雷德堡電磁波引發透明效應之研究

本文主要探討雷德堡態的電磁波引發透明效應(electromagnetic induced transparency，簡稱EIT)的相關研究。大致上可以分成理論和實驗兩個部分: 第一部分會先從雷德堡EIT穿透率的理論計算(第一章)及雷德堡能階的躍遷頻率和拉比頻率⋯等等一些實驗上所需要計算的參數(第二章)。未來實驗上所設計的能階，都能夠經由前述章節的介紹來預估實驗結果。第二部分將呈現我們的實驗結果。實驗的探測光頻率為 |5S1/2 F=2> →|5P3/2 F=3>，耦合光的頻率為|5P3/2 F=3>→nS1/2 F=2或nD5/2 F=2,3,4的雷德堡態。量測到的最大穿透率在38D5/2 F=2,3,4為10.28%。鑒於以前實驗室EIT的實驗經驗，探測光在EIT的系統中和耦合光相較之下為一弱光，不會影響EIT的穿透率。但是我們卻在優化EIT穿透率時發現會有一個穿透率最佳值對應於某一個探測光的拉比頻率(第三章)。同時也讓我們好奇是否二能階吸收的系統也能發現到一樣的現象(第四章)。最後第五章，我們將以795 nm雷射的EOM微分光譜模擬藍光雷射的鎖頻，使未來在EIT相關的應用實驗上能夠將藍光雷射頻率固定在我們所需要的躍遷上。

關鍵字

電磁波引發透明效應；雷德堡態；微分光譜；電光調制器

並列摘要

We studied the spectrum of electromagnetic induced transparency (EIT) driven to Rydberg states using room-temperature 87Rb atoms. We can divide this article into theory and experiment two parts. In the first part, we introduce the analytical transmission maximum theory of cascade EIT (chapter 1) and some experimentally parameters such as transition frequency to Rydberg state, coupling Rabi frequency etc…(chapter 2) In the future, we can calculate these parameters to predict the experiment result. In the second part, chapter three is the experimentally details of our EIT system, which is a probe field drove the transition from a 5S1/2 ground state to a 5P3/2 excited state, and a coupling field drove the transition from the 5P3/2 state to a Rydberg state of 55D5/2 or 57S1/2. The two fields form the cascade EIT scheme. We measured the EIT peak height in transmission as a function of the probe Rabi frequency at different polarization configurations, orbital, principle number and coupling power. The data showed that the EIT peak height reaches a maximum at an optimum probe Rabi frequency instead of monotonically decreasing with the probe Rabi frequency. We also thought whether a saturated absorption system has the same phenomenon. Because the system is also formed by a strong saturation beam and a weak probe beam counter propagating through the cell (chapter 4). Finally, in order to simulate frequency locked of blue laser, we studied the differential spectrum of 795 nm laser with EOM. We can modulate the Rydberg EIT signal with EOM to lock the blue laser’s frequency in the future.

並列關鍵字

EIT ； Rydberg state ； FM spectrum ； EOM

參考文獻

[1] [2] 游秩群，”熱原子的電磁波引發透明光譜及冷原子的四波混頻過程相位不匹配之理論研究”，國立清華大學，碩士論文，民國103年7月

[4] [5] M. Mack, F. Karlewski, H. Hattermann, S. H¨ockh, F. Jessen,D. Cano, and J. Fort´agh,” Measurement of absolute transition frequencies of 87Rb to nS and nD Rydberg states by means of electromagnetically induced transparency,” Phys. Rev. A 83, 052515 (2011)

[6] I. I. Beterov,* I. I. Ryabtsev, D. B. Tretyakov, and V. M. Entin, “Quasiclassical calculations of blackbody-radiation-induced depopulation rates and effective lifetimes of Rydberg nS, nP, and nD alkali-metal atoms with n ≤80,” Phys. Rev. A 79, 052504 (2009)

[8] J. Deiglmayr, M. Reetz-Lamour * , T. Amthor, S. Westermann,A.L. de Oliveira, M. Weidemu¨ller, ” Coherent excitation of Rydberg atoms in an ultracold gas,” Optics Communication 264 (2006) 293-298

[9] Jonathan D. Pritchard,‘’Cooperative Optical Non-linearity in a blockaded Rydberg Ensemble”, Durham University, 2011

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雷德堡電磁波引發透明效應之研究

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