title: Spin-spin correlators in the majorana representation.
abstract: In the Majorana representation of a spin 1/2 we find an identity which relates spin-spin correlators to one-particle fermionic correlators. This should be contrasted with the straightforward approach in which two-particle (four-fermion) correlators need to be calculated. We discuss applications to the analysis of the dynamics of a spin coupled to a dissipative environment and of a quantum detector performing a continuous measurement of a qubit's state.
authors.affiliation: Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Shnirman
authors.forename: Yuriy
authors.initials: Y
authors.lastname: Makhlin