IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Quantum irreversible decoherence behaviour in open quantum systems with few degrees of freedom. Application to 1H NMR reversion experiments in nematic liquid crystals.
Autor/es:
HÉCTOR H. SEGNORILE; RICARDO C. ZAMAR
Lugar:
San Carlos de Bariloche
Reunión:
Congreso; 98ª Reunión Nacional de de Física de la AFA; 2013
Institución organizadora:
AFA
Resumen:
An
experimental study of NMR spin decoherence in nematic liquid crystals is
presented [1]. The outcome of the experiments are analyzed in the framework of
a theory that considers the spins as an open quantum system coupled to a
quantum molecular environment, presented by the authors recently [2].
Decoherence
dynamics can be put in evidence by means of refocusing experiments of the dipolar
interactions. The experimental technique used in this work is based on the
MREV8 [3-5] pulse sequence. Non-idealities of the experimental setting, like
external field inhomogeneity, pulse misadjustments and the presence of
non-reverted spin interaction terms are analysed in detail and their effects on
the observed signal decay are estimated. It is found that, though all these
non-idealities could in principle affect the evolution of the spin dynamics,
their inuence can be mitigated and they do not present the characteristic
behaviour of the irreversible spin decoherence.
As
unique characteristic of decoherence, the experimental results clearly show the
occurrence of eigen-selectivity [2] in a time scale intermediate [6] between
those controlled by quantum interference of the closed spin system and
thermalization, in complete agreement with the theoretical predictions. We
conclude that the eigen-selection effect is the fingerprint of decoherence
associated with a quantum open spin system in liquid crystals. Besides,these
features of the results account for the quasi-equilibrium states of the spin
system, which were observed previously in these mesophases [7-11], and lead to
conclude that the quasi-equilibrium is a definite stage of the
spin
dynamics during its evolution towards equilibrium.
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H. H. Segnorile, and R. C. Zamar, arXiv:1305.0973 (2013).
[2]
H.H. Segnorile, and R.C. Zamar. J. Chem. Phys. 135, 244509 (2011).
[3]
P. Mansfield. J. Phys. C 4, 1444 (1971).
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[5]
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[6]
C. E. González, H. H.Segnorile, and R. C. Zamar. Phys. Rev. E 83, 011705
(2011).
[7]
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[8]
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[9]
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[10]
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Chem. Phys.130, 024501 (2009).