  Hybrid nanowires combining semiconductor and superconductor materials appear
well suited for the creation, detection, and control of Majorana bound states
(MBSs). We demonstrate the emergence of MBSs from coalescing Andreev bound
states (ABSs) in a hybrid InAs nanowire with epitaxial Al, using a quantum dot
at the end of the nanowire as a spectrometer. Electrostatic gating tuned the
nanowire density to a regime of one or a few ABSs. In an applied axial magnetic
field, a topological phase emerges in which ABSs move to zero energy and remain
there, forming MBSs. We observed hybridization of the MBS with the end-dot
bound state, which is in agreement with a numerical model. The ABS/MBS spectra
provide parameters that are useful for understanding topological
superconductivity in this system.
