Here are the details that the authors give in their abstract: "We show that, by exploiting different mechanisms for electron–nuclear interaction in the optical pumping process, we are able to control and image the sign of the nuclear polarization as a function of distance from an irradiated GaAs surface. This control is achieved using a crafted combination of light helicity, intensity and wavelength, and is further tuned via use of NMR pulse sequences. These results demonstrate all-optical creation of micron scale, rewritable patterns of positive and negative nuclear polarization in a bulk semiconductor without the need for ferromagnets, lithographic patterning techniques, or quantum-confined structures."
"using laser light to encode the spin-state of atomic nuclei on gallium arsenide chips", i wonder how they achieve this using laser. Is there any link to the paper? I know the conventional approach of encoding the spin on electrons.