Non-hermitian topology as a unifying framework for the Andreev versus Majorana states controversy

By Jesús Ávila, Francisco Peñaranda, E. Prada, Pablo Perez San-José, R. Aguado. Communications Physics, 2018

139 citations recorded by the source corpus.

Zero-energy Andreev levels in hybrid semiconductor-superconductor nanowires mimic all expected Majorana phenomenology, including $$2{e}^{2}/h$$2e2∕h conductance quantisation, even where band topology predicts trivial phases. This surprising fact has been used to challenge the interpretation of various transport experiments in terms of Majorana zero modes. Here we show that the Andreev versus Majorana controversy is clarified when framed in the language of non-Hermitian topology, the natural description for quantum systems open to the environment. This change of paradigm allows one to understand topological transitions and the emergence of zero modes in more general systems than can be described by band topology. This is achieved by studying exceptional point bifurcations in the complex spectrum of the system’s non-Hermitian Hamiltonian. Within this broader topological classification, Majoranas from both conventional band topology and a large subset of Andreev levels at zero energy are in fact topologically equivalent, which explains why they cannot be distinguished.The existence of Majorana zero modes have been potentially confirmed in superconductor-semiconductor nanowires but recent studies suggest the data can also be interpreted using Andreev bound states, throwing into doubt the conclusions regarding Majorana modes. To resolve this controversy the authors use non-Hermitian topology to determine the boundaries between the Majorana and Andreev states.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics

View Paper: https://www.semanticscholar.org/paper/c86b9fee1bf71fd043c1108347a5881f7b3066a9

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

In Condensed Matter Physics

Flore K. Kunst

Citations in the corpus

Non-Hermitian systems and topology: A transfer-matrix perspective (2018, methodology): “[29] J Avila, F Peñaranda, E Prada, P San-Jose, and R Aguado, “Non-Hermitian topology: a unifying framework for the Andreev versus Majorana states controversy,” arXiv:1807.”
Exceptional topology of non-Hermitian systems (2019, unknown): “This has been investigated in the context of superconducting junctions featuring EPs (Avila et al., 2018; Pikulin and Nazarov, 2012, 2013; San-Jose et al., 2016) as well as in interfaces between topological insulators coupled to ferromagnetic leads (Bergholtz and Budich, 2019; Chen and Zhai, 2018; P”