Signatures of Self-Organised Criticality in an Ultracold Atomic Gas

Self organisation provides an elegant explanation for how complex structures emerge and persist throughout nature. Surprisingly often, these structures exhibit remarkably similar scale-invariant properties. While this is sometimes captured by simple models, the connection to real-world systems is exceptionally hard to test quantitatively. Here we identify three key signatures of self-organised criticality in the dynamics of a driven-dissipative gas of ultracold atoms and provide a first characterisation of its universal properties. We show that population decay drives the system to a stationary state that is largely independent of the initial conditions and exhibits scale invariance and a strong response to perturbations. This establishes a well-controlled platform for investigating self-organisation phenomena and non-equilibrium universality with unprecedented experimental access to the underlying microscopic details of the system.