A Coplanar Waveguide Fed Hexagonal Shape Ultra Wide Band Antenna with WiMAX and WLAN Band Rejection

In this paper, a coplanar waveguide (CPW) fed hexagonal shape planar antenna has been considered for ultra-wide band (UWB). This antenna is then modified to obtain dual band rejection. The Wireless Local Area Network (WLAN) and Wireless Microwave Access (WiMAX) band rejections are realized by symmetrically incorporating a pair of L-shape slots within the ground plane as well as a couple of I-shape stubs inserted on the bottom side of radiating patch. The proposed antenna has stop bands of 5.05-5.92 GHz and 3.19-3.7 GHz while maintaining the wideband performance from 2.88 - 13.71 GHz with reflection coefficient of ≤ -10 dB. The antenna exhibits satisfactory omni-directional radiation characteristics throughout its operating band. The peak gain varies from 2 dB to 6 dB in the entire UWB frequency regions except at the notch bands. Surface current distributions are used to analyze the effects of the L-slot and I-shape stub. The measured group delay has small variation within the operating band except notch bands and hence the proposed antenna may be suitable for UWB applications

Management of wetlands of non-prominence from the perspective of benefit-degradation relation

Wetlands of non-prominence discussed here are some water bodies in the lower-gangetic floodplains of India. People surrounding these wetlands earn their livelihood and derive many direct and indirect benefits from them. To acquire benefits, often stakeholders subject them to environmental degradation. This study tries to identify the socio-economic activities in and around these wetlands to estimate the value of the benefits derived out of these activities, to measure the degradation of physical component of the wetlands, and to estimate the benefit-degradation relations for these wetlands. For the purpose of this study, ten wetlands in Bardhaman district in West Bengal, India were surveyed. The benefit and degradation were measured, and then the benefit-degradation relations have been estimated using regression models. From the benefit-degradation relations some alternatives for uses of wetlands have been worked out in an eco-friendly manner to find the conflicts that might emerge among the stakeholders.Length: pp.267-281WetlandsEnvironmental degradationAssessmentEcosystemsFisheriesHouseholds

Programmable quantum state discriminator by Nuclear Magnetic Resonance

In this paper a programmable quantum state discriminator is implemented by using nuclear magnetic resonance. We use a two qubit spin-1/2 system, one for the data qubit and one for the ancilla (programme) qubit. This device does the unambiguous (error free) discrimination of pair of states of the data qubit that are symmetrically located about a fixed state. The device is used to discriminate both, linearly polarized states and elliptically polarized states. The maximum probability of the successful discrimination is achieved by suitably preparing the ancilla qubit. It is also shown that, the probability of discrimination depends on angle of unitary operator of the protocol and ellipticity of the data qubit state.Comment: 22 pages and 9 figure

Quantum Information processing by NMR: Implementation of Inversion-on-equality gate, Parity gate and Fanout gate

While quantum information processing by nuclear magnetic resonance (NMR) with small number of qubits is well established, implementation of lengthy computations have proved to be difficult due to decoherence/relaxation. In such circumstances, shallow circuits (circuits using parallel computation) may prove to be realistic. Parity and fanout gates are essential to create shallow circuits. In this article we implement inversion-on-equality gate, followed by parity gate and fanout gate in 3-qubit systems by NMR, using evolution under indirect exchange coupling Hamiltonian.Comment: 24 pages, 7 figure

On Completely Mixed Stochastic Games

In this paper, we consider a zero-sum undiscounted stochastic game which has finite state space and finitely many pure actions. Also, we assume the transition probability of the undiscounted stochastic game is controlled by one player and all the optimal strategies of the game are strictly positive. Under all the above assumptions, we show that the $\beta$-discounted stochastic games with the same payoff matrices and $\beta$ sufficiently close to 1 are also completely mixed. We give a counterexample to show that the converse of the above result in not true. We also show that, if we have non-zero value in some state for the undiscounted stochastic game then for $\beta$ sufficiently close to 1 the $\beta$-discounted stochastic game also possess nonzero value in the same state

Impurity effects on semiconductor quantum bits in coupled quantum dots

We theoretically consider the effects of having unintentional charged impurities in laterally coupled two-dimensional double (GaAs) quantum dot systems, where each dot contains one or two electrons and a single charged impurity in the presence of an external magnetic field. Using molecular orbital and configuration interaction method, we calculate the effect of the impurity on the 2-electron energy spectrum of each individual dot as well as on the spectrum of the coupled-double-dot 2-electron system. We find that the singlet-triplet exchange splitting between the two lowest energy states, both for the individual dots and the coupled dot system, depends sensitively on the location of the impurity and its coupling strength (i.e. the effective charge). A strong electron-impurity coupling breaks down equality of the two doubly-occupied singlets in the left and the right dot leading to a mixing between different spin singlets. As a result, the maximally entangled qubit states are no longer fully obtained in zero magnetic field case. Moreover, a repulsive impurity results in a triplet-singlet transition as the impurity effective charge increases or/and the impurity position changes. We comment on the impurity effect in spin qubit operations in the double dot system based on our numerical results.Comment: published version on Physical Review B journal, 25 pages, 26 figure