A single light source in a thin layer of boron nitride flashes on and off in a couple of nanoseconds. You can create many such sources in the material, but each one used to work on its own. In the new work, they were made to glow together, like musicians playing in unison.
To achieve this, the sources were placed less than a wavelength of the emitted light apart. Then they start to influence each other: the flashes become shorter, and the overall brightness grows faster than if the sources simply added up. In the experiment, the flash time dropped from 1.85 nanoseconds to about 0.5 nanoseconds — almost down to the limit of what the equipment can detect.
Such synchronized emission was observed at room temperature, without complex mirrors or cooling to ultra-low temperatures. This paves the way for creating ultra-bright light sources and unusual light states for quantum technologies — based on two-dimensional materials that can be deposited on chips.
Hexagonal boron nitride is often called "white graphene": it also consists of layers one atom thick, but it is transparent and does not conduct electricity.
In the series "The Expanse," quantum communication technologies use entangled particles — ultra-bright sources based on boron nitride could make such communication more practical.