  Vortices are expected to exist in a supersolid but experimentally their
detection can be difficult because the vortex cores are localized at positions
where the local density is very low. We address here this problem by performing
numerical simulations of a dipolar Bose-Einstein Condensate (BEC) in a pancake
confinement at $T=0$ K and study the effect of quantized vorticity on the
phases that can be realized depending upon the ratio between dipolar and
short-range interaction. By increasing this ratio the system undergoes a
spontaneous density modulation in the form of an ordered arrangement of
multi-atom "droplets". This modulated phase can be either a "supersolid" (SS)
or a "normal solid" (NS). In the SS state droplets are immersed in a background
of low-density superfluid and the system has a finite global superfluid
fraction resulting in non-classical rotational inertia. In the NS state no such
superfluid background is present and the global superfluid fraction vanishes.
We propose here a protocol to create vortices in modulated phases of dipolar
BEC by "freezing" into such phases a vortex-hosting superfluid (SF) state. The
resulting system, depending upon the interactions strengths, can be either a SS
or a NS To discriminate between these two possible outcome of a "freezing"
experiment, we show that upon releasing of the radial harmonic confinement, the
expanding vortex-hosting SS shows tell-tale quantum interference effects which
display the symmetry of the vortex lattice of the originating SF, as opposed to
the behavior of the NS which shows instead a ballistic radial expansion of the
individual droplets. Such markedly different behavior might be used to prove
the supersolid character of rotating dipolar condensates.
