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Geometrical aspects of spin and vortex dynamics in electromagnetic and matter waves

Final Report Summary - SPIVOR (Geometrical aspects of spin and vortex dynamics in electromagnetic and matter waves)

This project addressed the fundamental problem of spin-orbit interactions (SOI) in the context of light and matter waves. The SOI effects arise due to the coupling of internal and external degrees of freedom in optical and quantum systems and become critically important at the nanoscales. This is a new interdisciplinary area of research at the confluence of nanooptics, plasmonics, and spintronics.
Our main achievement is the first self-consistent theoretical description and experimental implementation of the SOI dynamics in the generic non-paraxial optical and quantum fields. This involves and unifies a number of tasks of both fundamental and practical importance, such as (i) spin and orbital angular momenta (AM), (ii) spin-to-orbit AM conversions upon focusing and scattering, and (iii) spin and orbital Hall effects. The outcomes of our studies are 9 full-length papers (3 of them in Physical Review Letters), 2 book chapters, and 14 talks (with 8 of them − invited) given at international workshops and conferences. The main problems solved within the project are as follows.
This project develops a unifying interdisciplinary approach to light and matter wave systems with SOI. This creates an underpinning theoretical basis and open new perspectives for control of classical light and quantum particles at nanoscales using internal degrees of freedom. The potential impacts of the project are as follows:
On the fundamental level, this project delivers profound theoretical understanding of the SOI effects in vector waves, unify previously disjointed fundamental problems, and unveil deep interrelations between them. Our studies revealed the intimate connection between spin and orbital angular momenta of light, relativistic position operators of photons, Berry phases, Poynting energy flows, and spin-orbit interactions. It turns out that only when brought together, these fundamental concepts form a fairly complete picture of the internal degrees of freedom of light. Such thorough approach has a universal character and will be naturally applied to quantum systems within the framework of this project. This will deepen the analogy between the light and matter waves at the level of intrinsic geometrodynamical phenomena.
On the level of applications, this project investigates conceptually new methods for the control of wave fields at nanoscales. As we demonstrated, the SOI of light can be employed for nanoprobing, i.e. translation of subwavelength information about specimens into the far field. Since the spin of photons is associated with circular polarizations, all phenomena sensitive to circular polarizations could be strongly affected and sometimes dramatically enhanced by SOI. Thus, efficient probing schemes for chiral and magnetoactive structures can be further developed in the context of optical, plasmon-polariton, and vortex-electron waves.