量子干涉效應對低維度電子系統電性傳輸之影響

Abstract

我們將針對一系列以閘極局域的量子線與其他介觀系統做系統性的量子干涉效應對其電性傳輸之影響研究。最近，有一說:量子窄通道在接近關閉時其瞬間自旋極化形成單一自旋束縛態磁矩，因此會局域其附近通過帶相反自旋電子，因此元件間耦合被用以研究量子線的自旋傳輸；然依量子的干涉效應，只要彈道式電子都會因臨近的束縛態量子系統的存在而造成電性傳輸的修正，隨其中一量子線閘極偏壓掃描時，當兩量子線能態在費米面恰等列，兩波函數的量子干涉應該造成電導的共振。本工作將針對此共振電導曲線深入研究其Fano峰之寬度、不對稱性，並與其他理論實驗結果做比較；同時兩量子線的耦合強度與則曼分裂等效應對此共振電導曲線之影響也一併做更進一步探討。 閘極局域之類一維量子線常因一些未預期的的雜質而造成量子島線有額外的共振現象，此研究將利用刻意製造的束縛態量子線扮演雜質角色，將可釐清共振曲線與雜質特性之關聯。Fano效應是為一量子干涉效應的結果，從開發新穎共振奈米電子元件與基礎量子力學電荷的波函數本質探討兩觀點，都是非常值得廣泛地深入研究。

In all, we propose to investigate quantum interference effect on the electrical transport of gate-confined quantum wires and other mesoscopic systems systematically. Recently, interdevice coupling has been used to study spin transport in quantum wires originating from the idea that spin polarization near pinch off forms a spin-bound state to trap other passing by electrons of opposite spin. However, according to the quantum interference effect of ballistic electrons’ wavefunctions, the presence of other bound states of nearby quantum wire should affect the electrical transport of original quantum wire. The interference of the partial waves should give rise the conductance resonances whenever both energy levels of both quantum wires match by sweeping the gate voltage. Here, the resonance widths and the asymmetry parameters of Fano line shapes are investigated and compared to each other. Effects of coupling strength of two quantum wires and Zeeman splitting on the resonances are also under investigation. Resonance phenomena in quasi-one dimensional wires, defined by a split gate with impurities can also lead to a connection between the line shape and the parameters of the impurity. The Fano effect, a result of quantum interference, is of great interest both as a basis for the creation of new resonant nanoelectronic devices and for revealing the quantum-mechanical wave nature of the charge carriers.