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系統識別號 U0026-0509201300361600
論文名稱(中文) 磁光阱中低溫銫原子的電磁誘發透明
論文名稱(英文) Electromagnetically Induced Transparency of the Cold Cesium Atoms in a Magneto-Optical Trap
校院名稱 成功大學
系所名稱(中) 物理學系碩博士班
系所名稱(英) Department of Physics
學年度 101
學期 2
出版年 102
研究生(中文) 陳宏任
研究生(英文) Chen-Hung Ren
學號 L26001278
學位類別 碩士
語文別 中文
論文頁數 48頁
口試委員 指導教授-蔡錦俊
口試委員-陳泳帆
口試委員-黃守仁
口試委員-韓殿君
中文關鍵字 磁光陷阱  電磁誘發透明  銫原子 
英文關鍵字 magneto-optical trap  electromagnetically induced transparency  cesium 
學科別分類
中文摘要 我們使用磁光阱(Magneto-optical trap, MOT)凝聚了一個低溫銫原子團,數量為5.62×108 個原子,密度為3.03×1011 個/cm3,載入時間為761.81 ms,並在此低溫原子團中量測階梯式的電磁誘發透明(Ladder-type electromagnetically induced transparency)。實驗中使用探測雷射(Probe laser),從|62S1/2, F=4>耦合到中間態|62P3/2, F'=5>,和耦合雷射(Coupling laser),從|62P3/2, F'=5>耦合到最終態
|82S1/2, F"=4>,形成一個三能階系統。在此實驗中,我們將探測雷射頻率固定|62S1/2, F=4>到|62P3/2, F'=5>的共振頻率上,掃描耦合雷射頻率來得到無背景(background free)的電磁誘發透明光譜。當耦合雷射頻率於雙光子共振頻率時(two-photon resonance)可以得到電磁誘發透明的峰值位置。
我們分別使用抑制與恢復(Suppression and Recovery)和直接偵測探測光束穿透方法來觀察電磁誘發透明窗口的現象。抑制與恢復是當電磁誘發透明發生時原本被探測光束吹散的原子團因吸收降低而導致殘餘在磁光陷阱中的原子數變多,殘餘原子數變多意謂偵測到較強的螢光讀值,因為探測光束要足夠吹走磁光阱中的原子團所以強度不能太弱。適用於強探測光束情況下。而直接偵測探測光束的方式以弱探測光束情況下較為適合,因為太強的探測光束造成原子吸收部分遠小於未吸收部分導致整個電磁誘發透明光譜會有一個背景訊號存在著。實驗發現:直接偵測探測光束穿透的方法在低耦合雷射拉比頻率時可得到較好的訊噪比和較窄的電磁誘發透明窗口。實驗中,當耦合雷射的拉比頻率(Ωc)降低到2.15 MHz時,電磁誘發透明窗口線寬可小至1.72 MHz。此結果與相同實驗參數在室溫電磁誘發透明來做比較,我們發現,在同樣較小的Ωc情況下,低溫原子仍可得到較窄的電磁誘發透明窗口。
英文摘要 We construct the cold cesium atoms, which number is 5.62×108 atoms and density is 3.03×1011 atoms/cm3, by magneto-optical trap (MOT). The loading time is 761.81 ms. We applied the ladder-type electromagnetically induced transparency (EIT) in the cold cesium atoms. The three-level system is coupled by the probe field coupling the states"|62S1/2,F=4>" and "|62P3/2,F'=5>" , and the coupling field coupling the states"|62P3/2,F'=5>" and "|82S1/2,F"=4>" .In our experiment, we lock the probe laser frequency from"|62S1/2,F=4> " to "|62P3/2,F'=5> " and scan the coupling laser frequency to receive the background free EIT spectrum when coupling laser frequency is on two-photon resonance.
We observe the EIT window by the methods of suppression and recovery and directly detecting transmission of probe field, respectively. Suppression and recovery apply a probe laser to disperse cold atoms but it will be more residual cold atoms which mean higher fluorescence signal due to EIT. It will be suitable to strong probe laser because probe laser is enough powerful to disperse all of cold atoms in MOT. however, it will be better in low probe regime that I detect the transmission of probe laser directly. Probe laser is too strong that it exists a background signal in EIT spectrum because the absorption is less than part of unabsorption by cold atoms.The results with better signal-to-noise ratio and narrower EIT window are observed by directly detecting the transmission of probe field in lower coupling Rabi frequency. In ladder-type EIT, if the coupling Rabi frequency is lowered to 2.15 MHz, the linewidth of EIT window is narrowed to 1.72 MHz. We still find the smaller EIT linewidth is observed while EIT is applied in cold atoms, in comparison of that in room temperature cell, with the same lower coupling Rabi frequency.
論文目次 目次 Ⅰ
表目錄 Ⅲ
圖目錄 Ⅳ
中文摘要 Ⅵ
Abstract Ⅶ
誌謝 Ⅷ

