Scientists at the National Institute of Standards and Technology (NIST) have developed a new technique to stabilize the phase of weak light signals, a critical step toward building large-scale quantum communication networks. This method allows fragile quantum information to travel through optical fibers without being disturbed, overcoming a major hurdle where traditional methods require bright light that would otherwise destroy the quantum state. The team successfully demonstrated the system over a 120-kilometer link between NIST and the University of Maryland, proving it works with signals nearly 10,000 times weaker than standard methods.
The technique uses a stable laser reference to measure faint signals through interference, allowing precise phase control even when fewer than one million photons per second reach the destination. By removing the need for bright reference lights that corrupt the quantum link, this advance paves the way for distributed quantum sensors and interconnected quantum computers. The findings were published in the journal *Optica* in April 2025, marking a significant step toward practical quantum networking.
Keywords: phase stabilization, entangled photons, optical fiber
