Spin-selective coherent light scattering from ion crystals

We study coherent light scattering from linear crystals with up to twelve $^{40}\mathrm{Ca}^{+}$ ions, acting as single photon emitters. Light scattering is induced by two-photon laser excitation, starting from the ${S}_{1/2}\ensuremath{\rightarrow}{D}_{5/2}$ quadrupole transition at 729 nm followed by the ${D}_{5/2}\ensuremath{\rightarrow}{P}_{3/2}$ dipole transition at 854 nm, from where the ions decay back to the ${S}_{1/2}$ ground state via emission of a photon near 393 nm. We realize spin-selective excitation from the Zeeman-split ground states ${S}_{1/2}, \mathrm{m}=\ifmmode\pm\else\textpm\fi{}1/2$, of the ${\text{Ca}}^{+}$ ions and observe, in the far-field, spin-dependent interference patterns displaying the spin textures of the ion crystals. We investigate their dynamics by measuring the temporal evolution of the spatial Fourier frequencies of the observed patterns.