量子點光電特性及相關應用之研究(II)

Abstract

本計劃著眼於奈米尺寸量子點及材料光電特性的研究，涵蓋有電子間交互作用、量 子量測、量子點自發輻射及干涉量測的探討，這些課題近年來在量子計算與資訊相關領 域引起廣泛的興趣。在量子點電性方面的研究，我們將研究單-三重態的交換能量，受 自旋軌道影響的單-三重態弛豫時間以及量子點系統的糾纏程度；此外我們也分析量測 行為對量子系統的影響，由於系統與測量裝置之間有交互作用，造成量子點系統的電流 頻譜和噪訊有不同變化。對量子點光性方面的研究，我們研究金屬表面電漿對量子點自 發輻射率的影響，金屬結構包括有奈米金屬線、奈米金屬球及奈米金屬球陣列，期望能 改善發光元件的發光效率。進一步我們將實驗量測不同量子點系統的光學性質，包括利 用表面電漿增強點陣排列量子點的自發輻射，在變異電場條件下量子點自發輻射的變 化，進而架設量子點與其鏡像系統，觀察量子點的光激螢光與其鏡像之間的干涉現象。 因此我們希望藉由對量子點系統的研究，能夠提供以量子點做為基本元件在電性與光性 上所可能遭遇或必須了解的物理特性，並且增進了解當這量子點系統運用在量子計算與 量子資訊時所可能發生的物理現象。

Our investigations are devoted to electric and optical properties of quantum dots, ranging from exchange interaction, quantum measurement to photon emission and detection. Recently, these topics have attracted much attention in the fields of quantum computation and quantum information. Our proposal is divided into two parts. In the electric aspect, we study the physical properties of singlet and triplet states, such as exchange energy, relaxation and entanglement. In addition, we study non-Markovian transport process through quantum dots. Due to the interplay between the system and measuring device, current spectrum and noise become different. In the optical aspect, we study the influence of surface plasmons on spontaneous emission. The nanowires, nanospheres and nanosphere arrays are applied to increase the efficiency of light-emitting devices. Further, the spontaneous emissions of different quantum dot systems are studied experimentally. We measure the spontaneous emission of the single quantum dots coupled to the surface plasmons. The decay times of single quantum dots under different electric fields are analyzed in detail. Moreover, we observe the self-interference effect as the quantum dot is put close to a mirror by using the time-resolved photo-luminescence means.