标题： 玻色-爱因斯坦凝聚体的布朗运动观测 显示英文标题

标题： Observation of Brownian Motion of a Bose-Einstein Condensate

摘要： 我们报告了通过在六边形光晶格中制备的铷原子玻色-爱因斯坦凝聚体（BEC）在动量空间中观察到的经典布朗运动的实验结果。 在突然增加有效原子质量后，BEC整体行为像一个经典刚体，其质心由于原子损失和与周围热云的相互作用产生的朗之万力而受到随机动量冲击。 从物理上讲，这相当于通过突然淬火选择性地加热BEC质心自由度，而就相对坐标而言，BEC由排斥原子相互作用稳定，并且其内部动力学被由原子损失引起的强制蒸发冷却所抑制。 发展了一种现象学理论，该理论能够定量地解释实验数据。 显示英文摘要

摘要： We report on the experimental observation of classical Brownian motion in momentum space by a Bose-Einstein condensate (BEC) of Rubidium atoms prepared in a hexagonal optical lattice. Upon suddenly increasing the effective atomic mass, the BEC as a whole behaves as a classical rigid body with its center-of-mass receiving random momentum kicks by a Langevin force arising from atom loss and interactions with the surrounding thermal cloud. Physically, this amounts to selective heating of the BEC center-of-mass degree of freedom by a sudden quench, while with regard to the relative coordinates, the BEC is stablized by repulsive atomic interactions, and its internal dynamics is suppressed by forced evaporative cooling induced by atom loss. A phenomenological theory is developed that well explains the experimental data quantitatively.