49,111 research outputs found
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 -discounted stochastic games
with the same payoff matrices and 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 sufficiently close
to 1 the -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
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