title: Controlling spin-spin network dynamics by repeated projective measurements.
abstract: We show that coupled-spin network manipulations can be made highly effective by repeated projections of the evolving quantum states onto diagonal density-matrix states (populations). As opposed to the intricately crafted pulse trains that are often used to fine-tune a complex network's evolution, the strategy hereby presented derives from the "quantum Zeno effect" and provides a highly robust route to guide the evolution by destroying all unwanted correlations (coherences). We exploit these effects by showing that a relaxationlike behavior is endowed to polarization transfers occurring within a N-spin coupled network. Experimental implementations yield coupling constant determinations for complex spin-coupling topologies, as demonstrated within the field of liquid-state nuclear magnetic resonance.
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel.
authors.forename: Christian O
authors.initials: CO
authors.lastname: Bretschneider
authors.forename: Gonzalo A
authors.initials: GA
authors.lastname: Alvarez
authors.forename: Gershon
authors.initials: G
authors.lastname: Kurizki
authors.forename: Lucio
authors.initials: L
authors.lastname: Frydman