Researchers at Northwestern University have reached a milestone in quantum teleportation. For the first time, it was possible to transmit quantum information over a fiber optic cable that also carried regular Internet traffic.
This Development published in the journal Optica, could open the door to a new era of communications technology in which quantum and traditional networks coexist. Quantum teleportation uses the principles of quantum entanglement to exchange information between distant network nodes without the need to transmit physical particles. “Our work shows a path to next-generation networks that combine quantum and classical communications on a common infrastructure. This is a significant step for the future of quantum communications,” said Prem Kumar, leader of the study.
The biggest challenge was to transmit the quantum information within a fiber optic cable that carries numerous light particles from normal Internet traffic. Many scientists thought this was impossible because the sensitive photons of quantum information could be disturbed by the “noisy” signals of traditional data traffic. However, Kumar’s team came up with an innovative solution.
By studying light scattering patterns in fiber optic cables, the researchers identified a less frequented wavelength of light to place their photons. Special filters helped to minimize disruptions from regular Internet traffic.
In an experiment using a 30-kilometer-long fiber optic cable, the engineers tested the simultaneous transmission of quantum information and Internet data. The results showed that the quantum information was transmitted successfully and without interference.
In the future, the team plans to expand these experiments to larger distances and test the method in real fiber optic networks. One goal is to demonstrate so-called entanglement swapping technologies, in which entanglements can be exchanged between multiple pairs of photons – this would be a crucial step for distributed quantum applications. “Quantum teleportation makes it possible to establish secure connections between distant nodes,” explained Kumar. “And by choosing the right wavelengths of light, classical and quantum communications can use the same infrastructure without having to build new networks.”
