|The miniature transmitter communicates with a trusted authority to generate random cryptographic keys to encode and decode information|
Suggesting once again that government technology is a few years ahead of what they're telling everyone, researchers at the Los Alamos National Labs in New Mexico have revealed that they have been successfully running a quantum internet system for the last two-and-a-half years.
However, instead of a computer-to-computer network, like the internet we use to access the web, the Los Alamos quantum internet is a hub and spoke network, with a central "hub" server connecting all the "nodes" in a network, but no other internode connections.
Quantum cryptography offers the hope of perfectly secure digital communications. Unlike with conventional communications, a quantum message is changed when its observed. Therefore it's impossible to hide the footprints of a would-be snooper. Therefore a "one-time pad", a type of cipher used for encryption, can be exchanged with confidence, and then used for perfectly secure encryption.
Current technology allows the sending of secure quantum messages between A and B along a single length of fibre optic cable. Routing messages to C, D and Z, however, has proved problematic as the act of reading the routing destination alters the information. In 2011, a team at Northwestern University succeeded in routing a quantum bit, proving that it's technically feasible, but the expensive technology required means that commercial applications remain far off.The Los Alamos team have avoided this cost issue by restricting the reading of quantum information to the hub.
The nodes are able to write quantum bits, but can only read conventional bits. Only the hub is able to read and write quantum bits. By minimising the amount of expensive equipment required the team say their "network-centric quantum communications" is scalable.
The hub in their system receives a quantum "one-time pad" from a node and uses this to create a secure classical connection with that node.
Information therefore travels from node A to the hub along a secure, one-time pad enabled, connection, and is then routed from hub to node B using secure classical connection enabled by a different one-time pad.
The hub can also send information to another hub either classically, or via a pre-constructed quantum connection.
"This avoids the poor scaling of previous approaches that require a pre-existing trust relationship between every pair of nodes," the team say.
A "QKarD" hub device allows the system to be plugged into any fibre optic network. Ultimately, the network relies on the security of the central hub. If the hub is compromised then the entire network is compromised. But if it remains secure, then so too does your information.