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A breakthrough in quantum physics could pave the way to achieving a quantum Internet.
Noa Leach Published: December 20, 2024 at 4:00 pm
In a breakthrough for human communication, scientists have achieved the impossible: quantum teleportation. But before you shout “Beam me up, Scotty,” this new technology is not designed for teleporting people or things, but information.
Specifically, scientists have worked out how to teleport information almost instantly and over any distance – without needing any future technology. Instead, they think they can make quantum teleportation possible through existing networks.
“This is incredibly exciting because nobody thought it was possible,” said Prof Prem Kumar of Northwestern University in the US, who led the study.
“Our work shows a path towards next-generation quantum and classical networks sharing a unified fibre optic infrastructure. Basically, it opens the door to pushing quantum communications to the next level.”
Optical communications, meaning any communication method that converts signals into light to transmit information, are central to most telecommunications systems (fibre optics are a type of optical communication).
Published in the journal Optica, the new research proposes that the breakthrough could make these communications super secure and nearly instantaneous – limited only by the speed of light. ‘Like a bicycle on a busy highway’
So how does it work? Quantum teleportation relies on a phenomenon known as quantum entanglement, where two particles are linked regardless of how far apart they are, and don’t need to physically travel to exchange information.
While classical communications are made of millions of light particles, quantum communications only use pairs of single photons (light particles). Previously, researchers thought these individual photons wouldn’t be able to make it through the busy highway of classical communication particles – like a wobbly bicycle trying to weave around massive trucks in an underground tunnel.
But the Northwestern team, funded by the US Department of Energy, found a way to guide the delicate photons through. First, they studied how light scatters within fibre optic cables. Light consists of various wavelengths, and the team identified a specific wavelength that faces less interference from other signals, making it easier for photons to pass through. They placed the photon on this wavelength, and also added special filters to reduce noise from regular Internet traffic.
To test this, they then set up a 30km (18.6 mile)-long fibre optic cable with a photon at either end and then sent both regular Internet traffic and quantum information through it.
To their surprise, the test was successful: despite the busy Internet traffic whizzing through at the same time, the quality of quantum information at the receiving end was good. A huge breakthrough
“With 2025 designated by the UN as the International Year of Quantum Technology, this research is very timely,” Prof Jim Al-Khalili, who was not involved in the study, told BBC Science Focus.
“Quantum teleportation has been demonstrated before, but only under very careful laboratory conditions. The problem is that quantum-entangled particles used to teleport information quickly become entangled with everything else along their path.
“The entirety of telecommunications technology (and indeed the internet) relies on transmitting light (photons) through optical fibres. This work is the first demonstration of quantum teleportation of entangled photons through busy optical fibres carrying conventional telecommunications traffic.”
But why is it so important that this teleportation works over conventional networks? Surely the whole point of teleportation is that you don’t need cables. True – but this breakthrough takes away the need for new infrastructure, bringing its use in our daily lives considerably closer.
“Many people have long assumed that nobody would build specialised infrastructure to send particles of light,” Kumar said. “If we choose the wavelengths properly, we won’t have to build new infrastructure. Classical communications and quantum communications can coexist.”
Al-Khalili added: “Being able to make use of quantum teleportation in our existing infrastructure of optical fibre networks would be a huge breakthrough in achieving quantum networks. It will have many applications, from quantum cryptography and quantum sensing to quantum computing, and potentially even a new quantum Internet.”
Next, Kumar plans to test quantum teleportation over longer distances, as well as trying two pairs of entangled photons rather than one. This would achieve another milestone in quantum teleportation: entanglement swapping – when two particles that have never interacted before become entangled – which is important for improving the quality and security of a transmission.
After that, the team will test everything in real-life inground cables – the last step before it can become fully integrated into our communications networks.
About our expert
Jim Al-Khalili CBE FRS is a theoretical physicist who is currently Distinguished Professor Emeritus in Physics at the University of Surrey. He also presents The Life Scientific on BBC Radio 4 and has written numerous books, including The Joy of Science, The World According to Physics and Sunfall.
I take it you’re not planning on becoming a domiciliary nurse?