Scattering of atoms by light

M. Ya. Agre, Nikolai L. Manakov

It is shown that new effects in light scattering by oriented atoms and in orientation of an unpolarized atomic target due to the light scattering arise when channels of dissipation for the light energy are open. Thus, in scattering of linearly-polarized or unpolarized light, the degree of linear polarization and the angular distribution of scattered light depend on the initial atomic orientation. On the other hand, the orientation of unpolarized atoms appears in the scattering of unpolarized photons without registration of the scattered photon polarization. The orientation vector is perpendicular to the scattering plane, and the effect can be observed in a coincidence experiment.

James S. Douglas, Douglas, James Stewart

Systems of ultracold atoms in optical potentials have taken a place at the forefront of research into many-body atomic systems because of the clean experimental environment they exist in and the tunability of the system parameters. In this thesis we study how light scattered from these ultracold atomic gases reveals information about the state of the atomic gas and also leads to changes in that state.We begin by investigating the angular dependence of light scattered from atoms in optical lattices at finite temperature. We demonstrate how correlations in the superfluid and Mott insulator states affect the scattering pattern, and we show that temperature affects the number of photons scattered. This effect could be used to measure the temperature of the gas, however, we show that when the lattice band structure is taken into account the efficiency of this temperature measurement is reduced.We then investigate light scattering from small optical lattices where the Bose-Hubbard Hamiltonian can be solved exactly. For small lattices, scattering a photon from the atomic system significantly perturbs the atomic system. We develop a model of the evolution of the many-body state that results from the consecutive scattering and detection of photons. This model shows that light scattering pushes the system towards eigenstates of the light scattering measurement process, in some cases leading to a superposition of atomic states.In the second half of this thesis we study light scattering that depends on the internal hyperfine spin state of the atoms, in which case the scattered light can form images of the spatial atomic spin distribution. We demonstrate how scattering spatially correlated light from the atoms can result in spin state images with enhanced spatial resolution. We also show how using spatially correlated light can lead to direct measurement of the spatial correlations of the atomic spin distribution.We then apply this theory of spin-dependent light scattering to the detection of different spin states of ultracold gases in synthetic magnetic fields. We show that it is possible to distinguish between ground states in the quantum Hall regime using light scattering. Moreover, we show how noise correlation analysis of the spin state images can be used to identify the correlations between atoms and how a variant on phase-contrast imaging can reveal the relationship between the atomic spins.

A. P. Kazantsev, Gregory I. Surdutovich, Valery P. Yakovlev

Xiaoli Zhao

The phenomena of light scattering and several basic types of light scattering are briefly introduced and summarized in this article.In the quantum mechanics point of view,the light scattering was looked on as the interaction between photons and material atoms(scattering of photons and material atoms or collision),and their images was also given.Then all kinds of scattering,such as: Compton scattering,Rayleigh scattering and Raman scattering were discussed and analysed,and the relevant formulas were given.A lot of knowledge about the basic theory of light scattering and structure of atoms or molecules are obtained.