Scientists demonstrate high-fidelity quantum teleportation over long distances

The breakthrough could pave the way to develop technology to redefine global communication in future

A team of scientists from Fermi National Accelerator Laboratory and five other institutions claims that they have achieved a sustained, long-distance 'quantum teleportation' with fidelity (data accuracy) greater than 90 per cent.

The scientists said that they were able to teleport qubits made of photons over a distance of 44 km (27 miles) over a fibre-optic network using state-of-the-art low-noise superconducting nanowire single-photon detectors and off-the-shelf optical equipment.

This is the first time that scientists have demonstrated teleportation of photons with high accuracy over such a long distance.

The study was jointly conducted by researchers from the Fermi Lab (a US Department of Energy national laboratory affiliated with the Chicago University), NASA's Jet Propulsion Laboratory (JPL), Caltech, AT&T, Harvard University and the University of Calgary in Canada.

The team successfully achieved qubit teleportation on two systems: the Fermilab Quantum Network and the Caltech Quantum Network. The two systems were built and deployed by Caltech's public-private research programme on Intelligent Quantum Networks and Technologies (IN-Q-NET).

The scientists expressed their excitement with the breakthrough, noting that they it could pave the way to develop technology to "redefine how we conduct global communication".

"With this demonstration we're beginning to lay the foundation for the construction of a Chicago-area metropolitan quantum network," said Panagiotis Spentzouris, head of the Fermilab quantum science program and one of the co-authors of a paper published in PRX Quantum.

"We are very proud to have achieved this milestone on sustainable, high-performing and scalable quantum teleportation systems," said physicist Maria Spiropulu, from Caltech.

"The results will be further improved with system upgrades we are expecting to complete by the second quarter of 2021."

Quantum communication systems are considered to be more secure than conventional networks as they rely on the quantum properties of photons, rather than computer code that can be cracked by hackers. However, such systems are very complex and expensive to make.

Such systems rely on the quantum entanglement phenomenon, which occurs when subatomic particles, such as protons, become linked and start to influence one another regardless of the distance between them.

If two particles are entangled, then the state of one particle can be known by measuring the state of the other. The phenomenon can be used to create encrypted communications channels that are secured against hacking by the laws of quantum physics.

However, the delicate nature of quantum information makes it very difficult for scientists to beam entangled photons over long distances without interference. In long optical fibres, there is always a chance for noise to interfere with the entangled states.

In September 2020, an international research team, led by the scientists at University of Bristol, said that they had developed a prototype city-wide quantum network, which could be used to send completely secure and unhackable messages over the internet.

The researchers said their prototype is the largest-ever quantum network of its kind, with the potential to serve millions of people by enabling them to share encryption keys for their messages.

Also last year, a Chinese research team claimed that it had smashed the previous record for maintaining two quantum memories in an entangled state at maximum distance.

The researchers said they were able to realise entanglement of two quantum memories over 22 kilometres of field-deployed fibres via two-photon interference. With that feat, they broke the 1.3-kilometre record achieved during previous quantum memory experiments.

In July 2019, Scientists at Osaka University also claimed to have made a breakthrough in the development of quantum internet communications using lasers. The researchers said that their experiments showed that it was possible to translate "the information encoded in the circular polarisation of a laser beam" into the spin state of an electron caught in a quantum dot.