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.

References

At present, however, it is not clear if longer chains will lead to more stable Majorana quasiparticles due to odd-even effects, longer range hopping, unavoidable inhomogeneities or strong interaction which may induce zero modes of slightly different character.

— Search for Majorana Bound States in Short Chains of Proxmitised Quantum Dots  (2608.19911 - Bułka et al., 20 Aug 2026) in Section 1, Introduction

Beyond correlation effects, an important open question concerns the magnitude and robustness of the topological excitation gap. While the present work identifies topologically nontrivial phases through bulk-gap closings and Chern-number changes, the practical realization of Majorana modes is ultimately controlled by the size of the renormalized quasiparticle gap and its stability against disorder, finite temperature, and interaction effects.

— A First-Principles Multiscale Framework for Topological Superconductivity  (2609.10381 - Jacobs et al., 9 Sep 2026) in Section “Conclusion & Outlook,” final substantive paragraph

However, whether present devices have reached this regime remains an open question.

— Measurement-induced enhancement of the $X$-parity lifetime in a Majorana tetron  (2610.12223 - Laubscher et al., 8 Oct 2026) in Section 1, Introduction