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Unraveling the flow of information in a nonequilibrium process in the presence of hydrodynamic interactions

Biswajit Das1,*, Sreekanth K. Manikandan2,†, and Ayan Banerjee1,‡

  • *Contact author: bd18ip005@iiserkol.ac.in
  • †Contact author: sreekanth.manikandan@physics.gu.se
  • ‡Contact author: ayan@iiserkol.ac.in
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Phys. Rev. Applied 24, 034039 – Published 16 September, 2025

DOI: https://doi.org/10.1103/dvb3-b2v8

Abstract

Identifying the origin of nonequilibrium characteristics in a generic interacting system having multiple degrees of freedom is a challenging task. In this context, information-theoretic measures such as mutual information and related polymorphs offer valuable insights. Here we explore these measures in a minimal experimental model consisting of two hydrodynamically coupled colloidal particles, where a nonequilibrium drive is introduced via an exponentially correlated noise acting on one of the particles. We show that the information-theoretic tools considered enable a systematic, data-driven dissection of information flow within the system. These measures allow us to identify the driving node and reconstruct the directional dependencies between particles. Notably, they help explain a recently observed, counterintuitive trend in the dependence of irreversibility on interaction strength under coarse-graining [Das et al., Phys. Rev. E 112, L023401 (2025)]. Finally, our results demonstrate how directional information measures can uncover the hidden structure of nonequilibrium dynamics and provide a framework for studying similar effects in more complex systems.

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Outline

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Phys. Rev. Applied 24, 034039– Published 16 September, 2025
  • Received 5 May 2025
  • Revised 23 July 2025
  • Accepted 26 August 2025
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