Researchers at the National Institute of Standards and Technology successfully transmitted quantum-entangled particles across the Washington, D.C., metropolitan area on Aug. 24, advancing development of a practical quantum communications network over existing fiber-optic infrastructure.
The proof-of-concept demonstration represents both a scientific and strategic milestone, with the potential to reshape how the U.S. government, financial system and military protect sensitive communications, according to NIST.
Quantum entanglement enables communications that are theoretically impossible to intercept without detection. Any attempt to eavesdrop on a quantum-encrypted signal disturbs the quantum state of the particles, alerting the communicating parties to the intrusion.
The demonstration is particularly significant because researchers transmitted entangled particles through standard fiber-optic cables in the D.C. suburbs rather than purpose-built quantum channels. Using existing infrastructure dramatically reduces the cost and timeline for building out a practical quantum network.
The U.S. and China are in active competition to develop operational quantum networks, with major national security implications. China has invested heavily in quantum communications, launching a quantum satellite in 2016 and building a quantum communications backbone network connecting major cities.
A functioning quantum internet would provide unbreakable encryption for government communications, financial transactions and military command-and-control networks. Current encryption systems, which rely on mathematical complexity, are potentially vulnerable to future quantum computers.
NIST, an agency within the Commerce Department, has been a leading institution in quantum research and recently finalized post-quantum cryptography standards to protect against future quantum computing threats.
The demonstration is described as an important step toward building a practical quantum internet but significant engineering challenges remain before such a network could operate at scale across the country.