A measurement of the differential cross section has been performed for the photodisintegration of ⁴He into a proton plus a triton. This reaction is highly sensitive to the electromagnetic currents in the nucleus which arise from the exchange of mesons between nucleons. The study of light nuclei such as ⁴He, whose nucleonic structure is the simplest, holds the promise of perfecting a microscopic theory of nuclear dynamics, in which nuclear structure and reactions are understood in terms of fundamental particle interactions. The measurement was performed with a tagged-photon beam, using a large solid-angle charged particle detector developed for this and other similar experiments. The measurement was performed within the photon energy range between 63 and 71 MeV, and divided into four energy bins of 2 MeV each. The measurement of the differential cross section was confined to the angular range 36°-141° in the center-of-mass reference frame. The total cross section was determined to within a total uncertainty of 5%. The angular distribution was fitted to an expansion of Legendre polynomials in cos <i>θ</i> including terms of order 0-3. This measurement is in agreement with a previous measurement, and improves on the precision of the total cross section from the previous measurement by a factor of 6. A comparison is made with several theoretical calculations, and a qualitative agreement is found. These data suggest refinements to these calculations, in order to account for the quantitative differences. / Ph. D.

本論文包含兩個主題。第一部分研究無旋轉波近似下幾種原子與光的相互作用。第二部分研究駐波場耦合的電磁自感透明系統的反射和透射。它們的簡介如下。 / 第一部分。旋轉波近似即忽略掉原子與光相互作用哈密頓量中的反旋轉波項。它的有效性來自於能量守恆定律。但是在時間尺度非常小的情況下，根據海森堡不確定性原理，能量的不確定性可以很大，所以旋轉波近似不能應用于短時間行為的研究，比如量子芝諾和反芝諾效應，蘭姆位移，非共振極化以及超輻射和亞輻射中的能移。為超越旋轉波近似，我們對哈密頓量採用了么正變換。在變換之後的基矢之間，只有由帶修正係數的旋轉波項造成的躍遷。 / 我們從原子和真空的相互作用開始。對於氫原子來說，自由真空中沒有量子反芝諾效應，但是如果對真空態密度用腔或特異性材料做一些調製，量子反芝諾效應就會出現，蘭姆位移也會改變。我們接著研究原子和非真空光場的相互作用。我們計算了滿足光學定理的兩能級原子極化率。然後我們把么正變換用到了兩個全同原子和真空的相互作用，並計算了超輻射和亞輻射的輻射譜以及量子芝諾和反芝諾效應。 / 第二部分。在電磁自感透明系統裏，如果耦合光場為駐波，介質的極化率就會受到週期性調製而形成一維光子晶體。和傳統的傳輸矩陣不同的是，我們採用了麥克斯韋-劉維爾耦合波方程來處理這個系統並得到了光子晶體能帶的一個新的評判標準。起關鍵作用的物理量為非線性耦合係數除以波矢錯差和線性極化率的和，也就是非線性因素除以線性因素。 / 首先，我們研究了光子能帶的位置和寬度與實驗參數的量化關係。然後我們研究了溫度升高时光子晶體的融化以及向多普勒無關的多波混頻的轉化。如果在兩束對向傳播的耦合場之間引入失諧，駐波場的包絡會形成一個“飛行“的光子晶體。因為多普勒效應，順著飛行方向或者逆著飛行方向的探測光在一維光子晶體的坐標系裏具有不同的頻率。在靜止坐標系看，透射譜會在頻率上錯開並形成光學二極體。 / This thesis includes two topics. Part 1 is on the various atom-photon interactions without rotating-wave approximation (RWA). Part 2 is on the reflection and transmission in a standing wave coupled electromagnetically induced transparency (EIT) system. / Part 1. In the RWA, the counter-rotating terms in the atom-photon interaction Hamiltonian are neglected. Its validity is the result of energy conservation. However, if the time scale is sufficiently small, the uncertainly in the energy can become large, according to the Heisenberg uncertainty principle. Thus the RWA can not be applied in the study of the short time behavior, such as the quantum Zeno effect (QZE) and anti-Zeno effect (QAZE), the Lamb shift, the non-resonant polarizability and shifts in the superradiance and subradiance. To go beyond RWA, we apply a unitary transformation on the Hamiltonian. In the transformed basis, there are only secular transitions due to rotating terms with modified coupling constants. / We start from the interactions between atom and vacuum. For the hydrogen atom, there is no QAZE in free vacuum. However, with the modification in the density of states of the vacuum by a cavity or a meta-material, the QAZE appears and the Lamb shift changes. We then turn to the atom in light field, where the polarizability of a two-level atom is calculated and the results satisfy the optical theorem. The unitary transformation is then applied to two identical atoms interacting with vacuum. Their various emission spectra of the superradiance and subradiance and the QZE and QAZE are studied. / Part 2. In an EIT system, if the coupling field is a standing wave, the susceptibility of the medium is periodically modified to form a one-dimensional photonic crystal (1DPC). In contrast to the conventional treatment with transfer matrix, we use Maxwell-Liouville coupled-wave equations and propose new criteria for the bandgap of the photonic crystal (PC). The relevant quantity is the ratio between the nonlinear coupling coefficient and the wave vector mismatch plus the linear susceptibility, which is the nonlinear effect over the linear