Abhijit Kar Gupta

• M.Sc., Ph.D
• Professor (Associate) at Panskura Banamali College

That two losing (gambling) games, suitably combined, can result in a winning combination was shown by Juan M. R. Parrondo, and is known as the Parrondo paradox. We explored the periodic sequences of such games to see if it always holds, and why. A systematic study involving DTMC analysis and use of tree diagrams shows that a trade-off between the r...

Noise is known to disrupt a preferred act or motion. Yet, noise and broken symmetry in asymmetric potential, together, can make a directed motion possible, in fact essential in some cases. In Biology, in order to understand the motions of molecular motors in cells ratchets are imagined as useful models. Besides, there are optical ratchets and quant...

Parrondo's paradox is about a paradoxical game and gambling where two probabilistic losing games can be combined to form a winning game. While the counter intuitive game is interesting in itself, it can be thought of a discrete version of Brownian flashing ratchet which are employed to understand noise induced order. There are plenty of examples fr...

An interesting toy model has recently been proposed on Schumpeterian economic dynamics by Thurner {\it et al.} following the idea of economist Joseph Schumpeter. Punctuated equilibrium dynamics is shown to emerge from this model and some detail analyses of the time series indicate SOC kind of behaviours. The focus in the present work is to toss the...

We examine the concept of relaxation in the wealth exchange models that are recently proposed in econophysics to interpret wealth distributions. To quantify and characterize the process of relaxation, we define an appropriate quantity and evaluate that numerically for the systems of many agents. Also, heuristic arguments are provided in support of...

A class of conserved models of wealth distributions are studied where wealth (or money) is assumed to be exchanged between a pair of agents in a population like the elastically colliding molecules of a gas exchanging energy. All sorts of distributions from exponential (Boltzmann-Gibbs) to something like Gamma distributions and to that of Pareto's l...

A short, general overview of non-linearity in electrical (current) response in two different regimes and their origins are discussed. Special attention is paid to some recent experiments on non-linear response in inhomogeneous (composite) materials. A model percolating structure to study this behavior has been introduced. Results for this model and...

The kinetic gas theory, like the two-agent money exchange model, recently introduced in the econophysics of wealth distributions, is revisited. The emergence of a Boltzmann–Gibbs-like distribution of money into Pareto's law in the tail of the distribution is examined in terms of a 2×2 transition matrix with a general and simplified outlook. Some ad...

In our simplified description `wealth' is money ($m$). A kinetic theory of gas like model of money is investigated where two agents interact (trade) selectively and exchange some amount of money between them so that sum of their money is unchanged and thus total money of all the agents remains conserved. The probability distributions of individual...

The Social Percolation model recently proposed by Solomon et al. is studied on the Ising correlated inhomogeneous network. The dynamics in this is studied so as to understand the role of correlations in the social structure. Thus the possible role of the structural social connectivity is examined. Comment: 15 pages, 13 postscript figures, Tex file...

In a recent paper [Phys. Rev. B{\bf57}, 3375 (1998)], we examined in detail the nonlinear (electrical) dc response of a random resistor cum tunneling bond network ($RRTN$, introduced by us elsewhere to explain nonlinear response of metal-insulator type mixtures). In this work which is a sequel to that paper, we consider the ac response of the $RRTN...

We consider the scattering of electrons by a one-dimensional random potential (acting as a passive or active medium) and numerically obtain the probability distribution of the Wigner delay time (τ). We show that in a passive medium our probability distribution agrees with the earlier analytical results based on random phase approximation. We have e...

We consider the scattering of electron by a one-dimensional random potential (both passive and active medium) and numerically obtain the probability distribution of Wigner delay time ($\tau$). We show that in a passive medium our probability distribution agrees with the earlier analytical results based on random phase approximation. We have extende...

We study dielectric breakdown in a semi-classical bond percolation model for nonlinear composite materials introduced by us and the related breakdown exponent near the percolation threshold in two dimensions. The breakdown exponent after doing finite size scaling analysis is found to be $t_B \simeq$ 1.42. We discuss in detail the differences in our...

Study of various interesting features related to the nonlinear electrical response in composite materials through a model bond percolative system.

The DC-response, namely the $I$-$V$ and $G$-$V$ charateristics, of a variety of composite materials are in general found to be nonlinear. We attempt to understand the generic nature of the response charactersistics and study the peculiarities associated with them. Our approach is based on a simple and minimal model bond percolative network. We do s...

We study the statistics of reflection and transmission coefficients across a one-dimensional disordered electronic system in the presence of absorption. The absorption is introduced via a uniform imaginary part in the site energies in the disordered segment. Our results for the stationary distribution of the backscattered reflection coefficient dif...

We consider a model correlated percolative system on a 2D square lattice with a finite electric field applied accross its two opposite sides. We study the shape of the clusters formed with the addition of a new kind of bond (we call them tunneling bonds) which respond only above a finite threshold voltage. As expected, the clusters do have an overa...

We investigate a model correlated bond percolation problem on a 2D square lattice. We throw conducting bonds at random on a lattice. The nearest-neighbour gaps (which are not actually connected through conducting bonds) are bridged by some other ``tunneling'' bonds, which represent tunneling through these junctions under the application of high vol...

We look at some one-dimensional semi-infinite superlattices with an underlying Hamiltonian that is of the nearest neighbour, tight binding type. A real space rescaling procedure which is exact in one dimension is applied to obtain the location of the subbands. It has been found that these subbands never overlap in 1D, and we interpret this as a ban...

In contrast to a recent claim that the metal-insulator transition in the Harper model in one dimension does not occur sharply at $\lambda_{\rm C}=2t$, we find in a numerical study involving transmittances that there exists a sharp boundary between the localized and extended spectra in the parameter space (of $\lambda$, the amplitude of the incommen...

We propose a new type of localization namely subexponential localization, and our finite-size scaling analysis tends to indicate that it exists in a model potential with varying period in one dimension.