  The disk around the Herbig Ae/Be star HD 100546 has been extensively studied
and it is one of the systems for which there are observational indications of
ongoing and/or recent planet formation. However, up until now no resolved image
of the millimeter dust emission or the gas has been published. We present the
first resolved images of the disk around HD 100546 obtained in Band 7 with the
ALMA observatory. The CO (3-2) image reveals a gas disk that extends out to 350
au radius at the 3-sigma level. Surprisingly, the 870um dust continuum emission
is compact (radius <60 au) and asymmetric. The dust emission is well matched by
a truncated disk with outer radius of $\approx$50 au. The lack of
millimeter-sized particles outside the 60 au is consistent with radial drift of
particles of this size. The protoplanet candidate, identified in previous
high-contrast NACO/VLT L' observations, could be related to the sharp outer
edge of the millimeter-sized particles. Future higher angular resolution ALMA
observations are needed to determine the detailed properties of the millimeter
emission and the gas kinematics in the inner region (<2arcsec). Such
observations could also reveal the presence of a planet through the detection
of circumplanetary disk material.
