Roton-Maxon Excitation Spectrum of Bose Condensates in a Shaken Optical Lattice
arXiv:1407.7157 · doi:10.1103/PhysRevLett.114.055301
Abstract
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 shaking 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.
9 pages, 7 figures
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- Suppression of kHz-Frequency Switching Noise in Digital Micro-Mirror Devices
- Anisotropic superfluidity of two-dimensional excitons in a periodic potential
- Static-response theory and the roton-maxon spectrum of a flattened dipolar Bose-Einstein condensate
- Universal spatiotemporal dynamics of spontaneous superfluidity breakdown in the presence of synthetic gauge fields
- Bose-Einstein condensates in the presence of Weyl spin-orbit coupling
- Running condensate in moving superfluid