Use Green Function to Analyze the Dynamics of Damped Jaynes-Cummings Model
| Autor: | Ning-ShiangSheu, 許寧翔 |
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| Rok vydání: | 2012 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 100 In this thesis, we use three different methods to describe open quantum systems, in particular, to study the damped Jaynes-Cummings model at zero temperature. We begin with Liouville-von Neumann equation and Born approximation to obtain a time-convolution Master Equation. Then, we make Post-Markov approximation further and obtain a time-convolutionless Master Equation. The third method is based on Keldysh’s non-equilibrium Green function method plus Born approximation. Besides, we also solve exactly the damped Jaynes-Cummings model at zero temperature. We use these methods mentioned above to study the evolution of the probability of the excited state in damped Jaynes-Cummings model. We analyze the result of the exact solution to understand the effect of the coupling strength and spectrum width on the system. By compared the results obtained from the three different approaches with the exact solution, we find the validity of each approach. We also find that the non-equilibrium Green function approach is the most suitable one to study the dynamics of open systems, and may be extended to investigate the open systems dynamics in strong couplings and finite temperature in the future. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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