  We investigate the conductance of an Aharonov-Bohm (AB) interferometer
coupled to a quantum dot and two Majorana bound states on the edge of the
topological superconductor with finite length. When the tunnel couplings
between the Majorana bound states and the Aharonov-Bohm interferometer are
fixed to the specific phase, the differential conductance becomes zero
irrespective of all the parameters as long as the hoppings to the two Majorana
fermions on the opposite side are equal. The conductance at the zero bias
voltage does not change with the magnetic flux penetrating the ring for all
cases. When the energy level of the quantum dot is equal to the energy of the
Majorana bound states, the AB oscillation shows \pi periodicity due to the
particle-hole symmetry. The breaking of the time-reversal symmetry of the
topological superconductor results in 2\pi periodicity of the AB oscillation
for the specific phase of the tunnel coupling while the time-reversal symmetry
breaking leads to the mixing of the triplet and singlet states in the quantum
dot in another specific phase.
