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QUANTUMMETALINK
An emerging paradigm in metamaterials research
Metamaterials is an active area of investigation, with researchers looking to develop materials with properties beyond those available in nature. The QUANTUMMETALINK project combines theoretical and computational research to lay the foundations for ongoing developments in this discipline, as Professor Nicolae Panoiu explains
A new class of materials built from artificially engineered meta-atoms and meta-molecules, metamaterials have attracted a great deal of attention over recent years, with researchers looking to combine different elements to develop materials with properties tailored to specific applications. Based at University College London, Professor Nicolae Panoiu is the Principal Investigator of the QUANTUMMETALINK project, which centres on an emerging area of metamaterials research. “We are investigating quantum metamaterials, in which the interaction and properties of these metamaterials and their constituent parts are not only determined by classical laws of physics, like Maxwell equations, but also by quantum physics,” he says. The project combines theoretical and computational research to build strong foundations for the development of quantum metamaterials. “One third of the project is about theory, about describing the properties of quantum metamaterials. With solid-state physics, we can derive the properties of solids from the properties of atoms and molecules. We are trying to do the same thing for quantum metamaterials,” explains Professor Panoiu. “So, from the basic properties of the constituent parts, we try to derive the properties of whole metamaterials.”
A second area of research in the project relates to combining quantum mechanical and classical numerical methods to develop a new set of numerical methods and software tools. While the properties of some materials can be determined by using either classical or quantum numerical methods, there are currently no mature methods available to describe mixed structures. “For example, you can have a quantum dot or molecule coupled to a metallic nanoparticle, where the metallic particle is described by classical physics, by Maxwell equations, and the quantum dot and molecule are described by quantum Electron density of quantum plasmons of a graphene nano-flake.
physics. So we aim to come up with theoretical models and computational methods that describe such mixed structures,” explains Professor Panoiu. The third part of the project’s work involves exploring possible applications of quantum metamaterials; while there is rich potential in these terms, the main focus in research is about laying the foundations for future development. “This is a theoretical computational project, it’s not experimental,” stresses Professor Panoiu. “We look at different materials and we model them theoretically. We are collaborating with quite a few groups of experimentalists, and the hope is that our research will fire up their interest.”
Quantum metamaterials
This research is built on a thorough understanding of the fundamental building blocks or unit cells of quantum metamaterials, including quantum dots and quantum nanowires, the behaviour of which is described by the laws of quantum mechanics, more specifically the Schrodinger equation. Researchers are taking elements of the numerical methods that solve Maxwell equations and elements of the numerical methods that solve Schrodinger equation to develop new tools. “We know that these paradigms are coupled at some level. So we include, in these overall numerical methods, elements that describe this inter-mixing between classical dynamics
Molecular bridges linking two graphene nano-flakes (top) and schematics of nano-antennae made of such quantum basic components (bottom).
and the quantum dynamics,” explains Professor Panoiu. There are two main numerical methods that Professor Panoiu and his colleagues deal with in the development of these new software tools. “For example, we use finite difference methods for the classical part. For the quantum part, we use time-dependent density-functional theory, which gives us the energy spectra of the quantum system,” he continues. “These are the main methods used in electromagnetism on one side, and in quantum physics and quantum chemistry on the other.”
The project’s work in developing a theoretical framework and software tools provides the foundations for the third area of research, in exploring new science and novel applications. One major area of interest is investigating the optical properties of devices based on quantum metamaterials. “We want to determine some of the main constants
that would describe the optical properties of a material, the way they describe its interaction with light. For instance, the main optical coefficient characterizing optical properties of glass is its index of refraction” says Professor Panoiu. Likewise, optical coefficients like dielectric constant, magnetic permeability, or non-linear optical susceptibilities describe the optical properties of a quantum metamaterial. “We want to calculate these quantities, starting from the basic structure of the material,” continues Professor Panoiu. “So how do you go from the properties of quantum meta-atoms, meta-molecules, and the lattice in which they are arranged, to calculate the optical constants characterizing a quantum metamaterial?” This research could eventually help lay the foundations for the bottom-up development of metamaterials with specific physical properties. With deeper knowledge of the physical properties of basic components of a material, it may be possible to custom-design unit cells to achieve specific desired properties, whether it is an artificial magnetic response, giant optical activity or a negative refractive index. “ For example, when you know the properties of the material that you want to design – like the index of refraction in a certain frequency domain – how do you come up with a set of design rules and tools to develop it?” says Professor Panoiu. The project is still in its relatively early stages, but by the end of the five-year funding term Professor Panoiu and his colleagues aim to have developed a complete theory to describe quantum metamaterials, while they also have clear goals around the development of the software tools. “We want
to be able to derive these macroscopic constants, like dielectric constant and both linear and non-linear susceptibilities from first principles,” he explains. “We also plan to distribute the software and make it freely available to academia.”
This is a very active field of research, with both the commercial and academic sectors keen to explore the wider potential of metamaterials. With a more fully developed theoretical and computational framework, it could be possible to develop quantum metamaterials with properties beyond those currently available in natural materials. “The big promise of these metamaterials is that you can modify them and adapt their properties by designing their metaconstituents. There is a very large degree of flexibility in engineering such quantum metamaterials,” says Professor Panoiu.
Full Project Title
Quantum Metamaterials: A Theoretical and Computational Approach Towards Seamlessly Integrated Hybrid Classical/ Quantum Nano-structures (QUANTUMMETALINK)
Project Objectives
The project aims to develop a foundational theory of linear and nonlinear quantum metamaterials. Researchers will develop a theoretical framework that enables scientists to derive the effective, macroscopic properties of quantum metamaterials from the physical properties and spatial configuration of their quantum unit elements. Researchers will also develop numerical algorithms and software tools for quantum metamaterials, along with exploring new science and novel applications of quantum metamaterials.
Project Funding
Total cost: EUR 1 779 240 EU contribution: EUR 1 779 240 Coordinated in the United Kingdom
Contact Details
Project Coordinator, Professor Nicolae Panoiu Department of Electronic and Electrical Engineering University College London Torrington Place, London WC1E 7JE T: +44 (0)20 7679 2819 E: n.panoiu@ucl.ac.uk W: http://www.ee.ucl.ac.uk W: https://www.ee.ucl.ac.uk/~npanoiu/ERC.html
Professor Nicolae Panoiu
Professor Nicolae Panoiu is currently a Professor of Nanophotonics within the Department of Electronic and Electrical Engineering at University College London. His research interests include optical properties of photonic nanostructures and metamaterials, silicon photonics, and computational modelling of electromagnetic structures.
