First observations of excited electron bubbles in superfluid helium reveal puzzling features
The “particle in a box” is a standard second-year quantum-mechanics problem, much beloved by lecturers and mastered (or not) by successive generations of undergraduates. An electron bubble in liquid helium provides a strikingly simple example of this kind of system, and theory predicts that it should exhibit a series of excited states. But these states have never been demonstrated experimentally. Now Denis Konstantinov and Humphrey Maris of Brown University in the US have observed one of the excited states for the first time by exploding electrons bubbles with sound waves (D Konstantinov and H Maris 2003 Phys. Rev. Lett. 90 025302).
Read this article, by Peter McClintock from the Department of Physics at Lancaster University, in full in the April issue of Physics World.
