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H2020Individual fellowship2019–2021

ONTOP · On-demand Non-hermitian TOPology

Horizon 2020 — Marie Skłodowska-Curie Actions

Duration
2019-04-01 → 2021-03-31
EU contribution
€186,167
Participants
1
Scheme
MSCA-IF-EF-RI

Lines connect the coordinator with its partners.

Results in brief

On-demand Non-hermitian TOPology

In photonics, topology represents a new approach for guiding light in a way that is robust against structural disorder. Light is confined along the edge of a corresponding material and this confinement remains for straight or zig-zag interfaces alike. Traditionally, the considered media consist of periodic photonic-crystal structures. In contrast, this action aimed to produce a topological confinement in random media through an external-control scheme that compensates for the effect of disorder. Therefore, with this approach topology can be externally “imprinted” on any device and be used to confine photons “on-demand”—i.e., confine at will photons on one edge of the system or the other. Technologically speaking, the conception of topological devices at optical wavelengths is currently hindered by tedious fabrication requirements (that reveal costly) and the need for high-level resolution. This action introduces a new approach where topology is “post-processed” onto low-quality architectures, which could lead to the conception of low-cost devices (e.g., sensors, waveguides) whose topological properties can be externally programmed. The overall objectives of this proposal were: (1) to theoretically develop external-control schemes that manipulate the topological properties of disordered systems “on-demand”; (2) to experimentally demonstrate such concept on an acoustic setup; (3) to transfer such control schemes to optical platforms and different properties. The conclusion that can be drawn from this action clearly emphasizes its positive delivery. Scientifically, a new control scheme was developed to form topological effects in random structures (objective (1)) and this approach was extended to the control of different optical properties (objective (3)). An acoustic experiment has been developed (objective (2)) but the envisioned demonstration has been postponed due to the current pandemic. Four different papers were written, one published in Nature Communications, two currently under review in Physical Review Letters and Optics Express and a last one that will be submitted to Physical Review Letters within a few weeks. For the fellow, this action represented an opportunity to develop both a scientific network and a research program that would help him secure a permanent research position in Europe. Throughout the course of this fellowship, the fellow attended multiple interviews for assistant-professor positions and received different offers.

Data: CORDIS, © European Union

Project objective

Physical materials can display a topological order, i.e. a collective organization characterized by a discrete number or “topological charge”. Because the integer nature of this charge must be preserved throughout the structure, topological order is intrinsically immune to perturbations and the system is said to be topologically protected. Recently, the replication of topological protection in optics has raised the interest of the scientific community for its potential ability to overcome fundamental problems—like the influence of imperfections intrinsically present in nanoscale-fabrication processes, which currently preclude the development of multiple photonic technologies. Yet, at optical frequencies the weak response of materials often precludes a topological approach such that even careful designs can only partially deliver the expected protection. In contrast to material properties, gain and loss can be easily manipulated in optics. While the exploitation of non-hermitian systems—with non-conserved energy—recently enabled the formation of topological order in wave physics, it simultaneously questioned our theoretical understanding of topology and offered a large variety of new degrees of freedom that are yet to be explored.Here I suggest exploiting the versatility of optical gain-loss to imprint topological order “on-demand” onto otherwise topologically trivial systems. Through non-uniform spatial distributions of optical gain and loss I intend to demonstrate theoretically the formation of topological protection in random systems and implement my predictions in existing experimental platforms. In sharp contrast with the conventional conception of topology that relies on careful and rigid designs, this project will explore the possibility to engineer topology through external control. In this way, I will trigger a paradigmatic change that will enable the development of new photonic devices, whose topology can be manipulated and reconfigured “on-demand”.

Original text from CORDIS.

Participants

  • TECHNISCHE UNIVERSITAET WIEN · WienCoordinatorAustria

Links

Data: CORDIS, © European Union