Quantum Theory of Ion-Atom Interactions

Ming Li, Li You, Bo Gao

A quantum theory of ion-atom interaction that is applicable at energies comparable to or smaller than the atomic hyperfine splitting and that takes proper account of the effects of identical nuclei is presented, revealing the subtlety and the complexity of cold ion-atom interactions.

R. Gerritsma, Thomas Feldker, Henrik Hirzler +4 more

Andreas Hofmann

Bo Gao

We present some of the universal properties in ion-atom interaction derived from a newly formulated quantum-defect theory for the -1/r4 type of long-range interactions. For bound states, we present the universal bound spectrum, namely, the equivalent of the Rydberg formula, for ion-atom systems. For scattering, we introduce the concept of a universal resonance spectrum to give a systematic understanding of many resonances present in ion-atom scattering. The theory further provides a method for an accurate spectroscopic determination of the atomic polarizability. It also suggests the existence of atomlike molecules, in which multiple atoms orbit around a heavy ion.

Shanshan Ding, Michael Drewsen, J. Arlt +1 more

We explore the interaction between two trapped ions mediated by a surrounding quantum degenerate Bose or Fermi gas. Using perturbation theory valid for weak atom-ion interaction, we show analytically that the interaction mediated by a Bose gas has a power-law behavior for large distances whereas it has a Yukawa form for intermediate distances. For a Fermi gas, the mediated interaction is given by a power law for large density and by a Ruderman-Kittel-Kasuya-Yosida form for low density. For strong atom-ion interaction, we use a diagrammatic theory to demonstrate that the mediated interaction can be a significant addition to the bare Coulomb interaction between the ions, when an atom-ion bound state is close to threshold. Finally, we show that the induced interaction leads to substantial and observable shifts in the ion phonon frequencies.