Dynamical heterogeneity in active glasses is inherently different from its equilibrium behavior

Area of Science:

• Physics
• Soft Matter Physics
• Non-equilibrium Systems

Background:

• Activity-driven glassy dynamics are observed in various systems like cell migration and colony behavior.
• Active glasses were previously thought to resemble equilibrium glasses at an effective temperature.
• The physics of glass transition remains a complex and actively researched area.

Purpose of the Study:

• To investigate the fundamental differences between active and equilibrium glasses.
• To analyze the impact of activity on dynamic heterogeneity in glassy systems.
• To develop and validate theoretical models for active glassy dynamics.

Main Methods:

• Large-scale computer simulations were employed to model active glassy systems.
• Analytical mode-coupling theory (MCT) was extended for active systems.
• Four distinct methods were used to reliably estimate dynamic heterogeneity length scales.

Main Results:

• Active glasses are fundamentally different from equilibrium glasses, contrary to prior assumptions.
• While relaxation dynamics can appear equilibrium-like, activity significantly alters dynamic heterogeneity.
• Dramatic growth in dynamic heterogeneity was observed in active glasses, with varying scales for similar relaxation times.

Conclusions:

• The study reveals non-trivial effects of activity on dynamic heterogeneity, challenging previous assumptions.
• Extended active MCT provides good qualitative agreement with simulation results for dynamic heterogeneity.
• Findings offer new insights into the role of dynamic heterogeneity in glassy dynamics, with potential implications for equilibrium systems.