Jae-yoon Choi, Sang Won Seo, Woo Jin Kwon, Yong-il Shin
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. In addition, we investigate the relaxation dynamics of nonequilibrium states and observe nonexponential decay behavior. Free vortices are observed with ring-shape density ripples which stochastically appear in a perturbed sample after a long relaxation time.
View original:
http://arxiv.org/abs/1206.2232
No comments:
Post a Comment