Electrostatic Trapping of Neutral Atomic Particles

Excited neutral atoms having positive Stark energies may be trapped near magnitude minima of electrostatic fields. At moderate field strengths Rydberg atoms have trap depths comparable to ambient $\mathrm{kT}$ and as much as 100 times those of recently proposed optical-field traps. Polar molecules and metastable hydrogen and positronium atoms also can be trapped. A slow nondegenerate atom in a quadrupole field is harmonically bound. Sustained trapping and cooling should be possible, allowing Doppler-free few-atom spectroscopy and novel collision studies.