Quantum mechanics allows ‘cryptography over longer distances’

WASHINGTON - Physicists at the Georgia Institute of Technology in Atlanta are developing a new, more secure way to send such information across far distances, using existing cables and the laws of quantum mechanics.

Alex Kuzmich and colleagues have built a critical component of a quantum repeater, a device that allows quantum communications — such as the encryption keys used to encode data transmitted over traditional lines-to be relayed over larger distances.

Quantum cryptography is an emerging technology to send information as entangled particles of light. In theory, anyone who tries to tap into this information changes it in a way that reveals his or her presence.

Instead of converting electricity, it regenerates a communication signal to prevent it from degrading over distance. It contains two banks of memory, one to receive an entangled message and a second line to copy it.

Previously, the longest distance over which an encrypted key could be sent was approximately 100 kilometers. The new technology developed by the Georgia Tech team increases 30-fold the amount of time the memory can hold information.

The new device could someday also plug into existing fiber optic cables.

“In order to preserve the quantum entanglement, we perform conversion at very high efficiency and with low noise,” said Alexander Radnaev.

The team will describe this device at the Optical Society’s (OSA) 94th annual meeting, Frontiers in Optics (FiO) 2010, at the Rochester Riverside Convention Center in Rochester, N.Y., from Oct. 24-28. (ANI)