Ha Li-Chung, Clark Logan W, Parker Colin V, Anderson Brandon M, Chin Cheng
James Franck Institute, Enrico Fermi Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA.
James Franck Institute, Enrico Fermi Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.
Phys Rev Lett. 2015 Feb 6;114(5):055301. doi: 10.1103/PhysRevLett.114.055301. Epub 2015 Feb 3.
We present experimental evidence showing that an interacting Bose condensate in a shaken optical lattice develops a roton-maxon excitation spectrum, a feature normally associated with superfluid helium. The roton-maxon feature originates from the double-well dispersion in the shaken lattice, and can be controlled by both the atomic interaction and the lattice modulation amplitude. We determine the excitation spectrum using Bragg spectroscopy and measure the critical velocity by dragging a weak speckle potential through the condensate-both techniques are based on a digital micromirror device. Our dispersion measurements are in good agreement with a modified Bogoliubov model.
我们展示了实验证据，表明在振荡光学晶格中的相互作用玻色凝聚体形成了一种旋子-声子激发谱，这是一种通常与超流氦相关的特征。旋子-声子特征源于振荡晶格中的双阱色散，并且可以通过原子相互作用和晶格调制幅度来控制。我们使用布拉格光谱法确定激发谱，并通过在凝聚体中拖动弱散斑势来测量临界速度——这两种技术均基于数字微镜器件。我们的色散测量结果与修正的博戈留波夫模型高度吻合。
