Irreversible decoherence of dipole interacting nuclear spins coupled with a phonon bath

F. D. DOMÍNGUEZ; C. E. GONZÁLEZ; H. H. SEGNORILE; R. C. ZAMAR

Ciudad Autónoma de Buenos Aires

Congreso; V Jornadas de Fundamentos de Cuántica; 2015

UBA

Quantum dynamics of dipole interacting spin ensembles in solids arouses great interest in various fields of modern physics, both fundamental and applied. Decoherence and irreversibility are essential pieces for the understanding of the complex dynamics which precedes equilibrium, and they are ultimately linked with basic open questions such as the emergence of thermodynamic equilibrium from the underlying microscopic unitary quantum dynamics and the measurement problem of quantum mechanics. Within this context, is the challenging problem of explaining the mechanism that enables spins in solids to attain a quasi-equilibrium state over an early time scale -in their transit to equilibrium- long before the process governing thermalization may have acted. In this work we study the adiabatic decoherence of a system of dipole coupled spins interacting with a phonon bath. The system-environment coupling is introduced through the variations that the phonon field produces on the local dipolar energy, considered as the main contribution. The proposed model allows the estimation of decoherence rates in terms of parameters of the system. Using Nuclear Magnetic Resonance techniques on a single crystal sample of gypsum, we measure decoherence times as a function of the dipole-dipole energy, and find a marked dependence on the dipolar frequency, as predicted theoretically.