  While the possibility of topological superconductivity (TSC) in hybrid
heterostructures involving topologically nontrivial band structure and
superconductors has been proposed, the realization of TSC in a single
stoichiometric material is most desired for fundamental experimental
investigation of TSC and its device applications. Bulk measurements on YRuB$_2$
detect a single superconducting gap of $\sim$ 1 meV. This is supported by our
electronic structure calculations which also reveal the existence of
topological surface states in the system. We performed surface-sensitive
Andreev reflection spectroscopy on YRuB$_2$ and detected the bulk
superconducting gap as well as another superconducting gap of $\sim$ 0.5 meV.
From our analysis of electronic structure, we show that the smaller gap is
formed in the topological surface states in YRuB$_2$ due to the proximity of
the bulk superconducting condensate. Thus, in agreement with the past
theoretical predictions, we present YRuB$_2$ as a unique system that hosts
superconducting topological surface states.
