Proximity-induced supercurrent through topological insulator based nanowires for quantum computation studies

Proximity induced superconducting energy gap in the surface states of topological insulators has been predicted to host the much wanted Majorana fermions for fault tolerant quantum computation. Recent theoretically proposed architectures for topological quantum computation via Majoranas are based on large networks of Kitaevs one dimensional quantum wires, which pose a huge experimental challenge in terms of scalability of the current single nanowire based devices. Here, we address this problem by realizing robust superconductivity in junctions of fabricated topological insulator Bi2Se3 nanowires proximity coupled to conventional s wave superconducting W electrodes. Milling technique possesses great potential in fabrication of any desired shapes and structures at nanoscale level, and therefore can be effectively utilized to scale up the existing single nanowire based design into nanowire based network architectures. We demonstrate the dominant role of ballistic topological surface states in propagating the long range proximity induced superconducting order with high IcRN product in long Bi2Se3 junctions. Large upper critical magnetic fields exceeding the Chandrasekhar Clogston limit suggests the existence of robust superconducting order with spin triplet cooper pairing. An unconventional inverse dependence of IcRN product on the width of the nanowire junction was also observed.Comment: 12 page

Evolution of microstructure in spray formed Al–18%Si alloy

Spray atomization and deposition process has emerged as an alternative to ingot and powder metallurgy routes. In the present investigation, we study the microstructural control during spray deposition of hypereutectic Al–Si alloy, employing different nozzle to substrate distances. Spray deposition is carried out using convergent–divergent close-coupled nozzle design at deposition distances of 200, 300, 450, and 550 mm. Microstructural characterization of oversprayed powders as well as spray formed deposits was performed. Microstructural features obtained at smaller deposition distance consist of co-existing primary Si phase and needle like eutectic Si. Dendrites of α-Al phase are observed indicating a large undercooling of the liquid pool prior to solidification. A large number of pre-solidified particles with very fine microstructure, embedded in a relatively coarse region, typically characterize those evolved at large deposition distances. However, at intermediate deposition distances, uniform and refined primary Si phases, 3–8 μm size, are observed. An undercooling effect is manifested in both the spray deposits as well as powder particles. These microstructural features have been discussed in light of a proposed model, which describes the presence of two layers (1) solidification layer and (2) interaction layer in the liquid pool

Experimental Shear Study on Reinforced High Strength Concrete Beams Made Using Blended Cement

With the increased application of High Strength Concrete (HSC) inconstruction and lack of proper guidelines for structural design in India,behavioral study of high strength concrete is an important aspect ofresearch. Research on the behavior of HSC reinforced beams with concretestrength more than 60 MPa has been carried out in the past and is stillcontinuing to understand the structural behavior of HSC beams. Along withthe many benefits of the high strength concrete, the more brittle behavior isof concern which leads to sudden failure. This paper presents the behaviorof reinforced HSC beams in shear with considering the effects of variousfactors like shear reinforcement ratio, longitudinal reinforcement ratio, l/dratio (length to depth ratio), etc. Ten numbers Reinforced Concrete Beamsof various sizes using concrete mix with three different w/c ratios (0.46, 0.26and 0.21) were cast for shear strength assessment. The beams were tested insimply supported condition over two fixed steel pedestals with load rate of0.2 mm/minute in displacement control. Mid-point deflection was measuredusing LVDT. A comparative analysis of theoretical approaches of Eurocode, extension of current IS code up to M90 and the experimental datawas done to understand the behavior of beams. Shear capacities of beamswithout any factors of safety were used to assess the actual capacities andthen was compared with the experimental capacity obtained. Results ofthis study can be used in the design of high strength concrete and will bemore reliable in Indian continent as the regional materials and exposureconditions were considered

Entrepreneurship based empowerment among fisherwomen self help groups of Kerala

The present study was conducted to analyse the extent of empowerment achieved by fisherwomen through participation in the entrepreneurial activities of self help groups (SHGs) functioning in the fisheries sector. Data were collected from 180 SHG members in the Kollam, Ernakulam and Kasargod districts of Kerala. Aquaculture (55.5%) and value addition of fish (45.5%) were the entrepreneurial activities adopted by fisherwomen SHGs. Empowerment level of each SHG member was quantified by modifying the existing empowerment dimensions into an Empowerment Index (EI), consisting of 8 sub-dimensions. Extent of empowerment was found out by taking the difference of empowerment index before and after joining the SHG. Among the eight empowerment dimensions, higher difference was observed in confidence building (0.43) followed by economic empowerment (0.42) and decision making pattern (0.41). The study revealed that the level of involvement in entrepreneurial activity has increased the empowerment in terms of confidence building, self-esteem, decision making pattern, psychological and economic empowerment. However, the existing fisheries extension interventions through extension contact and training were found to be associated with only self esteem and psychological empowerment. Therefore, new and innovative extension interventions are suggested in the paper to influence other sub-dimensions like economic empowerment, confidence building and decision making pattern

