An Astronomical Solution to an Old Quantum Problem

This is a fascinating review of a very interesting paper. It is using an established concept that is "common" in astronomy, i.e. a satellite orbit around the earth-sun system exhibiting Lagrange points, and applying it to the electron orbits around the nucleus.

Now, in results reported in Physical Review Letters, H. Maeda (Japan Science and Technology Agency, Tokyo), J. H. Gurian, and T. F. Gallagher (University of Virginia) have beautifully demonstrated in the laboratory a solution to this problem of the spreading atomic electron wave packet using a trick that was discovered in astronomy long before the problem arose in quantum theory [3]. When a small satellite moves in a sun-earth system there are five stable points at which the satellite remains fixed with respect to the rotating sun-earth system (Fig. 1). These are the famous Lagrange L points. In 1994 Bialynicki-Birula et al. showed that stable Lagrange points could be produced in the atomic electron problem by applying a circularly polarized microwave field rotating in synchrony with an electron wave packet in a highly excited state (a so-called Rydberg atom) [4]. The electron wave packet then remains localized near the Lagrange point while circling the nucleus indefinitely. Effectively the atom is made to behave quite classically.

Don't forget that you can get a free copy of the original paper from that link.

Zz.