Transmission of excitations in a spin-1 Bose-Einstein condensate through a barrier
We investigate tunneling of excitations across a potential barrier separating two spin-1 Bose-Einstein condensates. Using mean-field theory at absolute zero temperature, we determine the transmission coefficients of excitations in the saturated magnetization state and unsaturated magnetization states. All excitations, except the quadrupolar spin mode in the saturated magnetization state, show the anomalous tunneling phenomenon characterized as perfect tunneling in the low-momentum limit through a potential barrier. The quadrupolar spin mode in the saturated magnetization state, whose spectrum is massive, shows total reflection. We discuss properties common between excitations showing the anomalous tunneling phenomenon. Excitations showing perfect tunneling have a gapless spectrum in the absence of the magnetic field, and their wave functions in the low-energy limit are the same as the condensate wave function.