Vortex Creation in Bose-Einstein Condensates by Diffraction on a Helical Light Grating

It is shown that diffraction of Bose-Einstein condensates on a helical light grating results in vortices in the condensate. Helical light gratings can be produced by light interference of a Gaussian laser beam with a helical one. Diffraction orders of the Bose-Einstein condensate contain vortices of corresponding topological charge. The phenomena is illustrated by numerical integration of the Gross-Pitaevskii equation in two dimensions.