CENTER FOR APPLIED MATHEMATICS AND THEORETICAL PHYSICS
UNIVERZA V MARIBORU UNIVERSITY OF MARIBOR
KREKOVA 2 SI-2000 MARIBOR SLOVENIA
Phone +(386) (2) 2355 350 and 2355 351 $\bullet$ Fax +(386) (2) 2355 360
Robnik@uni-mb.si $\bullet$ www.camtp.uni-mb.si
PROF.DR. MARKO ROBNIK, DIRECTOR

Seminarsko predavanje
Centra za uporabno matematiko in teoreticno fiziko

Decoherence of spin echoes

Doc.Dr. Tomaz Prosen
Oddelek za fiziko, Fakulteta za matematiko in fiziko
Univerza v Ljubljani

Abstract: We define a quantity, the so-called purity fidelity, which measures the rate of dynamical reversibility due to decoherence, observed e.g in echo experiments, in the presence of an arbitrary small perturbation of the total (system + environment) Hamiltonian. We derive a linear response formula for the purity fidelity in terms of integrated time correlation functions of the perturbation. Our theory (1) predicts, similarly to the case of fidelity decay (2), faster decay of purity fidelity the slower decay of time correlations is. In particular, we find exponential decay in quantum mixing regime and faster, initially quadratic and later typically gaussian decay in the regime of non-ergodic, e.g. integrable quantum dynamics.
References:
(1) T. Prosen and T. H. Seligman, 'Decoherence of spin echoes', Prepr. 2001, submitted
(2) T. Prosen and M. Znidaric, Prepr. 2001, nlin.CD/0111014, submitted to J.Phys.A

Seminarsko predavanje bo v sredo, 12. decembra 2001 ob 17:15 uri v seminarski sobi CAMTP na Krekovi 2, pritlicje desno. Vljudno vabljeni vsi zainteresirani, tudi študentje.

Prof.Dr. Marko Robnik
-- Direktor CAMTP --