Occurrence of dynamic irreversibility in multi-body quantum systems: A test employing nuclear magnetic resonance

PASTAWSKI, HORACIO M.; USAJ, GONZALO; IGLESIAS, RODRIGO A.; LEVSTEIN, PATRICIA R.

REVISTA MEXICANA DE FíSICA

SOCIEDAD MEXICANA DE FISICA

Lugar: COYOACAN 04511, MEXICO; Año: 1998 vol. 44 p. 1 - 1

0035-001X

font size="2"> The NMR technique allows to create a non-equilibrium local polarization and to detect its later evolution. Besides, it is possible to change the sign of the effective dipolar Hamiltonian and therefore retrace an apparently diffusive dynamics leading to a polarization echo. Our experiments in polycrystalline samples of (C5H5)Mn(CO)(3) and (C5H5)(2)Fe showed that those echoes attenuate as function of the time elapsed until the dynamics is reverted. In the former, a strong irreversible quadrupolar interaction (non inverted), produces an exponential decay. The latter has strong many-body interactions (reversible) whose quasi-chaotic dynamics has a local instability sensitive to the presence of small residual interactions (non-inverted). Thus an irreversible Gaussian decay appears. Numerical solutions of model systems agree with this hypothesis. To control the dynamical parameters we applied to structurally similar crystals: (C5H5)(2)Fe and (C5H5)(2)Co, a pulse sequence