玻色爱因斯坦凝聚中量子纠缠态的产生与量子控制

In order to explore the application of Bose-Einstein Condensates (BECs) to precision mesurement, we are going to study the quatnum control and generation entanglement with BECs. Firstly, starting with the definition on entanglement measures, the difference between the classical state with quantum entanglement (useful for precision measurement) is expected to be explained in terms of physical characters. Based on quantum dynamics of Bose Josephson Junction, involving the possible decoherence elements, such as dephasing with enviroments, atom loss induced by three-body collision, the best methods to generate the useful entanglement for precision measurement is expected to be explored with the help of optimal control theory. From the quatnum dynamics of Bose-Einstein Condensates trapped by one dimensional ring potential and its stationary solutions (including a few defects), we are going to investigate the possibility to generate the entanglement and find some useful initial states for precision measurement, and by solving the quantum evolutions for the wave function suffered atomic interaction, to find the conditions for realization the wave packet revival. Futher more, we extend the Talbot-Lau effect to the nonlinear case, and then discuss its application to quantum precision measurement. This proposal could be crucially important for the advancement of physics from both a fundamental and a technological point of view.

本项目以量子控制和在玻色爱因斯坦凝聚体中产生量子纠缠态为目的，以期对利用该凝聚体进行量子精密测量的物理原理进行探索性研究。主要研究内容有：从量子纠缠定义出发，深入理解对精密测量有利的量子纠缠态的物理本质，从物理特性上理解量子纠缠态与经典态在测量上的不同；以玻色约瑟夫森结量子动力学为基础，考虑具体操作中的位相耗散、粒子数损失等因素，利用优化理论寻找在凝聚体中产生最佳纠缠态的途径；以处于环状势中凝聚体的定态解（含杂质）及其在周期驱动外场下的量子动力学为基础，研究在此系统中产生量子纠缠态的可能性、寻找有利于精密测量的初始态。并通过对含有非线性相互作用下的量子动力学求解，研究在此系统中波函数的动力学演化特征，从而揭示其出现周期恢愎的条件。并讨论非线性Talbot-Lau效应及其在量子精密测量中的可能应用。本研究无论从量子理论本身，还是从量子精密测量应用的角度来看，都有非常重要的意义。

在基金的资助下，主要开展了以超冷原子气体为主体的、关于在量子纠缠产生、纠缠判据及其在提高量子测量方面的基础理论研究工作，并在相关方面上取得了具有国际影响力的研究工作，其中己发表PNAS一篇，PRL一篇，PRL接收一篇。同时，还合作开展了在强激光场中原子、分子电离中的量子现象的相关研究，对认识这一电离过程有积极推动作用，合作发表PRL文章一篇。.相关的研究工作，对深入认识在超冷原子体系中或少体系统中进行量子纠缠制备以及开展量子增强的干涉仪研究具有较为重要的理论指导意义。特别是，对纠缠这一重要的量子特性的研究有了进一步的深入认识，对以此为基础的量子信息和量子计量具有重要的理论意义。