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We set the theoretical basis for scattering cancellation and cloaking of quantum particle waves. We discuss the possibility of cloaking a spherical object from an impinging matter wave by using a homogeneous monolayer with properly tailored effective mass and potential. The method, based on cancellation of scattered s and p waves, is the quantum analog of plasmonic cloaking of electromagnetic waves. We show that it may be possible to use this cloaking mechanism to make semiconductor quantum dots effectively invisible to impinging electrons, providing interesting venues in nano-optics, quantum computing, and furtive quantum sensing. [ABSTRACT FROM AUTHOR]

We discuss here potential venues for applications and exotic features of quantum metamaterials. We explore the coupling of conventional electromagnetic metamaterials with quantum emitters and the wave properties of quantum metamaterials obtained by tailoring their effective band structure. We discuss anomalous enhancement effects in the quantum emission properties of individual and collections of small emitters in the presence of metamaterials, as well as matter-wave cloaking and anomalous tunneling phenomena for quantum mechanical waves in artificial materials with exotic band structures. [ABSTRACT FROM AUTHOR]

Acoustic metamaterials and metasurfaces have been explored in the past few years to realize a wide range of extreme responses for sound waves. As one remarkable phenomenon, extreme anisotropy and hyperbolic sound propagation are particularly challenging to realize compared to electromagnetic waves because of the scalar nature of airborne acoustics. In parallel, moiré superlattices and the rapidly expanding domain of twistronics have shown that large anisotropy combined with tailored geometrical rotations can enable tantalizing emerging phenomena, such as tailored phase transitions in metamaterials. Connecting these areas of research, here, we explore the realization of acoustic hyperbolic metasurfaces and their combination to drive topological phase transitions from hyperbolic to elliptic sound propagation. The transition point occurring at a specific rotation angle between two acoustic metasurfaces supports highly directional canalization of sound, opening exciting opportunities for twisted acoustics metasurfaces for robust surface wave guiding and steering. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman spectroscopy (SERS) is a promising optical method for analyzing molecular samples of various nature. Most SERS studies are of an applied nature, indicating a serious potential for their application in analytical practice. Dendritelike nanostructures have great potential for SERS, but the lack of a method for their predictable production significantly limits their implementation. In this paper, a method for controllably obtaining spatially separated, self-organized, and highly-branched silver dendrites via template synthesis in pores of SiO2/Si is proposed. The dendritic branches have nanoscale roughness, creating many plasmon-active "hotspots" required for SERS. The first held 3D modeling of the external electromagnetic wave interaction with such a dendrite, as well as experimental data, confirms this theory. Using the example of a reference biological analyte, which is usually used as a label for other biological molecules, the dendrites' SERS-sensitivity up to 10−15M was demonstrated with an enhancement factor of 108. The comparison of simulation results with SERS experiments allows distinguishing the presence of electromagnetic and chemical contributions, which have a different effect at various analyte concentrations. [ABSTRACT FROM AUTHOR]

A new class of phenomena stemming from topological states of quantum matter has recently found a variety of analogies in classical systems. Spin-locking and one-way propagation have been shown to drastically alter scattering of electromagnetic waves, thus offering an unprecedented robustness to defects and disorder. Despite these successes, bringing these new ideas to practical grounds meets a number of serious limitations. In photonics, when it is crucial to implement topological photonic devices on a chip, two major challenges are associated with electromagnetic dissipation into heat and out-of-plane radiation into free space. Both these mechanisms may destroy the topological state and seriously affect the device performance. Here, we demonstrate experimentally that the topological order for light can be implemented in all-dielectric on-chip prototype metasurfaces, which mitigate the effect of Ohmic losses by using exclusively structured dielectric materials, and we reveal that coupling of the system to the radiative continuum does not affect topological properties. We demonstrate the spin-Hall effect of light for spin-polarized topological edge states through near-field spectroscopy measurements. [ABSTRACT FROM AUTHOR]

Confining electromagnetic energy is crucial to enhance light-matter interactions, with important implications for science and technology. Here, the opportunities offered by trapping and confining light in open structures, based on the concept of embedded eigenstates within the radiation continuum enabled by zero-index metamaterials, are discussed. Building upon the physical insights offered by the analysis, a general platform is put forward that allows the realization of extremely high field enhancements in open structures under external illumination. Structures supporting embedded eigenstates represent a rare example of physical systems in which extreme-in principle unbounded-responses can be tamed. The proposed design recipe to realize bound states in the continuum also offers a simple model that allows testing of important questions that surround the concept of embedded eigenstates, such as their effect on the local density of photonic states. The findings help clarify which nano-optical and radio-wave applications may benefit from this unusual and singular response. [ABSTRACT FROM AUTHOR]

Optical metasurfaces, typically referred to as two-dimensional metamaterials, are arrays of engineered subwavelength inclusions suitably designed to tailor the light properties, including amplitude, phase and polarization state, over deeply subwavelength scales. By exploiting anomalous localized interactions of surface elements with optical waves, metasurfaces can go beyond the functionalities offered by conventional diffractive optical gratings. The innate simplicity of implementation and the distinct underlying physics of their wave-matter interaction distinguish metasurfaces from three-dimensional metamaterials and provide a valuable means of moulding optical waves in the desired manner. Here, we introduce a general approach based on the electromagnetic equivalence principle to develop and synthesize graded, non-periodic metasurfaces to generate arbitrarily prescribed distributions of electromagnetic waves. Graded metasurfaces are realized with a single layer of spatially modulated, electrically polarizable nanoparticles, tailoring the scattering response of the surface with nanoscale resolutions. We discuss promising applications based on the proposed local wave management technique, including the design of ultrathin optical carpet cloaks, alignment-free polarization beam splitters and a novel approach to enable broadband light absorption enhancement in thin-film solar cells. This concept opens up a practical route towards efficient planarized optical structures with potential impact on the integrated nanophotonic technology. [ABSTRACT FROM AUTHOR]

Extraction of electromagnetic energy by an antenna from impinging external radiation is at the basis of wireless communications and wireless power transfer (WPT). The maximum of transferred energy is ensured when the antenna is conjugately matched, i.e., when it is resonant and it has an equal coupling with free space and its load. This condition, however, can be easily affected by changes in the environment, preventing optimal operation of a WPT system. Here, we introduce the concept of coherently enhanced WPT that allows us to bypass this difficulty and achieve dynamic control of power transfer. The approach relies on coherent excitation of the waveguide connected to the antenna load with a backward propagating signal of specific amplitude and phase. This signal creates a suitable interference pattern at the load resulting in a modification of the local wave impedance, which in turn enables conjugate matching and a largely increased amount of extracted energy. We develop a simple theoretical model describing this concept, demonstrate it with full-wave numerical simulations for the canonical example of a dipole antenna, and verify experimentally in both near-field and far-field regimes. [ABSTRACT FROM AUTHOR]