Spectral Flow and Quantum Theory of Dissipation in the Vortex Core of BCS Superconductors

The dissipation process in a two-dimensional BCS superconductor, due to the quasiparticles in the core of a moving vortex, is studied from a quantum mechanical point of view, especially focusing on the spectral flow of the bound state energies in the vortex core. In order to clarify the nature of the spectral flow, we performed a numerical study of a finite system and, by extending the analysis to include the effect of impurities, we discuss the quantum mechanical origin of the dissipation in the vortex core.