effect. / First, we study the quantitative relation between the position and width of the photonic bandgap and the experimental parameters. We then show that, as the temperature rises, the 1DPC melts down and enters the Doppler-free wave-mixing regime. By introducing detuning between the two counter-propagating fields in the standing wave, we make the envelope of the standing wave move and form a ‘flying’ 1DPC. Owing to the Doppler Effect, the probe fields propagating along with or counter to the moving direction have different frequencies in the 1DPC frame. In the rest frame, the transmission spectra in two directions are thus shifted with respect to each other and we obtain an optical diode. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wang, Dawei = 無旋轉波近似下原子-光子相互作用和駐波耦合的電磁自感透明系統 / 王大偉. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 128-135). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Wang, Dawei = Wu xuan zhuan bo jin si xia yuan zi-guang zi xiang hu zuo yong he zhu bo ou he de dian ci zi gan tou ming xi tong / Wang Dawei. / Abstract --- p.iv / Acknowledgements --- p.vii / Table of Contents --- p.xi / List of Figures --- p.xiii / Chapter Part 1 --- Atom-photon interactions without rotating-wave approximation --- p.1 / Chapter Chapter 1 --- Introduction on atom-photon interactions --- p.2 / Chapter 1.1 --- Spontaneous emission --- p.2 / Chapter 1.2 --- Quantum Zeno and anti-Zeno effect --- p.8 / Chapter 1.3 --- Rotating-wave approximation --- p.10 / Chapter 1.4 --- Go beyond the rotating-wave approximation --- p.12 / Chapter 1.5 --- Non-dynamic Lamb shift --- p.15 / Chapter 1.6 --- Summary --- p.17 / Chapter Chapter 2 --- QZE, QAZE and Lamb shift in vacuum --- p.18 / Chapter 2.1 --- Introduction --- p.18 / Chapter 2.2 --- QZE in the free vacuum --- p.19 / Chapter 2.3 --- QAZE in modified vacuum --- p.21 / Chapter 2.4 --- Time Evolution of the Lamb Shift --- p.25 / Chapter 2.5 --- The Lamb shift in modified vacuum --- p.30 / Chapter 2.6 --- Summary --- p.35 / Chapter Chapter 3 --- Atom in light: polarizability and scattering --- p.37 / Chapter 3.1 --- Introduction --- p.37 / Chapter 3.2 --- The polarizability of a two-level atom without RWA --- p.39 / Chapter 3.3 --- The optical theorem --- p.43 / Chapter 3.4 --- The effects of the counter rotating terms --- p.46 / Chapter 3.5 --- The frequency shift --- p.48 / Chapter 3.6 --- Summary --- p.50 / Chapter Chapter 4 --- Spontaneous emission of two identicalatoms --- p.51 / Chapter 4.1 --- Introduction --- p.51 / Chapter 4.2 --- Unitary transform of the Hamiltonian --- p.52 / Chapter 4.3 --- Dynamicevolution --- p.57 / Chapter 4.4 --- Decay rates, Lamb shift and emission spectrum in the longtime limit --- p.59 / Chapter a) --- The decayrates --- p.59 / Chapter b) --- The Lamb shift --- p.60 / Chapter c) --- The emission spectra --- p.62 / Chapter 4.5 --- Short time evolution --- p.68 / Chapter 4.6 --- Summary --- p.70 / Chapter Appendix --- the shifts and decay rates of the symmetric and anti-symmetric states --- p.71 / Chapter Part 2 --- Standing wave coupled electromagnetically induced transparency system --- p.74 / Chapter Chapter 5 --- Introduction on electromagnetically induced transparency --- p.75 / Chapter 5.1 --- The electromagnetically induced transparency --- p.75 / Chapter 5.2 --- The susceptibilities of SWEIT --- p.81 / Chapter 5.3 --- Summary --- p.86 / Chapter Appendix --- the recursion relation and the proof of Eq.(212) --- p.86 / Chapter Chapter 6 --- From photonic crystal to Doppler-free wave-mixing --- p.90 / Chapter 6.1 --- Introduction --- p.90 / Chapter 6.2 --- The Maxwell-Liouville equations --- p.91 / Chapter 6.3 --- The photonic bandgaps --- p.93 / Chapter 6.4 --- The meltdown of the photonic crystal and the pulse matching --- p.99 / Chapter 6.5 --- Summary --- p.106 / Chapter Appendix A --- the Maxwell-Liouville equation --- p.106 / Chapter Appendix B --- a new criterion of photonic band-gaps --- p.109 / Chapter Chapter 7 --- The optical-diode by a flying photonic crystal --- p.112 / Chapter 7.1 --- Introduction --- p.112 / Chapter 7.2 --- Coupled-wave equations of the ‘flying’ photonic crystal --- p.113 / Chapter 7.3 --- The spectra of the optical diode --- p.118 / Chapter 7.4 --- The influence of the experimental parameters --- p.120 / Chapter 7.5 --- Summary --- p.126 / CURRICULUM VITAE --- p.136

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 211-214. / by Peter Eric Bosted. / Ph.D.

