超冷銣原子的磁轉移

Magnetic Transfer of Ultracold Rubidium Atoms

吳國豪

指導教授 ： 劉怡維

國立清華大學/理學院/物理學系/碩士(2013年)

https://doi.org/10.6843/NTHU.2013.00554

摘要

在本實驗中，我們將85Rb原子團由磁光陷阱移動到具有更高真空度的區域(science cell)，藉此提高原子生命週期；而我們移動原子的技術稱為磁轉移(magnetic transport)。在實驗中，我們量測了磁陷阱中原子的數量、密度以及溫度。
　　在實驗中我們利用Magnetic quadrupole trap成功的捕捉並移動原子，利用螢光法以及吸收影像法來量測並分析此原子團。最終我們在磁光陷阱中捕捉了約1.6×108個85Rb(5S1/2, F=2)原子，並且loading約27%的原子到磁陷阱中，之後我們再將約89.5%的原子由磁陷阱移動到science cell，最終我們在science cell中可得到約3.85×107個銣原子，相當於磁光陷阱中原子數量的24%。
經由量測，磁陷阱中的原子在較低真空度的區域中生命週期約2.2秒，而經由磁轉移到science cell後，原子的生命週期約20秒。

關鍵字

冷原子 ； 磁 ； 磁轉移 ； 磁光陷阱 ； 磁陷阱 ； 銣原子

並列摘要

We transferred the cold 85Rb from magnetic-optical-trap (MOT) to another ultra-high vacuum chamber (science cell), in order to increase the lifetime of the ultra-cold atoms. Two chambers are connected using a 3 mm×63 mm tube as a differential pump to maintain a large pressure difference. In the experiment, we caught and transferred the atoms by a moving magnetic quadrupole trap which is mounted on a linear track. We have successfully transfer 24% of the MOT atoms to the science cell after optimizing various experiment parameters, such as: magnetic capture strength, magnetic trap depth, moving acceleration, moving speed and etc.
We measured the quantity of the atom using the methods of the absorption image and the fluorescence image. 1.6×108 atoms are trapped in the MOT, and 3.85×107 atoms are transferred to the science cell. In the first chamber (MOT), the lifetime of the 85Rb atom is about 2.2sec.After transporting, the lifetime is increased to 20 sec. The total transfer sequence is only 2 sec and the lifetime of the cold atom has been inceased by an order of magnitude.

並列關鍵字

Rubidium ； Magnetic transfer ； Magnetic trap ； MOT

參考文獻

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