Density matrix approach to electromagnetically induced emission...
The thesis deals with theoretical description of the coherent interaction of polychro-matic light with multilevel atom within the hyperfine structure of the D1 transition in so-dium and rubidium atoms. Special attention is paid to the case of cold atoms. Our theoreti-cal treatment for the time evolution of the dressed atom is based entirely upon the density matrix approach. Propagating radiation fields are described by the reduced Maxwell’s field equations. Such a general formalism will enable us to reveal an enhancement of nonlinear-ity taking into account all the accessible multipoles of the density matrix. Thus we are able to show effects such as electromagnetically induced emission and the multiple light storage effect. We have exploited multiple light storage effect in order to obtain fast soliton train propagation in cold rubidium atoms. In addition, we have attempted to describe the space dependent group velocity and the delay/advancement of the light pulses. Finally, classical and quantum arrival-time distributions are discussed through the fast and slow light propa-gation in coherently prepared gaseous media. We have constrained ourselves to describe these effects in terms of the same set of equations, without approximations, while incorpo-rating homogeneous atomic relaxations. Throughout our thesis, we are motivated by the recent development in the fields of nonlinear optics and quantum information processing. Out of a variety of those modern spectroscopic techniques, we are going to mention briefly the discovery of dark resonance lines, oscillation without population inversion, coherent population trapping, electromagnetically induced transparency, electromagnetically in-duced absorption, light storage effect, slowing down of the group velocity of light, quan-tum switching effect, and three-photon electromagnetically induced transparency. These effects will assist us in controlling the group velocity of light and developing optical mem-ory devices as well as optical switches.
The thesis comprises of seven chapters. Mainly, we are interested in the coherent inter-action of light with the D1 line of alkali-atoms including the hyperfine structure. In brief, there are four dipole-allowed transitions. Chapter 1 describes stationary interaction of line-arly polarized light with sodium atom. It introduces the rotationally irreducible tensors for different ranks that are relevant to the D1 symmetry as well as its notations. Chapter 2 deals with the coherent interaction of two stationary beams as well as two pulsed fields where
the atom is described by the same basis tensors found in Chapter 1. Chapter 3 is devoted to the triple-colour excitation. Chapter 4 deals with the case when the light is amplitude or phase modulated. Chapter 5 reports a technique to produce advanced soliton train thought
a triple excitation. Chapter 6 assesses attempts to describe classical and quantum arrival-time distributions for pulsed dual-colour excitation. Finally Chapter 7 summarizes the the-sis and displays the conclusions. The thesis detailed layout is described as follows.
Gdańsk, 16th Oct. 2009
- Density matrix approach to electromagnetically induced emission...
- Abu Mohamed Alhasan
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