The world’s first operational network to use quantum cryptography is now operational beneath the streets of Cambridge, MA.
The Harvard University Applied Physics Department and the Boston University Photonics Center collaborated with BBN to build the network under Defense Advanced Research Projects Agency (DARPA) sponsorship. At the moment, the DARPA Quantum Network links BBN’s campus to Harvard University; soon it will stretch across the town to include Boston University as a third link.
Information travelling over open networks such as the Internet is often encrypted to prevent unauthorized eavesdropping. Currently, complex mathematical algorithms are the most common method used to scramble (encrypt) and de-scramble (decrypt) messages that require secure transmission.
Although this method can provide high levels of security, it is not infallible. In contrast, the DARPA Quantum Network introduces extremely high levels of security for Internet-based communications systems by encrypting and decrypting messages with keys created by quantum cryptography.
Quantum cryptography, invented by Charles Bennett and Giles Brassard in the 1980s, prepares and transmits single photons of light, through either fibre optic cable or the atmosphere, to distribute cryptographic keys that are used to encrypt and decrypt messages.
This method of securing information is radically different from methods based on mathematical complexity, relying instead on fundamental physical laws. Because very small (quantum) particles are changed by any observation or measurement, eavesdropping on a quantum cryptography system is always detectable.
The DARPA Quantum Network has improved on these techniques to create a secure six-node network that is 100% compatible with today’s Internet technology.
Patent-pending BBN protocols pave the way for quantum networks on a larger scale by providing “any to any” networking of quantum cryptography through a mesh of passive optical switches and cryptographic key relays.