Abstract
We investigate both experimentally and theoretically the relaxation of pseudo-pure maximally entangled states (Bell states) of two nuclear spins 1H-13C belonging to a molecule in a liquid. The Bell states are obtained by a method based on a detuned Hartmann-Hahn cross-polarization condition. Their entangled character is verified by quantum-state tomography. Our relaxation measurements reveal different relaxation rates for different Bell states. We interpret this difference as originating from cross-correlations between different relaxation mechanisms, thereby demonstrating that the measurements of the differential relaxation of Bell states are potentially useful for advanced NMR characterization of liquids.