Estimation of Quantum Correlations in Nuclear Spin Ensembles

Abstract

We study evolution of quantum correlations in ensembles of two-qubit nuclear spin systems via nuclear magnetic resonance techniques. We use discord as a measure of quantum correlations and the Werner state as an explicit example. We rst introduce di erent ways of measuring discord and geometric discord in two-qubit systems, and then we describe (a) quantitative measurement of discord for Werner-like states prepared using an entangling pulse sequence, (b) the e ciency of dynamical decoupling sequences in preserving quantum correlations,(c) the evolution of discord for a singlet-triplet mixed state during a radio-frequency spin-lock, and(d)measuring geometric discord for three-qubit case taking |S0>@|0> and GHZ state as an example.