非线性三能级体系的绝热朗道-齐纳隧穿

Adiabatic Landau-Zener tunnelling in nonlinear three-level system

研究了绝热条件下非线性三能级体系的朗道-齐纳隧穿.通过研究体系的本征值和本征态,发现当非线性不是很强时,三个能级的结构与线性情况相似,但中间能级所对应本征态的性质分段,这种分段导致绝热定理被破坏,引起所谓的绝热隧穿现象.由于本征态的不稳定性,造成隧穿率的混乱.当非线性较强时,能级结构发生非常复杂的扭曲,使绝热定理被更加严重地破坏.还讨论了这个模型在三势阱波色-爱因斯坦凝聚体系中的可能应用.

We investigate adiabatic Landau-Zener tunnelling in nonlinear three-level system. The levels and tunnelling probability are studied with respect to the nonlinearity. For weak nonlinearity, the structures of the levels are smooth and similar to their linear counterparts. However the eigenstates of the middle-level will be unstable for some system parameters, which leads to the adiabaticity to break down and the tunnelling probability chaotic. For strong nonlinearity, the structures of the levels are distorted, including double-ring-like distortion in lower-level and butterfly-like distortion in upper-level. The adiabaticity will be broken down more badly. Finally we give a possible application of the system in triple-well trapped Bose-Einstein condensates.