many quantum information technologies, including long-distance quantum networks. Using fiber-coupled devices, including state-of-the-art low-noise superconducting nanowire single-photon detectors and off-the-shelf optics, scientists from Fermilab, Caltech, AT&T, NASA’s Jet Propulsion Laboratory, the University of Calgary, and Harvard University have demonstrated sustained, long-distance (44 km of fiber) teleportation of photonic qubits at the telecommunication wavelength of 1,536.5 nm with state-of-the-art fidelity (> 90%).

A schematic diagram of the quantum teleportation system consisting of Alice, Bob, Charlie, and the data acquisition (DAQ) subsystems. Image credit: Valivarthi et al., doi: 10.1103/PRXQuantum.1.020317.

A schematic diagram of the quantum teleportation system consisting of Alice, Bob, Charlie, and the data acquisition (DAQ) subsystems. Image credit: Valivarthi et al., doi: 10.1103/PRXQuantum.1.020317.

Quantum teleportation is one of the most captivating predictions of quantum theory. It has been widely investigated since its seminal demonstrations over 20 years ago.

This is due to its connections to fundamental physics and its central role in the realization of quantum information technology such as quantum computers and networks.

The goal of a quantum network is to distribute qubits between different locations, a key task for quantum cryptography, distributed quantum computing, and sensing.

A quantum network is expected to form part of a future quantum Internet: a globally distributed set of quantum processors, sensors, or users thereof that are mutually connected over a network capable of allocating quantum resources between locations.

Many architectures for quantum networks require quantum teleportation, such as star-type networks that distribute entanglement from a central location or quantum repeaters that overcome the rate-loss trade-off of direct transmission of qubits.

“We’re thrilled by the new results. This is a key achievement on the way to building a technology that will redefine how we conduct global communication,” said co-author Dr. Panagiotis Spentzouris, head of the Fermilab quantum science program.

The researchers performed the measurements on the Caltech and Fermilab Quantum Network test beds (CQNET, FQNET), two teleportation systems built by Caltech’s multidisciplinary multi-institutional public-private research program on Intelligent Quantum Networks and Technologies (IN-Q-NET).

These unique quantum network test beds use state-of-the-art solid-state light detectors in a compact fiber-based setup and feature near-autonomous data acquisition, control, monitoring, synchronization, and analysis.

The teleportation systems, which are compatible both with existing telecommunication infrastructure and with emerging quantum processing and storage devices, represent a significant milestone towards a practical quantum Internet.

These networks are currently being used to improve the fidelity and rate of entanglement distribution, with an emphasis on complex quantum communication protocols and fundamental science.

“We are very proud to have achieved this milestone on sustainable, high-performing and scalable quantum teleportation systems,” said senior author Professor Maria Spiropulu, a researcher in the Division of Physics, Mathematics and Astronomy and the Alliance for Quantum Technologies at Caltech and director of the IN-Q-NET research program.

“The results will be further improved with system upgrades we are expecting to complete by Q2 2021.”

“The feat is a testament to success of collaboration across disciplines and institutions, which drives so much of what we accomplish in science,” added Dr. Joe Lykken, deputy director of research at Fermilab.

“I commend the IN-Q-NET team and our partners in academia and industry on this first-of-its-kind achievement in quantum teleportation.”

The team’s work was published in the journal PRX Quantum.

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Raju Valivarthi et al. 2020. Teleportation Systems Toward a Quantum Internet. PRX Quantum 1 (2): 020317; doi: 10.1103/PRXQuantum.1.020317