Periodic Reporting for period 2 - TOCHA (Dissipationless topological channels for information transfer and quantum metrology) Reporting period: 2020-01-01 to 2021-06-30 Summary of the context and overall objectives of the project The TOCHA project, funded under the Horizon 2020 EU research and development programme, has the ambition of harnessing topological concepts for future generation of devices and architectures across which information can flow without losses. This conceptually simple yet technologically and fundamentally challenging requirement is crucial for the development of technologies in fields ranging from information processing to quantum communication and metrology. In each of these areas, the dissipation of information is a key hurdle that leads, for example, to unacceptable thermal loads or error rates.TOCHA will investigate topological protection in novel materials and nanoscopic structures to empower electrons, phonons and photons to flow with little or no dissipation and, ultimately, crosslink them within a hybrid platform. This will entail the design of novel topological photonic/phononic waveguides and the engineering of disruptive heterostructures elaborated from the combination of topological insulators and ferromagnetic materials.Thanks to its high interdisciplinary embodiment involving electronic materials, optics, thermal management and metrology, TOCHA will help advance all levels of the value chain, from fundamental science to engineering and technology. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far The overarching goal of TOCHA is to nurture a paradigm shift by developing a new generation of topological devices based on novel materials and technologies that can provide a unique leap forward towards a deeper level of basic understanding of topological systems. The resulting advancement of manipulation of their topological states will enhance the handling and transport of (quantum) information and metrology. To this end, the TOCHA project proposes a radically new technology taking advantage of the unique properties of emerging materials, such as topological insulators and two-dimensional materials, novel heterostructures based on photonic/photonic crystals, as well as hybrid devices combining those systems.Objectives include:i) To develop low-loss waveguides based on photonic crystals hosting topological edge states with arbitrary shape.ii) To advance the use of topological-insulator materials and devices to higher operating temperatures and currentsiii) To develop quantum resistance standards based on the QAHE.iv) To gain a radically new fundamental knowledge of the interactions and correlations between photons, phonons and electrons in hybrid topological systems. 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 TOCHA project represents the first internationally EU coordinated multi-physics consortium on topological matter and its application in interconnects and quantum metrology. Because of the very early state of research into topological matter and, in particular, on ferromagnetic topological insulators (TIs), topological photonics and topological phononics, significant impact in the fundamental understanding of these systems is expected. Furthermore, the technology and know-how resulting from TOCHA could radically change our view of Information and Communication Technologies and Metrology, specifically by offering: i) Novel solutions to transfer information with low dissipation.ii) Topology in nano-photonics and -phononics devices, which are expected to significantly improve their performance and bring new functionalities.iii) New techniques to control photon-phonon coupling, which is of paramount importance not only in the quantum regime but also for optomechanics.iv) Novel approaches to quantum resistance standards for metrology, which might represent the first concrete application of TIs in the world.