Scientists designed the first all-photonic quantum repeaters that could define the future of data security.

Communications that use this type of quantum cryptography employ the laws of quantum physics to safely relay information from one user to another, the University of Toronto reported. The exchange is coded in the quantum states of photons, and it is so secure that it is nearly impossible to crack. The problems is that when photons are sent over a fiber as many as 90 percent are lost along the way, limiting the possible distance of communication.

To extend this range researchers have generally focused on "quantum repeaters," which act like mini quantum computers  and have the ability to store entangled photons and relay their signals down the fibers. They need to be stored at cool temperatures and at low repeat rates, making them extremely slow.

"There's a lot of interest in the community around designing a quantum Internet that will be more information-rich and more powerful, but these quantum states can also be fragile," said Professor Hoi-Kwong Lo (ECE) of The Edward S. Rogers Sr. Department of Electrical & Computer Engineering and the Department of Physics at the University of Toronto "Our motivation was to design a means for communicating securely and reliably over long distances."

These newly-proposed all-photonic repeaters boast higher quantum-communication rates use optical elements and highly entangled quantum states (cluster states). All-photonic repeaters could be used to network individual quantum computers, which are yet to be developed.

"Imagine in the future we have various quantum computers around the world, run by different users," Lo said. "We would want to convey information between them, but current modes of communication are not safe against attacks or losses."

The findings were published in a recent edition of the journal Nature Communication.