玻色-爱因斯坦凝聚体在光势阱中的量子隧穿

QUANTUM TUNNELING OF BOSE-EINSTEIN CONDENSATES IN OPTICAL LATTICES

微观粒子因具有波动性而能以一定的概率穿过比它动能更高的势垒,这一现象称为隧道效应.玻色－爱因斯坦凝聚体在不同的囚禁势阱中表现出不同的隧穿特性.文章作者用周期瞬子方法首次研究了光势阱中玻色－爱因斯坦凝聚体的量子隧穿.研究表明，处在光势阱中的玻色－爱因斯坦凝聚体不仅表现出Landau－Zener隧穿，而且出现新的Wannier－Stark隧穿，Wannier－Stark隧穿系数大约是Landau－Zener隧穿系数的1000倍，并得到了隧穿率随温度的变化规律，包括经典热激活、热助隧穿和量子隧穿.理论的计算结果与Yale大学和意大利INFM研究组关于Landau－Zener隧穿的实验结果相符合，同时给出了如何在实验上发现Wannier－Stark隧穿的参数区间.

Abstract In quantum tunneling a particle with energy E can pass through a high potential barrier V(>E) due to the wave character of the particle. Bose\|Einstein condensates can display very strong tunneling depending on the structure of the trap, which may be a double\|well or optical lattices. We employed for the first time to our knowledge the periodic instanton method to investigate tunneling of Bose\|Einstein condensates in optical lattices. Our results show that there are two kinds of tunneling in this system, Landau\|Zener tunneling between extended states of the system and Wannier\|Stark tunneling between localized states of the system, and that the latter is 1000 times faster than the former. We also obtain the total decay rate for a wide range of temperature, including classical thermal activation, thermally assisted tunneling and quantum tunneling. Our results agree with experimental data in references[1, 2].Finally, we propose an experimental protocol to observe this new phenomenon in future experiments. periodic instanton, Wannier\|Stark localization, Landau\|Zener tunneling, Wannier\|Stark tunneling