  We investigate tunneling properties of Bogoliubov mode in a Bose-Einstein
condensate. Using an exactly solvable model with a delta-functional barrier, we
show that each component in the two-component wavefunction (u,v) of low-energy
Bogoliubov phonon has the same form as the condensate wavefunction in the
supercurrent state. As a result, the currents J_u and J_v associated with u and
v, respectively, have the same tunneling properties as those of supercurrent
carried by condensate. Thus, the tunneling of low-energy Bogoliubov phonon
described by the tunneling of these two currents shows perfect transmission. We
also show that the supercurrent behaviors of Bogoliubov phonon still exist in
the presence of supercurrent carried by condensate, except in the critical
supercurrent state. In the critical current state, the perfect transmission is
absent, because J_u or J_v exceeds their upper limit given by the critical
value of the supercurrent associated with the condensate. Our results
consistently explain the recently proposed two tunneling phenomena associated
with Bogoliubov phonon, namely, the anomalous tunneling effect (perfect
transmission in the low-energy limit) and the breakdown of the perfect
transmission in the critical supercurrent state.
