Superfluidity and Phase Coherence in Very Degenerate Atomic Gases

9614133莱格特在过去的一年里，三个不同的实验室已经实现了稀薄原子气体中的玻色-爱因斯坦凝聚(BEC)现象，还有更多的实验室正在进入这一领域。所讨论的系统处于参数(密度、温度、隔离度)的范围内。许多数量级与之前已知的唯一呈现BEC的实验室系统的特征不同，即超流4He。因此，应该有可能利用这些系统对各种被认为适用于超流氦但从未在那里得到检验的想法进行实验测试，特别是探索BEC和被称为“超流”的复杂现象之间的精确关系。理论工作将在一般情况下和在稀薄原子气体的背景下进行，以检查超流体密度和零自转和持续电流现象的条件，并预测一些有趣的实验，这些实验显然在这些系统中是可行的。这笔赠款已经与物理系的理论物理项目共同审查，并正在与他们共同资助。%这笔资金支持一位资深的、杰出的圆周率派的工作，他在超流和其他凝聚态现象(如宏观量子隧道)的一般领域做出了许多深思熟虑的贡献。在最近的实验的推动下，这个项目将他带回到了与玻色-爱因斯坦凝聚和稀薄气体中的超流动性之间的关系相关的问题上。这笔赠款已经与物理系的理论物理项目共同审查，并正在与他们共同资助。***

9614133 Leggett Within the last year the phenomena of Bose-Einstein condensation (BEC) in dilute atomic gases has been realized in three different laboratories and many more are moving into this area. The systems in question lie in a regime of parameters (density, temperature, isolation _.) many orders of magnitude different from those which characterize the only previously known laboratory system believed to exhibit BEC, namely superfluid 4He. Consequently, it should be possible to use these systems to subject to experimental test a variety of ideas which are believed to apply to superfluid Helium but have never been tested there and in particular to explore the precise relation between BEC and the complex of phenomena which go under the name of "superfluidity". Theoretical work will be carried out, both in general and in the context of dilute atomic gases, to examine the superfluid density and the condition for the phenomena of zero rotation and of persistent currents, and to make predictions about a number of interesting experiments on the subject of "quantum phase coherence" and "phase memory" which are apparently feasible in these systems. This grant has been co-reviewed with the Theoretical Physics program in the Division of Physics and is being co-funded with them. %%% This grant supports the work of a senior, distinguished PI whose many thoughtful contributions to the general area of superfluidity and other condensed state phenomena (such as macroscopic quantum tunneling) are well known. This project, motivated by recent experiments, takes him back to the questions associated with relationship between Bose- Einstein condensation and superfluidity in dilute gases. This grant has been co-reviewed with the Theoretical Physics program in the Division of Physics and is being co-funded with them. ***