Quantum-dot based photonic quantum networks

Quantum dots embedded in photonic nanostructures have in recent years proven to be a very powerful solid-state platform for quantum optics experiments. The combination of near-unity radiative coupling of a single quantum dot to a photonic mode and the ability to eliminate decoherence processes imply that an unprecedented light-matter interface can be obtained. As a result, high-cooperativity photon-emitter quantum interfaces can be constructed opening a path-way to deterministic photonic quantum gates for quantum-information processing applications. In the present manuscript, I review current state-of-the-art on quantum dot devices and their applications for quantum technology. The overarching long-term goal of the research field is to construct photonic quantum networks where remote entanglement can be distributed over long distances by photons

Solid immersion lens applications for nanophotonic devices

Solid immersion lens (SIL) microscopy combines the advantages of conventional microscopy with those of near-field techniques, and is being increasingly adopted across a diverse range of technologies and applications. A comprehensive overview of the state-of-the-art in this rapidly expanding subject is therefore increasingly relevant. Important benefits are enabled by SIL-focusing, including an improved lateral and axial spatial profiling resolution when a SIL is used in laser-scanning microscopy or excitation, and an improved collection efficiency when a SIL is used in a light-collection mode, for example in fluorescence micro-spectroscopy. These advantages arise from the increase in numerical aperture (NA) that is provided by a SIL. Other SIL-enhanced improvements, for example spherical-aberration-free sub-surface imaging, are a fundamental consequence of the aplanatic imaging condition that results from the spherical geometry of the SIL. Beginning with an introduction to the theory of SIL imaging, the unique properties of SILs are exposed to provide advantages in applications involving the interrogation of photonic and electronic nanostructures. Such applications range from the sub-surface examination of the complex three-dimensional microstructures fabricated in silicon integrated circuits, to quantum photoluminescence and transmission measurements in semiconductor quantum dot nanostructures

Analysis of optical near-field energy transfer by stochastic model unifying architectural dependencies

We theoretically and experimentally demonstrate energy transfer mediated by optical near-field interactions in a multi-layer InAs quantum dot (QD) structure composed of a single layer of larger dots and N layers of smaller ones. We construct a stochastic model in which optical near-field interactions that follow a Yukawa potential, QD size fluctuations, and temperature-dependent energy level broadening are unified, enabling us to examine device-architecture-dependent energy transfer efficiencies. The model results are consistent with the experiments. This study provides an insight into optical energy transfer involving inherent disorders in materials and paves the way to systematic design principles of nanophotonic devices that will allow optimized performance and the realization of designated functions

Erbium dopants in silicon nanophotonic waveguides

The combination of established nanofabrication with attractive material properties makes silicon a promising material for quantum technologies, where implanted dopants serve as qubits with high density and excellent coherence even at elevated temperatures. In order to connect and control these qubits, interfacing them with light in nanophotonic waveguides offers unique promise. Here, we present resonant spectroscopy of implanted erbium dopants in such waveguides. We overcome the requirement of high doping and above-bandgap excitation that limited earlier studies. We thus observe erbium incorporation at well-defined lattice sites with a thousandfold reduced inhomogeneous broadening of about 1 GHz and a spectral diffusion linewidth down to 45 MHz. Our study thus introduces a novel materials platform for the implementation of on-chip quantum memories, microwave-to-optical conversion, and distributed quantum information processing, with the unique feature of operation in the main wavelength band of fiber-optic communication.Comment: 7 pages, 4 figure

Plasmon-enhanced generation of non-classical light

Strong light-matter interactions enabled by surface plasmons have given rise to a wide range of photonic, optoelectronic and chemical functionalities. In recent years, the interest in this research area has focused on the quantum regime, aiming to developing ultra-compact nanoscale instruments operating at the single (few) photon(s) level. In this perspective, we provide a general overview of recent experimental and theoretical advances as well as near-future challenges towards the design and implementation of plasmon-empowered quantum optical and photo-emitting devices based on the building blocks of nanophotonics technology: metallo-dielectric nanostructures and microscopic light sources

Interfacing single photons and single quantum dots with photonic nanostructures

Photonic nanostructures provide means of tailoring the interaction between light and matter and the past decade has witnessed a tremendous experimental and theoretical progress in this subject. In particular, the combination with semiconductor quantum dots has proven successful. This manuscript reviews quantum optics with excitons in single quantum dots embedded in photonic nanostructures. The ability to engineer the light-matter interaction strength in integrated photonic nanostructures enables a range of fundamental quantum-electrodynamics experiments on, e.g., spontaneous-emission control, modified Lamb shifts, and enhanced dipole-dipole interaction. Furthermore, highly efficient single-photon sources and giant photon nonlinearities may be implemented with immediate applications for photonic quantum-information processing. The review summarizes the general theoretical framework of photon emission including the role of dephasing processes, and applies it to photonic nanostructures of current interest, such as photonic-crystal cavities and waveguides, dielectric nanowires, and plasmonic waveguides. The introduced concepts are generally applicable in quantum nanophotonics and apply to a large extent also to other quantum emitters, such as molecules, nitrogen vacancy ceters, or atoms. Finally, the progress and future prospects of applications in quantum-information processing are considered.Comment: Updated version resubmitted to Reviews of Modern Physic