English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Krein-Hermitian Hamiltonians, i.e., Hamiltonians Hermitian with respect to anindefinite inner product, have emerged as an important class of non-HermitianHamiltonians in physics, encompassing both single-particle bosonicBogoliubov-de Gennes (BdG) Hamiltonians and so-called "$PT$-symmetric"non-Hermitian Hamiltonians. In particular, they have attracted considerablescrutiny owing to the recent surge in interest for boson topology. Motivated bythese developments, we formulate a perturbative Krein-unitary Schrieffer-Wolfftransformation for finite-size dynamically stable Krein-Hermitian Hamiltonians,yielding an effective Hamiltonian for a subspace of interest. The effectiveHamiltonian is Krein Hermitian and, for sufficiently small perturbations, alsodynamically stable. As an application, we use this transformation to justifycodimension-based analyses of band touchings in bosonic BdG Hamiltonians, whichcomplement topological characterization. We use this simple approach based onsymmetry and codimension to revisit known topological magnon band touchings inseveral materials of recent interest.

Krein-unitary Schrieffer-Wolff transformation and band touchings in bosonic Bogoliubov-de Gennes and other Krein-Hermitian Hamiltonians