本文選題：量子點 + 非平衡格林函數(shù)��； 參考：《北京工業(yè)大學》2015年碩士論文

【摘要】：由于設(shè)計和制作納米尺寸的電子器件的需要,低維納米體系的量子輸運性質(zhì)的研究成為了當前凝聚態(tài)物理領(lǐng)域的一個熱點。對低維納米體系的電子輸運的研究有助于我們對電子強關(guān)聯(lián)性質(zhì)有更深的理解。本論文采用非平衡格林函數(shù)方法、運動方程方法和玻色化技術(shù)研究了低維納米體系的電子輸運現(xiàn)象,其目的在于揭示對低維納米體系的新物理效應(yīng)和物理機制,以及解釋相關(guān)的物理實驗現(xiàn)象,并為設(shè)計和實現(xiàn)具有優(yōu)良性能的納米電子器件提供理論依據(jù)和物理模型。本論文共分五章。第一章和第二章分別介紹了相關(guān)理論研究背景和理論技術(shù)方法。其余三章介紹了本論文的研究工作。首先,本論文我們提出了對量子點和Luttinger液體耦合的系統(tǒng)在近藤區(qū)的量子輸運性質(zhì)進行了詳細的理論研究。數(shù)值模擬結(jié)果顯示在近藤區(qū)微分電導G(V,T)Vbμ顯示出隨偏壓的冪率變化關(guān)系,以及零偏壓電導隨溫度變化的冪率變化關(guān)系,G(0,T)Tbμ,指數(shù)是b=2/g-2,這里g與Luttinger液體中電子相互作用參數(shù)有關(guān),這些冪律變化關(guān)系與實驗結(jié)果非常相吻。我們發(fā)現(xiàn)了線性電導隨溫度變化的峰值maxG(T)在不同溫度區(qū)域的不同特點:(1)對于非常低的溫度T,1maxG Tb-μ;(2)對于相對低的溫度T,maxG Tbμ;(3)對于高溫TG,/2 1maxG(T)Tb-μ;這些不同的溫度區(qū)域電導峰值隨溫度不同變化冪律關(guān)系與不同的輸運機制有關(guān),給出了從低溫到高溫的完整溫度去的變化特性及規(guī)律。與此同時,這個冪律變化關(guān)系也解釋了2003年-2005年理論上和實驗上所給出的不同冪指數(shù)問題。其次,本論文研究了量子線內(nèi)電子相互作用和量子點上的庫倫相互作用共同對量子點與量子線相耦合體系在近藤區(qū)的量子噪聲的影響。本論文首先運用非平衡格林函數(shù)、運動方程以及玻色化技術(shù)推導出了此納米體系的噪聲公式,并根據(jù)此公式進行了數(shù)值模擬,數(shù)值結(jié)果顯示對于弱量子線內(nèi)相互作用,噪聲隨偏壓變化曲線中,在近藤溫度Tk附近的噪聲峰高隨量子線內(nèi)相互作用減弱而降低,而峰的位置幾乎保持不變,顯示出單溝道近藤效應(yīng)。這有助于通過散粒噪聲測定可靠地估計近藤溫度。但是隨著量子線內(nèi)相互作用的增強,噪聲峰最后消失,表明了單購近藤效益消失,并從單溝道近藤效益向到雙溝道近藤效應(yīng)轉(zhuǎn)變。數(shù)據(jù)擬合顯示量子噪聲隨偏壓呈現(xiàn)冪律變化關(guān)系。我們也計算了Fano因子:散粒噪聲S與電流I的比值,F=S/2e I。數(shù)值結(jié)果顯示隨量子線內(nèi)相互作用增強Fano因子增大。這個結(jié)果揭示了可以通過調(diào)制材料參數(shù)來控制Fano因子大小。最后,在這一部分我們研究了量子線內(nèi)電子相互作用和量子點與量子線間的庫倫相互作用共同對量子點和Luttinger液體導線相耦合在近藤區(qū)非平衡輸運性質(zhì)的影響。首先,應(yīng)用正則變換技術(shù),消去了量子點與量子線間的庫倫相互作用,并把這個它轉(zhuǎn)移到隧穿哈密頓中,同時,重整化了量子點與量子點上的庫倫相互作用;也重整化了量子線內(nèi)的電子相互作用。數(shù)值擬合結(jié)果顯示量子相變的出現(xiàn)。當重整化相互作用參數(shù)Y≈1時,出現(xiàn)近藤效應(yīng);當Y1時,隧穿效應(yīng)增強,單溝道相出現(xiàn)。衛(wèi)星dips變?yōu)榉�。當Y1時,近藤峰高度降低,并轉(zhuǎn)化為近藤dip,出現(xiàn)了雙溝道近藤效應(yīng)。單溝道與雙溝道。對效應(yīng)在Y≈1發(fā)生相變。Y1和Y1,分別對應(yīng)量子點和Luttinger液體導線之間的隧穿效應(yīng)分別抑制和增強,它們反映了兩種不同類型的激子輔助隧穿效應(yīng)。這些物理現(xiàn)象為將來的實驗中研究雙溝道近藤物理及相變提供了理論方法和依據(jù)。
[Abstract]:Due to the need for the design and fabrication of nanoscale electronic devices, the study of the quantum transport properties of the low dimensional nanoscale has become a hot spot in the field of condensed matter physics. The study of the electron transport of the low dimensional nanoscale system will help us to have a deeper understanding of the strong correlation properties of the electrons. This paper uses the nonequilibrium Green function. Methods, motion equations and boson techniques are used to study the electron transport of low dimensional nanoscale systems. The purpose is to reveal new physical and physical mechanisms for low dimensional nanoscale systems, and to explain the related physical experimental phenomena, and to provide theoretical and physical models for the design and implementation of nanoscale devices with excellent properties. This thesis is divided into five chapters. The first and second chapters introduce the relevant theoretical research background and theoretical and technical methods respectively. The other three chapters introduce the research work of this thesis. First, we present a detailed theoretical study of quantum transport properties of quantum dots and Luttinger liquid coupled systems in the rattan area. The results of the value simulation show that the relationship between the power rate variation with the bias voltage and the power rate variation of the zero bias electrical conductivity with the temperature change, G (0, T) Tb mu, the exponent is b=2/g-2, and the G and Luttinger liquids are related to the electron interaction parameters, and the relationship between the power law and the experimental