第一章 簡介 1

第二章 實驗理論 3
2.1磁光陷阱理論 3
2.1.1 都卜勒冷卻(Doppler cooling) 3
2.1.2 磁光陷阱(Magneto-optical-trap) 5
2.2電磁誘發透明(Electromagnetically induce transparency) 7

第三章 實驗架設 11
3.1 磁光陷阱架設 11
3.1.1 雷射系統 11
3.1.2 真空系統 16
3.1.3 磁場線圈架設 17
3.2 電磁誘發透明系統架設 20
3.2.1 探測雷射(Probe laser) 20
3.2.2 耦合雷射(Coupling laser) 20
3.3 光路架設 21
3.3.1 磁光阱光路架設 21
3.3.2 電磁誘發透明光路架設 21

第四章 實驗結果與分析 23
4.1 磁光陷阱條件量測 23
4.1.1 冷原子團的載入時間 23
4.1.2 冷原子團的數量量測 25
4.1.3 冷原子團的密度量測 27
4.2 電磁誘發透明量測 29
4.2.1 抑制與恢復(Suppression and Recovery) 29
4.2.2 偵測探測光束法 31
4.2.3 光密度(Optical density) 32
4.2.4 頻率校正 34
4.2.5 實驗數據與分析 36

第五章 結論 41

參考文獻 42
附錄一 抑制與恢復數據擬合圖 45
附錄二 直接偵測探測雷射數據擬合圖 47
參考文獻 [1] Steven Chu, J. E. Bjorkholm, A. Ashkin, and A. Cable, Experimental Observation of Optically Trapped Atoms, Phys. Rev. Lett. 57, 314 (1986)
[2] E. L. Raab, M. Prentiss, Alex Cable, Steven Chu, and D. E. Pritchard, Trapping of Neutral Sodium Atoms with Radiation Pressure, Phys. Rev. Lett. 59, 2631 (1987)
[3] Wolfgang Ketterle, Kendall B. Davis, Michael A. Joff'e, Alex Martin, and David E. Pritchard, High Densities of Cold Atoms in a Dark Spontaneous-Force Optical Trap, Phys. Rev. Lett. 70,2253 (1993)
[4] D. Miller, R. A. Cline, and D. J. Heinzen, Far-off-resonance optical trapping of atoms, Phys. Rev. A. 47, 4567 (1993)
[5] A. Hemmerich and T. W. Hänsch, Two-dimesional atomic crystal bound by light, Phys. Rev. Lett. 70, 410 (1993)
[6] A. Hemmerich, C. Zimmermann and T. W. Hänsch, Sub-kHz Rayleigh Resonance in a Cubic Atomic Crystal, Euro-phys. Lett. 22, 89 (1993)
[7] J. D. Miller, R. A. Cline, and D. J. Heinzen, Photoassociation spectrum of ultracold Rb atoms, Phys. Rev. Lett. 71, 2204 (1993)
[8] Erica. Cornell , Carl E. Wieman, Bose-Einstein Condensation in a dilute gas; the first 70 years and some recent experiments, Nobel Lecture (2001) http://www.nobelprize.org/nobel_prizes/physics/laureates/2001/cornellwieman-lecture.pdf
[9] S. H. Autler and C. H. Townes, Stark Effect in Rapidly Varying Fields, Phys. Rev. 100, 703 (1955)
[10] A. Imamoglu and S. E. Harris, Lasers without inversion: interference of dressed lifetiome-broadened states, Opt. Lett. 14, 1344 (1989)
[11] Richard G. Brewer, E. L. Hahn, Coherent two-photon processes: Transient and steady-state cases, Phys. Rev. A 11, 1641 (1975)
