  The occurrence of biological homochirality is attributed to symmetry breaking
mechanisms which are still debatable1. Studies of symmetry breaking require
tools for monitoring the population ratios of individual chiral nano-objects,
such as molecules, polymers or nanocrystals. Moreover, mapping their spatial
distributions may elucidate on the symmetry breaking mechanism. Recently,
researchers have utilized differential scattering or circular dichroism
microscopy to identify chirality on individual plasmonic nanostructures and
inorganic nanocrystals. However, these measurements are prone to optical system
artifacts. While luminescence is preferred for detecting single particle
chirality, the typical low optical activity of chromophores limits its
applicability. Here, we report on handedness determination of single chiral
lanthanide based nanocrystals, using circularly polarized luminescence, with
total photon count of $2\times 10^4$. We also utilize a machine learning
approach for correlative microscopy to determine and spatially map handedness
of individual nanocrystals with high accuracy. This technique may become
invaluable in studies of spontaneous symmetry breaking in chiral materials.
