Quantum Coherence Of Atoms In Atoms Vapor Filled With Buffer Gas

Quantum optics,the union of quantum field theory and physical optics,is a hot topic for researchers.The earlier quantum optics phenomenon,for example,black-body radiation,Raman scattering,photoelectric effect and so on,plays an important role during the process of recognizing the properties of light and the interaction between light and atoms.In recent years,the interaction between light and atomics,which has become an important field of quantum optics,promotes the development of quantum information.Many physicists are studying it.In the interaction between light and atoms,atomic coherence has been the focus in the quantum field.In the process ofelectromagnetically induced transparency,the medium absorption of probe field is weakened,and producessteep normal dispersion.Taking advantage of this feature,we can control the speed of light pulses.In addition,quantum information memory and single photon preparation are also applied.First,the thesis introduces the physics principles,background knowledge and recent research progress of three kinds of atomic coherence effects.Three kinds of atomic coherence are coherent population trapping,electromagnetically induced transparency and electromagnetically induced absorption.As we all know,in the study of atomic coherence effects,achieving optical amplification has great significance.Therefore,we use the Tripod-type double EIT level system to inhibit effectively the light field absorption and spontaneous emission noise by changing the atomic temperature,pump power and signal light detuning.It can achieve low noise optical amplification.The experiment and the theory are consistent.It has important signification for the development of quantum device and the preparation of non-classical light source.The study of coherence effects in the atomic vapor filled with buffer gas has been a hotspot.In this thesis,we research EIT in the Cs atomic vapor which is filled with Ne as buffer gas.First,in the V-type three-level system,we use the dark state theory to analysis and numerically simulate the relations between dephasing and probe field absorption.We also research the relations between the pressure of buffer gas and EIT experimentally.The results indicate that when the atomics temperature is constant,buffer gas pressure is bigger,the probe field absorption is stronger and EIT effect is less obvious.The physics behind the dephasing-induced control of interference is the competing between stimulated emission and spontaneous emission.