A team at the University of Toronto has designed the first all-photonic quantum repeaters that can ensure data is carried reliably and securely across long distances utilizing quantum cryptography.
Exploiting the laws of quantum mechanics to relay information between users, with the information coded in the quantum states of photons, isn’t novel. However, sending photons over fiber optics over long distances is a challenge– more than 90 percent of photons are lost over distances greater than 30 miles, which severely limits the feasibility.
Previous methods have revolved around quantum repeaters to extend the range. However, these repeaters act like mini quantum computers and need to be kept cool, while suffering from low repeat rates, making them inefficient and inconvenient to deploy.
To extend the range in a practical manner, the researchers, led by Hoi-Kwong Lo, professor of electrical and computer engineering at Toronto, have created all-photonic quantum repeaters that use only photons, without the demanding requirements of quantum interfaces.
“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,” says Lo. “Our motivation was to design a means for communicating securely and reliably over long distances.”
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