The idea of a quantum internet has great potential, but connecting it to the conventional internet poses challenges.
Now, new research suggests how existing and future networks could be combined.
Experiments conducted by researchers at Leibniz University Hannover in Germany have shown how quantum information and conventional data – the classical ones and zeros – can be transmitted over the same optical fiber.
Potentially, that could mean a nearly unhackable internet, using existing infrastructure to network multiple quantum computers together, one day providing their own processing power that can solve otherwise unsolvable computing tasks.
In quantum communication, closely related light waves need to be sent separately to protect their delicate entanglement — that is, separately from traditional data-carrying light waves — which makes it difficult to send them all down the same pipe.
“To realize the quantum internet, we need to transmit entangled photons over fiber optic networks,” says physicist Michael Kuess of Leibniz University of Hannover. “We would like to continue to use fiber optics for conventional data transmission as well.”
“Our research is an important step towards combining the classical and quantum internets.”
Using specially designed equipment, the team applied the so-called Serodyne technique, which shifts the phase of signals in optical fibers, placing quantum and classical data on the same frequency channel.
However, the quantum streams remain entangled, ensuring that the data streams do not interfere with each other. At the other end of the network, the streams can be separated again, allowing both types of data to be sent and received. This is a hybrid approach to communication.
This is the first time scientists have been able to transmit entangled light and unentangled data using the same frequency channel in an optical fibre – the same fibres that already form the backbone of the internet – meaning quantum technology could be deployed more quickly.
“Entangled photons block data channels in optical fibers, making them unusable for conventional data transmission,” says physicist Jan Heine of Leibniz University of Hannover.
Many challenges remain to be overcome, and research is ongoing to make it possible to transmit quantum information over long distances without splitting it, and to find ways to manage the traffic over existing networks.
But once operational, the quantum internet will add an invincible, ultra-secure layer of protection on top of the internet as we know it today, ensuring that any data that bad actors try to intercept will simply disappear.
“Our experiments show how successful a real-world implementation of a hybrid network can be,” Kues says.
This study Scientific advances.
