Physicists revive 1990s laser concept to propose a next-generation atomic clock

Researchers at the University of Colorado and University of Bonn have revived a superradiant laser concept from the 1990s to propose a next-generation atomic clock where atoms act as synchronized coordinated emitters. Published in Physical Review Letters, their three-level system overcomes earlier heating problems that prevented continuous lasing, potentially achieving linewidths as narrow as 100 microhertz—the smallest ever for an optical laser. Beyond timekeeping, the approach could enable ultra-precise gravitational wave detectors and potentially nuclear clocks insensitive to environmental disturbances.