Topological boundaries in non-Hermitian p-wave Kitaev chains with Rashba spin-orbit coupling

TL;DR

This paper explores how Rashba spin-orbit coupling and non-Hermitian effects influence topological phase transitions in spinful p-wave Kitaev chains, revealing model-dependent impacts and lower thresholds for topological changes.

Contribution

It provides the first detailed analysis of the interplay between non-Hermiticity and RSOC in topological phase transitions of Kitaev chains, including analytical and numerical results.

Findings

RSOC does not affect phase boundary in Hermitian uniform gain/loss model with weak spin-flip hopping

RSOC significantly alters phase boundaries in non-Hermitian regimes and quasiperiodic models

Non-Hermiticity and RSOC together induce topological transitions at lower potential strengths

Abstract

In this work, we investigate the combined effects of Rashba spin-orbit coupling (RSOC) and non-Hermiticity on topological phase transitions in spinful p-wave Kitaev chains. While previous studies have separately examined non-Hermitian (NH) extensions of Kitaev chains and the effects of RSOC in Hermitian systems, the interplay between these two mechanisms remains largely unexplored. We analyze this interplay by considering two distinct types of complex on-site potentials: (i) a uniform gain/loss term and (ii) a complex quasiperiodic potential. We demonstrate that the impact of RSOC is highly model-dependent. In particular, RSOC does not affect the topological phase boundary in the Hermitian limit of the uniform gain/loss model (provided the spin-flip hopping is weaker than the pairing strength), but significantly alters the topological landscape in the NH regime. In contrast, for the quasiperiodic model, RSOC modifies the phase boundaries in both the Hermitian and non-Hermitian cases. Notably, we find that the combined interplay of non-Hermiticity and RSOC drives topological transitions at significantly lower potential strengths compared to the Hermitian limit. We derive analytical expressions for the topological phase transitions in both cases and validate our predictions through numerical calculations of energy spectra and real-space winding numbers. This work provides a comprehensive understanding of how non-Hermiticity and RSOC cooperatively reshape topological phase diagrams in one-dimensional superconducting systems.