  The "Hydrogen atom" of magnetic Weyl semimetals, with the minimum number of
Weyl points, have received growing attention recently due to the possible
presence of Weyl-related phenomena. Here, we report a nontrivial electronic
structure of the ferromagnetic alluaudite-type compound
K$_{2}$Mn$_3$(AsO$_{4}$)$_3$. It exhibits only a pair of Weyl points
constrained in the $z$-direction by the two-fold rotation symmetry, leading to
extremely long Fermi arc surface states. In addition, the study of its
low-energy effective model results in the discovery of various topological
superconducting states, such as the "hydrogen atom" of a Weyl superconductor.
Our work provides a feasible platform to explore the intrinsic properties
related to Weyl points, and the related device applications.
