Signatures of Self-Organised Criticality in an Ultracold Atomic Gas

TL;DR

This paper demonstrates the presence of self-organised criticality in an ultracold atomic gas, showing scale-invariance, independence from initial conditions, and power-law distributed fluctuations, providing a new platform for studying non-equilibrium critical phenomena.

Contribution

It provides the first experimental observation of key signatures of self-organised criticality in a driven-dissipative ultracold atomic gas system.

Findings

Self-organisation leads to a stationary state independent of initial conditions.

Final density exhibits scale-invariance with a unique scaling function.

Number of excited atoms shows power-law distributed avalanches.

Abstract

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 that feature a critical point as an attractor for the dynamics, the connection to real-world systems is exceptionally hard to test quantitatively. Here we observe three key signatures of self-organised criticality in the dynamics of a driven-dissipative gas of ultracold atoms: (i) self-organisation to a stationary state that is largely independent of the initial conditions, (ii) scale-invariance of the final density characterised by a unique scaling function, and (iii) large fluctuations of the number of excited atoms (avalanches) obeying a characteristic power-law distribution. This establishes a well-controlled platform for investigating self-organisation phenomena and non-equilibrium criticality with unprecedented experimental access to the underlying microscopic details of the system.