This cloud-zapping laser could help scientists create a quantum internet

On an overcast day, ultrafast lasers could clear a path through the clouds, allowing easier contact with satellites traveling high above Earth.

Currently, cloudy weather limits scientists’ ability to send data to satellites via lasers, because the clouds scatter the lasers’ light. But a powerful, fast-pulsing laser can zap a tiny, cloud-free channel, allowing a second laser to slip through the hole and transmit information, a new study finds. The technique could assist scientists working to create worldwide quantum communications networks that rely on lasers to transmit particles of light, or photons.

The researchers demonstrated the idea using a laboratory cloud chamber, which mimicked cloudy conditions. When the first laser passed through a cloud, it rapidly heated the air, setting up a shock wave that shoved the cloud’s water droplets away from the beam, researchers from the University of Geneva report in the Oct. 20 issue of Optica. That action created a channel about a millimeter wide in the cloud, which allowed more of the second laser’s light to make it through the haze.

In the future, quantum physics could allow for ultrasecure transmission of data. But first, scientists must construct a worldwide quantum internet to send delicate quantum particles from one continent to another. As a step toward that goal, China created the world’s first quantum satellite in 2017 (SN: 12/23/17, p. 27), which exchanges laser light with stations on the ground.

Previously, researchers developing such satellites had to work around nasty weather. But now, it could be blue skies ahead.