An ordinary camera flash lasts thousandths of a second. An attosecond pulse is a trillion times shorter — in the time it takes, light travels a distance smaller than the size of an atom. Such flashes act as an ultra-high-speed shutter: they freeze the motion of electrons, letting us see them jump between orbitals or take part in a chemical reaction.
Until now, these 'shutters' had a problem — weak light. A short exposure gives a sharp frame, but the picture drowns in noise if you shoot a night city with a camera without a flash. To see details, you need a powerful pulse. The authors built a laser system that combines two light beams of different colors, precisely tuning them to each other. The beams merge into one ultra-short pulse, and a special focusing geometry prevents the light from scattering sideways, like gathering a diverging flashlight beam into a narrow ray with a lens.
The record 1.64 microjoules of energy in a single pulse opens the door to nonlinear effects: when light is so intense that it changes the properties of the medium it passes through. Previously, this required bulky accelerators or room-sized lasers. Now the source fits on a lab bench and delivers stable flashes shot after shot. This means experiments are coming where electrons will be not just observed but controlled participants — for example, in ultrafast switches for future electronics.
In 263 attoseconds, light travels just 79 nanometers — hundreds of times thinner than a human hair.
In Bruce Sterling's novel 'Schismatrix', the plot revolves around instantaneous events at the subatomic level — attosecond pulses could become a tool for exploring such worlds.