Coherence properties of a continuous atom laser
Coherence properties of a continuous atom laser
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连续原子激光器的相干特性
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
I. Carusotto
中科院分区：
文献类型：
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作者：
Y. Castin;R. Dum;E. Mandonnet;A. Minguzzi;I. Carusotto
摘要本文研究了在量子简并状态下假设热平衡的原子束在磁波导中蒸发冷却的相干性。这种气体经历二维的、横向的玻色-爱因斯坦凝聚，而不是完整的三维凝聚，因为磁导体的几何形状非常细长。利用原子场的一阶和二阶相关函数来表征气体沿导轴的相干性。在强量子简并态中，气体的相干长度比热德布罗意波长大得多。发现理想玻色气体模型中存在的大强度起伏被排斥原子相互作用强烈地减小；这一结论是用一维经典场近似得到的，当气体的温度远高于其化学势k B T»|μ|时有效。
Abstract We investigate the coherence properties of an atomic beam evaporatively cooled in a magnetic guide, assuming thermal equilibrium in the quantum degenerate regime. The gas experiences two-dimensional, transverse Bose-Einstein condensation rather than a full three-dimensional condensation because of the very elongated geometry of the magnetic guide. First order and second order correlation functions of the atomic field are used to characterize the coherence properties of the gas along the axis of the guide. The coherence length of the gas is found to be much larger than the thermal de Broglie wavelength in the strongly quantum degenerate regime. Large intensity fluctuations present in the ideal Bose gas model are found to be strongly reduced by repulsive atomic interactions; this conclusion is obtained with a one-dimensional classical field approximation valid when the temperature of the gas is much higher than its chemical potential, k B T » |μ|.