CORDIS - EU research results

Non-Hermitian Transport in Anderson forbidden land

Project description

Breaking Anderson’s barriers for photons: sudden jumps in non-Hermitian media

Anderson localisation is a famous quantum phenomenon first described in 1958 by American theoretical physicist Philip Warren Anderson. It is the absence of diffusion waves in a disordered medium due to the quantum reflections in the lattice that halt the wave function. Although initially studied in relation to electrons, photons have been increasingly investigated, particularly how disorder affects photon transport in a crystalline lattice. The European Research Council-funded Beyond_Anderson project will exploit its recently discovered groundbreaking way of transport in strongly Anderson-localised non-Hermitian media, allowing light to cross the ‘forbidden land’ of Anderson via sudden jumps. The project will investigate these sudden jumps in different contexts, forging a new path in both disordered photonics and novel lasing schemes.


This proposal is centered around the recently discovered (by the PI) ground-breaking way of transport in strongly Anderson localized non-Hermitian media. Initially Anderson localization was studied on electrons but it was later realized that photons provide an alternative cleaner route. However, one fundamental problem of photonics is that of inherent material losses. As the paradigm of parity-time symmetric optics indicates, the resolution of this problem is the judicious combination of gain and loss via index engineering. Such non-Hermitian paradigm provides the opportunity to overcome Anderson localization after sixty years by proposing a novel way of transport unique in the complex photonic media, something that is experimentally impossible in condensed matter physics. The key idea is the inclusion of appropriate gain-loss index profiles that allow light to cross the forbidden land of Anderson via sudden jumps, despite the fact that all eigenstates are localized. My proposal is focused on four directions that span out of the main theme of sudden jumps. The first one is the role of openness in the most general case of uncorrelated disorder. A second open question is that of existence of jumps in correlated media that support constant-intensity states. For both questions the maximization of the effect based on wavefront shaping and index engineering is important. A third question is the possibility of topologically protected jumpy transport in disordered topological insulators. Finally, I intend to examine the more difficult and fundamental problem of many-body effects on non-Hermitian jumpy transport. The underlying mathematical framework, is that of non-Hermitian random matrix theory and pseudospectrum, a widely used method in turbulence studies of fluid mechanics. My project is expected to open a new path in both disordered photonics that exploit the unique features of non-Hermiticity, namely extreme sensitivity, exceptional points, and novel lasing schemes.

Host institution

Net EU contribution
€ 1 525 000,00
70013 Irakleio

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Νησιά Αιγαίου Κρήτη Ηράκλειο
Activity type
Research Organisations
Total cost
€ 1 525 000,00

Beneficiaries (1)