Measurement of the spatial coherence of a trapped Bose gas at the phase transition
Measurement of the spatial coherence of a trapped Bose gas at the phase transition
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DOI：
10.1038/35003132
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发表时间：
2000-01-13
期刊：
影响因子：
64.8
通讯作者：
Esslinger, T
中科院分区：
文献类型：
--
作者：
Bloch, I;Hänsch, TW;Esslinger, T
稀释气体的玻色-爱因斯坦凝聚体的实验实现（1-3）允许在超低温下研究量子力学的基本概念，例如波动行为和干涉现象。干涉图案的形成基本上取决于系统的相位相干性;后者可以通过空间相关函数量化。长期相位相干性;范围（4-7）是玻色-爱因斯坦凝聚和相关宏观量子现象（如超导性和超流性）的基本因素。本文报道了铷原子弱相互作用玻色气体相位相干特性的直接测量。有效地，我们创建一个双缝磁囚禁原子使用无线电波场与两个频率分量。该系统的相关函数是通过评估两个物质波的干涉图样来确定的，这两个物质波来自于被困气体的空间分离的“狭缝”区域。在玻色-爱因斯坦凝聚的临界温度以上，相关函数显示出快速的高斯衰减，正如对热气体所预期的那样。在临界温度以下，相关函数有一个不同的形状：在缓慢衰减到一个平台上观察到，表明远程相位相干的冷凝馏分。
The experimental realization of Bose-Einstein condensates of dilute gases(1-3) has allowed investigations of fundamental concepts in quantum mechanics at ultra-low temperatures, such as wave-like behaviour and interference phenomena, The formation of an interference pattern depends fundamentally on the phase coherence of a system; the latter may be quantified by the spatial correlation function. Phase coherence over a long; range(4-7) is the essential factor underlying Bose-Einstein condensation and related macroscopic quantum phenomena, such as superconductivity and superfluidity. Here we report a direct measurement of the phase coherence properties of a weakly interacting Bose gas of rubidium atoms. Effectively, we create a double slit for magnetically trapped atoms using a radio wave field with two frequency components. The correlation function of the system is determined by evaluating the interference pattern of two matter waves originating from the spatially separated 'slit' regions of the trapped gas. Above the critical temperature for Bose-Einstein condensation, the correlation function shows a rapid gaussian decay, as expected for a thermal gas. Below the critical temperature, the correlation function has a different shape: at slow decay towards a plateau is observed, indicating the long-range phase coherence of the condensate fraction.