(Photonics.com) A Harvard and MIT team have announced a breakthrough that may be the missing link toward a practical quantum internet and a major step forward in the development of long-distance quantum networks. Quantum communication over long distances is affected by conventional photon losses, which is one of the major obstacles for realizing large-scale quantum internet.
Harvard and MIT researchers have found a way to correct for signal loss in quantum computing with a prototype quantum node that can catch, store, and entangle bits of quantum information. A quantum internet could be used to send unhackable messages, improve the accuracy of GPS, and enable cloud-based quantum computing.
“This demonstration is a conceptual breakthrough that could extend the longest possible range of quantum networks and potentially enable many new applications in a manner that is impossible with any existing technologies,” said Mikhail Lukin, professor of physics and co-director of Harvard Quantum Initiative.
According to the researchers, the solution to this involves a quantum repeater. Unlike classical repeaters, which amplify a signal through an existing network, quantum repeaters create a network of entangled particles through which a message can be transmitted.
Lukin’s lab has been working to harness a system that can perform both of these tasks effectively: silicon-vacancy color-centers in diamonds. These centers are tiny defects in a diamond’s atomic structure that can absorb and radiate light, giving rise to a diamond’s brilliant colors.
“Currently, we are working to extend this research by deploying our quantum memories in real, urban fiber optic links,” said Ralf Riedinger, a postdoctoral candidate in the Lukin group. “We plan to create large networks of entangled quantum memories and explore the first applications of the quantum internet.”

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