<p>We have performed a measurement of the photodisintegration of the lithium isotopes, 6Li and 7Li, using a monochromatic, polarised photon beam and a segmented neutron detector array which covers approximately 1/4 of 4Î srad. Using time-of-flight and scintillator light-output spectra we separate the data into individual reaction channels. This work is motivated by the need to compare with recent theoretical predictions and to provide data for future theoretical work. <p>For the photodisintegration of 6Li we took data at 12 photon energies between 8 and 35 MeV. We describe the data using a model consisting of two-body reaction channels and obtain angular distributions and absolute cross sections for many of these reaction channels. We compare our results with a recent Lorentz integral transform calculation (Bacca et al. Phys. Rev. C 69, 057001 (2004)). Our results are in reasonable agreement with the calculation, in contradiction with previous experimental results. <p>For the photodisintegration of 7Li, we took data at 9 photon energies between 10 and 35 MeV. We obtain cross sections for the reaction channel 7Li + Á ¨ n + 6Li(g.s.) at all photon energies with angular distributions at all but the highest energy. We obtain angular distributions and total cross sections for reaction channels involving excited states of the daughter nucleus, 6Li, at select energies. We hope that these measurements will provide incentive for new theoretical calculations. <p>We observe neutrons that can only be described by the reaction channel 7Li+Á ¨ n+6Li(10.0) which necessitates an excited state of 6Li with excitation energy Ex = 10.0 } 0.5 MeV that is not in the standard tables of excited states.

<p>We have performed a measurement of the photodisintegration of the lithium isotopes, 6Li and 7Li, using a monochromatic, polarised photon beam and a segmented neutron detector array which covers approximately 1/4 of 4Î srad. Using time-of-flight and scintillator light-output spectra we separate the data into individual reaction channels. This work is motivated by the need to compare with recent theoretical predictions and to provide data for future theoretical work. <p>For the photodisintegration of 6Li we took data at 12 photon energies between 8 and 35 MeV. We describe the data using a model consisting of two-body reaction channels and obtain angular distributions and absolute cross sections for many of these reaction channels. We compare our results with a recent Lorentz integral transform calculation (Bacca et al. Phys. Rev. C 69, 057001 (2004)). Our results are in reasonable agreement with the calculation, in contradiction with previous experimental results. <p>For the photodisintegration of 7Li, we took data at 9 photon energies between 10 and 35 MeV. We obtain cross sections for the reaction channel 7Li + Á ¨ n + 6Li(g.s.) at all photon energies with angular distributions at all but the highest energy. We obtain angular distributions and total cross sections for reaction channels involving excited states of the daughter nucleus, 6Li, at select energies. We hope that these measurements will provide incentive for new theoretical calculations. <p>We observe neutrons that can only be described by the reaction channel 7Li+Á ¨ n+6Li(10.0) which necessitates an excited state of 6Li with excitation energy Ex = 10.0 } 0.5 MeV that is not in the standard tables of excited states.

In this thesis, we explore the quantum dynamics of light interactions with optically thick collections of atoms. We provide a theoretical description of several recent experiments in which some key operations necessary for the implementation of quantum communication networks are demonstrated. Collective Raman scattering from an atomic ensemble is shown to produce probabilistic entanglement between the polarization of a scattered photon and an associated collective atomic excitation. The predicted correlations agree with experimental observations. We also propose a method to use cascade transitions to produce entanglement between a photon with a frequency in the telecom range (ideal for transmission over optical fibers) and a near infrared photon (ideal for storage in an atomic ensemble), and a description of the experimental demonstration is provided. We also propose and describe the implementation of a deterministic source of single photons. In addition, we generalize the theory of dark-state polaritons in ensembles of three level Lambda atoms to account for the nuclear spin degeneracy of alkali atoms. This generalized theory provides a description of the first demonstration of single photon storage and retrieval from atomic ensembles. Additionally, in the presence of a uniform magnetic field, we predict the occurrence of collapses and revivals of the photon retrieval efficiency as a function of storage time within the ensemble. These predictions are in very good agreement with subsequent experimental observations. We also exploit the ability of photon storage to entangle remote atomic qubits.

No description available.

Thesis (Ph.D) -- University of Western Sydney, 2007. / A thesis submitted to the University of Western Sydney, College of Health and Science, School of Engineering, in satisfaction of the requirements for the degree of Doctor of Philosophy. Includes bibliography.

Thesis (Ph. D. in Physics)--University of California, Berkeley, June 1955. / "Unclassified Physics." Includes bibliographical references (p. 74-75). 36

Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2007. / You Li, Committee Chair ; Citrin David, Committee Member ; Kuzmich Alex, Committee Member ; Fox Ronald, Committee Member ; Chapman Michael, Committee Member.