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Oxford University Press eBooks

Quantum mechanics

Peter J. Hore, Jonathan A. Jones, Stephen Wimperis

Published May 21, 2015• 0 citations
Publisher

Abstract

Introduction In Part B of this book we turn to a rigorous quantum mechanical description of NMR experiments. We explain what product operators really are, justify the way they have been used to understand the operation of NMR pulse sequences, and derive many...
DOI
10.1093/hesc/9780198703426.003.0007

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We present an NMR experiment to detect the evolution of a spin system during the transient to a quasi-equilibrium state. In this way, new evidence is presented in favor of irreversible decoherence as the mechanism which leads an initial out-of-equilibrium state to quasi-equilibrium. The results are obtained using a modified Jeener-Broekaert experiment where a spin reversion pulse sequence and a decode of coherence are included. The sequence also allows visualizing the evolution of the full spectra of the different coherences during the formation of the quasi-equilibrium. We use different reversion strategies on three nematic liquid crystal samples. We conclude that the eigen-selection observed as an evidence of irreversible decoherence is an indication that the spin system in liquid-crystal NMR experiments, conform actual quantum open systems, where the quasi-equilibrium is a rigorous description of their dynamics in a time-scale far earlier than thermal equilibrium.