Four researchers from the Institute of Photonics at Leibniz University Hannover have developed a new transmitter-receiver concept for transmitting entangled photons over an optical fibre. This breakthrough could enable the next generation of telecommunications technology, the quantum internet, to be routed via optical fibres. The quantum internet promises eavesdropping-proof encryption methods that even future quantum computers cannot decrypt, ensuring the security of critical infrastructure.
"To make the quantum internet a reality, we need to transmit entangled photons via fibre optic networks,” says Prof. Dr. Michael Kues, head of the Institute of Photonics and board member of the PhoenixD Cluster of Excellence at Leibniz University Hannover. "We also want to continue using optical fibres for conventional data transmission. Our research is an important step to combine the conventional internet with the quantum internet."
In their experiment, the researchers demonstrated that the entanglement of photons is maintained even when they are sent together with a laser pulse. "We can change the colour of a laser pulse with a high-speed electrical signal so that it matches the colour of the entangled photons," explains Philip Rübeling, a doctoral student at the Institute of Photonics researching the quantum internet. "This effect enables us to combine laser pulses and entangled photons of the same colour in an optical fibre and separate them again."
This effect could integrate the conventional internet with the quantum internet. Until now, it has not been possible to use both transmission methods per colour in an optical fibre. "The entangled photons block a data channel in the optical fibre, preventing its use for conventional data transmission," says Jan Heine, a doctoral student in Kues's group.
With the concept demonstrated for the first time in the experiment, the photons can now be sent in the same colour channel as the laser light. This implies that all colour channels could still be used for conventional data transmission. “Our experiment shows how the practical implementation of hybrid networks can succeed,” says Prof. Michael Kues. The research results were published in Science Advances.
Original article:
Philip Rübeling, Jan Heine, Robert Johanning and Michael Kues
Quantum and coherent signal transmission on a single frequency channel via the electro-optic serrodyne technique
Science Advances (2024)
https://doi.org/10.1126/sciadv.adn8907
Note to editors:
For further information, please contact Prof. Dr Michael Kues (tel +49 511 762 3539, email: michael.kues@iop.uni-hannover.de) and visit www.iop.uni-hannover.de and www.phoenixd.uni-hannover.de.
