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Collective Characteristics Of Bounded Quantum Plasma And Degenerate Fermi Gases

Posted on:2013-04-24Degree:MasterType:Thesis
Country:ChinaCandidate:Y T MaFull Text:PDF
GTID:2230330392950854Subject:Theoretical Physics
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A lot of complex systems have a basic characteristics, that is nonlinear interaction.Complex system of many novel physics phenomenon and nonlinear interaction are closelyrelated. Especially the dynamics behavior of a quantum system with the nonlinear in-teraction become a hot issue in recent years. As the new material forms outside of thesolid, liquid and gas: quantum plasma and Bose Einstein Condensate is such two com-plex quantum systems. At the same time, BEC closely related to quantum plasma, theresearch on BEC has important meaning for people to understand the characteristics ofquantum plasma.Both wave dispersion properties of the two components ultracold quantum plasma inbounded space, and the stability of two-component degenerate Fermi gases in a harminictrap with a quartic distortion are discussed in the thesis. The first chapter basicallyis divided into two parts: first of all, this chapter briefly introduces the fourth state ofmatter, that is plasma. Related characteristics of plasma (quantum efect, boundary efectand electronic exchange association efect) described in detail mainly. Second, separatelyfrom the basic definition of BEC, magnetic field Feshbach resonance, and the realizationof the Fermi condensed to introduce the BEC.The second chapter basically to analytical and numerical simulation the dispersionproperties of quantum plasma with exchange-correlation efects in cylindrical wave guide.Based on a quantum hydrodynamic model (QHD), the influences of the electron exchange-correlation potential, the radius of the wave guide, and the quantum efect on the disper-sion properties of the two component plasma are discussed. Firstly, using the orthogonalmodel analysis, discussing the dispersion properties of the quantum plasma with electronexchange-correlation efects in a cylindrical domain both in high frequency limit and lowfrequency limit, respectively. Second, the influences of the electron exchange-correlationpotential, the radius of the wave guide, and the quantum efect on the dispersion prop-erties of the two component plasma are discussed both analytically and numerically. Itis found that electronic exchange association efect, boundary efect and quantum ef-fect on the influence of the wave frequency, depending on the particle number densityand temperature. No matter in the low frequency, or in the high frequency cases, thewave frequency down-shifted by the electron exchange-correlation efects, up-shifted bythe quantum correction. And, the frequency-shifts by the electron exchange-correlationefects are significantly when radius of the wave guide is small, wave number is large,quantum efect is weak. The adjustment of the electron exchange-correlation efects, theradius of the wave guide, and the quantum parameter on the wave frequency in a bounded nano-waveguide are strongly coupled. Our articles will help understand the nanotubesquantum plasma collective inspiration efect, and will in future about this in experimentshave help.At the same time, in order to study the dynamic properties of ultra-cold quantumplasma further, we in the third chapter also discusses the dynamics characteristics ofultracold atoms BEC, which closely related to ultra-cold quantum plasma. In recentyears, due to the development of the cooling technology and realization the experimentabout Bose-Einstein Condensed of gaseous alkali metal atoms, a lot of theoretical workfrom all aspects of ultracold quantum field research and discussion. But so far, thetheoretical research on the stability of Fermi gases trapped in potential also limited toan ideal model, that is, in the harmonic trap and only exist s waves interaction. In fact,the potential well which trap Fermi gas is not pure harminic, and for those who havehyperfine structure of Fermi system efective p wave interaction can’t ignore, so the studyof the nature of the Fermi system when considering the potential of the harmonic trap theanharmonicity and interaction of p wave is very necessary. Therefore, the third chapterof this article discussed the stability problem of two-component degenerate Fermi gaseswith attractive interactions in a harminic trap with a quartic distortion in the mean-field.Using variational approaches, the stability condition of the system in a harminic trap witha quartic distortion under the efective s wave interaction and efective p wave interactionare derived. And the influences of anharmonicity and p-wave interaction on the stabilityof Fermi gas are discussed, respectively. It is shown that the p-wave interaction and theanharmonicity of harminic trap have material efect on the stability of Fermi gas, andhave an important efect on the particle numberal density distributing. Finally, in thefourth chapter of this paper, we summarize the main results and give an outlook of thefuture in this field.
Keywords/Search Tags:electron exchange-correlation, Dispersion relationship, two-component degenerate Fermi gases, harminic trap, stability
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