Some materials only conduct current on their surface, like an insulated wire. Now physicists have shown: if such a material is rapidly illuminated by a laser, surface electron waves twist into a quantum Möbius strip. This effect exists only while the light flickers: turn off the laser, and the twisted states vanish.

Periodic laser flashes create the conditions for these states to appear. They can be counted via entanglement entropy — a measure of quantum correlations. The most surprising part: the number of twisted strips can be any integer, like channels on an old TV. And each such state is immune to small defects: you can't untwist it without breaking the whole structure. In the future, this will help build quantum computers protected from noise.