Quantum anomalous vortex and Majorana zero mode in iron-based superconductor Fe(Te,Se)

In topological insulators doped with magnetic ions, spin-orbit coupling and ferromagnetism give rise to the quantum anomalous Hall effect. Here we show that in s-wave superconductors with strong spin-orbit coupling, magnetic impurity ions can generate topological vortices in the absence of external magnetic fields. Such vortices, dubbed quantum anomalous vortices, support robust Majorana zero-energy modes when superconductivity is induced in the topological surface states. We demonstrate that the zero-energy bound states observed in Fe(Te,Se) superconductors are possible realizations of the Majorana zero modes in quantum anomalous vortices produced by the interstitial magnetic Fe. The quantum anomalous vortex matter not only advances fundamental understandings of topological defect excitations of Cooper pairing, but also provides new and advantageous platforms for manipulating Majorana zero modes in quantum computing.Comment: final version, 8 pages, 3 figures + supplemental materia

A contractual analysis of state versus private ownership

We uniquely analyze the advantages and disadvantages of private ownership versus state ownership under various circumstances by focusing on three aspects: external risk, internal governance, and relative importance of owners versus managers. Our theoretical analysis indicates that private ownership is better than state ownership if the business environment is risky, corruption is limited, or the manager plays a more important role than the owner. Our empirical analysis supports our theoretical findings and reveals that better internal governance, more external risk and greater importance of the manager will magnify the benefits of privatization