Distributed quantum computation via optical fibers

We investigate the possibility of realizing effective quantum gates between two atoms in distant cavities coupled by an optical fiber. We show that highly reliable swap and entangling gates are achievable. We exactly study the stability of these gates in the presence of imperfections in coupling strengths and interaction times and prove them to be robust. Moreover, we analyze the effect of spontaneous emission and losses and show that such gates are very promising in view of the high level of coherent control currently achievable in optical cavities.     

Entanglement reciprocation between qubits and continuous variables

We investigate how entanglement can be transferred between qubits and continuous-variable (CV) systems. We find that one ebit borne in maximally entangled qubits can be fully transferred to two CV systems which are initially prepared in a pure separable Gaussian field with high excitation. We show that it is possible to retrieve the entanglement back to qubits from the entangled CV systems. The deposition of multiple ebits from qubits to the initially separable CV systems is also pointed out. We show that the entanglement transfer and retrieval are done at a quasisteady state.     

Hypervalent iodine mediated intramolecular cyclization of thioformanilides: expeditious approach to 2-substituted benzothiazoles

A new, mild, and efficient method has been developed for the synthesis of 2-substituted benzothiazoles via the intramolecular cyclization of thioformanilides by using hypervalent iodine reagents in CH2Cl2 at ambient temperature. The reaction proceeds via a thiyl radical in high yields to give the novel compound oxybis benzothiazole and is also amenable to generating combinatorial libraries of heterocyclic compounds by solid-phase synthesis.     

L1 regression estimate and its bootstrap

We study the asymptotic distribution of the L ₁ regression estimator under general conditions with matrix norming and possibly non i.i.d. errors. We then introduce an appropriate bootstrap procedure to estimate the distribution of this estimator and study its asymptotic properties. It is shown that this bootstrap is consistent under suitable conditions and in other situations the bootstrap limit is a random distribution. This work was supported by J.C. Bose National Fellowship, Government of India     

Optimal predictive densities and fractional moments

The maximum entropy approach used together with fractional moments has proven to be a flexible and powerful tool for density approximation of a positive random variable. In this paper we consider an optimality criterion based on the Kullback–Leibler distance in order to select appropriate fractional moments. We discuss the properties of the proposed procedure when all the available information comes from a sample of observations. The method is applied to the size distribution of the U.S. family income. Copyright © 2008 John Wiley & Sons, Ltd.     

Role of sugar in controlling reaction pattern: A comparative study with adenine and 2′-deoxyadenosine

Interaction between 2-methyl-1,4-naphthoquinone (MQ) and adenine (A) and 2′-deoxyadenosine (dA) reveals interesting differences with respect to electron transfer (ET) and hydrogen abstraction (HA). In our case A and dA exhibited ET from different sites, which has been associated to the presence of a sugar unit in dA. Sugar unit has also reduced the rate of ET from dA. We have utilized an external magnetic field in conjunction with our laser flash photolysis set-up to establish our data. In a polar MeCN/H₂O medium A and dA are found to promote ET but HA from dA is seen to be insignificant. However shifting to a heterogeneous micellar medium has been found to have a marked effect in increasing the HA rate for dA only. Separate experiments with 2′-deoxyribose sugar have revealed sugar moiety to be more susceptible to HA in SDS medium.     

An optimization based approach for deployment of roadway incident response vehicles with reliability constraints

In recent years transportation agencies have introduced patrol based response programs to remove roadway incidents rapidly. With the evolution of technology incident detection and notification from remote traffic operation centers is possible and patrols to detect incidents are not necessary. Instead, the response units can be placed at various depots in urban areas and dispatched to incident sites upon notification. In this paper, we propose a reliability based mixed integer programming model to find best locations of incidence response depots and assign response vehicles to these depots so that incidents can be cleared efficiently at a minimum cost. The approach is unique as it considers fixed and variable costs of vehicles and depots, occurrences of major and minor incidents, and reliability of response service in the same model. Numerical results are generated for an example problem and sensitivity analysis is conducted to explore the relationships between parameters of the problem.     

Multiferroic properties of NiS nanoplates grown within Na-4 mica

Nanoplates of NiS with thickness 0.6 nm were grown within the crystal channels of Na-4 mica. The thickness of the nanoplates is confirmed by atomic force microscopy. The nanocomposites exhibited multiferroic (both ferromagnetic and ferroelectric) behavior at room temperature. Ferromagnetism was adduced to an increase of surface defects as a result of the two-dimensional configuration of the sample. Ferroelectric behavior was explained as arising due to a small distortion in the crystal structure of NiS grown within the Na-4 mica channels. This was substantiated by the refined values of lattice constants as determined by profile matching of X-ray data by a computer program. A magnetodielectric effect was also observed in this nanocomposite with a change of 0.77% in the dielectric constant for a magnetic field of 0.6 T.     

Search for doubly charged Higgs boson pair production in pp¯ collisions at √s=1.96 TeV

We present a search for pair production of doubly charged Higgs bosons in the processes qqˉ→H(++)H(--) decaying through H(±±)→τ(±)τ(±),μ(±)τ(±),μ(±)μ(±). The search is performed in ppˉ collisions at a center-of-mass energy of √s = 1.96 TeV using an integrated luminosity of up to 7.0 fb(-1) collected by the D0 experiment at the Fermilab Tevatron Collider. The results are used to set 95% C.L. limits on the pair production cross section of doubly charged Higgs bosons and on their mass for different H(±±) branching fractions. Models predicting different H(±±) decays are investigated. Assuming B(H(±±)→τ(±)τ(±))=1 yields an observed (expected) lower limit on the mass of a left-handed H(L)(±±) boson of 128 (116) GeV and assuming B(H(±±)→μ(±)τ(±))=1 the corresponding limits are 144 (149) GeV. In a model with B(H(±±)→τ(±)τ(±))=B(H(±±)→μ(±)τ(±))=B(H(±±)→μ(±)μ(±))=1/3, we obtain M(H(L)(±±))>130 (138) GeV.