We propose novel quantum antennas and metamaterials with a strong magnetic response at optical frequencies. Our design is based on the arrangement of natural quantum emitters with only electric dipole transition moments at distances smaller than a wavelength of light but much larger than their physical size. In particular, we show that an atomic dimer can serve as a magnetic antenna at its antisymmetric mode to enhance the decay rate of a magnetic transition in its vicinity by several orders of magnitude. Furthermore, we study metasurfaces composed of atomic bilayers with and without cavities and show that they can fully reflect the electric and magnetic fields of light, thus, forming nearly perfect electric or magnetic mirrors. The proposed metamaterials will embody the intrinsic quantum functionalities of natural emitters such as atoms, ions, color center, or molecules and can be fabricated with available state-of-the-art technologies, promising several applications both in classical optics and quantum engineering.
We propose novel quantum antennas and metamaterials with a strong magnetic response at optical frequencies. Our design is based on the arrangement of natural quantum emitters with only electric dipole transition moments at distances smaller than a wavelength of light but much larger than their physical size. In particular, we show that an atomic dimer can serve as a magnetic antenna at its antisymmetric mode to enhance the decay rate of a magnetic transition in its vicinity by several orders of magnitude. Furthermore, we study metasurfaces composed of atomic bilayers with and without cavities and show that they can fully reflect the electric and magnetic fields of light, thus, forming nearly perfect electric or magnetic mirrors. The proposed metamaterials will embody the intrinsic quantum functionalities of natural emitters such as atoms, ions, color center, or molecules and can be fabricated with available state-of-the-art technologies, promising several applications both in classical optics and quantum engineering.
Abstract Natural materials typically interact weakly with the magnetic component of light which greatly limits their applications. This has led to the development of artificial metamaterials and metasurfaces. However, natural atoms, where only electric dipole transitions are relevant at optical frequencies, can cooperatively respond to light to form collective excitations with strong magnetic, as well as electric, interactions together with corresponding electric and magnetic mirror reflection properties. By combining the electric and magnetic collective degrees of freedom, we show that ultrathin planar arrays of atoms can be utilized as atomic lenses to focus light to subwavelength spots at the diffraction limit, to steer light at different angles allowing for optical sorting, and as converters between different angular momentum states. The method is based on coherently superposing induced electric and magnetic dipoles to engineer a quantum nanophotonic Huygens’ surface of atoms, giving full 2π phase control over the transmission, with close to zero reflection.
We show how to achieve single-photon control via a synthesized optical magnetic response without metamaterials, using quantum-mechanical electric dipole transitions of naturally occurring atoms. We demonstrate how arrays of atoms can be designed to absorb, store, and emit single photons and realize a quantum atomic Huygens' surface that allows for extreme wavefront engineering. The response can be further controlled by the quantum state of an optical cavity, generating entanglement between the cavity and the array, and hence the cavity and transmitted light.
Tremendous advances in the study of magnetic light-matter interactions have recently been achieved using man-made nanostructures that exhibit and exploit an optical magnetic response. However, naturally occurring emitters can also exhibit magnetic resonances in the form of optical-frequency magnetic-dipole transitions. Here we quantify the magnetic nature of light emission using energy- and momentum-resolved spectroscopy, and leverage a pair of spectrally close electric- and magnetic-dipole transitions in trivalent europium to probe vacuum fluctuations in the electric and magnetic fields at the nanometre scale. These results reveal a new tool for nano-optics: an atomic-size quantum emitter that interacts with the magnetic component of light. Light-matter interactions are generally dominated by electric fields and electric-dipole transitions. This study, however, quantifies magnetic contributions to light emission and so exploits the strong natural magnetic-dipole transitions in lanthanide ions to measure optical-frequency magnetic fields.
Quantum vacuum engineering is an active field of research. Here we use recent advances in the field of metasurface (2D-array of sub-wavelength scale nano-antennas) to construct an anisotropic quantum vacuum (AQV) in the vicinity of a quantum emitter located at some macroscopic distance from the metasurface. Such AQV can induce quantum interference among several atomic transitions, even when the transition dipole moment corresponding to the decay channels are orthogonal. Recently, there have been few theoretical proposal to use metamaterials to engineer the back-action. All these approaches, which works in the near field (few tens of nanometers from the surface), suffers from trapping an atom at these distance, surface interactions like quenching, Casimir force etc. Hence it’s pivotal to construct the back-action over macroscopic distance. We harness the polarization dependent response of a metasurface to engineer the back-action of the spontaneous emission from the atom to itself. We show strong anisotropy in the decay rate of a quantum emitter which is a manifestation of AQV. Engineering light-matter interaction over macroscopic distances opens new possibilities for long-range interaction between quantum emitters for quantum information processing, spin-optics/spintronics etc.
Abstract Quantum antennas couple localized quantum emitters to optical modes that can be collected, routed, and used in larger photonic systems. Their performance depends on photon delivery as well as single-photon purity, coherence, and indistinguishability. This Review connects the physics of light-matter interaction with the design of quantum-photonic interfaces. We compare semiconductor quantum dots, color centers, two-dimensional and molecular emitters, and examine plasmonic, dielectric, hybrid, cavity-coupled, and waveguideintegrated antenna architectures. We discuss how emitter position, dipole orientation, spectral matching, and material loss govern radiative enhancement and quenching, then assess performance through efficiency, brightness, photon statistics, and coupling to useful optical modes. Electromagnetic and quantum-optical modeling are considered alongside fabrication, deterministic emitter placement, and experimental characterization. We further examine how arrays and metasurfaces extend control to collective emission and quantum wavefronts, and survey applications in single-photon generation, communication, networking, computing, sensing, imaging, and ranging. Across these settings, rapid decay and strong local fields produce system-level gains only when useful photon delivery improves without compromising quantum-state quality. Low-loss design, spectral stabilization, reproducible integration, and complete photon-budget reporting emerge as priorities for scalable quantum-antenna platforms.
Photonic metamaterials are man-made materials with "lattice constants" smaller than the wavelength of light. Tailoring the properties of their functional building blocks (atoms) allows one to go beyond the possibilities of usual materials. For example, magnetic dipole moments at optical frequencies (mune1) become possible. This aspect substantially enriches the possibilities of optics and photonics and forms the basis for the so-called negative-index metamaterials. Here, we describe the underlying physics and review the recent progress in this rapidly emerging field