Localization and Topology in Noncentrosymmetric Superconductors with Disorder

Abstract: The celebrated Kitaev chain reveals a captivating phase diagram in the presence of various disorders, encompassing multifractal states and topological Anderson phases. In this work, we investigate the localization and topological properties of a dimerized topological noncentrosymmetric superconductor (NCS) under quasiperiodic and Anderson disorders. Using both global and local characterization methods, we identify energy-dependent transitions from ergodic to multifractal and localized states. Extended multifractal regimes emerge from the competition between dimerization, NCS order, and quasiperiodic modulation. This interplay causes localization to occur preferentially in different energy bands depending on the disorder strength, with the lowest bands exhibiting the highest sensitivity to parameter variations. We employ the real-space polarization method to compute the $\mathbb{Z}_2$ topological invariant, revealing alternating topological and trivial phases as the quasiperiodic potential increases, a behavior distinct from the typical topological Anderson phase diagram. Additionally, the topological states show remarkable robustness against Anderson disorder, providing new insights into topological phase stability in non-centrosymmetric systems. Finally, we propose a feasible experimental scheme based on superconducting Josephson junctions, where NCS-like behavior can be engineered via spatially modulated supercurrents. Our findings highlight the distinct roles of different disorder types in shaping localization and topology, providing insight into the engineering of Majorana zero modes and offering profound implications for topological quantum encryption schemes.