Investigations On The Properties Of Spontaneous Emission Of An Atom Near The Chiral Metamaterial And Topological Insulator Structure

Spontaneous radiation is a kind of quantum effect,which is a basic problem in the field of quantum optics.Spontaneous radiation is the transition from the excited state to the ground state.At the beginning,people also thought that spontaneous radiation was an inherent nature of the atom and was ineffective for it.In 1946,Purcell's research showed that the spontaneous emission rate of atoms in the cavity is obviously different from that in vacuum.Since then,people have known that we can control the spontaneous emission by changing the environment of the atom.Because of the important role of spontaneous emission in high-precision measurement and quantum information technology,people have been studying the control method of spontaneous emission for more than half a century,and have achieved some impressive results.Since twenty-first Century,due to the development of material science,more and more material discovered and produced,which has novel electromagnetic characteristic.There are more and more special materials used to control spontaneous emission of atoms,such as left-handed materials,photonic crystal,hyperbolic metamaterial and so on.In this paper,the spontaneous emission of a two-level atom near the interface of chiral metamaterial,near the interface of chiral metamaterial covered by Chern insulator,near the topological insulator plate,and a cavity composed of topological insulator plates are studied and analyzed.The specific work in this thesis is as follows:(1)Firstly,the basic concept of spontaneous radiation and the methods of controlling spontaneous radiation are reviewed,then the quantization of electromagnetic field and the interaction between atoms and fields are introduced,and the expression of spontaneous decay rate is deduced by Dyadic Green's function.(2)The spontaneous emission of a two level atom near the interface of chiral metamaterial and the interface of chiral metamaterial covered by Chern insulator is studied.Due to the presence of chiral parameter,the spontaneous decay rate of an atom near the interface of chiral metamaterial is obviously enhanced compared with the ordinary interface.Because of the influence of Chern number,covering with Chern insulator layer makes the spontaneous emission of the atom near the interface obviously suppressed,which realize the regulation of the spontaneous emission rate of the atom.Then the spontaneous decay rate of the dipoles parallel or perpendicular to the interface is discussed respectively,and the radiation mode decay and evanescent mode decay are analyzed in detail.(3)The spontaneous radiation of the two level atom near the interface and in the cavity oftopological insulators plates is studied.Because of the topological magnetoelectric effect,the spontaneous decay rate under this model is quite different from that of the ordinary material.Besides,we also discussed many impacts of the spontaneous decay rate in detail,such as the thickness of the topological insulator layer,the dissipation of the material,the position of the atom and the change of the cavity length.and Logistic mapping has high recognition rate and strong security.