[12] T. Zanon, S. Guerandel, E. de Clercq, D. Holleville, N. Dimarcq, and A. Clairon, High Contrast Ramsey Fringes with Coherent-Population-Trapping Pulses in a Double Lambda Atomic System, Phys. Rev. Lett. 94, 193002 (2005)
[13] K.-J. Boller, A. Imamolu, and S. E. Harris, Observation of electromagnetically induced transparency, Phys. Rev. Lett. 66, 2593 (1991)
[14] Hai Wang, David Goorskey, and Min Xiao, Enhanced Kerr Nonlinearity via Atomic Coherence in a Three-Level Atomic System, Phys. Rev. Lett. 87, 073601 (2001)
[15] A. Kasapi, Maneesh Jain, G. Y. Yin, and S. E. Harris, Electromagnetically Induced Transparency: Propagation Dynamics, Phys. Rev. Lett. 74, 2447 (1995)
[16] S. E. Harris and Y. Yamamoto, Photon Switching by Quantum Interference, Phys. Rev. Lett. 81, 3611 (1998)
[17] Jason J. Clarke and William A. van Wijngaarden, Hongxin Chen, Electromagnetically induced transparency using a vapor cell and a laser-cooled sample of cesium atoms, Phys. Rev. A 64, 023818 (2001)
[18] Carl Wieman, Gwenn Flowers, and Sarah Gilbert, Inexpensive laser cooling and trapping experiment for undergraduate laboratories, Am. J. Phys. 63, 317 (1995)
[19] John Weiner, Vanderlei S. Bagnato and Sergio Zilio, Paul S. Julienne, Experiments and theory in cold and ultracold collisions, Rev. Mod. Phys. 71, 1–85 (1999)
[20] 何宗勳,「銫原子中階梯式電磁誘發透明的躍遷特性」,國立成功大學物理研究所博士論文 (2013)
[21] 張瑞園,「綴飾態原子的量子干涉和雙原子分子的軌道角動量去耦合」,國立成功大學物理研究所博士論文 (2007)
[22] 何宗勳,「低溫銫原子中階梯狀能階的躍遷」,國立成功大學物理研究所碩士論文 (2007)
[23] 呂美如,「在雷射冷凝銫原子中做原子躍遷的精密量測」,國立成功大學物理研究所碩士論文 (2004)
[24] 楊景中,「雷射頻率對磁光聚的影響」,國立成功大學物理研究所碩士論文 (2001)
[25] Ray-Yuan Chang, Wei-Chia Fang, Bai-Cian Ke, Zong-Syun He, Ming-Da Tsai, Yi-Chi Lee, and Chin-Chun Tsai, Suppression and recovery of the trapping of atoms using a ladder-type electromagnetically induced transparency, Phys. Rev. A 76, 055404 (2007)
[26] 陳維甫,「利用電磁誘發透明測量銫原子雷德堡態的精確頻率」,國立成功大學物理研究所碩士論文 (2013)
[27] S. M. Iftiquar, G. R. Karve, and Vasant Natarajan, Subnatural linewidth for probe absorption in an electromagnetically-induced-transparency medium due to Doppler averaging, Phys. Rev. A 77, 063807 (2008)
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