介由移動位能陷阱的量子粒子傳輸

Abstract

近期的粒子捕捉技術帶來了藉由移動中位能陷阱傳輸單一量子粒子的可能性。在我們的研究中，我們展示了一系列的數值模擬來討論不同加速方式所造成的粒子逃脫位能陷阱的機率。我們可以用在慣性位能中因為額外的加速度而產生的移動座標系來演示位能陷阱運動的影響。於此，有兩個逃脫機制，其一為因為慣性位能而產生的位能壘所致的穿隧效應，另一個則是因為座標突然改變而造成的Nonadiabatic transition。在此論文中我們討論在已給定的傳輸距離及傳輸時間下，逃脫位能陷阱的機率與傳輸量子粒子的關聯性。 我們發現以下的趨勢:

1.長距離與短時間下的傳輸會有較高的逃脫機率

2.在短距離和長時間下的傳輸 會有較低的逃脫機率

3.定值的加速度在高逃脫機率下有較良好的作用(長時間與短距離)

4.在加速度為高階時間函數時,在低逃脫機率區域中能有效降低逃脫機率

Recent development in the trap technology has opened new possibilities in the transport of a quantum particle by a moving trapping potential. In this study, we performed a series of numerical simulation to discuss the probability to escape from the trapping potential with various types of acceleration schemes. The effect of the trap potential motion can be taken by introducing the moving frame, where the inertial potential due to the acceleration is added. There are two escape mechanisms. One is tunneling due to the potential barrier created by the inertial potential. The other one is the nonadiabatic transition due to the sudden change of frame. In this thesis we discuss the escape probability associated with the transport of a quantum particle for given distance and time for transport. We have found the following tendencies:

1. Long distance and short time transport has large escape probability. 2. Short distance and long time transport has small escape probability. 3. Constant acceleration scheme works well for a transport in the large escape probability region (short distance and long time). 4. The acceleration as function of time should be high order polynomial to suppress the escape probability in the small escape probability region.