超冷原子系统的相变及其普适行为研究

项目名称： 超冷原子系统的相变及其普适行为研究

项目编号： No.11334001

项目类型： 重点项目

立项/批准年度： 2014

项目学科： 数理科学和化学

项目作者： 周小计

作者单位： 北京大学

项目金额： 320万元

中文摘要： 超流相变中的普适临界现象是物理学的基本问题，超冷玻色原子气体的出现为从实验上研究这类普适临界行为提供了新的机遇。该系统的气体特性使得许多在液氦里无法实现的量子调控和探测手段成为可能。针对这些新的机遇，紧密结合理论，拟集中开展如下实验研究：(1) 利用Talbot-Lau（TL）干涉仪研究磁阱中原子气体的关联在临界区域的普适行为，分析有限尺度和相互作用对临界行为的影响，得到系统关联临界指数的高精度测量结果；(2) 建立光阱中的玻色－爱因斯坦凝聚系统并加上无序势，研究系统的临界行为和相图；(3) 结合TL干涉仪和高阶关联的分析，研究不同空间构型光晶格系统中的新奇量子相变及其普适行为。通过这些研究，建立和发展TL干涉仪这一探测临界关联的新手段，实现不同物态的相变，争取实验上首次观察到超冷玻色气体在整个临界区域的普适关联行为，探索无序势和光晶格作用下玻色气体中超流相变的新的临界行为。

中文关键词： 超冷原子气体;相变;普适临界行为;光晶格;无序势

英文摘要： Critical phenomenon in superfluid phase transition is a fundamental issue in physics. Ultra-cold Bose gas has provided a new system for experimental study of this critical phenomenon. Due to its gaseous nature, many techniques of quantum manipulation and detection which are not realizable in liquid helium system are now possible for the ultra-cold Bose gas system. To take this advantage, we propose to conduct the following studies: (1) With the Talbot-Lau (TL) interferometer, we study the critical phenomenon of a magnetically-trapped Bose gas, analyze the finite size and interaction effects, and obtain high-accuracy experimental values of critical exponents. (2) We study the critical behavior and phase diagram for the ultra-cold atomic gas under a combined optical trap and random potential. (3) We study how the critical behavior is affected by the different spatial geometric structure of optical lattices with the TL interferometer and the second-order correlation. With these studies, we will establish and perfect the TL interferometer as a new and powerful probe of critical phenomenon for different matter states, try to observe the universal behavior in the whole critical regime, and explore possible new critical behavior of the ultra-cold Bose gas in the disordered potential and optical lattices.

英文关键词： Ultracold atomic gases ;Phase transition ;Universal critical behavior ;Optical lattice;Random potential