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Study of quasi-conserved quantities in atomic BEC and dilute quantum gases

原子BEC和稀量子气体中准守恒量的研究

基本信息

批准号：
15540381
负责人：
WATANABE Shinichi
金额：
$ 2.3万
依托单位：
The University of Electro- Communications
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

We studied adiabaticity and nonlinear dynamics in the context of the manipulation and control of the Bose-Einstein condensate (BEC) made of an atomic gas. We conducted a pilot study of the mechanism for the unanticipated creation of quantum vorticies in an experiment pertaining to the construction of a beam-splitter in a BEC-interferometer. Since the numerical techniques and the computer codes required for the analysis of BEC have much in common with those for the ultra-short laser pulses and their application to atomic physics, we observed a new development by applying the techniques to the ionization of atoms in ultra-intense laser fields and to the high-harmonics generation.With a view to the representation of two-body interactions, we employed a computation scheme based on theoretical chemistry, and evaluated the mobility of an ion in a low-temperature gas of helium, thereby carrying out a dynamical analysis of the mobility and comparing it with experimental results. Quite unexpectedly, we pinned down the cause of the hitherto unsolved polarization-limit problem.In addition to such discoveries, there emerged new challenges. For instance, the transformation of an atomic pair into a molecule at ultra-low temperatures constitutes a nonlinear STIRAP problem, which is an important issue under the present theme and is all the more applicable to related problems because of the universal mathematical nature of the nonlinear STIRAP problem. We expect more challenges will appear in relation to the adiabaticity and nonlinear dynamics in many-body physics at low temperatures. A new experimental development is equally likely in the field of ultra-short laser pulses and their interactions with atoms. We look forward to contributing to further progress.

我们研究了由原子气体构成的玻色-爱因斯坦凝聚体（BEC）的绝热性和非线性动力学。我们在bec干涉仪中分束器的构造实验中，对量子涡旋的意外产生机制进行了初步研究。由于BEC分析所需的数值技术和计算机代码与超短激光脉冲及其在原子物理中的应用有许多共同之处，我们观察到将这些技术应用于超强激光场中原子的电离和高次谐波的产生有了新的发展。针对两体相互作用的表征，我们采用了基于理论化学的计算方案，对离子在低温氦气中的迁移率进行了评估，从而对迁移率进行了动力学分析，并与实验结果进行了比较。出乎意料的是，我们找到了迄今尚未解决的极化极限问题的原因。除了这些发现之外，还出现了新的挑战。例如，原子对在超低温下向分子的转变构成了一个非线性STIRAP问题，这是本主题下的一个重要问题，由于非线性STIRAP问题具有普遍的数学性质，因此更适用于相关问题。我们预计低温下多体物理中的绝热和非线性动力学将面临更多的挑战。在超短激光脉冲及其与原子的相互作用领域，同样有可能出现新的实验进展。我们期待着为取得进一步进展作出贡献。