Probing phase fluctuations in a 2D degenerate Bose gas by free expansion.

@article{Choi2012ProbingPF,
  title={Probing phase fluctuations in a 2D degenerate Bose gas by free expansion.},
  author={Jae-yoon Choi and Sang Won Seo and W. J. Kwon and Y. Shin},
  journal={Physical review letters},
  year={2012},
  volume={109 12},
  pages={
          125301
        }
}
We measure the power spectrum of the density distribution of a freely expanding two-dimensional (2D) degenerate Bose gas, where irregular density modulations gradually develop due to 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… 

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