Unconventional quantum criticality in a non-Hermitian extended Kitaev chain

TL;DR

This paper explores unconventional quantum criticality in a non-Hermitian extended Kitaev chain, revealing multiple gapless points, unique critical behaviors, and the impact of non-Hermiticity on phase transitions and critical exponents.

Contribution

It uncovers novel quantum critical phenomena in a non-Hermitian Kitaev chain, including isolated critical points and distinct critical exponents, expanding understanding beyond Hermitian models.

Findings

Multiple gapless points with shifting locations in momentum space.

Introduction of non-Hermiticity leads to isolated critical points.

Distinct critical exponents differ from Hermitian cases.

Abstract

We investigate the nature of quantum criticality and topological phase transitions near the critical lines obtained for the extended Kitaev chain with next nearest neighbor hopping parameters and non-Hermitian chemical potential. We surprisingly find multiple gap-less points, the locations of which in the momentum space can change along the critical line unlike the Hermitian counterpart. The interesting simultaneous occurrences of vanishing and sign flipping behavior by real and imaginary components, respectively of the lowest excitation is observed near the topological phase transition. Introduction of non- Hermitian factor leads to an isolated critical point instead of a critical line and hence, reduced number of multi-critical points as compared to the Hermitian case. The critical exponents obtained for the multi-critical and critical points show a very distinct behavior from the Hermitian case.