NMR Loschmidt echoes as quantifiers of decoherence in interacting spin systems

C.M. SANCHEZ; P.R. LEVSTEIN; R. H. ACOSTA; A.K. CHATTAH

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

AMER PHYSICAL SOC

Año: 2009 vol. 80 p. 12328 - 123287

1050-2947

In this work we present solid-state nuclear magnetic-resonance experiments to study decoherence in the dynamics of many-spin systems. We characterize the global Loschmidt echo and the distribution of multiplequantum coherence orders during the evolution under dipolar and double-quantum Hamiltonians. To study an infinite 1H system and a closed cluster of nuclear spins we use polycrystalline adamantane and the liquid crystal 5CB in the nematic mesophase, respectively, as model systems. The infinite or finite nature of the system is clearly manifested through spin counting measurements. Comparison between experimental and numerical results gives insights on the decoherence mechanisms in these systems. Contrastingly, the dominating mechanism in 5CB affects all coherence orders in the same way, while in adamantane higher  orders of coherence decay faster than the lower ones.