Quantum dynamics under coherent and incoherent effects of a spin bath

ERNESTO P. DANIELI; GONZALO A. ÁLVAREZ; LUIS E. F. TORRES; HORACIO M. PASTAWSKI

Córdoba, Argentina

Taller; 2º Taller Regional de Física Estadística y sus Aplicaciones a la Física de la Materia Condensada (TREFEMAC'04); 2004

We develop the Keldysh formalism for the polarization dynamics of an open spin system. We address the problem of cross-polarization transfer in NMR, in which the nuclear spin system 13C-1H is in contact with a spin reservoir. Considering fasta fluctuations regime in the environment, one obtains an analytical solution showing effects missed by the secular approximation of the Quantum master Equation for the density matrix. There is a frequency decrease depending on the system-environment escape rate; and a general phase shift responsible for the correct quantum quadratic short time behavior. Considering full memory of the environment correlations yields a progressive slow down of the Rabi frequency.