Christopher L. Holloway

A thermometer that doesn't lie for years. Ordinary resistance thermometers, even very accurate ones, start to err over time: the material ages, contacts oxidize, and readings drift. The new quantum thermometer works differently: it uses the rubidium atoms themselves as a reference.

A cloud of cesium atoms was made to behave like a single quantum string. By shining a laser and letting the particles interact, scientists launched self-sustaining oscillations — a rhythm emerged without an external conductor. Radio waves acted like frets on a fingerboard: it was possible to smoothly vary the sounding frequency.

Two roads on a map converge at a single point, but drivers know there is no intersection there: one route passes over the other on a bridge. Energy levels of a Rydberg atom in a varying electric field behave in much the same way. As the field strengthens, the levels draw closer, but instead of merging, they repel and diverge, leaving a gap between them.