  We present a unified description of a junction between $s$-wave (BCS)
superconductors and a junction between $p$-wave superconductors in a
topologically nontrivial phase, which relies on a scattering state expansion.
We compute Josephson current and thermal noise in the two kinds of junction and
exhibit some characteristic features for a junction of two topological
superconductors hosting Majorana zero-energy modes.
