arXiv:0808.1648 · Physical Review A
Radio-frequency-driven dipole-dipole interactions in spatially separated volumes
Atreju Tauschinsky, C. S. E. van Ditzhuijzen, Lambertus D. Noordam, H. B. van Linden van den Heuvell
Abstract
Radio-frequency (rf) fields in the MHz range are used to induce resonant energy transfer between cold Rydberg atoms in spatially separated volumes. After laser preparation of the Rydberg atoms, dipole-dipole coupling excites the $49s$ atoms in one cylinder to the $49p$ state while the $41d$ atoms in the second cylinder are transferred down to the $42p$ state. The energy exchanged between the atoms in this process is $33\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$. An external rf field brings this energy transfer into resonance. The strength of the interaction has been investigated as a function of amplitude $(0--1\phantom{\rule{0.3em}{0ex}}\mathrm{V}∕\mathrm{cm})$ and frequency $(1--30\phantom{\rule{0.3em}{0ex}}\mathrm{MHz})$ of the rf field and as a function of a static-field offset. Multiphoton transitions up to fifth order as well as selection rules prohibiting the process at certain fields have been observed. The width of the resonances has been reduced compared to earlier results by switching off external magnetic fields of the magneto-optical trap, making sub-MHz spectroscopy possible. All features are well reproduced by theoretical calculations taking the strong ac Stark shift due to the rf field into account.