Northwestern University researchers have joined forces with BBN Technologies to demonstrate what they are calling the first truly quantum cryptographic data network. The university has combined its quantum noise-protected data-encryption technology with quantum key distribution technology from BBN on a 5.5-mile SONET link between BBN headquarters and Harvard University.

Quantum cryptography uses single photons of light to distribute keys to encrypt and decrypt messages. Because quantum particles are changed by any observation or measurement, even the simplest attempt at snooping on the network interrupts the flow of data and alerts administrators.