Alendu Baura

Study of non-Markovian dynamics of a charged particle in presence of a magnetic field in a simple way

In this paper, we have investigated the dynamics of a Brownian particle in the presence of a magnetic field. The present investigation is generalized considering different kinds of force fields, magnetic field, and non-Markovian thermal bath. The properties of the Brownian particle have been calculated based on the multi-dimensional Fokker-Planck description of stochastic processes. It leads to the study of non-Markovian dynamics of a Brownian particle in the presence of a magnetic field in a simple way. Using the present simple method, we have identified several important signatures of magnetic field and non-Markovian thermal bath in the dynamics.

Noise induced escape through an unstable limit cycle in the presence of a fluctuating barrier

The escape of Brownian particles through an unstable limit cycle in the presence of deterministic barrier fluctuations has been studied. It has been observed that with increasing non-Gaussian character of the noise, resonant activation gets suppressed and periodically forced resonant activation becomes robust. Secondly, the ratio of the mean lifetimes in the presence and in the absence of barrier fluctuation increases very rapidly with the damping constant for Gaussian noise unlike that for the non-Gaussian case. This ratio decreases sharply for deviation of the noise behavior from Gaussian characteristics. The Arrhenius plot, on the other hand, exhibits deviation from linearity particularly at large noise strength for both Gaussian and non-Gaussian cases. The deviation is large for non-Gaussian noise. We have also shown that additive colored non-Gaussian noise can induce RA-like phenomena even in a system having harmonic potential energy.

Tuning of barrier crossing time of a particle by time dependent magnetic field

We have studied the effect of time dependent magnetic field on the barrier crossing dynamics of a charged particle. An interplay of the magnetic field induced electric field and the applied field reveals several interesting features. For slowly oscillating field the barrier crossing rate increases remarkably particularly at large amplitude of the field. For appreciably large frequency a generically distinct phenomenon appears by virtue of parametric resonance manifested in multiple peaks appearing in the variation of the mean first passage time as a function of the amplitude. The parametric resonance is more robust against the variation of amplitude of the oscillating field compared to the case of variation of frequency. The barrier crossing time of a particle can be tuned para-metrically by appropriate choice of amplitude and frequency of the oscillating magnetic field.

Synchronization of Nonidentical Coupled Phase Oscillators in the Presence of Time Delay and Noise

We have studied in this paper the dynamics of globally coupled phase oscillators having the Lorentzian frequency distribution with zero mean in the presence of both time delay and noise. Noise may be Gaussian or non-Gaussian in characteristics. In the limit of zero noise strength, we find that the critical coupling strength (CCS) increases linearly as a function of time delay. Thus the role of time delay in the dynamics for the deterministic system is qualitatively equivalent to the effect of frequency fluctuations of the phase oscillators by additive white noise in absence of time delay. But for the stochastic model, the critical coupling strength grows nonlinearly with the increase of the time delay. The linear dependence of the critical coupling strength on the noise intensity also changes to become nonlinear due to creation of additional phase difference among the oscillators by the time delay. We find that the creation of phase difference plays an important role in the dynamics of the system when the intrinsic correlation induced by the finite correlation time of the noise is small. We also find that the critical coupling is higher for the non-Gaussian noise compared to the Gaussian one due to higher effective noise strength.

Magnetic field induced dynamical chaos

In this article, we have studied the dynamics of a particle having charge in the presence of a magnetic field. The motion of the particle is confined in the x-y plane under a two dimensional nonlinear potential. We have shown that constant magnetic field induced dynamical chaos is possible even for a force which is derived from a simple potential. For a given strength of the magnetic field, initial position, and velocity of the particle, the dynamics may be regular, but it may become chaotic when the field is time dependent. Chaotic dynamics is very often if the field is time dependent. Origin of chaos has been explored using the Hamiltonian function of the dynamics in terms of action and angle variables. Applicability of the present study has been discussed with a few examples.

Study of Thermodynamically Inspired Quantities for Both Thermaland External Colored Non-Gaussian Noises Driven Dynamical System

We have studied dynamics of both internal and external noises-driven dynamical system in terms of information entropy at both nonstationary and stationary states. Here a unified description of entropy flux and entropy production is considered. Based on the Fokker-Planck description of stochastic processes and the entropy balance equation we have calculated time dependence of the information entropy production and entropy flux in presence and absence of nonequilibrium constraint (NEC). In the presence of NEC we have observed extremum behavior in the variation of entropy production as function of damping strength, noise correlation, and non-Gaussian parameter (which determine the deviation of external noise behavior from Gaussian characteristic), respectively. Thus the properties of noise process are important for entropy production.