Periodic Reporting for period 2 - OPTOlogic (Optical Topologic Logic) Reporting period: 2021-09-01 to 2023-02-28 Summary of the context and overall objectives of the project The project’s overall aim is to use multi-color, electric field waveforms, structured in both time and space, to control the topological state of quantum materials at PHz rates. Patterning Chern topological insulators in space and time by patterning light will be leveraged for PHz information processing. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far Material-agnostic, robust non-resonant schemes for creating light-induced Chern insulators have been theoretically developed, using light with polarization states tailored to the symmetry of the lattice. The schemes were shown to work for various graphene-like materials – both pristine graphene and gapped systems. Detailed analysis was done for pristine graphene, hexagonal Boron Nitride, and MoS2. Generation of valley-selective excitations in all of these materials has been theoretically found.Our investigation has shown that even linearly polarized fields have been found to generate valley-selective excitation and light-induced topology in graphene-type materials. In particular, the impact of the orbital angular momentum of light on the topological state of a 2D quantum material has been analysed and a new scheme for Chern number engineering has been theoretically developed. The scheme explicitly takes advantage of controlled OAM of a light beam.As observable, high harmonic generation has been shown to provide sub-femtosecond-resolved information about light-induced topological state and valley-selective excitations. Interestingly, and somewhat unexpectedly, high harmonic radiation generated in intense light-matter interaction was found to have quantum photon statistics that reflects the quantum system dynamics, suggesting a possible new route for mapping out quantum material response.Experimental work included establishing a framework to prepare and to diagnose quantum materials, setup of cutting-edge light sources with waveform control and polarization patterning capabilities, setup and test of new diagnostics methodologies that are field sensitive. Angle-resolved high-harmonic photoelectron spectroscopy established new experimental observables for probing topological properties.Unexpected and unforeseen results: A new type of light -- synthetic chiral light -- has been found to arise from the presence of longitudinal field component in multi-color structured vortex beams. These beams are envisioned as the key tool for patterning light-induced topology. The unique properties of this light in the interaction with chiral matter have been identified, leading to giant enantio-sensitive signals.The work performed so far resulted in publications in high-profile journals: Nature Physics, Nature Photonics, Nature Communications, Optica. 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) Completely new schemes for light-induced topology have been found, which open routes to valleytronics at PHz rates. This is clearly beyond state of the art. The same applies to sub-femtosecond resolved high harmonic spectroscopy of light-induced topology and valley-selective excitations.It has been thought that valley-selective excitations are not possible in pristine graphene, but the work within this project demonstrated that this commonly wisdom is wrong.It has been thought that valley-selective excitations in hexagonal materials require circular fields, but this common wisdom has also been proven wrong.An important wider societal impact of the project so far is the unexpected discovery of new all-optical tools for highly efficient chiral discrimination. Given the importance of chiral sensing in chemistry, biology and medicine, this discovery has major potential for societal implications well beyond the original expectations of this project.A new light source has been developed which constitutes now the brightest coherent light source with coverage from UV to THz, even superseding synchrotron user facilities by 5 orders of magnitude. OPTOlogic logo
