arXiv subjects

Moupriya Das

Publications and source records attributed to Moupriya Das.

6 recordsLinked to original sources

arXiv2026

Dynamic hysteresis in an autocatalytic reaction network

Here we show that an autocatalytic reaction network can exhibit dynamic hysteresis as a result of the competition between its intrinsic relaxation time scale and that of the periodic drive. The autocatalytic reaction steps generate bistability in the concentration of the autocatalytic species, and periodic pumping of the product species provides the external drive. Hysteresis arises from the lag between the concentration response of the autocatalytic species and the external periodic drive. The resulting hysteresis-loop area quantifies the extent of the system's hysteretic response. Using the periodically driven Schl\"ogl model as a representative bistable chemical system, we use this loop area to determine how the magnitude of the hysteretic response is controlled by the driving protocol, intrinsic fluctuations, and the size of the system. Varying the driving frequency and the strength of the fluctuations causes a turnover of the hysteresis loop area, whereas the area changes monotonically with driving amplitude and system size. These trends identify the driving protocol and fluctuation strength as primary controls on the magnitude of dynamic hysteresis. In contrast to stochastic resonance, which is typically associated with weak periodic forcing and noise-assisted amplification, dynamic hysteresis can characterize the reaction-system response over a wider range of external control conditions. We further show that the delayed concentration response is mirrored in Shannon entropy and in the total entropy production rate, connecting dynamic hysteresis to information-theoretic and stochastic-thermodynamic measures of irreversibility. Overall, we identify and interpret the role of the controlling factors in chemical dynamic hysteresis and suggest implications for efficient chemical logic gates and eventually, chemical computers.

cond-mat.stat-mech↗

arXiv2026

Exploring the entropic asymmetry on logical stochastic resonance with energetically equivalent intrinsic outputs

Small-scale systems are inherently subject to environmental noise that can be harnessed constructively to realize reliable logic operations -- a phenomenon known as logical stochastic resonance (LSR), where a bistable system produces correct logical outputs within an optimal window of noise intensity. The Brownian dynamics governed by appropriate inputs inside a double-well potential, modeling the bistable system, mimic the logic operations. The two wells of this potential represent two distinct logical output states 0 and 1. Asymmetry in this potential is known to be essential for improving logical reliability. However, prior studies have focused on energetic asymmetry, characterized by unequal depths of the two wells of the potential. This left the role of the width asymmetry in the potential, unexplored. This latter class of asymmetry emerges due to the dissimilar widths of the two wells of the potential. It can be classified as the entropic asymmetry between the two logical output states. Here, we systematically investigate the effect of width or the entropic asymmetry in the system on the logical response for OR and AND gate operations. Unlike energetic asymmetry, width asymmetry preserves the energetic equivalence of the two intrinsic logical output states, making it a geometric effect. We find that increasing width asymmetry consistently improves the optimal P(logic), the quantifier measuring the successful logical outcome. Moreover, when it is combined with an energetic bias, it produces reliable logic gate operation at a significantly reduced energetic cost compared to the symmetric case. The requirement of this energy bias also diminishes gradually with the increasing degree of width asymmetry in the potential.

cond-mat.stat-mech↗

arXiv2025

Dynamic hysteresis and transitions controlled by asymmetry in potential: energetic and entropic aspects

We aim to investigate the precise role of the asymmetry in the underlying potential on the process of dynamic hysteresis. So far, the theoretical modeling of this phenomenon of fundamental importance has been done considering symmetric bistable systems. The influence of asymmetry in the bistable potential has been explored in related contexts, such as first passage time estimates, escape dynamics, stochastic resonance, etc., highlighting the importance of the aspect of asymmetry in the systems. However, the perspective of developing a thorough theoretical understanding in this context remained overlooked in the case of dynamic hysteresis. Here, we scrutinize how the asymmetry in the potential influences this process, considering the physical model of a Brownian particle in a double-well potential subject to a periodic forcing. We analyze in detail the effect of two distinct types of asymmetry in the intrinsic potential, one corresponding to the different depths and the other subject to the separate widths of the two wells of the double-well potential representing the bistable system. Our study reveals that the hysteretic effect predominantly decreases with increasing asymmetry in both types of the system, reflected in the reduced hysteresis loop area. This observation suggests that the introduction of the appropriate asymmetry in the potential can quantitatively regulate the outputs of the dynamic hysteresis. This modulation can be beneficial for controlling devices' outputs in which dynamic hysteresis plays a role. Moreover, importantly, the implemented asymmetries in the potential can induce symmetry breaking in the response of the systems. This gives rise to asymmetric dynamic hysteresis loops, signifying the dynamic transition to an asymmetric phase, in moderate conditions, which is absent in the symmetric systems in the same scenarios.

