Physicists harness twisted mathematics to make powerful laser

By Davide Castelvecchi

Researchers have exploited the twisty nature of topological physics to produce a high-quality beam of laser light — a step that could lead to the first practical application of this burgeoning field. A team of physicists describes its device, and the theory behind the technology, in two studies1,2 published on 1 February in Science.

The demonstration “brings topological photonics substantially closer to real applications”, says Marin Soljačić, a physicist at the Massachusetts Institute of Technology in Cambridge.

Topology is a branch of mathematics that studies shapes and their possible arrangements in space — from simple knotted loops to the higher-dimensional universes of string theory. Since the 1980s, physicists have discovered a number of states of matter that derive odd properties from topological phenomena, such as the way that magnetization — pictured as a field of arrows — winds around a material. (Some of the founders of the field received the 2016 Nobel Prize in Physics.)

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