本實驗以二維磁光陷阱(2D Magneto-Optical Trap;2D MOT)作為核心，藉 以實現電磁引發透明(Electromagnetically Induced Transparency;EIT)以及未來偏 振糾纏光子對的產生。
由於 2D MOT 其中一軸的位能井近似於 0，因此原子團會沿此量子軸 (quantization axis)延伸而呈現橢球形。若將光子沿量子軸入射可增加光子與物質 交互作用的機率，並且由於此軸路徑上近乎無磁場梯度，在 EIT 與四波混頻 (Four Wave Mixing;FWM)時不需在意磁場所產生的量子退相干(quantum decoherence)。
我們的系統由兩台雷射及一台 tapered amplifier(TA)的架構組成，其中一台 雷射為外腔雷射，作為 master laser，另一台則是一般二極體雷射，作為 slave laser。
此次主要的目標在於穩定 MOT 以及 EIT 的量測，其中的原理參考了史丹 佛大學的 S. E. Harris 教授的文章 1,2，並選用 Rb87 直交架設 (right-angle setup， 即 coupling & probe 呈 90 度夾角) ，以便為後續 FWM 做準備。

In this thesis, we utilize 2D MOT (Magneto-Optical Trap) for realizing EIT (Electromagnetically Induced Transparency) and generating polarization-entangled photon pairs in the near future.
The cold atoms may expand as ellipsoidal cloud due to the zero-line field which we consider as quantum axis in 2D MOT. The photon-atom interaction could be enhanced if the photons propagate in this direction. Besides, there is almost no magnetic field gradient on the quantum axis. As a result, we can neglect quantum decoherence in EIT and FWM (Four Wave Mixing).
There are two lasers and a TA (tapered amplifier) in our system. One of them is ECDL (external cavity diode laser), as a master laser; another is a regular diode laser, as a slave.
Our goals are MOT stabilization and EIT measurements. We consult the articles1,2 from professor S. E. Harris at Stanford before building the system, and chose Rb 87 right-angle setup in order to get fully entangled biphotons by FWM in the future.

摘要 ...........................................................................................................................i
誌謝 ..........................................................................................................................iii
第一章 實驗相關理論 ...................................................................................................1
1.1 MOT 理論 .............................................................................................................1
1.2 EIT 理論 ...............................................................................................................5
1.2.1 EIT Hamiltonian...............................................................................................6
1.2.2 Von Neumann Equations...............................................................................11
1.2.3 Density matrix 之解 ......................................................................................13
1.2.4 電擊化率(Electric Susceptibility) χ ...............................................................15
1.2.5 都卜勒效應 20 1.2.6 超精細結構與偏振光下的 EIT..........................................21
第二章 實驗儀器與架設...............................................................................................26
2.1 Master Laser 光路...............................................................................................27
2.2 飽和吸收光譜(Saturation Spectroscopy)優化.....................................................28
2.3 Tapered Amplifier(TA)頻譜 ................................................................................31
2.4 TA controller—LDC2500B 操作......................................................................... 33
2.5 Probe beam 光路 ...............................................................................................34
2.6 Coupling beam 光路 ..........................................................................................38
2.7 光電倍增管(Photomultiplier tube;PMT) ..............................................................40
2.8 時序控制裝置:Timing box——SRS_DG535 .........................................................42
2.9 EOM 掃頻 ...........................................................................................................46
2.10 水冷機(Chiller)—NESLAB_HX150 .....................................................................48
第三章 實驗 結果與數據處理 ......................................................................................49
3.1 原子團 OD(Optical Density) ................................................................................49
3.2 Small-angle measurements(小角度量測) ...........................................................50
3.3 Right-angle measurements(直交量測) ...............................................................52
3.4 結論 ...................................................................................................................59
實驗注意事項 .............................................................................................................60
參考文獻 ....................................................................................................................61

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