The effect of environment induced pure decoherence on the generalized Jaynes-Cummings model

We have studied the effect of environment induced pure decoherence on the generalized Jaynes-Cummings model (JCM). This generalized JCM is introduced to take into account both atom-field interaction and a class of spin-orbit interactions in the same framework. For generalized JCM with atom-field interaction, it is shown that along with the suppression of the oscillatory behaviour of the atomic and field variables, in the steady state, atomic energy is transferred to the field or vice versa through the dressed state coherence depending on the initial condition of the atom-field system and the model under consideration. It is also shown that initial Poissonian field acquires a sub-Poissonian character in the steady state and thus all the nonclassical properties are not erased by the decoherence in JCM. An interesting effect of this decoherence mechanism is that it affects the population and coherence properties of the individual subsystem in a different way. As an example of generalized JCM with spin-orbit interaction, the dynamics of spin of the hydrogen atom in a magnetic field is studied to show the effect of decoherence.     

Laser diode to monomode elliptic core fiber excitation via hemispherical lens on the fiber tip: Efficiency computation by ABCD matrix with consideration for allowable aperture

Employing Gaussian field distributions for both the source and the fiber, we report a simple theoretical prediction of the coupling efficiency of a laser diode to a single-mode elliptic core fiber via hemispherical lens on the fiber tip. The analysis is based on ABCD matrix for hemispherical lens under paraxial approximation. Our formalism takes care of the allowable aperture of the hemispherical lens. The present analysis prescribes analytical expressions for the coupling efficiency and the concerned calculations are executable by pocket calculator.     

Chirp-free nanosecond laser amplifier for precision spectroscopy

We describe a simple method for greatly reducing optical phase perturbations in a nanosecond pulsed dye amplifier. The laser dye mix is tailored to produce a susceptibility near zero at the operating wavelength. Frequency shifts are reduced to less than 3 MHz, and frequency chirping to less than 10 MHz, without significant loss of amplified power. This technique has been used to improve the accuracy of precision far-UV wavelength measurements in H(2) to ~7 parts in 10(9).     

Rhenium chemistry of azooximes: oxygen atom transfer, azoimine chelation, and imine-oxime contrast

The concerned azooximes (L1OH, 1) are of type p-X-C6H4C(N2Ph)(NOH) (X = H, Me, Cl). The reaction of [Re(MeCN)Cl3(PPh3)2] with [Ag(L1OH)(L1O)] in cold dichloromethane-acetonitrile solvent has furnished the green colored ionized azoimine complex [ReV(O)Cl(PPh3)2(L1)](PF6), 2. In effect L1O- has undergone oxidative addition, the oxygen atom being transferred to the metal site. Upon treatment of [ReV(NPh)Cl3(PPh3)2] with L1OH in solution, the neutral azoimine complex [ReV(NPh)Cl3(L1H)], 3, resulted due to the spontaneous transfer of the oxime oxygen atom to a PPh3 ligand, which is eliminated as OPPh3. In contrast, the oxime of 2-acetylpyridine (L2OH, 4) did not undergo oxygen atom transfer and simply afforded the imine-oxime complex [ReV(NC6H4Y)Cl2(PPh3)(L2O)], 5, upon reacting with [ReV(NC6H4Y)Cl3(PPh3)2] (Y = H, Me, Cl). The spectral and electrochemical properties of 2, 3, and 5 and the structures of three representative compounds are reported. In the cation of 2 (X = H) the two PPh3 ligands lie trans to each other and the equatorial plane is defined by the five-membered azoimine chelate ring and the oxo and chloro ligands. The oxo ligand which forms a model triple bond (Re-O length 1.616(6) A) lies cis to the imine-N atom. In 3 (X = Cl) the ReCl3 fragment has meridional geometry and the imido nitrogen lies trans to the imine nitrogen of the planar azoimine chelate ring. In 5 x H2O (Y = Me), the Cl, oximato-N, and P atoms define an equatorial plane and the pyridine-N lies trans to the imido-N. The water of crystallization is hydrogen bonded to the oximato oxygen atom (O...O, 2.829(5) A). Reaction models in which chelation of the azooxime precedes oxygen atom transfer are proposed on the basis of oxophilicity of trivalent rhenium, Lewis acid activity of pentavalent rhenium, electron withdrawal by the azo group, and observed relative disposition of ligands in products.     

Affine inequivalence of cubic Maiorana–McFarland type bent functions

We consider cubic Maiorana–McFarland type bent functions having no affine derivatives. By using an invariant proposed by Dillon in 1975 we identify subclasses of inequivalent bent functions within this class. These can also be identified by [4, Theorem B]. However, our technique involves only elementary derivations. We also include some computational results.     

A Facile One‐Pot Synthesis of 3,5‐Disubstituted Isoxazole Derivatives Using Hydroxy (Tosyloxy) Iodobenzene

Hydroxy (tosyloxy) iodobenzene (HTIB), a hypervalent iodine reagent, has been extensively used for oxidative transformations. We have developed a one‐pot synthesis wherein aldoximes when reacted with alkynes in the presence of HTIB result in the direct formation of isoxazoles. This simple and straightforward reaction allows for ease of purification while leading to the formation of high purity 3,5‐disubstituted isoxazoles in moderate yields.     

A novel Raman spectroscopic approach to identify polymorphism in leflunomide: a combined experimental and theoretical study

Polymorphism is an important characteristic which affects the activity, solubility and other physical properties of a compound and can be induced by varying temperature, pressure and solvent. The presence and conversion of α to β polymorphic forms of an anti‐rheumatic drug leflunomide have been studied by temperature‐dependent and in situ Raman observations. Both α and β polymorphs were found to co‐exist in the temperature interval 367–372 K. The α form alone exists below 367 K and the β form alone above 373 K. The CO stretching band clearly demonstrates the α → β conversion because of breaking of N–H···O bond and formation of N–H···N bond. On cooling the Raman spectra suggest the irreversibility of this conversion. Thermodynamic stability, crystal parameters and surface morphology of both forms in the leflunomide powder used for the present study have been verified by differential scanning calorimetry, X‐ray powder diffraction and scanning electron microscopy. Copyright © 2015 John Wiley & Sons, Ltd.     

Nanofluidic channels by anodic bonding of amorphous silicon to glass to study ion-accumulation and ion-depletion effect

A unique phenomenon, ion-enrichment and ion-depletion effect, exists in nanofluidic channels and is observed in amorphous silicon (α-Si) nanochannels as shallow as 50 nm. As a voltage is applied across a nanochannel, ions are rapidly enriched at one end and depleted at the other end of the nanochannel. α-Si is deposited on glass by plasma enhanced chemical vapor deposition and is selectively etched to form nanochannels. The depth of nanochannels is defined by the thickness of the α-Si layer. Low temperature anodic bonding of α-Si to glass was used to seal the channel with a second glass wafer. The strength of the anodic bond was optimized by the introduction of a silicon nitride adhesion promoting layer and double-sided bonding resulting from the electric field reversal. Completed channels, 50 nm in depth, 5 micron wide, and 1 mm long were completely and reliably sealed. Structures based on nanochannels 50-300 nm deep were successfully incorporated into nanofluidic devices to investigate ionic accumulation and depletion effect due to overlapping of electric double layer.     

Convergence of linear functions of Pfeifer records

The probabilistic behaviour of partial sums of upper and lower records has been studied in the literature. In this article, we take a broader view and study partial sums of record like sequences. We show that such sequences converge in distribution to normal and lognormal distribution. In particular our results apply to Pfeifer records. We also show the strong convergence of partial sums of lower Pfeifer records under suitable assumptions.