Quantum‐optical analogies using photonic structures

Engineered photonic waveguides have provided in the past decade an extremely rich laboratory tool to visualize with optical waves the classic analogues of a wide variety of coherent quantum phenomena encountered in atomic, molecular or condensed‐matter physics. As compared to quantum systems, optics offers the rather unique advantage of a direct mapping of the wave function evolution in coordinate space by simple fluorescence imaging or scanning tunneling optical microscopy techniques. In this contribution recent theoretical and experimental advances in the field of quantum‐optical analogies are reviewed. Special attention is devoted to some relevant optical analogies based on the use of curved photonic structures, including: coherent destruction of tunneling in driven bistable potentials; coherent population transfer and adiabatic passage in laser‐driven multilevel atomic systems; quantum decay control and Zeno dynamics; electronic Bloch oscillations and Zener tunneling, Anderson localization and dynamic localization in crystalline potentials.     

A three‐level dark state and double‐control single‐photon logic gates via quantum coherent control

Multilevel quantum coherence and its quantum‐vacuum counterpart, where a three‐level dark state is involved, are suggested in order to achieve new photonic and quantum optical applications. It is shown that such a three‐level dark state in a four‐level tripod‐configuration atomic system consists of three lower levels, where constructive and destructive quantum interference between two control transitions (driven by two control fields) arises. We point out that the controllable optical response due to the double‐control tunable quantum interference can be utilized to design some fascinating new photonic devices such as logic gates, photonic transistors and switches at quantum level. A single‐photon two‐input XOR logic gate (in which the incident “gate” photons are the individual light quanta of the two control fields) based on such an effect of optical switching control with an EIT (electromagnetically induced transparency) microcavity is suggested as an illustrative example of the application of the dark‐state manipulation via the double‐control quantum interference. The present work would open up possibility of new applications in both fundamental physics (e.g., field quantization and relevant quantum optical effects in artificial systems that can mimic atomic energy levels) and applied physics (e.g., photonic devices such as integrated optical circuits at quantum level).     

Coupled magnetic resonator optical waveguides

Optical resonators are important devices that control the properties of light and manipulate light–matter interaction. Various optical resonators are designed and fabricated using different techniques. For example, in coupled resonator optical waveguides, light energy is transported to other resonators through near‐field coupling. In recent years, magnetic optical resonators based on LC resonance have been realized in several metallic microstructures. Such devices possess stronger local resonance and lower radiation loss compared with electric optical resonators. This study provides an overall introduction on the latest progress in coupled magnetic resonator optical waveguide (CMROW). Various waveguides composed of different magnetic resonators are presented and Lagrangian formalism is used to describe the CMROW. Moreover, several interesting properties of CMROWs, such as abnormal dispersions and slow‐light effects, are discussed and CMROW applications in nonlinear and quantum optics are shown. Future novel nanophotonic devices can be developed using CMROWs.     

Spinning microresonator-induced chiral optical transmission

Chiral quantum optics is a new research area in light-matter interaction that depends on the direction of light propagation and offers a new path for the quantum regulation of light-matter interactions. In this paper, we study a spinning Kerr-type microresonator coupled with Λ-type atom ensembles, which are driven in opposite directions to generate asymmetric photon statistics. We find that a photon blockade can only be generated by driving the spinning resonator on right side without driving the spinning microresonator from the left side, resulting in chirality. The coupling strength between system modes can be precisely controlled by adjusting the detuning amount of the atomic pump field. Because of the splitting of the resonant frequency generated by the Fizeau drag, the destructive quantum interference generated in right side drive prevents the nonresonant transition path of state |1,0⟩ to state |2,0⟩. This direction-dependent chiral quantum optics is expected to be applied to chiral optical devices, single-photon sources and nonreciprocal quantum communications.     

Hybrid photonic circuit for multiplexed heralded single photons

A key resource for quantum optics experiments is an on‐demand source of single and multiple photon states at telecommunication wavelengths. This letter presents a heralded single photon source based on a hybrid technology approach, combining high efficiency periodically poled lithium niobate waveguides, low‐loss laser inscribed circuits, and fast (>1 MHz) fibre coupled electro‐optic switches. Hybrid interfacing different platforms is a promising route to exploiting the advantages of existing technology and has permitted the demonstration of the multiplexing of four identical sources of single photons to one output. Since this is an integrated technology, it provides scalability and can immediately leverage any improvements in transmission, detection and photon production efficiencies.     

