我們架設了一套銫原子雙磁光聚來冷卻凝聚銫原子，雙磁光聚系統的真空結構主要由兩個可獨立運作的真空系統互相連結，連結上選用氣導極低的管路，因此擁有原子源（Cs and Rb）的那一側將會處在較低的真空度，而另一側能因Differential Pumping而抽氣至超高真空的範圍。

　　雙磁光聚系統的優點是在低真空度側，以較高的Loading Rate將原子預先冷卻後，用另一道雷射均勻的推到超高真空側，以另外一套磁光聚系統把已經處在低溫的原子抓住並再次冷卻壓縮，超高真空下的第二個磁光聚將因背景氣體壓力極小而較為穩定而能承受較長時間的壓縮與蒸發冷卻，到達更低的溫度，到目前為止我們低真空側的氣壓約2．10-8Torr而高真空側約在5．10-10Torr。
　　
　　雷射方面使用Sacher Lasertechnik的TEC 100的雷射做為主MOT（Magneto-Optical Trap）雷射，它採用外部光柵的回饋來達成頻率的調變與2MHz的窄頻寬，除了MOT Beam外我們用另一台TEC 100來作為Repmper Beam以將off-resonant的原子打回Cooling Cycle，這兩套系統都使用DFSAS（Doppler-Free Saturation Absorption Spectroscopy）來作為穩頻。
　　
　　磁場方面採用1/8”銅管通以冷卻水，在主真空腔上下兩側各纏繞120圈，並在真空腔中央產生2.15 Gauss/cm．A的磁場梯度。
　　
　　這套系統在完成後將能夠進行光晶格，Dipole Trap，BEC，高精密能階量測，原子分子碰撞以及量子運算的基礎實驗。

　　We constructed a Double Magneto-Optical Trap (MOT) System in order to trap and cool down Cs atoms. The vacuum part of the system is composed of two independently running vacuum system connected with a low conductance tubing. The part near Cs atom source will be at lower vacuum and the other part at high vacuum, which is called differential pumping.

　　Double MOT System is preferred because at lower vacuum side MOT could collect Cs atoms much faster and could be homogeneously pushed into higher vacuum area, where MOT could have longer lifetime for further cooling and experiments. Lower background gas pressure can save more time for evaporative cooling, further compression to arrive lower temperature and higher phase density. By now our system have 2x10-8 Torr at lower vacuum side and 5x10-10Torr at higher vacuum side.
　　
　　Magnetic field is constructed by 2 coils, each in 120 turns 1/8” copper tubing and after cooling water running through it could bear 40A at the temperature of 43℃.These coils are spatially oriented in Anti-Helmholtz scheme and generate 2.15 Gauss/cm-A at trap center.

　　We use one TEC100 (Sacher Lasertechnik) for main MOT beam and the other for repumper beam. TEC100 uses grating feedback to reduce the laser bandwidth to 2MHZ, which is suitable for hyperfine structure. MOT beam is divided into six beams and conducted to cross as three pairs of counter propagating beams at MOT center. Repumper beam is directly conducted to run across MOT center in order to pump off-resonant atoms back to cooling cycles. These two laser uses Doppler-Free Saturation Absorption Spectroscopy (DFSAS) for frequency lock.

　　After accomplishment of this system, we could do optical lattice, dipole trap, BEC, hyper fine structure, atom/molecules collisions at ultracold temperature and basic Quantum Information Science (QIS) experiments.

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