Dynamic Analysis Of Photon Echo In The Dressed State Representation

Entering on a new century, the quantum characteristic of interaction between light and matter will become the fundamental problems of information science, in which the more fundamental one is to explore a new technique with the realization to store and recall an arbitrary quantum state. Regarding storage and recall of quantum state one of main dependent theoretical bases is photon echo of instantaneous optical processes. Based on the recent research of the photon echo, in order to further apply the photon echo technique to the photon information storage, from quantum interference angle, the dynamic process for the quantum information storage and recall 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 photon echo is realized theoretically by means of Stark-chirped rapid adiabatic passage (SCRAP). The paper is divided into three parts. In the first part, the quantum mechanics picture is given clearly for the two-level system. In the second part, the physics idea of SCRAP technique is analyzed. Finally, the dynamic process of the photon echo in the dressed state representation is discussed, and the photon echo is realized theoretically by means of SCRAP technique.Part One:The pictures of some parts of basic physics parameters in atom systems are given by brand-new means of 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 the physics mechanism ofπpulse, 2πpulse andπ/2 pulse is analyzed by this means.Part Two:SCRAP is analyzed by means of level-crossing technique and dressed state theory. In this passage two laser pulses are used: one is a near-resonant pump pulse, which can excite particles from ground state to excited state; the other is a far-resonant strong Stark pulse, which can move two levels to form two crossings of diabatic states. The transfer of populations is controlled by the delay between the two pulses and the detuning of the pump pulse:①When△≠0, the adiabatic-diabatic scenario achieves complete population transfer between the two states;②When△＝0, with the theoretical analysis and numerical calculation, the system remains robust and maximum coherence supcrposition. Moreover the robustness of the population is insensitive to variations in the intensities of the pump and Stark pulses.Part Three:In this section, based on the dressed state theory, the passage of the photon echo is analyzed in detail, and the physics picture is given clearly for the interaction between light and atoms. The dynamic process of the interaction is described using the method of the Bloch vectors. Three cases arc discussed:①For on-resonant case, the physics picture of the dynamic process for the information storage and recall with photon echo is described;②When having dctuning, as the dctuning increases, the intensity of photon echo will decrease if the area of pump pulse is constant;③The photon echo is realized theoretically by means of SCRAP technique. This means takes no account of the area of pump pulse. It can provide a more convenient method and inaugurate a new research way for the photon echo.