An alternative formalism for two-dimensional NMR

W. Nosel, Peter S. Allen

Bo Gestblom

Geoffrey Bodenhausen

J. Jeener

The use of multiple bases moving with respect to each other in quantum dynamics is discussed. This procedure is formally equivalent to the use of interaction pictures, but it leads to an intuitively simpler interpretation of the calculations. A close analogy is shown between the rotating frames of classical NMR theory and the use of moving (rotating) bases in the corresponding quantum presentation, for the traditional basic NMR experiment and for two problems involving Berry's phase.

Jonas Maziero, R. Auccaise, Lucas C. Céleri +6 more

"We review the theoretical and the experimental researches aimed at quantifying or identifying quantum correlations in liquid-state nuclear magnetic resonance (NMR) systems at room temperature. We first overview, at the formal level, a method to determine the quantum discord and its classical counterpart in systems described by a deviation matrix. Next, we describe an experimental implementation of that method. Previous theoretical analysis of quantum discord decoherence had predicted the time dependence of the discord to change suddenly under the influence of phase noise. The experiment attests to the robustness of the effect, sufficient to confirm the theoretical prediction even under the additional influence of a thermal environment. Finally, we discuss an observable witness for the quantumness of correlations in two-qubit systems and its first NMR implementation. Should the nature, not the amount, of the correlation be under scrutiny, the witness offers the most attractive alternative."