DYNAMICAL MASS OF A QUANTUM VORTEX IN A JOSEPHSON-JUNCTION ARRAY

The real-time response to a small external perturbation of a vortex in a quantum Josephson junction array. with long-range Coulomb interacti on between Cooper pairs, is analyzed. While the static damping is zero for vortex velocities below-some threshold value nu(th) (which implie s the possibility of ballistic motion), a dynamical friction due to th e coupling. to the plasma oscillations is always present for frequenci es higher than a given threshold co,h. The latter approaches zero when the velocity increases to nu(th). However, radiative dissipation of t he vortex affects the threshold for ballistic motion. We discuss the c onditions under which a mass can be defined Tor the vortex as a quantu m particle.