Exploring topological phenomenon in RF circuits

Project Information

Topo-circuit

Grant agreement ID: 833797

DOI

10.3030/833797

Project closed

EC signature date 10 April 2019

Start date 4 October 2019

End date 3 October 2021

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 212 933,76

EU contribution

€ 212 933,76

Coordinated by

THE UNIVERSITY OF BIRMINGHAM
United Kingdom

Periodic Reporting for period 1 - Topo-circuit (Exploring topological phenomenon in RF circuits)

Reporting period: 2019-10-04 to 2021-10-03

Summary of the context and overall objectives of the project

This project shows successful attempts on the realization of novel topological effects in electrical circuits and provides many theoretical and experimental foundations for the future realization of many novel topological effects that are difficult to be implemented in in quantum electronics and photonics. The project combined ER and host supervisor’s expertise in theory of topological phases of matter and techniques of electrical circuit design, and equipped the ER to carry out cutting edge research in various topological circuits having unconventional topological effects.

This project provides not only possibilities for designing novel RF circuits that could function properly under different types of circuit defects and tolerance, but also a new platform for exploring and experimentally demonstrating topological phenomena with ease and low cost. The proposed research work is truly multidisciplinary involving the investigation of topological materials (theoretical physics, condensed matter physics), designing and manufacturing RF circuit board (classical electro-magnetic wave, electric engineering), experimental characterization of nontrivial edge mode and Weyl degeneracies (electronic techniques), and developing accurate and efficient simulation tools for calculating circuit responses of both linear and nonlinear topological circuits (numerical methods and computer engineering).

The overall objectives for the project “Topo-circuit” described in the proposal include the following four aspects:
RO1: To develop two-dimensional topological circuits with nontrivial topological edge states, which are robust to various types of disorders and defects.
RO2: To develop topological insulators on flexible substrates.
RO3: To develop nonlinear topological circuits with topological properties depending on the input intensity.
RO4: To use 3D topological circuits as a platform to study Weyl points and nodal lines at RF frequencies.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During this project, Dr. Liu had published 4 papers in high impact journals on photonics and condensed matter of physics. All publications had been acknowledged to the support of this fellowship. The papers are listed as below:

[P1] Liu S, Shao R, Ma S, et al. Non-Hermitian skin effect in a non-Hermitian electrical circuit [J]. Research, 2021, Article ID 5608038.

[P2] Liu S, Ma S, Yang C, et al. Gain and loss induced topological insulating phase in a non-Hermitian electrical circuit [J]. Physical Review Applied, 2020, 13: 014047.

[P3] Liu S, Ma S, Zhang L, et al. Octupole corner state in three-dimensional topological circuit [J]. Light: science & applications, 2020, 9:145.

[P4] Liu S, Ma S, Shao R, et al. Edge state mimicking topological behavior in a one-dimensional electrical circuit. New Journal of Physics, 2021, 23: 103005.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The European society has benefited from novel concept of topological circuit proposed in this project. This project has introduced both new theoretical and experimental tools to the analyses and characterization of many novel topological insulators/semimetals in electrical circuits. New methodologies and fundamental insights in this area could have a significant economic and environmental impact. In this project, Dr. Liu has achieved different types of topological circuits showing exotic physics, including a two-dimensional version of Su–Schrieffer–Heeger model circuit, a 3D topological circuit which hosts 0D corner state, non-Hermitian electrical circuit whose nontrivial topology is induced by the introduction of gain and loss, and a non-Hermitian skin effect in a variation of SSH topological circuit with nonreciprocity. Mostly importantly, electrical circuits are emerging as an ideal experimental platform for emulating topological effects, as they show much higher flexibility in implementing desired hopping, gain and loss, nonreciprocity and even nonlinearity. For example, owing to the unique advantages of engineering long-range hopping and sufficient nonlinearity in circuit, topological circuits are becoming increasingly popular as a perfect platform for emulating non-abelian band theory and nonlinear topological physics, and also a cost-effective platform for teaching topological materials. The wide variety of circuit devices allows direct mapping from tight-binding models to electrical circuits, thus enabling the realization of many novel topological systems with non-Hermitian, nonlinear, non-abelian effects, which are extremely challenging to implement in quantum systems.

screen shot of the publication list