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Nag S.,Jadavpur University | Sinha S.,Jadavpur University | Sadhukhan S.,Jogesh Chandra Chaudhuri College | Dutta T.,St Xaviers College | Tarafdar S.,Jadavpur University
Journal of Physics Condensed Matter | Year: 2010

Crack patterns in desiccating clay suspensions are drastically altered by the addition of polymers. In this paper we report a systematic study of the effect of varying the composition of a clay-polymer composite on the formation of crack patterns. Experiments as well as computer simulations have been done. Details of the morphology and fractal dimension of the experimental patterns are observed and the simulation is done on a two-dimensional spring network model. We find a transition from a completely fragmented fractal pattern at high clay content to a continuous film at about 50% clay content. The results of the simulation are in good qualitative agreement with the experiments. The study is expected to be of importance for clay-polymer composites. These can be designed to give improved mechanical and electrical properties for practical applications. © 2009 IOP Publishing Ltd. Source


Bhar A.,Jogesh Chandra Chaudhuri College | Sen A.,University of Calcutta | Sarkar D.,University of Calcutta
Quantum Information Processing | Year: 2013

In this paper we investigate the effect of superposition of states on local conversion of pure bipartite states under deterministic LOCC. We are able to form a bridge between comparable and incomparable classes of states through the linear superposition of states. For example, if we consider two pairs of incomparable states, then their superposition may result into a comparable pair of states. We investigate many such cases and provide some of the results in tabular form. We also investigate the entanglement behavior of such classes of states, specifically their monotone nature. Finally we provide some bounds of different measures of entanglement based on the idea of comparability and incomparability under deterministic LOCC. © 2012 Springer Science+Business Media, LLC. Source


Sen A.,University of Calcutta | Sarkar D.,University of Calcutta | Bhar A.,Jogesh Chandra Chaudhuri College
Quantum Information Processing | Year: 2013

We check the decoherence dynamics of Measurement-induced Nonlocality (in short, MIN) and compare it with geometric discord for two qubit systems. There are quantum states, on which the action of dephasing channel cannot destroy MIN in finite or infinite time. We check the additive dynamics of MIN on a qubit state under two independent noise. Geometric discord also follows such additive dynamics like quantum discord. We have further compared non-Markovian evolution of MIN and geometric discord under dephasing and amplitude damping noise for pure state and it shows distinct differences between their dynamics. © 2013 Springer Science+Business Media New York. Source


Maity S.K.,Jogesh Chandra Chaudhuri College | Dutta A.,Bose Institute of India | Kumar S.,Jadavpur University | Sinha T.P.,Bose Institute of India
Physica Scripta | Year: 2013

The electrical properties of a rare-earth based double perovskite oxide barium ytterbium niobate, Ba2YbNbO6 (BYN), synthesized by the solid-state reaction technique are investigated. The Rietveld refinement of the x-ray diffraction pattern suggests that the compound has a cubic phase at room temperature with a Fm3m space group. The room temperature Raman spectrum also supports the cubic crystal structure of BYN. The frequency-dependent dielectric dispersion of the material is investigated in the temperature range from 303 to 603 K. The Cole-Cole model is used to analyze the dielectric relaxation phenomenon. The complex impedance data are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element in parallel, where the ideal capacitance part is replaced by a constant phase element. The frequency dependent conductivity spectra follow the double power law. The scaling behavior of the imaginary part of the dielectric constant (ε″) suggests that relaxation describes the same mechanism at various temperatures in BYN. © 2013 The Royal Swedish Academy of Sciences. Source


Sen A.,University of Calcutta | Sarkar D.,University of Calcutta | Bhar A.,Jogesh Chandra Chaudhuri College
Journal of Physics A: Mathematical and Theoretical | Year: 2012

Measurement-induced nonlocality was introduced by Luo and Fu (2011 Phys. Rev. Lett. 106 120401) as a measure of nonlocality in a bipartite state. In this paper, we will discuss the monogamy property of measurement-induced nonlocality for some three- and four-qubit classes of states. Unlike discord, we find quite surprising results in this situation. Both the GHZ- and W-states satisfy monogamy relations in the three-qubit case; however, in general there are violations of monogamy relations in both the GHZ-class and W-class states. In the case of the four-qubit system, monogamy holds for most of the states in the generic class. The four-qubit GHZ-state does not satisfy the monogamy relation, but the W-state does. We provide several numerical results including counterexamples regarding the monogamy nature of measurement-induced nonlocality. We will also extend our results of the generalized W-class to n-qubit systems. © 2012 IOP Publishing Ltd. Source

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