  Here we show that under quantum reconnection, simulated by using the
three-dimensional Gross- Pitaevskii equation, self-helicity of a system of two
interacting vortex rings remains conserved. By resolving the fine structure of
the vortex cores, we demonstrate that total length of the vortex system reaches
a maximum at the reconnection time, while both writhe helicity and twist
helicity remain separately unchanged throughout the process. Self-helicity is
computed by two independent methods, and topological information is based on
the extraction and analysis of geometric quantities such as writhe, total
torsion and intrinsic twist of the reconnecting vortex rings.
