Correlation functions of cold bosons in an optical lattice (8 pages)
Correlation functions of cold bosons in an optical lattice (8 pages)
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DOI：
10.1103/physreva.70.063622
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发表时间：
2004-07
影响因子：
2.9
通讯作者：
R. Bach;K. Rzążewski
中科院分区：
文献类型：
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作者：
R. Bach;K. Rzążewski
受玻色物质波场崩塌和复苏的实验观测的启发，我们研究了光学晶格中冷玻色子的关联函数。在一个简单的模型中，我们研究了两种状态：一种采用了常用的相干态概念，另一种遵循原子总数守恒。我们确定了这些国家行为不同的罕见情况。然而，通常情况下，他们的预测是一致的，因此：作为“相互作用时间”的函数，密度中的干涉图案经历了崩溃和复苏。确切地说，在复兴时期，系统模拟了理想气体的情况，其中所有的关联函数都被分解，而在演化的崩溃阶段，系统有效地表现得就像最初没有远程相干一样。然而，即使在后一种情况下，也应该在一次实验中看到干涉图案。我们强调列平均的作用，它实际上对应于对二维实现集合的平均观察。我们还注意到，与通常的看法相反，在对莫特状态的一次观察中也应该看到干扰图案。
Motivated by the experimental observation of collapses and revivals of Bose matter wave field, we investigate correlation functions of cold bosons in an optical lattice. Within a simple model we examine two kinds of states: one that employs the commonly used notion of coherent states, and one that obeys the total number of atoms conservation. We identify rare situations at which these states behave differently. Typically, however, their predictions coincide and so: As a function of 'interaction time' the interference pattern in the density undergoes collapse and revival. Exactly at revival times the system mimics the ideal gas case, in which all correlation functions factorize, while in the collapsed phase of the evolution the system effectively behaves as if initially there was no long-range coherence. Even in the latter case though, an interference pattern should be seen in a single experiment. We stress the role of column averaging, which in fact corresponds to an averaged observation of an ensemble of two-dimensional realizations. We also note that, contrary to the common belief, an interference pattern should also be seen in a single observation of a Mott state.