單一半導體量子點之量子糾纏態及量子操控

Abstract

半導體量子點近似於完美的二能階系統，已被證實在量子資訊及量子運算有高度 應用價值，例如以單一量子點產生量子光源或以量子點建構固態量子位元。本計畫針 對量子點之量子光源以及固態量子位元兩大主題，擬研究量子點之量子糾纏光子輻 射，以及量子點能階之量子同調操控。主要研究議題包括：(1)量子點細結構分裂調變 以及糾纏光子輻射；(2)高效率糾纏光子光源；(3)量子點激子態之相位演化及操控； (4)量子點之電磁波引發透明現象；(5) 半導體及量子點自旋克爾效應。本研究將建立 糾纏態的偵測與分析方法，並結合耦合共振腔產生高效率糾纏光子對。此外也將利用 激子細結構分裂，研究其激子態相位演化及操控方法，藉此達到以量子點為媒介轉換 光子的偏振態。我們試圖在固態量子點系統中，實現原子系統的電磁波引發透明效應， 進而研究其慢光及非線性現象。本研究也將發展偵測單一自旋態的磁光克爾效應的精 密量測技術，進而研究量子點單一自旋態的操控方法。

Semiconductor quantum dots (QDs) have been considered as nearly ideal two-level systems and proven to be very promising for applications in quantum information science and quantum computations, such as using single QDs as quantum light sources or as solid-state quantum bits. In this project, following the two main themes of QD-based quantum light sources and solid-state quantum bits, we propose to study the quantum entanglements of the emitted photon pairs and quantum coherent controls of exciton states for quantum gate operations. The targets include: (1) The control of exciton fine-structure splitting and the generation of entangled photon pairs; (2) Highly efficient QD-based entangled photon sources; (3) The detection and control of quantum phase evolutions of exciton states in QDs; (4) Electromagnetically induced transparency in single QDs; (5) Magneto-optical Kerr effect of single spin in single QDs. We will establish the detection and analysis methods for the emitted entangled photons. We will design and fabricate suitable coupled microcavities with embedded QDs for generating efficient entangled photon pairs. In addition, the detection and control of quantum phase evolutions of exciton states in QDs will be studied. By controlling the exciton fine-structure splitting, the control of polarization states of single photons can be realized by mediating single QDs. We will also try to implement the electromagnetically induced transparency effect in QD systems, and by which to study the phenomena of slow light and its nonlinear optical properties. We intend to establish the technique of detecting single spins in single QDs based on the magneto-optical Kerr effect for the study of controlling single spin state in solid state environments.