Imagine a superhighway where cars zoom along with barely a slowdown: that's what a layer of ultraclean semiconductor looks like, where electrons travel vast distances without a single collision. Scientists have built a transistor in which electrons run twice as fast as in any similar device before.

Usually, when you turn such a material into an electronic device, you inevitably scratch it, contaminate it, and heat it, and the road gets ruined. Here, they did things differently: all the steps for creating contacts and gates were done on a separate sapphire wafer, which was then flipped over and gently pressed onto the clean material. It's like building a bridge on the shore and then lowering it onto the road without touching the asphalt.

This trick preserved the perfect smoothness of the quantum layer. The electrons in it form a two-dimensional gas: they move only in a plane, like billiard balls on a perfectly flat table. Now that the road is unspoiled, physicists can run experiments they could only dream of before: for example, trapping electrons in clever quantum traps or creating devices sensitive to the slightest magnetic fields.