Steinhauer J, Ozeri R, Katz N, Davidson N
Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel.
Phys Rev Lett. 2002 Mar 25;88(12):120407. doi: 10.1103/PhysRevLett.88.120407. Epub 2002 Mar 12.
We report a measurement of the excitation spectrum omega(k) and the static structure factor S(k) of a Bose-Einstein condensate. The excitation spectrum displays a linear phonon regime, as well as a parabolic single-particle regime. The linear regime provides an upper limit for the superfluid critical velocity, by the Landau criterion. The excitation spectrum agrees well with the Bogoliubov spectrum in the local density approximation, even close to the long-wavelength limit of the region of applicability. Feynman's relation between omega(k) and S(k) is verified, within an overall constant.
我们报告了对玻色-爱因斯坦凝聚体的激发谱ω(k)和静态结构因子S(k)的测量结果。激发谱呈现出线性声子区域以及抛物线型单粒子区域。根据朗道准则，线性区域给出了超流临界速度的上限。在局部密度近似下，激发谱与博戈留波夫谱吻合得很好，甚至在适用区域的长波长极限附近也是如此。在一个整体常数范围内，验证了费曼关于ω(k)和S(k)的关系。
