摘要

近年來世界上許多團隊致力於發展量子位元，為達成此目標，人們需要準備一個二能階系統，並於其中實現此二能階的任意疊加態，以展示同調量子控制。在實驗上有許多物理系統能作為實現量子位元的候選人，量子點基於其定義明確的能階，而成為了一個最成功的例子。目前實驗上已有許多方法能實現量子點，例如半導體異質結構。在此論文中，我們將討論如何操控矽量子點中的電子，並在未來實現量子位元。
在進行閘極定義矽量子點的製程之前，我們必須清楚瞭解矽和二氧化矽異質結構中反轉通道二維電子氣的傳輸性質。因此我們做了許多不同線寬的奈米線及霍爾棒來研究二維電子氣的截止電壓、載子濃度和電子移動率。未來我們將設計並製造閘極定義矽量子點元件，以期能夠精準地調控量子點的電位能，並由全電控的庫倫阻塞實驗來控制量子點中的電子數目。最終希望能夠讓量子點中只剩下一個電子。這些實驗結果將使我們更了解矽量子點的傳輸性質，並幫助改善元件的製程技術，以期在不久的將來實現量子位元。

Abstract
In recent years, many groups have contributed to the field of quantum bits (qubits) [1]. To achieve this goal, people need to prepare a two-level system and then demonstrate coherent quantum control to achieve any superposition state of this two-level system. There are many candidate systems that can realize such qubit operations experimentally [2]. Quantum dot (QD) [3] is one of the most successful system that has been used to develop qubits because of its well-defined quantized energy level. QD has been realized experimentally in a lot of ways, such as semiconductor heterostructure. Here, we focus on controlling electron charges in silicon QD, hoping to realize qubits soon.
Before fabricating silicon gate-defined QD device [4], we have to clearly understand the transport properties of inversion layer two-dimensional electron gas (2DEG) in the Si/SiO2 heterostructure [5]. As a result, nanowire and Hall bar gating Si/SiO2 heterostructure devices with different linewidths are needed to investigate the threshold voltage, carrier density, and mobility of the 2DEG. In the future, we will design and fabricate the gate-defined QD device, which enables to precisely control the electrostatic potential of the QD and consequently the number of electrons within it. Furthermore, Coulomb Blockade (CB) [6] measurements in these QD devices will be perform, which can demonstrate the electrical control of electron occupation. We hope the last one electron occupation in QD can be reach. These results help us characterize the transport properties of QD and improve our fabrication know-hows for the realization of semiconductor QD qubits.

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