Ellen Phiddian
Cosmos science journalist
Researchers have used a fibre-optic internet cable to perform quantum teleportation – while it simultaneously sent internet traffic.
The feat, say the team, means that existing internet infrastructure could be used for quantum communication.
They’ve published their findings in Optica.
“This is incredibly exciting because nobody thought it was possible,” says lead researcher Professor Prem Kumar, from Northwestern University, USA.
“Our work shows a path towards next-generation quantum and classical networks sharing a unified fibreoptic infrastructure. Basically, it opens the door to pushing quantum communications to the next level.”
Quantum teleportation is a means of exchanging information over big distances, using particles that have been quantum entangled.
“In optical communications, all signals are converted to light,” says Kumar.
“While conventional signals for classical communications typically comprise millions of particles of light, quantum information uses single photons.”
Internet cables – filled as they are with light – were thought too crowded to attempt quantum teleportation, because the single photons would get lost.
But the researchers have found a specific wavelength of light which, along with special filters – can reduce the noise.
“We carefully studied how light is scattered and placed our photons at a judicial point where that scattering mechanism is minimized,” says Kumar.
“We found we could perform quantum communication without interference from the classical channels that are simultaneously present.”
The team set up an experimental 30km fibre-optic cable to test their theory. They were able to send quantum information and internet traffic through it simultaneously.
“Quantum teleportation has the ability to provide quantum connectivity securely between geographically distant nodes,” says Kumar.
“But many people have long assumed that nobody would build specialised infrastructure to send particles of light.
“If we choose the wavelengths properly, we won’t have to build new infrastructure. Classical communications and quantum communications can coexist.”
The team is now seeking to make the process work over longer cables, as well as standard underground internet cables (rather than the test cable they used in the lab).
