Understanding collective behaviour in non-equilibrium systems

Our research combines analytical theory, statistical mechanics, kinetic equations and large-scale numerical simulations to understand how asymmetry, activity and stochastic fluctuations generate novel collective phenomena. We study nonreciprocal interacting systems, active matter and nonequilibrium phase transitions across lattice and continuum models.

Research Themes at a Glance

Irreversibility and Asymmetric Interactions

Effective interactions in many natural and artificial systems are often nonreciprocal, violating the conventional action–reaction symmetry that underlies equilibrium statistical mechanics. We develop lattice spin models, kinetic theories, and continuum descriptions to understand how asymmetric interactions generate novel phases, irreversible critical phenomena, and emergent travelling states.

Collective Dynamics of Active Particles

Active matter provides a powerful framework for understanding how energy-consuming particles spontaneously organize into complex structures. Our research explores the roles of visual perception, quorum sensing, and adaptive motility in producing rotating clusters, dynamic aggregation, and activity-controlled phase separation in self-propelled colloidal systems.

Theory of Nonequilibrium Phase Transitions

A central goal of our work is to connect microscopic stochastic dynamics with macroscopic collective behaviour in systems operating far from equilibrium. By combining master equations, Monte Carlo methods, Langevin dynamics, and nonlinear stability analysis, we investigate fluctuation-driven ordering, irreversible phase transitions, and pattern formation across lattice and continuum models.

Stochastic Transport and First-Passage Dynamics

Transport and switching in nonequilibrium systems are often governed by stochastic first-passage events. We combine Langevin dynamics, master equations, Gillespie simulations, and coarse-grained birth–death models to study cargo transport, delay-induced switching, and noise-driven dynamics in biological and active systems.

Recent Publications

2026
Nonreciprocal McKean–Vlasov Equations: From Stationary Instabilities to Travelling Waves
arXiv:2605.07597
2026
Nonreciprocal Blume–Capel Model with Antisymmetric Single-Ion Anisotropies
Arjun R., P. P. Patra and A. V. Anil Kumar
Physical Review E 113, 064140 (2026)
2026
Kinetic Random-Field Nonreciprocal Ising Model
Arjun R. and A. V. Anil Kumar
Physical Review E 113, 034101 (2026)
2025
Emergence of Rotating Clusters in Active Brownian Particles with Visual Perception
R. M. Chandra, A. B. John and A. V. Anil Kumar
Journal of Chemical Physics 163, 234904 (2025)
2024
Ising Model with Non-Reciprocal Interactions
arXiv:2403.06875
2020
Phase Separation in a Two-Dimensional Binary Colloidal Mixture by Quorum Sensing Activity
J. Singh and A. V. Anil Kumar
Physical Review E 101, 022606 (2020)

Contact

A. V. Anil Kumar
School of Physical Sciences
National Institute of Science Education and Research (NISER), Bhubaneswar
India


Email: anil@niser.ac.in