Probing Phase Fluctuations in a 2D Degenerate Bose Gas by Free Expansion
arXiv:1206.2232 · doi:10.1103/PhysRevLett.109.125301
Abstract
We measure the power spectrum of the density distribution of a freely expanding 2D degenerate Bose gas, where irregular density modulations gradually develop due to the initial phase fluctuations in the sample. The spectrum has an oscillatory shape, where the peak positions are found to be independent of temperature and show scaling behavior in the course of expansion. The relative intensity of phase fluctuations is estimated from the normalized spectral peak strength and observed to decrease at lower temperatures, confirming the thermal nature of the phase fluctuations. We investigate the relaxation dynamics of nonequilibrium states using the power spectrum. Free vortices are observed with ring-shaped density ripples in a perturbed sample after a long relaxation time.
5 pages, 4 figures
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- Spin-driven stationary turbulence in spinor Bose-Einstein condensates
- Noise correlations of two-dimensional Bose gases
- A Non-Gaussian Variational Approach to Fermi Polarons in One- and Two-dimensional Lattices
- Detecting Phase Coherence of 2D Bose Gases via Noise Correlations
- CNN-Based Vortex Detection in Atomic 2D Bose Gases in the Presence of a Phononic Background