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Banerji J.,Quantum Optics and Quantum Information Group
Contemporary Physics | Year: 2011

Most of us came to know about the method of least squares while trying to fit a curve through a set of data points. The parameters of the curve are obtained by solving a set of equations (called the normal equations). Although widely used, this approach is not foolproof and, in some cases, it can even give results that are plain wrong! This happens due to some subtleties that are often overlooked by the user. In this paper, we demonstrate, by means of a simple numerical example, what can go wrong and how to fix them. Using only elementary matrix algebra, we introduce (and show the importance of) singular value decomposition, discrete Picard condition, Tikhonov regularisation, the L-curve and the L-curve criterion in addressing the subtle points of this method so that stable and reliable results are obtained in the end. © 2011 Taylor & Francis. Source


Bandyopadhyay A.,Hooghly Engineering and Technology College | Bandyopadhyay A.,Quantum Optics and Quantum Information Group | Prabhakar S.,Quantum Optics and Quantum Information Group | Singh R.P.,Quantum Optics and Quantum Information Group
AIP Conference Proceedings | Year: 2011

We calculate the Wigner (quasi)probability distribution function of the quantum optical elliptical vortex (QEV) generated by coupling squeezed vacuum states of two modes. The coupling between the two modes is performed by using beam splitter (BS) or a dual channel directional coupler (DCDC). The quantum interference due to coupling between the two modes promises the generation of controlled entanglement for quantum computation and quantum tomography. We compute the entanglement of such QEV formed by non-classical radiation field, using Wigner function. We report a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive. © 2011 American Institute of Physics. Source


Giri D.K.,P.A. College | Giri D.K.,Quantum Optics and Quantum Information Group | Singh R.P.,Quantum Optics and Quantum Information Group | Bandyopadhyay A.,Quantum Optics and Quantum Information Group | Bandyopadhyay A.,Hooghly Engineering and Technology College
Optical and Quantum Electronics | Year: 2014

We study a scheme for quantum teleportation of a single-mode squeezed coherent state using entangled two-mode squeezed vacuum. We establish the analytic expression of displacement gain dependent fidelity in terms of the squeezing coherent parameter r and quantum channel parameter p. The dependence of the optimum displacement gain for teleporting a squeezed coherent state upon the EPR entanglement is discussed. It shows that the fidelity of teleportation can be improved by tuning the displacement gain. We find that the fidelity increases with the increase of EPR parameter, while it decreases with the increase of the squeezing coherent parameter of the signal. We get infinite squeezing as a resource is required for an ideal and perfect teleportation of unknown input states. We show that the nonclassical properties of an unknown state to be teleported can be preserved in the teleportation. © 2013, Springer Science+Business Media New York. Source


Bandyopadhyay A.,Quantum Optics and Quantum Information Group | Bandyopadhyay A.,Hooghly Engineering and Technology College | Singh R.P.,Quantum Optics and Quantum Information Group
Optics Communications | Year: 2011

We calculate the Wigner quasiprobability distribution function of the quantum elliptical vortex in elliptical beam (EEV), produced by coupling squeezed coherent states of two modes. The coupling between the two modes is performed by using beam splitter (BS) or a dual channel directional coupler (DCDC). The quantum interference due to the coupling between the two modes promises the generation of controlled entanglement for quantum computation and quantum tomography. © 2010 Elsevier B.V. All rights reserved. Source


Bandyopadhyay A.,Quantum Optics and Quantum Information Group | Bandyopadhyay A.,Hooghly Engineering and Technology College | Prabhakar S.,Quantum Optics and Quantum Information Group | Singh R.P.,Quantum Optics and Quantum Information Group
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2011

We calculate the entanglement of a generalized elliptical vortex formed by quantized radiation field, using Wigner quasiprobability distribution function for such states. We find a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive. © 2011 Elsevier B.V. Source

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