Stability of Majorana quasiparticles in longer quantum-dot chains

Determine whether extending proximitised quantum-dot Kitaev chains to longer chains produces more stable Majorana quasiparticles, taking into account odd-even effects, longer-range hopping, unavoidable inhomogeneities, and strong interactions that may generate zero modes of a different character.

Background

The paper discusses short quantum-dot realizations of Kitaev chains, including experimentally realized two- and three-dot structures, and considers a sandwich geometry in which a chain of quantum dots is coupled to an s-wave superconductor and a semiconductor with strong spin-orbit coupling. Although the paper analyzes how protection of zero-energy modes changes with chain length in an idealized model, it identifies an unresolved issue concerning whether longer chains yield genuinely more stable Majorana quasiparticles in realistic settings.

The stated uncertainty is motivated by several effects that become increasingly relevant as the chain length grows: odd-even effects, longer-range hopping, spatial inhomogeneities, and strong interactions. The latter may produce zero modes whose physical character differs from that of conventional Majorana quasiparticles.