Nonclassical correlation in NMR quadrupolar systems

The existence of quantum correlation (as revealed by quantum discord), other than entanglement and its role in quantum-information processing (QIP), is a current subject for discussion. In particular, it has been suggested that this nonclassical correlation may provide computational speedup for some quantum algorithms. In this regard, bulk nuclear magnetic resonance (NMR) has been successfully used as a test bench for many QIP implementations, although it has also been continuously criticized for not presenting entanglement in most of the systems used so far. In this paper, we report a theoretical and experimental study on the dynamics of quantum and classical correlations in an NMR quadrupolar system. We present a method for computing the correlations from experimental NMR deviation-density matrices and show that, given the action of the nuclear-spin environment, the relaxation produces a monotonic time decay in the correlations. Although the experimental realizations were performed in a specific quadrupolar system, the main results presented here can be applied to whichever system uses a deviation-density matrix formalism.Comment: Published versio

Experimentally Witnessing the Quantumness of Correlations

The quantification of quantum correlations (other than entanglement) usually entails laboured numerical optimization procedures also demanding quantum state tomographic methods. Thus it is interesting to have a laboratory friendly witness for the nature of correlations. In this Letter we report a direct experimental implementation of such a witness in a room temperature nuclear magnetic resonance system. In our experiment the nature of correlations is revealed by performing only few local magnetization measurements. We also compare the witness results with those for the symmetric quantum discord and we obtained a fairly good agreement

Espectroscopia de 31P-RMN de vermicomposto de aparas de grama.

O uso de fertilizante fosfatado (superfosfato simples) na vermicompostagem de aparas de grama inibiu o desenvolvimento das minhocas, sendo que a adição de carvão vegetal às misturas minimizou esse efeito deletério. As espécies de fósforo detectadas por RMN nos diferentes vermicompostos diferiu significativamente, sendo que naquelas que receberam fertilizante fosfatado a concentração do anion pirofosfato foi consideravelmente maior do que nas demais, onde prevalecia fosfatos na forma orgânica ou como fosfato monoamônico. Essa conversão do superfosfato simples em pirofosfato poderia explicar a acidificação e salinização do composto e vermicomposto que receberam esse fertilizante, causando a inibição do desenvolvimento das minhocas. O uso de carvão vegetal diminui a formação de pirofosfato aos níveis observados para os tratamentos sem fertilizante fosfatado

NMR Relaxation by Redfield's equation in a spin system I=7/2I=7/2

Redfield's master equation is solved analytically for a nuclear system with spin $I=7/2$. The solutions of each density matrix element are computed using the irreducible tensor operator basis. The $^{133}$Cs nuclei of the caesium-pentadecafluorooctanoate molecule in a lyotropic liquid crystal sample at the nematic phase and at room temperature was used as an experimental setup. Experimental longitudinal and transverse magnetization dynamics of the $^{133}$Cs nuclei signal were monitored and by numerical procedures the theoretical approach generates valuable mathematical expressions with the highest accuracy. The methodology introduced could be extended without major difficulties to other nuclei species

Extração seletiva da fração húmica característica das Terras Pretas de Índio.

As Terras Pretas de Índios (TPI) da região amazônica diferem marcadamente dos solos adjacentes pela sua alta fertilidade e maior conteúdo de carbono. Essa alta fertilidade, e em particular a capacidade desses solos manterem-na, a despeito do uso intenso e degradativo (resiliência) são atribuídas ao seu elevado conteúdo de matéria orgânica pirogênica. Dessa forma as TPI nos apresentam um excelente modelo para a melhoria da fertilidade do solo e sequestro de carbono. Entretanto, apesar dos esforços para reproduzir esses solos, não há métodos analíticos para validar essas tentativas. Os ácidos húmicos (AH) extraídos de TPI com soluções aquosas a pH 7 e 10,6 apresentam características peculiares, não observadas em AH regulares, a saber: estruturas aromáticas policondensadas e funcionalizadas com grupos carboxílicos. Essas estruturas, recalcitrantes e reativas, explicariam a alta fertilidade e resiliência desses solos especiais. O método sugerido pode ser utilizado na avaliação das propostas para reproduzir as TPI

Environment-induced sudden transition in quantum discord dynamics

Non-classical correlations play a crucial role in the development of quantum information science. The recent discovery that non-classical correlations can be present even in separable (unentangled) states has broadened this scenario. This generalized quantum correlation has been increasing relevance in several fields, among them quantum communication, quantum computation, quantum phase transitions, and biological systems. We demonstrate here the occurrence of the sudden-change phenomenon and immunity against some sources of noise for the quantum discord and its classical counterpart, in a room temperature nuclear magnetic resonance setup. The experiment is performed in a decohering environment causing loss of phase relations among the energy eigenstates and exchange of energy between system and environment, resulting in relaxation to a Gibbs ensemble