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Jiguang zazhi

The transformation of density matrix of four-level system in solid laser

Tang Mei-juan

Published Jan 1, 2006• 0 citations
OpenAlex

Abstract

Solid laser is a four-level system.This paper utilizes theories of quantum mechanics and Kraus operator,to analysis the four-level system which in the case of absorption as well as radiation.The object of the research is to probe into the transformation properties of density matrix.The result shows that probability of absorption and radiation condition is satisfied,between the second excited state and the first excited state forms reversion of particles and prepares for producing laser.It also shows that when particles transform from the second excited state to the first excited state and the first excited state to the ground state at very high probability,the system produces laser.

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Journal of Physics B Atomic Molecular and Optical Physics•Sep 8, 2017•8 citations
Solid laser is a four-level system.This paper utilizes theories of quantum mechanics and Kraus operator,to analysis the four-level system which in the case of absorption as well as radiation.The object of the research is to probe into the transformation properties of density matrix.The result shows that probability of absorption and radiation condition is satisfied,between the second excited state and the first excited state forms reversion of particles and prepares for producing laser.It also shows that when particles transform from the second excited state to the first excited state and the first excited state to the ground state at very high probability,the system produces laser.
Ruby laser is a three-level system.This paper utilizes theories of Kraus operator,to analysis the three-level system which is in the case of absorption as well as radiation .The object of the research is to probe into the transformation properties of density matrix.The result show that when particles transform from ground state to the second excitated state and from the second excitated state to the first excitated state at very high probability,the system forms reversion of particles and prepares for producing laser.It also show that when particles transform from the first excitated state to the ground state at very high probability,the system produces laser.
The radiation and one-step absorption of the four-level atom is studied.Atom's motivated state is not stable,it inevitably disintegrate into the lower energy state,which makes the phenomenon of radiation.This paper is on the basis of theories of quantum mechanics and Kraus operator,utilizing the reducible density rectangular method to probe into the transformation of density matrix opposite angles element and non-opposite angles element of the four-level atom,which in the case of the radiation and one-step absorption.The coherence properties of quantum states are analyzed.
A four-level atomic system interacting with two laser fields and one probe field has been transformed into a four-level Dressed-Atom System interacting with a weak probe absorption field by means of the Dressed-Atom states. By using perturbation theory to solve the density matrix equations in Dressed-Atom representation, the analytic expressions for absorption spectrum are obtained. The properties of absorption spectrum are discussed in detail. Finally, the induced electric dipole moment between the atomic levels and its relation with the absorption spectrum are deduced.
In this paper we report on the study of two and multi-level atoms interacting with multiple laser beams. The semi-classical approach is used to describe the system in which the atoms are treated quantum mechanically via the density matrix operator, while the laser beams are treated classically using Maxwells equations. We present results of a two level atom interacting with single and multiple laser beams and demonstrate Rabi oscillations between the levels. The effects of laser modulation on the dynamics of the atom (atomic populations and coherences) are examined by solving the optical Bloch equations. Plots of the density matrix elements as a function of time are presented for various parameters such as laser intensity, detuning, modulation etc. In addition, phase-space plots and Fourier analysis of the density matrix elements are provided. The atomic polarization, estimated from the coherence terms of the density matrix elements, is used in the numerical solution of Maxwells equations to determine the behaviour of the laser beams as they propagate through the atomic ensemble. The effects of saturation and hole-burning are demonstrated in the case of two counter propagating beams with one being a strong beam and the other being very weak. The above work is extended to include four-wave mixing in four level atoms in a diamond configuration. Two co-propagating beams of different wavelengths drive the atoms from a ground state |1〉 to an excited state |3〉 via an intermediate state |2〉. The atoms then move back to the ground state via another intermediate state |4〉, resulting in the generation of two additional correlated photon beams. The characteristics of these additional photons are studied.
Abstract The absorption features of a probe field propagating through a four-level N-type atomic system in the presence of two coherent radiation fields is studied analytically by using a density matrix formulation. The system has two ground levels and two excited levels. A weak probe laser couples the upper ground level to the lower excited level whereas a strong control field connects the lower ground level to the lower excited level. The coupling field acts between the upper ground level and the upper excited level. The transition parameters of the 87 Rb D 1 line have been used to simulate the probe response. The simulated probe absorption shows a gain-like structure depending on the relative field intensities. The spectral features of the probe response exhibit substantial differences under thermal averaging as compared to a Doppler-free condition. The splitting of simulated probe absorption can be explained by the dressed state model. Electromagnetically induced absorption (EIA) is observed in the simulated probe response curve when the spontaneous decay of the population from the uppermost excited state to the lower ground state is absent.