基於電磁誘發透明機制的同調光記憶體之光場轉換

Light field conversion based on coherent optical memory using electromagnetically induced transparency scheme

林聖翔(Sheng-Xiang Lin)

指導教授 ： 陳應誠

共同指導教授 ： 林俊達(Guin-Dar Lin)

國立臺灣大學/理學院/物理學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201802546

摘要

基於電磁誘發透明的同調光記憶體提供了一個工具去轉換探測光[1,2]，藉由在讀取的過程中，操縱不同的激發原子同調的控制場，去轉換探測光的偏極、頻率跟行進的方向。然而，實際執行上無可避免地會遇到一些問題，舉例來說，在真實原子中，因為儲存與讀取過程的躍遷偶極矩的不匹配而導制的能量損失[3]。在本文中，我們發現儘管在這種條件下，轉換光的能量效率可以超過存取光的效率，而且這取決於在儲存與讀取過程的躍遷偶極矩的比值，我們提供了一個詳細的理論計算討論相關的問題，以及提供了在冷銫原子實驗上的數據;在我們的分析中發現，在讀取的過程中，讀取過程的頻寬與剛從原子同調取出來的光的比值可以解釋這一類型的能量損失。

關鍵字

同調光記憶體 ； 電磁誘發透明 ； 光場轉換

並列摘要

Coherent optical memory based on electromagnetically induced transparency (EIT) provides a tool to convert the polarization, frequency, and propagation direction of the probe light by using different control fields driving an atomic transition during the retrieval process [1,2]. However, it is inevitable to face some issues, such as energy loss which is caused by the different transition dipole moments between two transitions used in storage and retrieval processes in real atoms [3]. In this thesis, we found that despite in this condition, efficiency of the converted probe pulse could surpass the one of stored light pulse, and it depends on the ratio between the transition dipole moment in the retrieval transition and the one in the storage transition. We provide a detailed theoretical study on this issue and present the experimental results in cold cesium atoms. Moreover, the results could be understood by
analyzing the spectral bandwidth in retrieval processes. In our analysis, the ratio of the spectral bandwidth between the retrieval process and the pulse retrieved from the ground-state coherence can account for this kind of loss.

並列關鍵字

Coherent optical memory ； Electromagnetically-induced transparency ； light field conversion

參考文獻

[1] Yong-Fan Chen, Pei-Chen Kuan, Shih-Hao Wang, Chang-Yi Wang, and Ite A. Yu. Manipulating the retrieved frequency and polarization of stored light pulses. Opt. Lett., 31(23):3511–3513, Dec 2006.

[2] Alexey V. Gorshkov, Axel André, Michael Fleischhauer, Anders S. Sørensen, and Mikhail D. Lukin. Universal approach to optimal photon storage in atomic media. Phys. Rev. Lett., 98:123601, Mar 2007.

[3] Pei-Chen Guan, Yong-Fan Chen, and Ite A. Yu. Role of degenerate zeeman states in the storage and retrieval of light pulses. Phys. Rev. A, 75:013812, Jan 2007.

[4] Pieter Kok, W. J. Munro, Kae Nemoto, T. C. Ralph, Jonathan P. Dowling, and G. J. Milburn. Linear optical quantum computing with photonic qubits. Rev. Mod. Phys., 79:135–174, Jan 2007.

[5] Mark Fox. Quantum optics: an introduction. Oxford Master Series in Atomic, Optical and Laser Physics. Oxford Univ. Press, Oxford, 2006.