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Thesis (Ph.D.); Submitted to the University of California at Berkeley, Berkeley, CA (US); 1 Sep 2003. / Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--55023" Li, Liang-shi. USDOE Director. Office of Science. Office of Basic Energy Sciences (US) 09/01/2003. Report is also available in paper and microfiche from NTIS.

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: static density and magnetic structure functions of a melt of flexible polymers whose monomers possess bond-directed dipoles which interact with each other. In order to observe the effect of screening of the dipolar interaction on the structure functions we obtain results for cases with and without steric interactions and also for cases with and without Debye-H¨uckel screening of the dipole moments. / AFRIKAANSE OPSOMMING: Approximation” RPA) om die statiese digtheids- en magnetiese struktuurfunksies te bereken vir ’n smelt van hoogsbuigsame polimere, waarvan die monomere dipole langs die verbindings besit wat met mekaar in wisselwerking tree. Om die effek van afskerming op die dipolare wisselwerking en die struktuurfunksies te kan waarneem, bepaal ons resultate vir die gevalle met en sonder steriese wisselwerkings en ook vir gevalle met en sonder die Debye-H¨uckel afskerming van die dipoolmomente.

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Adrian C. Melissinos. / "November 10, 1958." Reprinted from The physical review, vol. 115, no. 1, pp. 126-129, July 1, 1959." / Includes bibliographical references. / Army Signal Corps Contract DA36-039-sc-78108. Dept. of the Army Task 3-99-20-001 and Project 3-99-00-000.

In this thesis the entanglement properties of atom-atom, atom-photon, and photon-photon are investigated. The recent developments of quantum computation as well as quantum information and communication have attracted much interest in the generation of these entanglements in the laboratory. To generate atom-photon entanglement, I discuss a model system in the cavity QED setup. By using a four-level atom and two resonant cavity modes, we can generate atom-photon entanglement almost deterministically. An extension of the above model to a six-level atom and again two resonant cavity modes can generate entangled photon pairs by appropriately adjusting system parameters. I then investigate the atom-atom entanglement in a 1D harmonic trap. I show the dependence of the pair entanglement on the scattering length and temperature, as well as the particle symmetry requirement (bosons or fermions). Among many peculiar properties in a 1D system, we briefly discuss the Fermi-Bose duality". While the entanglement properties of a single-channel model have recently been obtained for 1D and 3D systems, I thus study the entanglement of a multi-channel process in a cylindrical harmonic trap. I discuss the dependence of entanglement on the trap geometry. Finally I present detailed studies of the spin mixing between two Rb87 atoms in a single lattice site. The topic is emphasized on various motional state approximations and dipolar effect. Various motional state approximations can cause up to 20% error to experimental data. I also find that the dipolar interaction can lead to an experimentally observable frequency shift in a cylindrical harmonic trap with very large aspect ratio. The spin mixing of spin-2 manifold has also been discussed.

The work presented in this thesis describes an investigation into the properties and behaviour of a new class of nonlinear optical organic chromophores. This study contributes to the optimisation of nonlinear optical molecules through an improved understanding of the relationships between the molecular nonlinear optical properties and the measured macroscopic quantities. A series of highly dipolar non-linear optical chromophores with absorption typically in the range of 350-500 nm have been synthesised by the reactions of amines with tetracyanoquinodimethane (TCNQ). One of the advantages of these materials is the large molecular figure of merit (μβ where μ is the molecular dipole moment and P is the second order polarisability), which theoretically allows large nonlinear optical coefficients to be obtained. The molecular dipole moments of these chromophores were determined both experimentally and theoretically, and were found to agree. The nonlinear optical properties of these compounds in solution were studied using an electric field induced second harmonic generation (EFISH) technique. The measurements of μβ at 1064 nm and 1907 nm in chloroform and acetone are presented. Moderate μβ values were obtained but β is found to be unexpectedly small in chloroform and shows unusual dispersion characteristics in this solvent compared to acetone. Further concentration investigations revealed features that suggest the presence of aggregates within solution. Optical spectroscopy measurements provide evidence of new species whose presence and conformation were found to be solvent-dependent. The results of this work highlight the need for an entire concentration range to be studied if accurate determination of molecular properties of highly dipolar molecules is required. Guest-host polymer films of these materials have been corona poled using a constant current corona triode. Detailed characterisation studies of the second order nonlinearities using second harmonic generation (SHG) were compared to a less dipolar molecule. These investigations showed that the highly dipolar TCNQ derivatives show severe aggregation within the polymer films. The magnitude of the SHG that can be obtained from such systems is therefore limited by this aggregation.

De nos jours, l'incomplétude du modèle standard des particules est largement reconnue. L'une de ses failles les plus évidentes est le manque d'explication de l'énorme excédent de matière par rapport à l'antimatière dans l'univers, que l'on appelle l'asymétrie baryonique de l'univers. De nouvelles violations de CP (conjugaison de charge et parité spatiale) absentes dans le modèle standard sont supposées être responsables de cette asymétrie. Une telle violation pourrait être observée dans la matière ordinaire à travers un ensemble d'interactions violant les symétries de parité et de renversement du temps (impaires pour P,T) dont les prépondérantes sont les interactions du moment dipolaire électrique de l'électron (eEDM), électron-nucléon scalaire-pseudoscalaire (enSPS) et du moment quadripolaire magnétique nucléaire (nMQM). Ainsi, une preuve expérimentale d'une constante d'interaction impaire pour P,T serait une preuve de cette nouvelle physique au-delà du modèle standard. Le calcul des paramètres moléculaires correspondants est réalisé en utilisant une approche d'interaction de configurations relativiste à quatre composantes dans des molécules diatomiques polaires contenant un actinide, qui sont des systèmes particulièrement appropriés pour les expèriences eEDM, tels que ThO qui a permis d'assigner à l'eEDM la borne supérieure la plus contraignante et ThF+ qui sera utilisé dans une expérience à venir. Ces résultats sont d'une importance cruciale dans l'interprétation des mesures puisque les constantes fondamentales ne peuvent être évaluées que si l'on associe les mesures de décalages énergétiques et les paramètres moléculaires théoriques. / Nowadays, the incompleteness of the Standard Model of particles is largely acknowledged. One of its most obvious shortcomings is the lack of explanation for the huge surplus of matter over antimatter in the universe, the so-called Baryon Asymmetry of the Universe. New CP (Charge conjugation and spatial Parity) violations absent in the SM are assumed to be responsible for this asymmetry. Such a violation could be observed in ordinary matter through a set of interactions violating both parity and time-reversal symmetries (P,T-odd), among which the preponderant ones are the electron Electric Dipole Moment (eEDM), the electron-nucleon scalar-pseudoscalar (enSPS) and the nuclear magnetic quadrupole moment (nMQM) interactions. Hence, an experimental evidence of a non-zero P,T-odd interaction constant would be a probe of this New Physics beyond the Standard Model. The calculation of the corresponding molecular parameters is performed by making use of an elaborate four-component relativistic configuration interaction approach in polar diatomic molecules containing an actinide, that are particularly adequate systems for eEDM experiments, such as ThO that allowed for assigning the most constraining upper bound on the eEDM and ThF+ that will be used in a forthcoming experiment. Those results will be of crucial importance in the interpretation of the measurements since the fundamental constants can only be evaluated if one combines both experimental energy shift measurements and theoretical molecular parameters.