Majorana fermion exchange in strictly one dimensional structures

It is generally thought that adiabatic exchange of two identical particles is impossible in one spatial dimension. Here we describe a simple protocol that permits adiabatic exchange of two Majorana fermions in a one-dimensional topological superconductor wire. The exchange relies on the concept of "Majorana shuttle" whereby a $\pi$ domain wall in the superconducting order parameter which hosts a pair of ancillary Majoranas delivers one zero mode across the wire while the other one tunnels in the opposite direction. The method requires some tuning of parameters and does not, therefore, enjoy the full topological protection. The resulting exchange statistics, however, remains non-Abelian for a wide range of parameters that characterize the exchange.Comment: 5 pages, 4 figures, supplemental material is include

Quantization and 2π2\pi Periodicity of the Axion Action in Topological Insulators

The Lagrangian describing the bulk electromagnetic response of a three-dimensional strong topological insulator contains a topological `axion' term of the form '\theta E dot B'. It is often stated (without proof) that the corresponding action is quantized on periodic space-time and therefore invariant under '\theta -> \theta +2\pi'. Here we provide a simple, physically motivated proof of the axion action quantization on the periodic space-time, assuming only that the vector potential is consistent with single-valuedness of the electron wavefunctions in the underlying insulator.Comment: 4 pages, 1 figure, version2 (section on axion action quantization of non-periodic systems added

A study on the effects of productivity of human resources in banking network and work ethics

Today, human resources are considered as the most important assets of any organization. Generally, human being has specific ethical features on personality characteristics forming the attitude, speech and behavior. It is possible that some factors create different attitudes, speech and behavior among people who are in one particular position. These human characteristics influence the efficiency and effectiveness of organization. The present study aims to investigate the relationship between work ethics and human resources productivity in banking network of city of Zahedan, Iran. The study chooses a sample of 236 employees who worked for different banks in city of Zahedan, Iran in 2013. To analyze the data, Pearson correlation test, Friedman ranking and independent t-test were used. The results show that there was a significant association between work ethics components and productivity (efficiency and effectiveness) of human resources

Investigating The Factors Affecting Successful BSC Implementation In The MAPNA Railway Sector

As a performance appraisal system and besides other traditional financial appraisal systems, Balanced Score Card (BSC) evaluates performance of organizations from three other perspectives, including customers, internal business processes, and growth and learning perspectives. As a whole, three main groups of effective factors on successful implementation of BSC are recognized, including Organizational, Staff and Top Management factors. In the verified model, these factors are shown. In the study done in the MAPNA railway sector, a sample of 35 persons was drawn to be used for the distribution of questionnaires. To verify the validity of the questionnaire, the face-validity method was used, and to verify its reliability, we used Cronbach's ?. To determine the degree of normality of our data, we used the Kolomogorov-Smironov method. Also, Spearman non-parametric correlation tests were used to test the hypotheses. The results verify all three hypotheses which indicate effectiveness of top management, staff and organizational factors in successful implementation of BSC. Top management is the most important factor, followed by organizational and staff. After verification of all three hypotheses, researchers tried to estimate the dependent variable (that is, successful implementation of BSC) using multiple regression analyses and the three main independent variables. This shows the simultaneous impact of the three independent variables on successful implementation of BSC. Based on the results, only staff factor is not statistically significant. It means that, for successful implementation of BSC, if “Top Management” and “Organizational” factors are considered correctly, indices related to staff automatically improve, too

Stability of Majorana Fermions in Proximity-Coupled Topological Insulator Nanowires

It has been shown previously that a finite-length topological insulator nanowire, proximity-coupled to an ordinary bulk s-wave superconductor and subject to a longitudinal applied magnetic field, realizes a one-dimensional topological superconductor with an unpaired Majorana fermion (MF) localized at each end of the nanowire. Here, we study the stability of these MFs with respect to various perturbations that are likely to occur in a physical realization of the proposed device. We show that the unpaired Majorana fermions persist in this system for any value of the chemical potential inside the bulk band gap of order 300 meV in Bi$_2$Se$_3$ by computing the Majorana number. From this calculation, we also show that the unpaired Majorana fermions persist when the magnetic flux through the nanowire cross-section deviates significantly from half flux quantum. Lastly, we demonstrate that the unpaired Majorana fermions persist in strongly disordered wires with fluctuations in the on-site potential ranging in magnitude up to several times the size of the bulk band gap. These results suggest this solid-state system should exhibit unpaired Majorana fermions under accessible conditions likely important for experimental study or future applications.Comment: 17 pages, 13 figure