ICFO – The Institute of Photonic Sciences

About: ICFO – The Institute of Photonic Sciences is a facility organization based out in Barcelona, Spain. It is known for research contribution in the topics: Quantum & Quantum entanglement. The organization has 872 authors who have published 1965 publications receiving 56273 citations.

Knotting fractional-order knots with the polarization state of light

Abstract: The fundamental polarization singularities of monochromatic light are normally associated with invariance under coordinated rotations: symmetry operations that rotate the spatial dependence of an electromagnetic field by an angle θ and its polarization by a multiple γθ of that angle. These symmetries are generated by mixed angular momenta of the form Jγ = L + γS, and they generally induce Mobius-strip topologies, with the coordination parameter γ restricted to integer and half-integer values. In this work we construct beams of light that are invariant under coordinated rotations for arbitrary rational γ, by exploiting the higher internal symmetry of ‘bicircular’ superpositions of counter-rotating circularly polarized beams at different frequencies. We show that these beams have the topology of a torus knot, which reflects the subgroup generated by the torus-knot angular momentum Jγ, and we characterize the resulting optical polarization singularity using third- and higher-order field moment tensors, which we experimentally observe using nonlinear polarization tomography. The polarization structure around polarization singularities can exhibit arbitrary fractional rotations when tracing around the singularity, due to an underlying topology of a torus knot imprinted by the chosen ratio of frequencies contained in the light beam.

Plasmonic Nanoantennas Enable Forbidden Förster Dipole-Dipole Energy Transfer and Enhance the FRET Efficiency

Abstract: Forster resonance energy transfer (FRET) plays a key role in biochemistry, organic photovoltaics, and lighting sources. FRET is commonly used as a nanoruler for the short (nanometer) distance between donor and acceptor dyes, yet FRET is equally sensitive to the mutual dipole orientation. The orientation dependence complicates the FRET analysis in biological samples and may even lead to the absence of FRET for perpendicularly oriented donor and acceptor dipoles. Here, we exploit the strongly inhomogeneous and localized fields in plasmonic nanoantennas to open new energy transfer routes, overcoming the limitations from the mutual dipole orientation to ultimately enhance the FRET efficiency. We demonstrate that the simultaneous presence of perpendicular near-field components in the nanoantenna sets favorable energy transfer routes that increase the FRET efficiency up to 50% for nearly perpendicular donor and acceptor dipoles. This new facet of plasmonic nanoantennas enables dipole–dipole energy transfer that...

Randomness in quantum mechanics: philosophy, physics and technology

Abstract: This progress report covers recent developments in the area of quantum randomness, which is an extraordinarily interdisciplinary area that belongs not only to physics, but also to philosophy, mathematics, computer science, and technology. For this reason the article contains three parts that will be essentially devoted to different aspects of quantum randomness, and even directed, although not restricted, to various audiences: a philosophical part, a physical part, and a technological part. For these reasons the article is written on an elementary level, combining simple and non-technical descriptions with a concise review of more advanced results. In this way readers of various provenances will be able to gain while reading the article.

Dynamics of many-body photon bound states in chiral waveguide QED

Abstract: A proposed optical waveguide would take a light pulse and break it into sets of strongly correlated photons, which may give a leg up to certain quantum technologies.

Structural Coloring of Glass Using Dewetted Nanoparticles and Ultrathin Films of Metals

Abstract: Metal nanoparticles have been used for coloring glass since antiquity. Colors are produced by light scattering and absorption associated with plasmon resonances of the particles. Recently, dewetting at high temperature has been demonstrated as a straightforward high-yield/low-cost technique for nanopatterning thin metal films into planar arrays of spherical nanocaps. Here, we show that by simply tuning the contact angle of the metal dewetted nanocaps one can achieve narrow resonances and large tunability compared with traditional approaches such as changing particle size. A vast range of colors is obtained, covering the visible spectrum and readily controlled by the choice of film thickness and materials. The small size of the particles results in a mild dependence on incidence illumination angle, whereas their high anisotropy gives rise to strong dichroism. We also show color tuning through interference by simply adding an ultrathin metal film at a designated distance from the dewetted particle array. Ou...