NewGenActive · A New Generation of Active Matter Models

The development of non-equilibrium statistical physics has provided a powerful tool to understand anddescribe the collective dynamics of a wide range of chemical, biological and social systems. In thisframework, active matter has raised as one of the most significant topics in this domain, mainlyaddressing the features of many-body dynamics with self-propelled units such as bacteria colonies, birdflocks and pedestrians walks. Based on the observation of collective motion like size synchronization andwave propagation in epithelial tissues, we will introduce a new class of active matter models tounderstand the microscopic physical mechanisms underlying these dynamics. Motivated by the physicalcomplexity of biological units, we will extend the concept of activity to the ability of the individualparticle to change an internal degree of freedom, related to its size or to an energetic landscape, and wewill explore the non-equilibrium phase transitions and collective behavior originating from this property.Our research project consists of three main objectives: (i) we will first extensively investigate the phasediagram of actively deforming particles, and compare it to the experimental observations to capture theessential mechanisms of phase transitions and wave propagation; (ii) we will then explore the interplaybetween phase synchronization and microscopic energy landscapes to understand the minimal ingredientsfor liquid-liquid phase separation, where two fluids spontaneously separate from a mixed phase; (iii) wewill finally study the energetics of these models, quantifying the energy gain/cost of each phase andstudying how phase transitions can be optimized. The exploration of these models represents a potentialbreakthrough in the physics of soft matter, clarifying the microscopic ingredients at the basis of severalchemical and biological dynamics and introducing a fertile ground for the emergence of new physics.