矽基量子點元件和束縛電位的理論分析

Analysis of Silicon-based Quantum Dot Qubit Devices and Confinement Potential Profiles

劉上傑(Shang-Jie Liou)

指導教授 ： 管希聖

國立臺灣大學/理學院/物理學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202004129

摘要

近年來，半導體量子點因其成為構建實用量子計算機的有前途的候選者的前景而備受關注。本文主要研究由實驗同事設計和製造的Si-MOS量子位器件的理論模擬。從理論上得出的數值模擬和解析解將使我們對研究對象有更深入的了解。我們面臨的一個主要問題是，我們沒辦法很輕易知道當在較高的電位柵極上施加柵極電壓時，量子點的確切勢能分佈是如何。這可能取決於器件的幾何形狀，上柵極的結構以及上柵極與量子點量子位之間的距離。在這裡，我們開發了一種數學技巧，該技巧允許我們在量子位器件中量子點的深度獲得特定的勢能分佈。我們將此技術應用於調查具有不同電位柵極的兩種量子位器件的勢能曲線。一種設備是手指型結構，另一種是我們實驗同事製造的兩層MOS結構。然後，我們分析獲得的勢能曲線的保真度。可以將這種技術應用於任何量子位設備，以獲得針對特定目標勢能曲線的柵極電壓的初始調整。我們還使用配置交互方法計算並仿真了兩層Si-MOS量子位器件的電荷穩定性圖。

關鍵字

量子位元

並列摘要

In recent years, semiconductor quantum-dot qubits have attracted much attention due to their prospect of being a promising candidate for building a practical quantum computer. This thesis focuses on the device modeling of a Si-MOS qubit device designed and fabricated by our experimental colleagues. The use of numerical simulation and analytical solutions derived theoretically will allow us to have a deeper understanding of the research target. One major problem we face is what the exact potential energy profile at the quantum dot channel is when we apply the gate voltage on upper accumulation and depletion gates. This may depend on the geometry of the device, the structure of the upper gates and the distance between the upper gates and the quantum dot qubit. Here we develop a target gating technique that allows us to obtain a specific target potential energy profile at the depth of the quantum dot channel in a qubit device by tuning the upper gates. We apply this target gating technique to investigating the potential energy profiles of two qubit devices with different upper gates. One device is the finger-type structure, and the other is the two-layer structure fabricated our experimental colleagues. We then analyze the fidelity of the obtained potential energy profiles. This technique can be applied to any qubit device to obtain initial tuning of the gate voltages for a certain target potential energy profile. We also calculate and simulate the charge stability diagram for the two-layer Si-MOS qubit device by using the configuration interaction method.

並列關鍵字

qubit

參考文獻

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