Self-organized criticality

Self-organized criticality describes out-of-equilibrium scenarios and the general laws of various complex dynamical phenomena ranging from the likelihood of earthquakes or the spread of forest fires. This organization principle tunes a system to a stationary state independent of the initial conditions, and only small perturbations are necessary to result in a critical response. Whitlock and coworkers report self-organized criticality in an ultracold atomic gas driven to highly excited Rydberg states. They achieve this criticality by adding a crucial feedback mechanism to the many-body dynamics of the system: population decay. These results provide an experimental platform in which complex and dynamical behavior can be linked to the underlying microscopic physics. More generally, the results could enable a better understanding of a variety of non-equilibrium phenomena in different branches of science.