Laser cooling and optical trapping of potassium with tunable interaction toward quantum gas production

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/74298

Title:	Laser cooling and optical trapping of potassium with tunable interaction toward quantum gas production
Authors:	廖冠博;Liao, Guan-Bo
Contributors:	物理學系
Keywords:	鉀-39 原子;雷射冷卻;光學陷阱;磁費許巴赫共振
Date:	2017-09-25
Issue Date:	2017-10-27 13:42:43 (UTC+8)
Publisher:	國立中央大學
Abstract:	本實驗的目標是要實現鉀-39 原子的全光學式量子氣體，我們透過小角度交叉重疊兩道光學陷阱(optical dipole trap,ODT)來增加捕獲的原子數目並限縮原子在軸方向的運動。使用這個長寬比小於 20 的複合式光學陷阱，可以穩定補捉 1 ~ 2106個鉀原子。然後我們使用磁費許巴赫共振技術去控制原子間的交互作用，並測量了從 20 G 至 560 G 之間的所有譜線，我們發現許多譜線在理論工作的文獻中有發表，但目前沒有任何的實驗發表記錄，我們藉由費許巴赫共振技術的幫助將鉀原子團的溫度降至 10 μk 以下時發現，S 波散射長度與二體彈性碰撞截面積被有效放大，藉由費許巴赫共振的幫助，通過強制蒸發冷卻，最佳相空間密度提高到 7 10-3。 ;The goal of this experiment is to realize all-optical 39K Bose-Einstein Condensates (BEC). We improved the trap loading of a near-IR laser by crossing two beams at a small angle for good loading and tighter axial conﬁnement. With this composite trap, we can routinely trap 1 ∼ 2×106 cold 39K atoms and conﬁne them in a potential well with a trap aspect ratio of less than 20. We then used magnetic Feshbach resonance (FR) to control the atomic interaction in the optical trap. The S-wave scattering length is greatly tuned to improve the two-body elastic collision rate in the trap. We scanned the magnetic ﬁeld from 20 ∼ 560 G and found intra-spin and inter-spin resonances. Several peaks we found were predicted by literature but not experimental reported to our knowledge. With the help of FR, the best phase space density was increased to 7×10−3 by force evaporative cooling.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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