Polaritons are joint excitations of light and matter and constitute an important field of study in optics. Historically, many new types of polaritons have been discovered by inspecting novel and interesting material systems, with graphene plasmons being a prominent example. Project TOPLASMON aims to study and harness the polaritons in an even newer material category - topological materials - which have recently been discovered and are intensively studied in condensed matter physics. These materials include topological insulators, which have conducting edges but insulating bulks, and Weyl Semimetals, which support unique Fermi-arc states. At the heart of project TOPLASMON is a novel measurement system, which combines a recently invented cryogenic scanning near field microscope with a THz laser and detector. This setup will allow, for the first time, the observation of topological polaritons of several varieties: (1) Chiral polaritons in topological insulators which exhibit reduced backscattering from defects. Specifically, I will working with the recently realized 2D topological insulators. (2) Fermi-arc Polaritons in Weyl Semimetals, whose dispersion is tied in with the properties of the underyling crystal, thereby probing the properties of these new materials. These polaritons are expected to have an in-plane hyperbolic dispersion and may even lead to realization of miniaturized optical isolators, leading to an important technological breakthrough. (3) Strong plasmonic resonances. I will study plasmon-polariton excitations in topological material, at frequencies near the plasmonic resonance. Empowered by the exceedingly long electron scattering times measured in several recent experiments, highly confined plasmons with unprecedentedly long propagation distances are exoected, a dramatic result for both science and technology. This proposal is therefore set to open a new study area at the forefront of research both in condensed matter and nanophotonics.

6th generation (6G) mobile broadband communications will transform the communications industry, leading to high speed networks capable of linking integrated communication, sensing, and computing capabilities to fuse the physical, biological, and cyber worlds. However, 6G infrastructure will require a significant increase in data transfer rate (>10 times larger than current standards), ultra-low power consumption (100GHz), high sensitivity, small footprint and low power consumption, represents an ideal solution able to meet all the requirements for the realization of a MIMO system operating at unprecedented frequencies. TERACOMM envisions the realization and the demonstration of the receiver module of a graphene-based wireless MIMO system able to reach data rates >100Gbps for short range applications. Industrial links, protection of intellectual property, and commercial exploitation will lie at the heart of the project from the outset, in order to maximize the potential for this technology to realize a significant social and economic impact.

With eNANO I will introduce a disruptive approach toward controlling and understanding the dynamical response of material nanostructures, expanding nanoscience and nanotechnology in unprecedented directions. Specifically, I intend to inaugurate the field of free-electron nanoelectronics, whereby electrons evolving in the vacuum regions defined by nanostructures will be generated, guided, and sampled at the nanoscale, thus acting as probes to excite, detect, image, and spectrally resolve polaritonic modes (e.g., plasmons, optical phonons, and excitons) with atomic precision over sub-femtosecond timescales. I will exploit the wave nature of electrons, extending the principles of nanophotonics from photons to electrons, therefore gaining in spatial resolution (by relying on the large reduction in wavelength) and strength of interaction (mediated by Coulomb fields, which in contrast to photons render nonlinear interactions ubiquitous when using free electrons). I will develop the theoretical and computational tools required to investigate this unexplored scenario, covering a wide range of free-electron energies, their elastic interactions with the material atomic structures, and their inelastic coupling to nanoscale dynamical excitations. Equipped with these techniques, I will further address four challenges of major scientific interest: (i) the fundamental limits to the space, time, and energy resolutions achievable with free electrons; (ii) the foundations and feasibility of pump-probe spectral microscopy at the single-electron level; (iii) the exploration of quantum-optics phenomena by means of free electrons; and (iv) the unique perspectives and potential offered by vertically confined free-electrons in 2D crystals. I will face these research frontiers by combining knowledge from different areas through a multidisciplinary theory group, in close collaboration with leading experimentalists, pursuing a radically new approach to study and control the nanoworld.

Nonlinear optical processes are at the foundation of many applications in modern science and engineering. The emerging field of Quantum Technologies is now demanding that we push these processes into the realm of Quantum Nonlinear Optics (QNLO) where nonlinear effects occur at the level of individual photons. Achieving such a regime would allow the generation and manipulation of non-classical states of light and would open exciting new scenarios involving quantum many-body physics of light. Despite the great efforts that have been invested along this line of research, significant improvements are still necessary to fully achieve the QNLO regime. QUANLUX aims to tackle this challenge by proposing a novel light-matter interface consisting of ordered atomic arrays as an ideal platform to implement QNLO processes. The ultimate objectives consist in identifying new strategies for QNLO protocols that can possibly surpass previously established performance bounds as well as investigating the complex emergent behaviour of strongly interacting photons. To tackle and solve these demanding problems the fellow will make use of advanced numerical and theoretical techniques developed in condensed matter and many-body physics (e.g. tensor networks and diagrammatic approaches) that will be acquired through dedicated training visits to experts in the field. The proposed dissemination and outreach program will progressively spread the outcome of the action to the scientific community and to the general public reinforcing the impact of the research’s results. The originality and multidisciplinary nature of the proposal have the potential to revolutionize the major paradigms currently used to implement QNLO processes and drive a technological innovation in the construction of light-matter interfaces. The action will be conducted by Giuseppe Calajò who will join the Theoretical Quantum Nanophotonics group lead by Prof. Darrick Chang at ICFO, Spain.