Juan Francisco Lam

Resonant Optical Suppression of the Van der Waals Force

The behavior of a single two-level atom in the presence of strong resonant light fields was first described by Mollow[l] and Cohen-Tannoudji[2], and observed by Schuda[3]. The interaction of light with two atoms coupled by Van der Waals forces has been described previously only well off resonance [4], however. Here we show that stationary pair systems of this kind, driven by light fields resonant with double-excitation pair transitions, exhibit unique features[5]. These include a seven-line resonance fluorescence spectrum and resonant suppression of the Van der Waals force.

Quantum Evolution of 2-Level Atoms in the Presence of a State Selective Reservoir

Recently, we have shown that the nearly degenerate four-wave mixing (NDFWM) process can provide a direct and simultaneous measurement of the longitudinal (1/T1) and transverse (1/T2) relaxation rates of a resonant two-level atom. Furthermore, we observed that in the presence of buffer gases, the linewidth of the resonance describing the longitudinal relaxation process experiences a significant narrowing, below that of the natural width. Using a theoretical model, the narrowing was accounted for as arising from collisional effects in the ground state population[1] These observations were made for the case where the radiation fields are co-polarized,and we concluded that NDFWM offers a unique technique for the measurement of the ground state velocity changing cross-section[2].

Atomic Coherence Effects in Resonant Four-Wave Mixing Spectroscopy of Sodium

This paper presents preliminary experimental and theoretical results on two new aspects of sub-Doppler spectroscopy using resonant four-wave mixing and cw tunable dye lasers. The first technique uses degenerate four-wave mixing (DFWM) to study optically induced Zeeman coherences while the second technique uses nondegenerate FWM to study excited atomic states.