  We study the stability and structure of vortices emerging in two-dimensional
quantum dots in high magnetic fields. Our results obtained with exact
diagonalization and density-functional calculations show that vortex structures
can be found in various confining potentials. In non-symmetric external
potentials we find off-electron vortices that are localized giving rise to
charge deficiency or holes in the electron density with rotating currents
around them. We discuss the role of quantum fluctuations and show that vortex
formation is observable in the energetics of the system. Our findings suggest
that vortices can be used to characterize the solutions in high magnetic
fields, giving insight into the underlying internal structure of the electronic
wave function.
