Resonance frequency shift in spatially separated optical fields

E. V. Baklanov

An analysis is made of the problem of a resonance frequency shift in three spatially separated optical fields. The dependence of the resonance position on the optical field phases gives rise to an uncontrolled shift which in the case of a Maxwellian gas and a thermal atomic beam is of the order of the resonance width. The physical reference point for frequency measurements is a saturated absorption resonance (Lamb dip).

G. S. Agarwal

B Ya Dubetskiĭ

A theoretical analysis is made of a resonant interaction of two-level atoms with the field of three strong spatially separated standing waves. It is shown that this interaction should give rise to a resonance of width equal to the reciprocal of the transit time between the fields and this resonance should be observed for all rational values of the ratio of the distances by which the waves are separated in space. Calculations are made of the corrections to the flux of particles excited in an atomic beam and to the power absorbed by a gas because of the interaction of atoms with the three fields. It is found that because of recoil a resonance of this kind splits into an infinite series of components separated by intervals of the order of the recoil frequency. The results are given of a numerical calculation of the strongest components of this resonance. The shift and deformation of lines due to quadratic Doppler effect are considered. The results of the calculations are compared with the available experimental data.

S. P. Andreev, Valerii S. Lisitsa

Evgenii B. Aleksandrov, A. M. Bonch-Bruevich, N. N. Kostin +1 more

Atreju Tauschinsky, C. S. E. van Ditzhuijzen, Lambertus D. Noordam +1 more

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.