噪声对双势阱玻色-爱因斯坦凝聚体系自俘获现象的影响

Influence of noise on self-trapping of Bose-Einstein condensates in double-well trap

研究了对称双势阱玻色-爱因斯坦凝聚体系(BEC)存在均匀噪声或高斯噪声时的自俘获现象.结果发现噪声的存在破坏了自俘获现象的临界行为特征,使得原来约瑟夫森振荡和自俘获之间的临界点变成了一个过渡区域,而且噪声强度越大,这个过渡区域展得越宽.同时发现,对于确定的相互作用强度,当噪声强度增大到一定程度时,相平面会出现混乱,如果这时固定噪声强度增大相互作用强度,相平面中的轨道会重新出现.对纯量子系统加噪声后,自俘获同样不存在临界值,而是存在一个临界区域,且随噪声的增强临界区域会展宽.与平均场近似情况下不同的是,纯量子情况下噪声促进自俘获的产生,且噪声越强自俘获越明显.

In this paper we study serf-trapping of Bose-Einstein condensates in a symmetric double-well potential with uniform noise or Gaussian noise existing respectively. We find that both uniform noise and Gaussian noise destroy the critical behavior of selftrapping with the interaction increasing and create a transition zone between Josephson oscillation and self-trapping, between which exists a critical point originally. Furthermore, the stronger the noise becomes, the wider the transition zone is. Meanwhile, we find that the phase space falls into complete confusion when we increase noise intensity to a certain extent with interaction fixed, and the trajectories reappear after we increase the interaction without increasing the noise intensity. In the fullquantum situation, when noise exists there is a transition zone instead of a critical value, and stronger noise creates wider transition zone, which is the same as in mean field treatment. What is different is that in full-quantum situation noise creates self-trapping, and the stronger the noise, the more obvious the self-trapping becomes.