  Spin-orbit coupled semiconducting nanowires with proximity-induced
superconductivity are expected to host Majorana zero modes at their endpoints
when a sufficiently strong magnetic field is applied. The resulting phase would
be a one-dimensional topological superconductor. However, while a variety of
experiments have been performed observing a zero bias conductance peak
(suggestive of Majorana zero modes), the topological nature of these physical
systems is still a subject of debate. Here we suggest a quantitative test of
the degree to which a system displaying a zero bias peak may be considered
topological. The experiment is similar to previous measurements of conductance,
but is performed with the aid of a quantum dot at the wire's end. We arrive at
the surprising result that the non-local nature of the topological system may
be identified through a local measurement.
