Laser light reveals the hidden quantum properties of crystals - The Brighter Side of News
Two ultrashort laser pulses revealed a difficult-to-measure quantum property in an atomically thin semiconductor. Combining optical measurements with an analytical model yielded a local Berry curvature consistent with theoretical calculations. The approach could help track rapid changes in electronic quantum states, although broader applications require further testing. A crystal can send electrons sideways even without an external magnetic field. Behind that unexpected motion lies Berry curvature, a geometric property of electronic quantum states. Measuring it experimentally, however, has remained considerably harder than calculating it. A collaboration between the universities of Jena and Regensburg has demonstrated an optical approach to that problem. In Nature Photonics, the team describes how ultrashort laser pulses and an analytical model revealed local Berry curvature in tungsten diselenide. The experiment examined a semiconductor layer less than one nanometer thick. Its response to light provided a quantitative estimate that agreed with theoretical predictions.
