
VOLUME 67 (1998)  ISSUE 2 
PAGE 124

Critical velocity and event horizon in paircorrelated systems with "relativistic" fermionic quasiparticles
Kopnin N.B., Volovik G.E.
PACS: 04.70.Dy, 67.57.De, 74.60.Jg
The condition for the appearance of event horizon is considered in such paircorrelated systems (superfluids and superconductors) where the fermionic quasiparticles obey "relativistic" equations. In these systems, the Landau critical velocity of superflow corresponds to the speed of light. In conventional systems, such as swave superconductors, the superflow remains stable even above the Landau threshold. We show, however, that, in the "relativistic" systems, the quantum vacuum becomes unstable and the superflow collapses after the "speed of light" is reached, so that the horizon cannot appear. Thus an equilibrium dissipationless superflow state and the horizon are incompatible due to quantum effects. This negative result is consistent with the quantum Hawking radiation from the horizon, which would lead to a dissipation of the flow.

