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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.

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.

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.

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.

Karmakar S.,University of Calcutta | Sen A.,University of Calcutta | Bhar A.,Jogesh Chandra Chaudhuri College | Sarkar D.,University of Calcutta
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

Monogamy is a defining feature of entanglement, having far-reaching applications. Recently, Regula et al. [Phys. Rev. Lett. 113, 110501 (2014)PRLTAO0031-900710.1103/PhysRevLett.113.110501] proposed a stronger version of monogamy relation for concurrence. We have extended the strong monogamy inequality for another entanglement measure, viz., negativity. In particular, we have concentrated on the four-qubit system and provided a detailed study on the status of strong monogamy on pure states. Further, we have analytically provided some classes of states for which negativity and squared negativity satisfy strong monogamy. Numerical evidences have also been shown in proper places. Our analysis also provides cases where strong monogamy is violated. © 2016 American Physical Society.

Sen A.,University of Calcutta | Sarkar D.,University of Calcutta | Bhar A.,Jogesh Chandra Chaudhuri College
Quantum Information Processing | Year: 2016

Recent findings suggest, separable states, which are otherwise of no use in entanglement dependent tasks, can also be used in information processing tasks that depend upon the discord type general non-classical correlations. In this work, we explore the nature of uncertainty in separable states as measured by local quantum uncertainty. Particularly in two-qubit system, we find separable X state which has maximum local quantum uncertainty. Interestingly, this separable state coincides with the separable state, having maximum geometric discord. We also search for the maximum amount of local quantum uncertainty in separable Bell diagonal states. We indicate an interesting connection to the tightness of entropic uncertainty with the state of maximum uncertainty. © 2015, Springer Science+Business Media New York.

Sen A.,University of Calcutta | Bhar A.,Jogesh Chandra Chaudhuri College | Sarkar D.,University of Calcutta
Quantum Information Processing | Year: 2014

Local quantum uncertainty was introduced as a measure of quantum uncertainty in an quantum state as achievable on single local measurement. However, such quantity do satisfy all necessary criteria to serve as measure of discord-like quantum correlation and it has no closed formula except only for (formula presented) system. Here, we consider orthogonal invariant class of states which includes both the Werner and Isotropic class of states and explore the possibility of closed form formula. Further, we extend our quest to the possibility of closed form of geometric discord and measurement-induced nonlocality for this class. We also provide a comparative study of the bounds of general quantum correlations with entanglement, as measured by negativity, for an interesting subclass of states. © 2014, Springer Science+Business Media New York.

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.

Sadhukhan S.,Jogesh Chandra Chaudhuri College | Dutta T.,St Xaviers College | Tarafdar S.,Jadavpur University
Physica A: Statistical Mechanics and its Applications | Year: 2011

When two or more different materials are combined to form composites, the property of the composite may be quite different. This depends on relative interaction strengths of cohesion between similar and adhesion between dissimilar particles. We study crack formation in composites through a very general spring network model on a square lattice. The spring model shows the distortion of the lattice, prior to fracture and this affects the pattern of subsequent cracks, unlike the prevalent random fuse models, where no distortion is allowed. Two different types of sites (A and B) are distributed randomly on the lattice, representing two different constituents. There are springs of three types connecting them (AA, BB and AB). We assign two spring parameters for each type of spring. These are a spring constant and a breaking threshold. We show that intermediate compositions may require higher energy to induce the first sample spanning break than either pure A or pure B. So the breaking energy goes through a maximum as the concentration of one component varies from 0% to 100%. The position and height of the peak depend on the spring parameters. © 2010 Elsevier B.V. All rights reserved.

Nath J.,Jogesh Chandra Chaudhuri College | Nath A.,St Xaviers College Autonomous
Proceedings of the 2012 World Congress on Information and Communication Technologies, WICT 2012 | Year: 2012

It is now a prime research area to understand microRNA (miRNA) in a quantitative manner. The researchers across the globe have been working on quantitative estimation of microRNA (miRNA) from different angles. Our present study would be a new addition in the present scenario. The miRNAs are non-coding short ribonucleic acid (RNA) molecules, approximately ∼25 nucleotides long. MiRNAs help in understanding the entire scope of post-transcriptional gene regulation. MiRNAs regulate numerous cellular processes and have roles in tissue remodeling. In the present work the authors made an exhaustive study on deciphering the inherent statistical behavior in pre-mature miRNA strings through few statistical parameters namely Hurst Exponent values, Variance, Poly String Mean and Poly String Standard Deviation. These four parameters not only quantify miRNA but also classify the miRNA strings. In the present work the authors have to tried to explore the quantification and classification based on statistical results on nucleotide strings of pre-mature miRNAs of the three organisms Homo sapiens (hsa), Macaca mulatta (mml) and Pan troglodytes (ptr). © 2012 IEEE.

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