Publications

Google Scholar

In Preparation

1. Unifying deterministic and stochastic thermodynamic speed limits on observables
   Swetamber Das and Jason R. Green
2. Classical-mechanical advantage in parameter estimation
   Mohamed Sahbani, Swetamber Das, and Jason R. Green

In Review

1. Force Anti-Alignment and the Geometry of Nonequilibrium Dynamics
   Erez Aghion and Swetamber Das (2026)
   Abstract

   Recent experiments have shown that entropy production in driven microscopic systems can be strongly nonuniform in space and, in some cases, anticorrelated with local fluctuations. While stochastic thermodynamics successfully quantifies the energetic cost of such nonequilibrium processes, it remains unclear how underlying forces are organized to generate spatially nonuniform entropy production. Here we show that entropy production admits a natural force-level interpretation: it arises when external driving forces and entropic gradients fail to cancel through perfect anti-alignment. We introduce a time-dependent force-correlation coefficient that provides a geometric measure of this misalignment and links force organization directly to entropy production. For overdamped dynamics, perfect force anti-alignment defines a thermodynamic stall condition with vanishing net transport but finite entropy production, while departures from this geometry quantify additional irreversibility. Applying this framework to both constant and time-dependent driving protocols, we construct geometric representations that relate entropy production, transport, and driving strength within a unified framework. More broadly, this work positions force geometry as an organizing principle for nonequilibrium thermodynamics, clarifying how vectorial force organization complements current-based bounds and provides a geometric perspective on spatially heterogeneous entropy production. We outline how these ideas extend to underdamped dynamics, where inertia introduces additional geometric structure in the organization of entropy production.
2. Geometry- and inertia-limited chaotic growth in classical many-body systems
   Swetamber Das (2026)
   Abstract

   Chaotic instability in many-body systems is commonly quantified by the largest Lyapunov exponent, yet general constraints on its magnitude in classical interacting systems remain poorly understood. Here we establish explicit, Hamiltonian-specific upper bounds on the largest Lyapunov exponent for classical many-body systems with local interactions. These bounds arise from instantaneous stability constraints on the Hamiltonian flow and are expressed in terms of inertial scales and the curvature of the interaction potential. We show that they naturally separate into two qualitatively distinct classes: non-violable bounds, controlled by worst-case local curvature scales and inertia and insensitive to spatial structure, and ergodic ceilings, which retain spectral information and encode collective modes and finite-size effects under generic dynamical evolution. For a paradigmatic one-dimensional coupled-rotor chain (Josephson junction array), the ergodic ceiling admits a closed analytic form and produces a dynamically inaccessible region for sustained chaotic growth in the Lyapunov exponent--energy plane, which we confirm numerically. In contrast to non-violable estimates, the ergodic ceiling yields a sharper constraint on chaotic growth by capturing collective suppression mechanisms absent at the level of local curvature alone. Remarkably, in the thermodynamic limit the ergodic ceiling asymptotically approaches an inertial ceiling that limits sustained Lyapunov growth, becoming independent of temperature and interaction strength. While classical systems do not admit universal chaos bounds, our results identify a broad class of natural Hamiltonian systems in which chaotic growth is inherently limited by inertia and interaction geometry, thereby setting a minimal microscopic timescale for long-time loss of memory of initial conditions.

   [arXiv:2602.21149]
3. Phase space volume preserving dynamics for non-Hamiltonian systems
   Swetamber Das and Jason R. Green (2025)
   [arXiv:2511.04960]
4. Dynamical system analysis of quantum tunneling in an asymmetric double-well potential
   Swetamber Das and Arghya Dutta (2025)
   [arXiv:2510.24100]

Published/Accepted

1. Phase-space contraction rate for classical mixed states
   Mohamed Sahbani, Swetamber Das, and Jason R. Green (2025)
   Phys. Rev. E 111, 054130.
2. Spectral bounds on Lyapunov exponents and entropy production in differentiable dynamical systems
   Swetamber Das and Jason R. Green (2025)
   J. Phys. A: Math. Theor. 2025 58(3) 035003.
3. Maximum speed of dissipation
   Swetamber Das and Jason R. Green (2024)
   Phys. Rev. E (Letter) 109, L052104.
4. Observing the dynamics of an electrochemically driven active material with liquid electron microscopy
   Wyeth S. Gibson, Justin T. Mulvey, Swetamber Das, Serxho Selmani, Jovany G. Merham, Alex Rakowski, Eric Schwartz, Allon I. Hochbaum, Zhibin Guan, Jason R. Green, and Joseph P. Patterson (2024)
   ACS Nano 18 (18), 11898–11909. (theory support)
5. Classical Fisher information for differentiable dynamical systems
   Mohamed Sahbani, Swetamber Das, and Jason R. Green (2023)
   Chaos 33, 103139. Featured Article.
6. Speed limits on deterministic chaos and dissipation
   Swetamber Das and Jason R. Green (2023)
   Phys. Rev. Res. (Letter) 5(1):L012016.
7. Density matrix formulation of dynamical systems
   Swetamber Das and Jason R. Green (2022)
   Phys. Rev. E 106, 054135.
8. Tunability enhancement of gene regulatory motifs through competition for regulatory protein resources
   Swetamber Das and Sandeep Choubey (2020)
   Phys. Rev. E 102, 052410.
9. Power-law trapping in the volume-preserving Arnold-Beltrami-Childress Map
   Swetamber Das and Arnd Bäcker (2020)
   Phys. Rev. E 101, 032201.
10. Controlling synchronization in coupled area-preserving maps using stickiness
    Swetamber Das (2019)
    Accepted in AIP Advances.
11. Transport, diffusion, and energy studies in the Arnold-Beltrami-Childress map
    Swetamber Das and Neelima Gupte (2017)
    Phys. Rev. E 96, 032210.
12. Synchronization, phase slips and coherent structures in area-preserving maps
    Swetamber Das, Sasibhusan Mahata, and Neelima Gupte (2017)
    Indian Academy of Sciences Conference Series 1, 205-212.
13. Synchronization in area-preserving maps: Effects of mixed phase space and coherent structures
    Sasibhushan Mahata, Swetamber Das, and Neelima Gupte (2016)
    Phys. Rev. E 93, 062212.
14. Dynamics of impurities in three-dimensional-volume preserving map
    Swetamber Das and Neelima Gupte (2014)
    Phys. Rev. E 90, 012906.
15. On an Asymptotic Case of the Complex Lorenz Model
    Swetamber Das (2010)
    Proceedings of International Conference on Applied Physics & Mathematics, Kuala Lumpur, Malaysia (May 7–10, 2010), 579-583.
    Published by IEEE