Spin-selective coherent light scattering from ion crystals

We study coherent light scattering from linear crystals with up to twelve ${}^{40}{\text{Ca}}^{+}$ ions, acting as single photon emitters. Light-scattering is induced by two-photon laser excitation, starting from the S${}_{1\mathrm{/}2}\to$ D${}_{5\mathrm{/}2}$ quadrupole transition at 729~nm followed by the D${}_{5\mathrm{/}2}\to$ P${}_{3\mathrm{/}2}$ dipole transition at 854~nm, from where the ions decay back to the S${}_{1\mathrm{/}2}$ ground state via emission of a photon near 393~nm. We realize spin-selective excitation from the Zeeman-split ground states S${}_{1\mathrm{/}2}$, m$=\pm 1\mathrm{/}2$, 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.