  The insertion of a magnetic impurity in a superconductor induces a first
order quantum phase transition as the coupling to the electronic spin density
increases. As the transition is crossed, a discontinuity is exhibited by
various quantities, like the total spin density, the total gap function and the
gap function at the impurity location. The location of other quantum phase
transitions have been detected by singularities in entanglement measures of the
system. In this work we show that the single-site and two-site von Neumann
entropies, the mutual information and the Meyer-Wallach measure show
discontinuities at the quantum phase transition. The negativity is less
sensitive to the transition. We study in detail these quantities as a function
of spin coupling and distance from the impurity center.
