No Arabic abstract
The integration of nanoscale electronics with conventional optical devices is restricted by the diffraction limit of light. Metals can confine light at the subwavelength scales needed, but they are lossy, while dielectric materials do not confine evanescent waves outside a waveguide or resonator, leading to cross talk between components. We introduce a paradigm shift in light confinement strategy and show that light can be confined below the diffraction limit using completely transparent artificial media. Our approach relies on controlling the optical momentum of evanescent waves, an important electromagnetic property overlooked in photonic devices. For practical applications, we propose a class of waveguides using this approach that outperforms the cross talk performance by 1 order of magnitude as compared to any existing photonic structure. Our work overcomes a critical stumbling block for nanophotonics by completely averting the use of metals and can impact electromagnetic devices from the visible to microwave frequency ranges.
Topological states of light have received significant attention due to the existence of counter-intuitive nontrivial boundary effects originating from the bulk properties of optical systems. Such boundary states, having their origin in topological properties of the bulk, are protected from perturbations and defects, and they show promises for a wide range of applications in photonic circuitry. The bulk-boundary correspondence relates the N-dimensional bulk modes to (N-1)-dimensional boundary states. Recently, the bulk-boundary correspondence was generalized to higher-order effects such that an N-dimensional bulk defines its (N-M)-dimensional boundary states. Prominent examples are topological corner states of light in two-dimensional structures that have been realized at the micrometer-scale. Such corner states, due to their tight confinement in all directions, provide a novel route towards topological cavities. Here we bring the concept of topological corner states to the nanoscale for enhancing nonlinear optical processes. Specifically, we design topologically nontrivial hybrid metasurfaces with C6-symmetric honeycomb lattices supporting both edge and corner states. We report on direct observations of nanoscale topology-empowered localization of light in corner states revealed via a nonlinear imaging technique. Nanoscale topological corner states pave the way towards on-chip applications in compact classical and quantum nanophotonic devices.
Nanoscale quantum optics explores quantum phenomena in nanophotonics systems for advancing fundamental knowledge in nano and quantum optics and for harnessing the laws of quantum physics in the development of new photonics-based technologies. Here, we review recent progress in the field with emphasis on four main research areas: Generation, detection, manipulation and storage of quantum states of light at the nanoscale, Nonlinearities and ultrafast processes in nanostructured media, Nanoscale quantum coherence, Cooperative effects, correlations and many-body physics tailored by strongly confined optical fields. The focus is both on basic developments and technological implications, especially for what concerns information and communication technology, sensing and metrology, and energy efficiency.
We report both sub-diffraction-limited quantum metrology and quantum enhanced spatial resolution for the first time in a biological context. Nanoparticles are tracked with quantum correlated light as they diffuse through an extended region of a living cell in a quantum enhanced photonic force microscope. This allows spatial structure within the cell to be mapped at length scales down to 10 nm. Control experiments in water show a 14% resolution enhancement compared to experiments with coherent light. Our results confirm the longstanding prediction that quantum correlated light can enhance spatial resolution at the nanoscale and in biology. Combined with state-of-the-art quantum light sources, this technique provides a path towards an order of magnitude improvement in resolution over similar classical imaging techniques.
The origin of long-range attractive interactions has fascinated scientist along centuries. The remarkable Fatio-LeSages corpuscular theory, introduced as early as in 1690 and generalized to electromagnetic waves by Lorentz, proposed that, due to their mutual shadowing, two absorbing particles in an isotropic radiation field experience an attractive force which follows a gravity-like inverse square distance law. Similar Mock Gravity interactions were later introduced by Spitzer and Gamow in the context of Galaxy formation but their actual relevance in Cosmology has never been unambiguously established. Here we predict the existence of Mock-Gravity, inverse square distance, attractive forces between two identical molecules or nanoparticles in a quasi monochromatic isotropic random light field, whenever the light frequency is tuned to an absorption line such that the real part of the particles electric polarizability is zero, i.e. at the so-called Froehlich resonance. These interactions are scale independent, holding for both near and far-field separation distances.
Hyperbolic phonon polaritons (HPhPs) in hexagonal boron nitride (hBN) enable the direct manipulation of mid-infrared light at nanometer scales, many orders of magnitude below the free-space light wavelength. High resolution monochromated electron energy-loss spectroscopy (EELS) facilitates measurement of excitations with energies extending into the mid-infrared while maintaining nanoscale spatial resolution, making it ideal for detecting HPhPs. The electron beam is a precise source and probe of HPhPs, that allows us to perform novel experiments to observe nanoscale confinement in HPhP structures and directly extract hBN polariton dispersions for both modes in the bulk of the flake and modes along the edge. Our measurements reveal technologically important non-trivial phenomena, such as localized polaritons induced by environmental heterogeneity, enhanced and suppressed excitation due to two-dimensional interference, and strong modification of high-momenta excitations of edge-confined polaritons by nanoscale heterogeneity on edge boundaries. Our work opens exciting prospects for the design of real-world optical mid-infrared devices based on hyperbolic polaritons.