Entrepreneurship based empowerment among fisherwomen self help groups of Kerala

The present study was conducted to analyse the extent of empowerment achieved by fisherwomen through participation in the entrepreneurial activities of self help groups (SHGs) functioning in the fisheries sector. Data were collected from 180 SHG members in the Kollam, Ernakulam and Kasargod districts of Kerala. Aquaculture (55.5%) and value addition of fish (45.5%) were the entrepreneurial activities adopted by fisherwomen SHGs. Empowerment level of each SHG member was quantified by modifying the existing empowerment dimensions into an Empowerment Index (EI), consisting of 8 sub-dimensions. Extent of empowerment was found out by taking the difference of empowerment index before and after joining the SHG. Among the eight empowerment dimensions, higher difference was observed in confidence building (0.43) followed by economic empowerment (0.42) and decision making pattern (0.41). The study revealed that the level of involvement in entrepreneurial activity has increased the empowerment in terms of confidence building, self-esteem, decision making pattern, psychological and economic empowerment. However, the existing fisheries extension interventions through extension contact and training were found to be associated with only self esteem and psychological empowerment. Therefore, new and innovative extension interventions are suggested in the paper to influence other sub-dimensions like economic empowerment, confidence building and decision making pattern

Use of bottom ash as part replacement of sand for making concrete blocks

Coal-based thermal power plants all over the world facing serious problems of handling and disposal of the ash produced. The productive use of coal Bottom Ash (BA) is the best way to alleviate the problems associated with its disposal. This paper covers the studies on laboratory scale evaluation of vibro compaction concrete blocks using BA I, BA II & BA III collected from three different location of Coal Fed Thermal Power Station. In the present investigation laboratory investigation have been carried to utilize BA as part replacement of sand in concrete. This study cover manufacture of concrete blocks without flyash & with BA using for making solid block as per specification laid down in IS:2185 using vibro compaction machine. Three different sources of BA were used in concrete mix each @ 30%, 40% & 50% replacement by weight of sand were adopted in making concrete blocks. Comparative study of compressive strength of concrete at different age of curing, wet density, drying shrinkage is reported in this study. Wet density is found to be lower in blocks containing BA & dry shrinkage values are found well within the limits of specifications. Concrete Blocks having BA @ 30% by weight of sand are found suitable for use in the manufacture of concrete blocks

Improvement in short-circuited coaxial flange for evaluating microwave superconducting properties at low temperature

5-10In the present study, we have proposed an improvement in terms of the determination of S-parameters of an open flange from its characteristic impedance and propagation constant. With the help of these S-parameters, the actual reflection coefficient of YBCO films deposited on LAO substrate is obtained from the measured reflection coefficient. The surface impedance of three YBCO films is obtained in the range of few ohms in the frequency range from 1 GHz to 40 GHz. The surface resistance of the films reduces at liquid nitrogen temperature, i.e., 77 K, whereas, the surface reactance slightly increases due to kinetic inductance. The conductivity and skin depth are also determined to validate the improvement in the method

A simple method to estimate the loading effects of Al/Si on the characteristic impedance of multilayer microstrip line

The present study aims to experimentally determine the microwave transmission and reflection properties of aluminum thin film grown on silicon using sputtering. A simple microstrip line based structure has been used for the microwave characterization in the frequency range 10 MHz to 26.5 GHz. Complex S-parameter measurements reveal only small differences on silicon loading and aluminum/silicon loading in comparison to the microstrip line. The characteristic impedance (Z) of the microstrip line loaded with silicon and with aluminum/silicon have been obtained corresponding to the length of the loadings using two port microwave analysis. Comparison of loaded microstrip line with no loading shows large changes in the real part well as imaginary part of the characteristic impedance in the frequency range less than 10 GHz. Percentage changes in the real (Z) and imaginary (Z) have been found as ± 40% and ± 10% in average, respectively, for silicon loading in comparison to the no loading case, whereas these changes have been found to be below ±5% for aluminium/silicon loading, thus these smaller changes suggest the similar responses for aluminium/silicon loading and no loading. The results reveal that the propagation can be restored with the application of aluminum with any semiconductor or dielectric as loading on the microstrip line, which shows its potential to be explored for making an individual microwave component

Improvement in short-circuited coaxial flange for evaluating microwave superconducting properties at low temperature

In the present study, we have proposed an improvement in terms of the determination of S-parameters of an open flange from its characteristic impedance and propagation constant. With the help of these S-parameters, the actual reflection coefficient of YBCO films deposited on LAO substrate is obtained from the measured reflection coefficient. The surface impedance of three YBCO films is obtained in the range of few ohms in the frequency range from 1 GHz to 40 GHz. The surface resistance of the films reduces at liquid nitrogen temperature, i.e., 77 K, whereas, the surface reactance slightly increases due to kinetic inductance. The conductivity and skin depth are also determined to validate the improvement in the method