Fixed-point quantum search

The quantum search algorithm consists of an iterative sequence of selective inversions and diffusion type operations, as a result of which it is able to find a state with desired properties (target state) in an unsorted database of size N in only sqrt[N] queries. This is achieved by designing the iterative transformations in a way that each iteration results in a small rotation of the state vector in a two-dimensional Hilbert space that includes the target state; if we choose the right number of iterative steps, we will stop just at the target state. This Letter shows that by replacing the selective inversions by selective phase shifts of pi/3, the algorithm preferentially converges to the target state irrespective of the step size or number of iterations. This feature leads to robust search algorithms and also to new schemes for quantum control and error correction.     

Simulation of high frequency positron behaviour in argon gas

Positron annihilation and average energy in argon have been investigated in the presence of external high frequency electric and steady magnetic fields. The effect of temperature has also been studied. Two models of positron atom interaction have been employed and compared with experimental results wherever possible.     

Positron life times in helium gas

The life time of positrons in helium gas has been studied in the presence of high frequency electric and steady magnetic fields. The life time depends upon the frequency and attains a maximum value when the frequency of the electric field equals the cyclotron frequency.     

Mössbauer evidence against the existence of intermediate ferromagnetic phase in reentrant spin glass systems (PdxPt1−x)3Fe

⁵⁷Fe Mossbauer and Magnetization investigations in the series (Pd_xPt_1–x)₃Fe clarifies some of the aspects of multiple magnetic phase transitions. The data discount the intorpretation of at Fe in terms of well defined phase transitions as per the Gabay-Toulouse model. The reentrant behaviour seems to arise from the constrained dynamics of interacting clusters.     

Synthesis of Indolo and benzimidazoquinazolines and benzodiazepines

Indolo[1,2-c] quinazolines, indolo[1,2-d] [1,4]benzodiazepines, indolo [1,2-d] [1,4]benzodi-azepin-6-ones and benzimidazo[1,2-d] [1,4] benzodiazepin-6-ones were synthesized. In an acid medium, the indoloquinazolines were produced from 2-(o-aminophenyl)indole and acyl halides. However, in the presence of sodium acetate, the acylated amine was obtained and was cyclized to the indolobenzodiazepinones using sodium hydride. The syntheses are described in detail and characterization data are given.     

57Fe Mössbauer studies in a new cluster spin glass system RuxFeGa (0.5≦x≦1.5)

⁵⁷Fe Mössbauer and bulk magnetization studies have been carried out in a new magnetic system Ru_xFeGa for 0.5x1.5. The system is seen to freeze into a cluster spin glass phase at 70 K. The freezing temperature and the hyperfine field at Fe at the lowest measured temperature, 190 kOe, is essentially same for all values of x investigated.     

Folding and Imaging of DNA Nanostructures in Anhydrous and Hydrated Deep‐Eutectic Solvents

There is great interest in DNA nanotechnology, but its use has been limited to aqueous or substantially hydrated media. The first assembly of a DNA nanostructure in a water‐free solvent, namely a low‐volatility biocompatible deep‐eutectic solvent composed of a 4:1 mixture of glycerol and choline chloride (glycholine), is now described. Glycholine allows for the folding of a two‐dimensional DNA origami at 20 °C in six days, whereas in hydrated glycholine, folding is accelerated (≤3 h). Moreover, a three‐dimensional DNA origami and a DNA tail system can be folded in hydrated glycholine under isothermal conditions. Glycholine apparently reduces the kinetic traps encountered during folding in aqueous solvent. Furthermore, folded structures can be transferred between aqueous solvent and glycholine. It is anticipated that glycholine and similar solvents will allow for the creation of functional DNA structures of greater complexity by providing a milieu with tunable properties that can be optimized for a range of applications and nanostructures.