Synthesis of a classical atom: wavepacket analogues of the Trojan asteroids

The reason why atomic physicists are interested in celestial mechanics is s imple: the gravitational and Coulombic potentials are mathematically identi cal and a one-electron atom is, therefore, governed by the same Hamiltonian as is the Kepler problem. However, once one goes beyond the two-body Keple r problem the connections between atomic physics and celestial mechanics be come less direct. For example, the three-body problem, nr aguably the raiso n d'etre of celestial mechanics for several centuries, has received relativ ely little attention from atomic physicists because it does not have a dire ct quantum counterpart three quantum particles cannot rr;mutually attract o ne another and at the same time interact through a purely Coulombic force l aw. Nevertheless, in the last file years several research groups have disco vered that quantum analogues of a particular limit of the three-body proble m, the restricted three-body problem, not only exist brit contain dramatica lly new physics. This article will describe this work and in particular wil l demonstrate the possibility of producing localized electronic states in a toms that are direct analogs of the coherent states of the harmonic oscilla tor. These coherent wavepackets behave in a similar, way to the coherent st ates of the harmonic oscillator and the resulting atom mimics a 'classical' or Bohr atom although external fields must be used to maintain their integ rity. Such, wavepacket states are of as much fundamental interest in laser chemistry as they are in atomic, molecular, optical, and solid state physic s. The potential applications of time-evolving quantum wavepackets seem lim itless; some examples of their uses include: the exploration of the boundar y between classical and quantum mechanics, the investigation of the interpr etation of quantum mechanics by creating experimental realizations of such classic experiments as Schrodinger's Cat, the control of chemical reaction dynamics to achieve laser isotope separation, the storage of coherence for quantum computational or communications purposes, and the construction of o ptical switches and modulators.