Figure 12: Experimental results on the contrast problems. The inner disk mimics the spin 1, while the outside ring mimics the spin 2. The two surfaces are separated by a thin black circle. (a) is a reference image before the application of the control field when the two spins are at the north pole of the Bloch sphere. (b) represent the contrast after a real experiment. The panel (b) corresponds to , while the panel (c) to , that is, the remaining and magnetization components after the optimized pulse. A color has been associated to each value of the contrast between 0 and 1, 0 and 1 corresponding, respectively, to the colors black and white. In the experiment, relaxation parameters are taken to be  ms,  ms for the inner sample and  ms,  ms for the outside sample.