A method to directly measure the local entropy production rate of an active-matter system

Sunghan Ro of the Technion-Israel Institute of Technology, Buming Guo of New York University, and colleagues — in an effort led by NYU Simons Center’s Stefano Martiniani — have devised a method for measuring local entropy production rate in active matter systems. In the image above, active Brownian particles are driven toward the center of the ring structure via a series of funnels.  Local entropy production is largest at the funnel tips (shown in yellow) where the particle trajectories bifurcate, and contributions to the entropy production from particle collisions is higher in regions with higher particle density. Hence, the region within the inner ring is brightest, and the region outside the outer ring is darkest.

This work is published as the cover article in Physical Review Letters and has been selected for a Viewpoint in Physics magazine. The method, which involves comparing forward and time-reversed particle trajectories, could allow researchers to reveal the impact of local entropy production rates on the global dynamics of complex systems.

Reference:

Model-Free measurement of local entropy production and extractable work in active matter

Sunghan Ro, Buming Guo, Aaron Shih, Trung V. Phan, Robert H. Austin, Dov Levine, Paul M. Chaikin, and Stefano Martiniani
Phys. Rev. Lett. 129, 220601 – Published 21 November 2022
DOI: 10.1103/PhysRevLett.129.220601