宮本 克彦

Quantum state conversion from the higher-order polarization states of photons on a higher-order Poincaré sphere (HOPS) with spin angular momentum (SAM) and orbital angular momentum (OAM) to an electron system in a semiconductor host is an interesting topic for high-density quantum media conversion with high degrees of freedom (DoFs). In this paper, we present the spatial spin structure states of electrons on a higher-order Bloch sphere, corresponding to HOPS states, using the similarity between the electron states on the Bloch sphere and the polarization states on the Poincaré sphere. Furthermore, the coherent transfer of the spatial structure of photon polarization to the spin structure state of electrons was demonstrated for the first time in GaAs/AlGaAs quantum wells using a V-shaped three-level system. The results provide insights into the simultaneous coherent transfer of SAM and OAM from the extended states of photon-to-electron systems, leading to the realization of the quantum state transfer of the high-dimensional entangled states of photons to electron spins with different DoFs.

Skyrmions, topologically stable configurations of a three-component vector field with sophisticated textures, have been considered in many contexts, including atomic physics, Bose–Einstein condensates, liquid crystals, and magnetic materials. Although optical counterparts of skyrmions have extensively been studied theoretically and recently demonstrated in the laboratory experiments, their experimental mapping is challenging due to the fine, three-dimensional, and complicated structure of their polarization distributions. Here, we propose and demonstrate a straightforward mapping of the polarization textures of optical Néel-, Bloch-, and anti-skyrmions based on the radiation pressure and direct imprinting of the skyrmion textures on azopolymers. These results not only elucidate the exotic interaction that occurs between topologically protected quasiparticles of light and matter but also provide a simple approach for generation and characterization of optical skyrmions, based on a dual-path polarization shaping configuration with a single spatial light modulator, and their measurements based on the radiation pressure.

We demonstrate high-definition, direct-printing of micron-scale metallic dots, comprised of close-packed gold nanoparticles, by utilizing the optical vortex laser-induced forward transfer technique. We observe that the spin angular momentum of the optical vortex, associated with circular polarization, assists in the close-packing of the gold nanoparticles within the printed dots. The printed dots exhibit excellent electrical conductivity without any additional sintering processes. This technique of applying optical vortex laser-induced forward transfer to metallic dots is an innovative approach to metal printing, which does not require additional sintering. It also serves to highlight new insights into light–matter interactions.

Multicolor visible high-order Bessel (Bessel-vortex) beams which have a helical wavefront and a long confocal length have garnered significant interest for applications in materials processing and biomedical technologies. In this paper, we demonstrate the direct generation of multicolor (523, 605 and 637 nm) Bessel-vortex beams from a Pr³⁺-doped water-proof fluoro-aluminate glass (Pr³⁺: WPFG) fiber laser with an intracavity lens which induces chromatic and spherical aberration. The handedness of the generated Bessel-vortex beam is selectively controlled through lateral displacement of the intra-cavity lens.

We demonstrate the formation of surface relief structures in azo-polymers which exhibit multiple spiral arms, through irradiation of a rotating petal-like beam formed by the coherent superposition of Laguerre-Gaussian modes with opposite handedness. Intriguingly, the fabricated relief structures reflect full geometric parameters of the irradiated petal beam, such as handedness, topological charge, initial azimuthal phase and even ellipticity, corresponding to azimuthal and polar angles along equator and meridian planes of an orbital Poincaré sphere. The handedness, or direction of rotation, of the fabricated structures with multiple spiral arms could be controlled via the rotation and polarization directions of the irradiating laser field. This effect highlights an exotic coupling between the optical intensity gradient induced mass transport of the irradiated material and the spin angular momentum characteristics of the irradiating optical field. The azimuthal orientation of the surface relief structures could also be tuned by altering the initial relative phase between the coherently superposed Laguerre-Gaussian modes with opposite handedness, constituting the irradiating petal laser field. This work offers new insights into fundamental interactions which occur between light and matter, and we believe, will pave the way towards advanced technologies, such as ultrahigh density optical data storage.