  Experimental evidence for Majorana bound states largely relies on
measurements of the tunneling conductance. While the conductance into a
Majorana state is in principle quantized to $2e^2/h$, observation of this
quantization has been elusive, presumably due to temperature broadening in the
normal-metal lead. Here, we propose to use a superconducting lead instead,
whose gap strongly suppresses thermal excitations. For a wide range of
tunneling strengths and temperatures, a Majorana state is then signaled by
symmetric conductance peaks at $eV=\pm\Delta$ with quantized height
$G=(4-\pi)2e^2/h$. For a superconducting scanning tunneling microscope tip,
Majorana states appear as spatial conductance plateaus while the conductance
varies with the local wavefunction for trivial Andreev bound states. We discuss
effects of nonresonant (bulk) Andreev reflections and quasiparticle poisoning.

Mesoscale and Nanoscale Physics;Superconductivity