  Topological superconductors (TSCs) have a full gap in the bulk and gapless
surface states consisting of Majorana fermions, which have potential
applications in fault-tolerant topological quantum computation. Because TSCs
are very rare in nature, an alternative way to study the TSC is to artificially
introduce superconductivity into the surface states of a topological insulator
(TI) through proximity effect (PE)1-4. Here we report the first experimental
realization of the PE induced TSC in Bi2Te3/NbSe2 thin films as demonstrated by
the density of states probed using scanning tunneling microscope. We observe
Abrikosov vortices and lower energy bound states on the surface of topological
insulator and the dependence of superconducting coherence length on the film
thickness and magnetic field, which are attributed to the superconductivity in
the topological surface states. This work demonstrates the practical
feasibility of fabricating a TSC with individual Majorana fermions inside
superconducting vortex as predicted in theory and accomplishes the
pre-requisite step towards searching for Majorana fermions in the PE induced
TSCs.
