Light Pulses In The ¦«-three-level System In The Storage And Transmission

Quantum optics opens a new window for the build of quantum state and some basic researches and large numbers of application.With the development and study of quantum calculation,we must be related to the problem about the dynamical interaction between light and matter.Then,a basic problem is how to search for a new technology to carry out the high fidelity storage and restoration of random quantum state.In recent years,the research of theory and experiment indicate that regarding storage and restoration of quantum state,one of main dependent theoretical bases is photon echo.From the quantum interference angle,the dynamic process for the quantum information storage and restoration with photon echo is analyzed.In this paper,based on the dressed state and quantum interference theory,the physics mechanism of the photon echo is analyzed,and the problem of the transfers of optical pulse in matter is also analyzed.The paper is divided into three parts.In the first part,the quantum mechanics picture is given clearly for the three-level system.In second part,the physics idea of information storage and restoration in three-level system is analyzed.In third part,the dynamic process of the photon echo in the dressed state representation and the problem of the transfers of optical pulse in system are discussed.Part One:The pictures of some parts of basic physics parameters in atom systems are given by the evolution laws in the bare state expressed by wave function in the dressed state,such as transition probabilities,density matrix elements,Bloch vectors,etc.From these pictures,the more deep-seated physics meaning is dug out.At last,we introduce a numerical calculation method which always be used.Part Two:Based on the physics idea of photon echo technology in the two-level system,we analyze and discuss the physics process of the information storage and restoration in three-level system by the method of the Bloch vectors.Different population transfer is produced between the system levels by choosing different intensity of pulse and different relaxation speed between the system levels:â‘ Choosing suitable intensity of pulse get the ground state |1> and excited state |2> become the maximum coherence superposition,which can make the maximum information read-in,then,we carry out that the particle population complete transfer twice between excited state |2> and metastable state |3>.â‘¡Choosing suitable intensity of pulse get the population complete transfer between ground state |1> and excited state |2>,then we carry out the particle population complete transfer between excited state |2> and metastable state |3>,and make the maximum coherence superposition between excited state |2> and metastable state |3> at last.Part Three:In this section,based on the dressed state theory,the dynamic process of the information storage and restoration in three-level system is expressed by the new representation,and the physics picture is given clearly for the interaction between light and matter.The dynamic process of the interaction is described by the method of the Bloch vectors.The process of the interaction with the information read-in and read-out is expressed by the photon echo technology clearly.Then,the physics description of the transmit process of laser pulses in the matters is given under the coherent population trapping.And,the analytic solution of the equation of decaying wave is given under the rapid adiabatic passage technology.After that,we discuss the satisfy of adiabatic condition,the relation between the proportion of the oscillation intensity and the proportion of pulse width.