cond-mat.stat-mech↗

arXiv2025

Improving the efficiency of finite-time memory erasure with potential barrier shaping

Erasure of the binary memory, 0 or 1, is an essential step for digital computation involving irreversible logic operations. The erasure of a bit of a classical bit of memory is accompanied by the evolution of a minimum amount of heat set by the Landauer bound kTln2, achieved in the asymptotic limit. However, the erasure of memory needs to be completed within a finite time for practical computation. The higher the speed of erasure, the greater the amount of heat released, which is unfavorable to the environment. Therefore, this is a fundamental challenge to reduce the evolved heat related to finite-time memory erasure. Here, we address this crucial aspect of information thermodynamics. We proceed by considering the model where the two memory states correspond to the two wells of a bistable potential that is asymmetric in terms of the width of its two wells. Moreover, they are separated by an asymmetric barrier. This type of asymmetry models the two binary memory states occupying different phase-space volumes, but are energetically equivalent. We examine the effect of the degree of asymmetry on the success rate of the erasure process and the work done or heat released associated with it. We find that this characteristic asymmetry in the underlying potential plays a very significant role in improving the efficiency of the erasure process. Our study establishes the fact that one can reach below the Landauer bound in an appropriate asymmetric setup. Importantly, it develops a quantitative understanding of the deviation from the Landauer limit as a function of the degree of asymmetry in the governing potential. We identify the effective free energy change for the finite-time bit erasure process as a general lower bound for the work done or evolved heat even when the departure from the Landauer limit is observed. We retrieve the approach towards the Landauer limit under the symmetric setup.

cond-mat.stat-mech↗

arXiv2018

Critical fluctuations and slowing down of chaos

Fluids cooled to the liquid-vapor critical point develop system-spanning fluctuations in density that transform their visual appearance. Despite the rich phenomenology of this critical point, there is not currently an explanation of the underlying mechanical instability. How do structural correlations in molecular positions overcome the destabilizing force of deterministic chaos in the molecular dynamics? Here, we couple techniques from nonlinear dynamics and statistical physics to analyze the emergence of this singular state. Our numerical simulations reveal that the ordering mechanisms of critical dynamics are directly measurable through the hierarchy of spatiotemporal Lyapunov modes. A subset of unstable modes softens near the critical point, with a marked suppression in their characteristic exponents reflecting a weakened sensitivity to initial conditions. Finite-time fluctuations in these exponents, however, exhibit diverging dynamical timescales and power law signatures of critical dynamics. Collectively, these results are symptomatic of a critical slowing down of chaos that sits at the root of our statistical understanding of the singular thermodynamic responses at the liquid-vapor critical point.

cond-mat.stat-mech↗

arXiv2017

Self-averaging fluctuations in the chaoticity of simple fluids

Bulk properties of equilibrium liquids are a manifestation of intermolecular forces. Here, we show how these forces imprint on dynamical fluctuations in the Lyapunov exponents for simple fluids with and without attractive forces. While the bulk of the spectrum is strongly self-averaging, the first Lyapunov exponent self-averages only weakly and at a rate that depends on the length scale of the intermolecular forces; short-range repulsive forces quantitatively dominate longer range attractive forces, which act as a weak perturbation that slows the convergence to the thermodynamic limit. Regardless of intermolecular forces, the fluctuations in the Kolmogorov-Sinai entropy rate diverge, as one expects for an extensive quantity, and the spontaneous fluctuations of these dynamical observables obey fluctuation-dissipation like relationships. Together, these results are a representation of the van der Waals picture of fluids and another lens through which we can view the liquid state.

cond-mat.stat-mech↗