Ordinary light is like a crowd in a square: each photon moves on its own, bumping into others and scattering. But in some media, photons start running together like a pack of dogs: they bunch up. Scientists have built a random fiber laser where light particles gather into especially dense clusters. This effect is called superbunching of photons.

Inside the fiber, light scatters off imperfections, and under certain conditions photons stop being independent. By varying the pump power, the researchers controlled the degree of bunching — from nearly solitary photons to tight groups where a single pulse contained tens of times more photons than usual. This behavior is linked to phase transitions in the light field, just as water turns into ice, light shifts into a new state with different statistics.

The practical payoff is in imaging. The scientists used superbunched light for 'ghost' imaging in time: instead of a regular picture, they reconstructed the shape of a light pulse by sending only a small fraction of photons to the detector. The stronger the bunching, the fewer measurements are needed for a clear result. This promises faster and more sensitive methods in optical sensing and quantum optics.