Interference effects in a two-color laser beam interaction with alkali-metal atoms

Abstract

The interaction of an alkali-metal atom with two different color laser beams is analyzed. The quantum interference effect is studied in weak and strong field limits. Our theoretical results are related to the recent experimental data for the S 1/2 →S 1/2 two-photon transition in Na and Rb atoms. It is shown that the interference profile becomes narrow for moderately strong fields and the destruction of the interference is predicted for very strong ones. The electromagnetically induced interference effects are analyzed. The role of the relaxation processes is examined.

Collision-induced destructive quantum interference

“…The excitation spectrum for generating 4-5 emission can be obtained by fixing the emission frequency ω = ω 45 and tuning the frequencies of the laser fields (I) and (II), respectively, near the 3S-3P and 3P-5S resonant transitions while the two-photon resonance condition be satisfied, that is, S( ) = Re (z, )| z=i ω 45 . In [16], the authors calculated the population in level 4 by perturbation expansion of the density matrix element ρ 44 up to the fourth order. In this paper, we do not calculate the population ρ 44 , but calculate the excitation spectrum for generating 5S-4P emission.…”

“…In this paper, we do not calculate the population ρ 44 , but calculate the excitation spectrum for generating 5S-4P emission. As analysed in [12,19], the population ρ 44 in [16] includes collision-free population (related to Raman scattering (3P 1/2,3/2 -4P)) and collisionaided population (related to the resonant emission (5S-4P)). Since we study the interference between the two collision-assisted two-step two-photon transition pathways 1-2-4 and 1-3-4, which results in the real population of level 4, and the intensity of 4-5 emission is the direct measure of the real population in level 4, the excitation spectrum for generating 4-5 emission can be used to examine the collision-induced quantum interference.…”

“…Very recently, we have theoretically and experimentally studied the collision-induced constructive interference in an open -type four-level system driven by a single laser field [12]. Here, we further study the collision-induced destructive interference in an open rhomb-type five-level system driven by two laser fields, where the system is similar to that studied in [14,16].…”

“…The laser field polarization dependence of the interference has been experimentally studied in two-colour twophoton polarization spectroscopy [14,15]. According to the experimental studies in [14,15], the dependence of quantum interference on the strength of the two laser fields has been recently theoretically studied in a close rhomb-type multi-level system [16]. However, they neglect the effect of the collisional damping on the quantum interference.…”

Temporal and spatial evolution of collision-induced stimulated effects in alkali atoms

“…The first attempt at a theoretical analysis of this system was presented by Czub et al (1986). However, in this work they did not include the propagation effects and the growth of the Raman beam through the stimulated emission (one-photon process) on the collisionbroadened 2 P 1/2 → 2 S 1/2 transition.…”