title: Asymmetric long josephson junction acting as a ratchet for a quantum field.
abstract: We study the escape rate of flux quanta in a long Josephson junction having an asymmetric spatial inhomogeneous critical current density. Such a junction can behave as a ratchet when driven by an ac current in the presence of a magnetic field. This rectification gives rise to a dc voltage V(dc) across the junction. The usual approach of particlelike tunneling cannot describe this rectification, and a quantum field theory description is required. We also show that, under specific conditions, the rectification direction, and consequently V(dc), can change its sign when varying the temperature T near the crossover temperature T* between the quantum and classical regimes.
authors.affiliation: Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198, Japan.
authors.forename: A O
authors.initials: AO
authors.lastname: Sboychakov
authors.forename: Sergey
authors.initials: S
authors.lastname: Savel'ev
authors.forename: A L
authors.initials: AL
authors.lastname: Rakhmanov
authors.forename: Franco
authors.initials: F
authors.lastname: Nori