Dissociation dynamics of singly charged vorticesinto half-quantum vortex pairs

摘要

The quest for identification and understanding of fractional vorticity is a major subject ofresearch in the quantum fluids domain, ranging from superconductors, superfluid Helium-3 tocold atoms. In a two-dimensional Bose degenerate gas with a spin degree of freedom, thefundamental topological excitations are fractional vortical entities, called half-quantum vortices. Convincing evidence for the existence of half-quantum vortices was recently provided inspinor polariton condensates. The half-quantum vortices can be regarded as the fundamentalstructural components of singly charged vortices but, so far, no experimental evidence of thisrelation has been provided. Here we report on the direct and time-resolved observation of thedynamical process of the dissociation of a singly charged vortex into its primary components,a pair of half-quantum vortices. The physical origin of the observed phenomenology is foundin a spatially inhomogeneous static potential that couples the two spin components of thecondensate.