通常在做拉曼轉換(Raman transition)的時候，都會假設轉換是具有同調性質的，也就是說轉換後的原子，是在兩態之間具有相干態(coherent state)。然而一般在實驗上，測量拉曼轉換有多少比例由狀態A轉移到狀態B時，無法分別是轉換過程是在兩態之間具有相干態後，因為觀測而塌縮，亦或是從狀態A換到狀態B，之後被探測到而已。
在此篇論文中，將會介紹利用雷射冷卻，讓銣(Rb85)原子冷卻，並透過拉比震盪(Rabi oscillation)以及光波拉曼(Optical Raman)混和的拉姆齊干涉儀(Ramsey interferometry)，檢測原子經過拉曼之後的同調性質。為此利用磁光陷阱(Magneto-tptical trap)，捕捉並冷卻原子團至約10μK，隨即利用拉比震盪製備量子相干態並打入與微波不同相位的光波拉曼，以此掃描不同情況下的機率分布，以反推原子經過光波拉曼的同調性。
關鍵字:拉曼躍遷同調性、拉姆齊干涉儀

In this thesis, we will introduce how to test the coherence of atom which is affected by a Raman transition. For this purpose, we build a Magneto-Optical trap system to capture and cool down atoms, which are Rubidium 85. After cooling, our atoms are cooled to 10 µK . Then, we prepare atoms in coherent state by using a Rabi oscillation. Finally, we inject a Raman pulse and scan the phases between Rabi oscillation and Raman transition to inference how the coherence of atom is. In the end, we demonstrate that Raman pulses with different direction of the external magnetic field will transfer atoms into states with different coherences.

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