  We demonstrate that antiferromagnet-superconductor (AF-S) junctions show
qualitatively different transport properties than normal metal-superconductor
(N--S) and ferromagnet-superconductor (F-S) junctions. We attribute these
transport features to presence of two new scattering processes in AF--S
junctions, i.e., specular reflection of holes and retroreflection of electrons.
Using the Blonder-Tinkham-Klapwijk formalism, we find that the electrical and
thermal conductance depend nontrivially on antiferromagnetic exchange strength.
Furthermore, we show that the interplay between the N\'eel vector direction and
the interfacial Rashba spin-orbit coupling leads to a large anisotropic
magnetoresistance. The unusual transport properties make AF--S interfaces
unique among the traditional condensed-matter-system-based superconducting
junctions.
