Los Alamos National Labs, the famous US government laboratory founded in 1943 to develop the atomic bomb, has been operating a "quantum internet" for two-and-a-half years, the organisation has revealed.
A quantum internet system theoretically enables completely secure communication, based on quantum cryptography.
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The theory is that the act of measuring a quantum object, such as a photon, will always change it. Hence, attempts to eavesdrop on such communications will always leave behind evidence.
However, because the act of routing itself affects the quantum object, it has only been achievable for point to point communications - as opposed to the multiple hops required of standard internet communications.
The system was built by a team led by Richard Hughes at Los Alamos National Labs in New Mexico. Their idea is based on a hub and spoke network, whereby all communications are routed from the perimeter via a secure central hub. The hub, using photon detectors, decrypts incoming messages before re-routing them conventionally.
However, such a hub and spoke model encounters scalability problems as the number of connections to the hub increases.
In a paper, Hughes and this team described it as "a new, scalable instantiation of quantum cryptography, providing key management with forward security for lightweight encryption, authentication and digital signatures in optical networks".
It continues: "Results from a multi-node experimental test-bed utilising integrated photonics quantum communications components, known as QKarDs, include:
Quantum identification; Verifiable quantum secret sharing; Multi-party authenticated key establishment, including group keying; and, Single-fibre quantum-secured communications that can be applied as a security retrofit/upgrade to existing optical fibre installations."
The quantum internet research revealed by Los Alamos, though, is not the first such dabbling. The US Defense Advanced Research Projects Agency (DARPA) established the world's first quantum-encrypted network at BBN Labs, part of defence contractor Raytheon, in 2003.
The network was subsequently developed to enable BBN and Harvard University to link directly via a "dark fibre" link in Cambridge, Massachusetts in June 2004.
