Swiss Scientists Prove Durability Of Quantum Network

Scientists and engineers have proven the worth of quantum cryptography in telecommunication networks by demonstrating its long-term effectiveness in a real-time network. Their international network, created in collaboration with ID Quantique and installed in the Geneva metropolitan area and crossing over to the site of CERN in France, ran for more than one-and-a-half years from the end of March 2009 to the beginning of January 2011.

Published Dec. 2 in the Institute of Physics and German Physical Society's New Journal of Physics, the researchers' study documents the longest ever deployment of a quantum key distribution (QKD) network and demonstrates its robustness and reliability when coupled with a real-time telecommunications network.

Cryptography -- the practice of protecting information from third parties -- has long been achieved by encrypting data with a set of complex mathematical algorithms; however, with the power of computers continuing to increase, it is becoming harder to make these algorithms watertight.

Physics has rather conveniently come up with a solution to this ever-growing problem through a process known as quantum key distribution (QKD). QKD is a process that enables two parties to share a secret key before using that key to protect data they want to send over a network.

The key that the two parties share is built up from a stream of photons -- the basic unit of light. In a theoretical scenario where Alice and Bob want to protect a piece of information with a quantum key, Alice would send a stream of photons to Bob with each one having a specific orientation, called polarisation: photons can 'spin' vertically, horizontally and diagonally.