results is very close to the experimental results. The different characteristics of the peak maxG (T) of the linear conductivity with the temperature change were found in different temperature regions: (1) for very low temperature T, 1maxG Tb- mu; (2) for relatively low temperature T, maxG Tb mu; (3) for high temperature TG, /2 1maxG (T). At the same time, this power law relationship also explains the different power exponents given in theory and experiment in -2005 in 2003. Secondly, this paper studies the interaction of the electron in quantum lines and the interaction of the Kulun interaction on the quantum dots. The influence of quantum dots and quantum wire coupled system on the quantum noise in the rattan area. This paper first derives the noise formula of the nanoscale system by using the nonequilibrium Green function, motion equation and boson technique, and the numerical simulation is carried out according to the formula. The numerical results show the interaction within the weak quantum line, and the noise is biased with the bias. In the variation curve, the height of the noise peak near the rattan temperature Tk decreases with the interaction of the quantum wire, and the position of the peak is almost invariable, showing the effect of the rattan effect in the single channel. This helps to reliably estimate the temperature of the rattan through the determination of the particle noise. But with the enhancement of the quantum wire interaction, the noise peak is finally disappearing. It is clear that the benefit of the single purchase of the near rattan vanishes, and changes from the benefit of the single trench to the rattan. The data fitting shows the relationship between the quantum noise and the bias voltage. We also calculated the ratio of Fano factor: the ratio of the particle noise S to the current I, and the F=S/2e I. numerical results show that the enhancement of the Fano factor increases with the interaction of the quantum wire. The results reveal that the size of the Fano factor can be controlled by the modulation of the material parameters. Finally, in this part, we have studied the effect of the interaction of the quantum wires and the interaction of quantum dots and the quantum wires between the quantum dots and the quantum wires on the nonequilibrium transport properties of the quantum dots and the Luttinger liquid wire in the rattan region. First, the application of the Fano is positive. The transformation technique eliminated the interaction between the quantum dots and the quantum lines of Kulun and transferred it to the tunneling Hamilton, and reformed the interaction between the quantum dots and the Kulun on the quantum dots, and reformed the electron interaction within the quantum wire. When the parameter Y is 1, there is a near rattan effect. When Y1, the tunneling effect is enhanced and the single channel phase appears. The satellite dips becomes the peak. When Y1, the height of the near rattan peak is reduced and converted to rattan dip. The effect of the double channel and the double channel appears in the double channel. The effect of the phase transition.Y1 and Y1 of the effect is between the quantum dots and the Luttinger liquid wires respectively in Y. The tunneling effect is suppressed and enhanced respectively. They reflect two different types of exciton assisted tunneling effect. These physical phenomena provide a theoretical method and basis for the study of the physics and phase transition of the double channel in the future.
【學位授予單位】：北京工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：O471.1

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