Quantum teleportation over a busy internet cable opens the door for quantum applications without requiring specialized infrastructure.
Engineers at Northwestern University have demonstrated quantum teleportation over a fiber cable already carrying internet traffic. It marks the first time this has been achieved, according to the university.
The discovery paves the way to the possibility of combining quantum communication with existing internet cables, which would significantly simplify the infrastructure needed for advanced sensing technologies or quantum computing.
“This is incredibly exciting because nobody thought it was possible,” said Northwestern’s Prem Kumar, who led the study.
“Our work shows a path towards next-generation quantum and classical networks sharing a unified fiber optic infrastructure. Basically, it opens the door to pushing quantum communications to the next level,” he said.
Quantum teleportation is only limited by the speed of light and enables a new, ultra-fast, and secure way to share information between distant network users. It harnesses quantum entanglement, a technique in which two particles are linked regardless of the distance.
Instead of particles physically traveling to deliver information, entangled particles exchange information over great distances without physically carrying it. The receiving particle can be “very far away,” according to Jordan Thomas, the paper’s first author.
“The photon itself does not have to be sent over long distances, but its state still ends up encoded onto the distant photon. Teleportation allows the exchange of information over great distances without requiring the information itself to travel that distance,” he said.
Before this new study, published in the journal Optica, researchers were unsure whether quantum teleportation could work in cables carrying classical communications. The concern was that millions of other light particles would overwhelm the delicate photons.
However, Kumar and his team found a solution by using less crowded light wavelengths and special filters to reduce noise, allowing the photons to navigate the busy traffic.
“We carefully studied how light is scattered and placed our photons at a judicial point where that scattering mechanism is minimized,” Kumar said. “We found we could perform quantum communication without interference from the classical channels that are simultaneously present.”
The team tested their new method by setting up a 30-kilometer-long fiber optic cable with a photon at each end. They simultaneously sent quantum information and high-speed Internet traffic through the cable.
To execute the teleportation protocol, researchers performed quantum measurements at the mid-point and then measured the quality of the quantum information at the receiving end. They found that the quantum information was successfully transmitted.
“Although many groups have investigated the coexistence of quantum and classical communications in fiber, this work is the first to show quantum teleportation in this new scenario,” Thomas said.
“This ability to send information without direct transmission opens the door for even more advanced quantum applications being performed without dedicated fiber,” he said.
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