Fig. 5
From: Dynamical equilibration across a quenched phase transition in a trapped quantum gas
Defect visualisation at late evolution times. Shown here are representative density side views containing respectively (top to bottom) 1, 2 and 3 solitonic vortices in the condensate. a, b Experimental densities obtained after condensate free expansion, integrated along a transverse (a) or longitudinal (b) axis. c–e Numerical simulations showing corresponding characteristic in situ density and phase plots for (t − tbec) ≈ 250 ms and τR = 84 ms. Specifically: c condensate density isosurfaces from different viewing angles (set by z = 0, or y = 0). d Corresponding isosurfaces from the x = 0 viewing angle. e Planar phase profiles of two-dimensional cuts at z = 0 and y = 0: the latter, only pick up defects crossing the z = 0, or y = 0 lines (see also Supplementary Figs. 6 and 7, and Supplementary Movie 4, for further visualisations, including during the entire dynamical evolution). In comparing experimental and simulated images, we note that the long dark stripes, spanning the entire transverse direction, seen in the experimental images arise as a result of expansion, with such images only containing information about the axial positions of the defects, and not their orientation. This is in contrast to the simulated images, depicting in situ observations: in particular, the simulated phase profiles at such late evolution times reveal a non-uniform distribution of the 2π phase winding around the density minimum of the vortex filaments, which is direct evidence of their solitonic vortex nature. Expansion of such solitonic vortices is known65,66 to lead to dark vertical stripes, highlighting the consistency between experimental and simulated profiles
