Fig. 5. Experimental confirmation of the Aubry transition in atomic and colloidal systems.

a Sketch of an experimental setup with two interacting chains of laser-cooled YB positive ions inside a linear trap which is created by four quadrupole electrodes. The two laser beams are used for the illumination of the ions and for performing vibrational spectroscopy. The ions are imaged onto an electron multiplying CCD camera⁵². b Illustration of an extended two-dimensional micron-sized colloidal monolayer consisting of several thousand particles which are interacting with an optical substrate potential created by three interfering laser beams. Variation of the corrugation amplitude of the substrate potential is achieved by changes in the laser intensity⁵³. Both experiments confirm the existence of a transition from a superlubric to a pinned state in agreement with theoretical predictions.