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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Casimir effect and van der Waals forces in multilayer systems

Alternative title: Casimir effekt og van der Waals krefter i multilags-systemer

Awarded: NOK 8.7 mill.

Quantum electrodynamic fluctuation forces, which generalize the idealized force predicted by Casimir in 1948, have moved to an ever more central position in our understanding of mesoscopic forces between surfaces and between molecules and surfaces. Casimir-Lifshitz and Casimir-Polder forces generalize and transform the notion of van der Waals forces. The project consisted of 2(3) parts: one practical part which studied among else things greenhouse gas molecules CO2 and CO4 in melting ice and water, effective polarization models for gas molecules for gas molecules in fluids, and nanoscale switching in quantum mechanical levitation induced by a phase transition in tin. Then, there was another more fundamental part of the project (actually the original Casimir effect): Casimir force on dielectric balls, repulsive Casimir forces, and negative entropy aspects related to the Casimir effect. A third sub-part was the influence from the Casimir effect in cosmology. We have in the project period published 45 articles in scientific refereed journals, and have held about 35 presentations at various workshops and conferences throughout Europe. In the period June 11-16, 2018, we arranged at NTNU "Summer school and Workshop on the Casimir Effect: Theory and Applications", with about 45 participants in all, about half of them PhD students. With economic support also from the "Julian Schwinger Foundation", USA, we could invite also PhD students from remote countries such as South America and USA. Our project was very internationally oriented. For instance, our summer school led to the establishment of new contacts and collaboration projects.

Hoved-delen av forskningsrabeidet har ligget innenfor de praktiske aspektene av Casimireffekten, som angitt i søknaden. Det betyr anvendelse av Lifshitz formalismen og "density functional theory" i komplekse systemer. Anvendelsespotensialet ligger blant annet i forståelse av CH4 innfangning og CO2 lagring. Vi har skrevet en rekke artikler om emnet, i samarbeid med våre internasjonale partnere. Det bør spesielt nevnes artikkelen Distance-dependent sign reversal in the Casimir-Lifshitz torque", av P. Thiyam et al., Phys. Rev. Lett. 120, 131601 (2018). Manipulering av Casimirkraften, i særdeleshet dens retning, er noe som har stor interesse i forbindelse med MEMS/NEMS. I tillegg til de anvendte aspektene har vi også sett på grunnlaget for Casimir teorien, i dielektriske materialer (denne QED retningen var Casimirs eget utgangspunkt i 1948). Disse arbeidene er blitt gjort delvis i samarbeid med K. A. Milton og hans gruppe i Oklahoma.

Quantum electrodynamic fluctuation forces, which generalize the idealized force predicted by Casimir in 1948, have moved to an ever more central position in our understanding of mesoscopic forces between surfaces and between molecules and surfaces. Casimir-Lifshitz and Casimir-Polder forces generalize and transform the notion of van der Waals forces. Advances in experimental technique and development of new theoretical tools have enabled this transformation. There remain highly controversial issues to be resolved, such as the nature of thermal corrections, the form of Casimir friction, and whether it is realistic to achieve Casimir repulsion and levitation. The driver, however, is the potential applications of these phenomena to physical systems. Here, we want to link developments in theory to what is needed in practical situations, such as the interaction of molecular gases with oil shale. The project will be carried out and completed at the Department of Energy and Process Engineering, Norwegian University of Science and Technology (NTNU) together with researchers from the Centre for Materials Science and Nanotechnology at the University of Oslo (UiO). Joint subprojects with the co-applicants from the USA, Germany, Brazil, Sweden and Australia will involve short and long-term research visits. We will also arrange a combined summer school and workshop at NTNU during 2018. Two postdocs and one researcher (1/2 position) will be hired, and visiting researchers will be supported by the grant. Collaboration via the internet will facilitate progress and coordination of research activities. Strong interaction with our research partners and collaborators will facilitate rapid progress in research and serve for networking, exchanging knowledge, and scientific visibility. Long-term international research visits by the postdoc and researchers will increase scientific productivity and strengthen the collaborations.

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FRINATEK-Fri prosj.st. mat.,naturv.,tek