Daniel Marrujo returns to Brookhaven National Laboratory for the second day of a two-day Micro Journeys deep dive, this time heading into the lab’s quantum networking facility with a panel of the world’s leading experts in the field. Associate Laboratory Director Gabriella Carini, staff scientists Soumyajit Mandal, Julián Martínez-Rincón & Paul Stankus, and research scientists Sven Herrman & Prashansa Mukim walk through Brookhaven’s real-world quantum network test bed, a 161-mile system with five nodes spanning Long Island, Stony Brook University, Brooklyn, and Columbia University. The episode moves from entangled photons and the physics of quantum communication, to free-space telescope links capable of transmitting single photons through open air, to custom-built microelectronics engineered for the most extreme environments on Earth, and finally to a NASA-led mission searching for the universe’s earliest, darkest chapter from the far side of the moon.
At the center of the conversation is a fundamental limitation of classical networks: information sent as digital bits can be intercepted, copied, and manipulated without detection. Quantum communication solves this differently because a quantum state is destroyed the moment it’s measured, any attempt to eavesdrop is inherently detectable. But building a real, long-distance quantum network comes with steep physical costs. Photons are lost over distance in fiber, entanglement can’t simply be “boosted” the way a classical signal can, and demonstrating true quantum repeaters, the technology needed to extend range without breaking entanglement, has never been done at scale.
Brookhaven’s answer is a working test bed that generates, swaps, and routes entangled photons across real commercial infrastructure, paired with free-space telescope links and next-generation microelectronics built to operate in environments as inhospitable as liquid nitrogen temperatures and deep space, laying the groundwork for what researchers describe as an unhackable “quantum internet.”