Here we report on our recent experimental efforts towards the design, fabrication and characterization of various metasurface structures that would allow spatial and temporal control of photon emission from atomic ensembles, as well as state preparation of solid state and atomic quantum emitters. The emphasis is placed on the development of two distinct categories of structures: (i) Micro- and meso-scale free-space self-polarizing confocal cavities formed by dielectric metasurfaces. (ii) flat hyper-gratings fabricated on the surface of a diamond, which would make the radiation pattern from NV centers in the diamond to be highly directional so that the emitted photons can be collected with high efficiency.
Here we report on our recent experimental efforts towards the design, fabrication and characterization of various metasurface structures that would allow spatial and temporal control of photon emission from atomic ensembles, as well as state preparation of solid state and atomic quantum emitters. The emphasis is placed on the development of two distinct categories of structures: (i) Micro- and meso-scale free-space self-polarizing confocal cavities formed by dielectric metasurfaces. (ii) flat hyper-gratings fabricated on the surface of a diamond, which would make the radiation pattern from NV centers in the diamond to be highly directional so that the emitted photons can be collected with high efficiency.
Manipulating photoluminescence from solid-state quantum emitters (QEs) on demand is of central importance for advanced quantum nanophotonic technologies. In comparison with conventional free-space approaches relying on bulky optical components, emitter-integrated metasurfaces provide a compact and efficient route for shaping photon emission directly at the source. Recent progress has established a common platform in which QE-excited surface plasmon polaritons (SPPs) are transformed by surrounding metasurfaces into free-space radiation with tailored propagation direction, polarization state, relative intensity, and spatial structure. This review highlights two complementary strategies that have recently been utilized for shaping quantum emission. The first is emitter-coupled meta-optics, which enables versatile photon sources with arbitrary polarization states, off-normal directionality, and multichannel emission by means of phase-engineered anisotropic meta-atoms. The second is vectorial scattering holography, including multiplexed implementations, which allows direct reconstruction of arbitrarily structured and polarization-multiplexed emission from individual nanodiamonds. Together, these approaches unlock unprecedented degrees of freedom for nanoscale light shaping and provide a promising route toward scalable quantum photonic devices and high-capacity information processing.
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.
In this thesis we investigate two domains of control over the photonic emission from NV centers. In the first part of the thesis, which focuses on emission control in the spatial domain, we will be exploring the design of a nanophotonic structure that would be able to control the directionality of photon emission from NV centers. We will be using the inverse design methodology known as adjoint optimization to design the structure. Furthermore we will present FDTD simulations to assess the performance of the designed structure and compare its performance with existing structures. We then present some preliminary experimental results from a confocal microscopy setup we built in our lab. \n \nIn the second part of the thesis, which focuses on emission control in the spectral domain, we investigate the potential of using single NV centers for photon conversion between the microwave and optical regimes. The conversion between the microwave photons, that couple to superconducting qubits, and optical photons, that are used in long range communication and memories, is an important component in realizing an extended quantum network. In our proposed scheme, we explore the use of Λ system in NV centers coupled to optical and microwave cavities as a platform for efficient conversion between the microwave and optical regimes. We present analytical and numerical simulations to identify the required characteristics of the system to achieve high conversion efficiencies.
Efficient collection of fluorescence from nitrogen vacancy (NV) centers in diamond underlies the spin-dependent optical read-out that is necessary for quantum information processing and enhanced sensing applications. The optical collection efficiency from NVs within diamond substrates is limited primarily due to the high refractive index of diamond and the non-directional dipole emission. Here we introduce a light collection strategy based on chirped, circular dielectric gratings that can be fabricated on a bulk diamond substrate to redirect an emitter's far-field radiation pattern. Using a genetic optimization algorithm, these grating designs achieve 98.9% collection efficiency for the NV zero-phonon emission line, collected from the back surface of the diamond with an objective of aperture 0.9. Across the broadband emission spectrum of the NV (600-800 nm), the chirped grating achieves 82.2% collection efficiency into a numerical aperture of 1.42, corresponding to an oil immersion objective again on the back side of the diamond. Our proposed bulk-dielectric grating structures are applicable to other optically active solid state quantum emitters in high index host materials.
From metamaterials to metasurfaces, optical nano-structure has been widely investigated for novel and high efficiency functionalities. Apart from the intrisinsic properties of composite material, rich capabilities can be derived from the judicious design of metasurfaces, which enable more excellent and highly integrated optical devices than traditional bulk optical elements. In the meantime, the abundant manipulation abilites of light in the classical domain can be carried over into quantum domain. In this review, we highlight recent development of quantum optics based on metasurfaces, ranging from quantum plasmonics, generation, manipulation and appplication of quantum light to quantum vaccum engineering etc. Finally, some promising avenues for quantum optics with the help of optical metasurface are presented.
The two-dimensional designer metasurfaces have been established as a new class of versatile and powerful optical solution for controlling the classical light in various degrees of freedom such as phase, amplitudes, polarization and angular momentum. Expanding the control capability of metasurface from classical light to quantum state of single photons is an emerging direction that can lead to a new regime of light-matter interaction and applications for quantum technology. In this talk, we will present our proposal and experimental demonstration of manipulating photonic quantum states enabled by an unprecedented design of metasurface. We show the control over the quantum states and the effective quantum interaction between single photons, which is impossible by traditional optics. Our work greatly empowers the operations and functionalities of optical quantum technologies.