  Physical spin configurations corresponding to topological excitations,
expected to be present in the XY limit of a quantum spin 1/2 Heisenberg
anti-ferromagnet, are probed on a two dimensional square lattice . Quantum
vortices (anti-vortices) are constructed in terms of coherent staggered spin
field components, as limiting case of meronic (anti-meronic) configurations .
The crucial role of the associated Wess-Zumino-like (WZ-like) term is
highlighted in our procedure . The time evolution equation of coherent spin
fields used in this analysis is obtained by applying variational principle on
the quantum Euclidean action corresponding to the Heisenberg anti-ferromagnet
on lattice . It is shown that the WZ-like term can distinguish between vortices
and anti-vortices only in a charge sector with odd topological charges. Our
formalism is distinctly different from the conventional approach for the
construction of quantum vortices (anti-vortices) .
