Quantum cryptography devices and networks, which transport photons whose properties can be used to represent the 1s and 0s of digital information, could also benefit from repeaters. Today's prototype quantum cryptography systems provide theoretically perfect security, but these systems can't carry information over long distances. . . .
Quantum cryptography devices and networks, which transport photons whose properties can be used to represent the 1s and 0s of digital information, could also benefit from repeaters. Today's prototype quantum cryptography systems provide theoretically perfect security, but these systems can't carry information over long distances.

Researchers from the NASA-Caltech Jet Propulsion Laboratory have found a way to make a quantum repeater using ordinary optical equipment. Practical quantum repeaters could boost the reach of quantum cryptography systems, and eventually enable quantum networks. The device would allow for an exponential improvement in the distance quantum bits can be transmitted.

The challenge was finding a way to preserve entanglement, which links particle properties like polarization regardless of the distance between the particles.

The link for this article located at Technology Review is no longer available.