NIST researchers transmit entangled photons over 62 km of real-world cable

Researchers at the US National Institute of Standards and Technology (NIST) have successfully transmitted entangled photons across 62 kilometers (approximately 38.5 miles) of existing network cabling. The experiment, published in the Journal of Optical Communications and Networking, marks a significant milestone for the development of a quantum internet.

Unlike previous laboratory successes, this test utilized real-world infrastructure. Much of the fiber-optic cabling was strung on street-side poles between NIST and the University of Maryland, exposing the quantum states to environmental noise such as temperature fluctuations, wind, vibrations from traffic, and even contact with birds.

While the distance does not set a new world record, physicist Yicheng Shi described the achievement as a successful stress test of quantum networking systems in a noisy, non-ideal environment. Maintaining quantum entanglement over such distances is critical for future technologies that aim to provide ultra-secure communication and link the capabilities of quantum computers.