arXiv subjects

Emmanouil T. Kokkinakis

Publications and source records attributed to Emmanouil T. Kokkinakis.

3 recordsLinked to original sources

arXiv2025

Defect-driven incoherent skin localization

The process of dephasing during wave evolution has traditionally been viewed as an obstacle to localization, leading to diffusion even in strongly disordered Hermitian lattices. In contrast, here we demonstrate how the interplay of dephasing with non-Hermitian defects can be harnessed to engineer wave localization. Specifically, we identify a novel dynamical localization phenomenon characterized by wavefunction accumulation at the lattice's boundary due solely to dephasing, despite globally reciprocal couplings. Furthermore, we study the incoherent skin effect arising from coupling asymmetry, and investigate the interplay between these antagonistic localization mechanisms. By reframing dephasing from a hindrance into a tool, this study overturns established paradigms of wave localization and paves the way for novel approaches to controlling localization phenomena in non-Hermitian physics.

cond-mat.dis-nn↗

arXiv2025

Self-trapping and skin solitons in two-dimensional non-Hermitian lattices

Two-dimensional non-Hermitian photonic lattices with asymmetric couplings offer rich possibilities for controlling wave localization, through the emergence of the non-Hermitian skin effect at lattice corners or sides. Incorporating optical nonlinearity fundamentally alters these boundary-localization characteristics. Here we show that in a two-dimensional Hatano-Nelson lattice with Kerr nonlinearity, the interplay between self-trapping and directional propagation leads to position dependent amplitude thresholds. Single-site excitations having above a critical amplitude become confined to their initial position, with lower thresholds near the position where the linear eigenmodes are localized and higher thresholds within the lattice's bulk. Additionally, we study the differences of this dynamical interplay, for wider initial excitations, between the focusing and defocusing Kerr-nonlinearity regimes. Lastly, we identify skin soliton solutions in a variety of two-dimensional lattice geometries featuring coupling asymmetry.

nlin.PS↗

arXiv2025

Dephasing-induced jumps in non-Hermitian disordered lattices

Changes in the wavefunction's phase during propagation in a random Hermitian lattice, a process known as dephasing, results in diffusion rather than Anderson localization. However, when non-Hermiticity is introduced, the wave behavior changes drastically. In particular, we demonstrate that in weakly disordered non-Hermitian lattices, dephasing enhances eigenmode localization which results in abrupt jumps between spatially distant regions. These jumps, which are absent under purely coherent conditions, emerge from the interplay between complex disorder and dephasing.

cond-mat.dis-nn↗