Rick van Bijnen, Cornee Ravenbergen, Sjoerd Smit, Edgar Vredenbregt and Servaas Kokkelmans

Ultracold atomic gases provide a rich playground for realizing textbook examples of condensed matter phenomena. A recent novel direction is the creation of crystalline structures of highly excited Rydberg atoms, which can be a model for dilute metallic solids with tunable parameters, and provide access to the regime of strongly coupled systems. In practise, crystal creation is made difficult by the 'Rydberg blockade', where one atom in the Rydberg state shifts the energy levels of thousands of its neighbours out of resonance with the excitation laser. By careful shaping of the excitation laser pulse, we exploit the blockade effect and show how to create large, crystalline structures. In our experiment, we facilitate the creation of ordered Rydberg structures by imprinting local excitations in a disordered atomic gas using spatial light modulators (SLMs). SLMs are diffractive optical elements that make it possible to control the intensity of light in the far ?eld and create (almost) any desired intensity pattern. In this way, crystal- like structures of Rydberg atoms with adjustable parameters such as ionic lattice spacing, interparticle interaction strength and electron tunnelling probability can be produced.