Polarization gradient light masks in atom lithography

In atom lithography, neutral atoms are focused by laser light to form a periodic pattern on a substrate. We have realized two-dimensional structuring of chromium on a silicon substrate employing a polarization gradient light mask with uniform intensity. The generated structures exhibit peak-to-peak distances below half the laser wavelength. The results are explained by a theoretical model which takes into account the magnetic substructure of the atomic transition employed and the influence of a static magnetic field.