Self organisation provides an elegant explanation for how complex structures emerge and persist throughout nature and society.
Surprisingly often, these self-organised structures are found to exhibit remarkably similar fractal-like or scale-invariant properties. While this is sometimes captured by simple models, the connection to real-world complex systems is exceptionally hard to test quantitatively.
In this talk I will present the experimental observation of self-organised criticality in the dynamics of a driven-dissipative gas of ultracold Rydberg atoms and a first characterisation of its universal properties. Our measurements show that population decay is a crucial aspect of the nonlinear dynamics that drives the system to a stationary state that is largely independent of the initial conditions and exhibits scale invariance. This establishes a well-controlled platform for investigating self-organisation phenomena and non-equilibrium universality with experimental access to the underlying microscopic details of the system.