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Controlling the Atomic Spontaneous Emission by External Driving Fields and Photonic Crystals

Author: SongChongXi
Tutor: LiuNianHua
School: Nanchang University
Course: Theoretical Physics
Keywords: Spontaneous emission Quantum Interference Photonic crystal Spontaneous emission spectrum
CLC: O562
Type: Master's thesis
Year: 2011
Downloads: 17
Quote: 0
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Abstract


Spontaneous emission of atoms in the excited states of atoms in the spontaneous action of no external disturbance transition to a low energy level state and emit a photon process, is one of the important research topic in the field of quantum optics. Different atomic spontaneous radiation in the frequency, phase, polarization direction and the direction of propagation has a certain arbitrariness, non-coherent, so how to effectively control the atomic spontaneous emission quantum optics research hotspot. Spontaneous emission depends not only on the level structure of the atom itself, also associated with the atom in which the surrounding environment. Control atomic spontaneous radiation is generally mainly two methods; change atoms coupled environment, such as with appropriate libraries coupling, is located in the optical cavity, a photonic crystal. Photonic crystal material density of states with the free vacuum field is very different, its unique influence and change of the density of states of the quantum interference effects, as well as high-precision measurement, lasing without inversion, quantum computing and quantum information theory provides a potential application value. Another is the use of applied driving field or multi-level quantum interference between the atomic transition channel to control the spontaneous emission of atoms. This article focuses on the four-level atomic system driven in the the free vacuum low-frequency microwave field coherent control of spontaneous emission and photonic crystal atomic spontaneous emission behavior. In the second chapter, we discuss the evolution of the low-frequency microwave field of spontaneous emission properties of the four-level atomic system and atomic level population over time. The four-level atoms by a coherent probe field, a coupling laser field and a low-frequency microwave field drive, two upper level by the low-frequency microwave field coupling. The study found that the nature of the spectrum is mainly dependent on the phase and amplitude of the microwave field, by properly adjusting the phase and amplitude of the low-frequency microwave field, you can get different spectral characteristics, such as spectral narrowing line enhancement, spectral line suppression, spectral line quenched. In the third chapter, we consider plus the spontaneous radiation behavior of the two driving field under the four-level atoms in a photonic crystal, the system consists of an upper level and three lower energy levels, of which the two lower level another the next level through thermal reservoir and the upper level of photonic crystal coupled through the coupling of the two driving field and on the level. Different initial conditions, the relative position and applied the detuning of the driving field photonic crystal band-edge of the spontaneous emission spectrum. The results show that when the atomic transition frequency is located in the outer belt edge, by selecting the appropriate parameters, it is possible to control the generation and disappearance of the black line, however, when the atomic transition frequency in the band gap in the photonic crystal, the atomic spontaneous emission by strongly inhibited. Due to the presence of the driving field by adjusting the frequency detuning, the atomic spontaneous emission spectrum, we found some interesting phenomena such as spectral narrowing line enhancement, spectral line suppression. In the fourth chapter, we discuss the three-level atom in a photonic crystal spontaneous emission spectroscopic properties of the defect mode. A higher level, the other on the level through the coupling of a thermal reservoir and the lower level of the photonic crystal containing defects through vacuum thermal Library lower level coupled, the results show that, when introduced in the photonic crystal defect modes found in the atomic spontaneous The new transparent window in the radiation spectrum, plus driving field is removed, the spontaneous emission spectrum presented Lorentz, the emergence of a new transparent window is the result of the defect mode and the applied drive field together. In addition, by changing the relevant parameters of the defect mode can control the nature of the atomic spontaneous emission.

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CLC: > Mathematical sciences and chemical > Physics > Molecular physics, atomic physics > Atomic Physics
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