Entropy Squeezing Effect Of A Three-level Atom Interacting With Single Model Field

The theoretical establishment and experimental realization of the squeezing effect of quantum systems(e.g.atoms and optical fields)are great advances in modern quantum optics and quantum information science.Atomic squeezing is widely used in quantum entanglement witnessing and detection,quantum information processing of continuous variables,quantum metrology,high precision atomic clock,gravitational wave interferometer and so on.M.F.Fang has proposed a new concept of entropy squeezing of the atom and field by applying the uncertainty relation of entropy to the study of the squeezing of the atom and field,and proved that the entropy squeezing of atomic observable defined by the uncertainty relation of entropy can break through limitation of variance compression defined by Heisenberg uncertainty relation and realize high sensitivity measure of squeezing effect of quantum systems.In this thesis,the theory of entropy squeezing of two-level atoms is extended to three-level atoms,the effect of entropy squeezing of three-level atoms is studied,and some meaningful results are obtained.The theory and innovative results obtained in this paper are as follows:In the first chapter,the research background of variance squeezing and entropy squeezing of atom and field systems are introduced,and the works in this paper are listed.In the second chapter,the Heisenberg uncertainty relation and the entropy uncertainty relation,as the starting points of the definitions of variance squeezing and entropy squeezing,are introduced respectively.Then the basic theories of variance squeezing and entropy squeezing of two-level atoms are illustrated,and the characteristics of variance squeezing and entropy squeezing of two-level atoms are discussed.Compared with the atomic variance squeezing,the advantages andcharacteristics of atomic entropy squeezing are shown.In the third chapter,the basic theory of three-level atom is briefly introduced.Three basic atomic models including cascade three-level atom,? type three-level atom and (1 type three-level atom are emphatically introduced.The dynamics of atom inversion population is discussed by means of its reduced density matrix of the three-level atom,and the periodic collapse and revivals of three-level atomic operators are shown.In the fourth chapter,the entropy squeezing effect of the cascade three-level atoms interacting with a single-mode field is studied.Firstly,the general definition of entropy squeezing of three-level atom is given based on the uncertainty relation of entropy of the two conjugate observations of three-level atoms.Then,the formula for calculating the entropy of cascaded three-level atoms is derived by using its reduced density matrix.Finally,the entropy squeezing properties of cascaded three-level atoms interacting with a single-mode field are discussed by numerical calculation.The results show that the interaction between cascaded three-level atoms and a single-mode field can produce obvious entropic squeezing effect by choosing a suitable superposition state of three-level atoms.These results are of great significance to the preparation of information resources for ultra-low quantum noise three-level systems.In the fifth chapter,the summary and prospect are given.