Friction under microscope in a trapped-ion optical-lattice emulator
Friction is the ubiquitous phenomenon of sticking and energy dissipation at the interface between objects. According to the widely known empirical laws of friction, it is proportional to the load on the interface and independent of velocity. However, atomistic models and some atomic force probe experiments exhibit superlubricity below a critical value of the interface interaction strength, as well as a complex dependence on velocity, temperature and the relative lattice structure. Using cold 1D ion crystals in an optical lattice, we study these phenomena with microscopic control and atom-by-atom sub-site resolution not available in any solid state probes, allowing us to build a bottom-up understanding of the physics of friction.