中性原子的激光导引及其应用

文章综述了采用中空光纤中红失谐高斯模式,红失谐高斯激光束,中空光纤中蓝失谐消逝波和蓝失谐暗中空光束实现中性原子激光导引的原理,方法和实验及其最新进展,并简单介绍了激光导引原子技术在原子光学领域中的应用。     

High‐resolution spectral characterization of two photon states via classical measurements

Quantum optics plays a central role in the study of fundamental concepts in quantum mechanics, and in the development of new technological applications. Typical experiments employ sources of photon pairs generated by parametric processes such as spontaneous parametric down‐conversion and spontaneous four‐wave‐mixing. The standard characterization of these sources relies on detecting the pairs themselves and thus requires single photon detectors, which limit both measurement speed and accuracy. Here it is shown that the two‐photon quantum state that would be generated by parametric fluorescence can be characterised with unprecedented spectral resolution by performing a classical experiment. This streamlined technique gives access to hitherto unexplored features of two‐photon states and has the potential to speed up design and testing of massively parallel integrated nonlinear sources by providing a fast and reliable quality control procedure. Additionally, it allows for the engineering of quantum light states at a significantly higher level of spectral detail, powering future quantum optical applications based on time‐energy photon correlations.     

Thin film optimization design of organic–inorganic hybrids for waveguide high‐rejection optical filters

We report the fabrication of transparent, low surface roughness (<0.1 nm), and low‐loss (1.5 ± 0.2 dB cm^–1, 532 nm) thin films of organic–inorganic hybrids with controlled refractive index values stable under aging. High‐rejection optical filters based on first‐order Bragg gratings inscribed in channel waveguides were fabricated using UV‐laser writing. Their high‐rejection figure of merit (～24 dB) is the best value found until now for organic–inorganic hybrids reinforcing the potential of sol–gel technology in the integration of optoelectronic components based on hybrid materials, namely in the fabrication of cost‐effective integrated optics devices. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

暗中空光束的产生及应用

综述了几何光学、模式变换、光学全息、计算全息、横模选择、中空光纤等几种产生暗中空光束的方法,并简单介绍了暗中空光束在原子光学及其他领域的应用。     

空芯光波导在光谱气敏检测中的应用

空芯光波导(HWG)用于光谱气体检测中,既可以实现光路的传输,又可以充当气体样品池实现长光程高灵敏度测量,具有体积小,响应时间快、成本低、光路稳定灵活等优点。介绍了基于镀银/碘化银的空芯光波导(Ag/AgI-HWG)、光子带隙空芯光波导(PBG-HWG)和基片集成空芯光波导(iHWG)等类型的空芯光波导,并总结了近年来空芯光波导在光谱气敏检测中的研究及进展,梳理了其应用方式及应用领域。研究表明,空芯光波导替代传统的气体池与傅里叶变换红外光谱(FTIR)、激光吸收光谱和拉曼光谱等不同的光谱技术结合已取得一系列成果,且已经应用于环境监测、呼气诊断和工业过程检测和控制等领域。其中,基于中红外激光吸收光谱的空芯光波导传感器组成相对简单,成本较低,与各类光波导的兼容性和环境适应性较强,发展前景较好。总之,随着激光技术、光波导技术和光谱技术的发展,基于空芯光波导的光谱气体检测正在迅速发展,并逐步由实验室走向现场应用。     

二维量子片及其光学研究进展

以石墨烯为代表的二维材料因其独特的结构和优异性能而受到广泛关注.随着二维材料在无限小的方向不断发展,二维(材料)量子片逐渐引起人们极大的兴趣.二维量子片不仅保留了二维材料的本征特性,而且表现出量子限域和突出的边缘效应,为二维材料的潜在应用带来全新机遇.本文详细介绍了二维量子片的基本概念,制备现状与光学性能的研究进展,特...     

Electron quantum optics in ballistic chiral conductors

The edge channels of the quantum Hall effect provide one dimensional chiral and ballistic wires along which electrons can be guided in an optics‐like setup. Electronic propagation can then be analyzed using concepts and tools derived from optics. After a brief review of electron optics experiments performed using stationary current sources which continuously emit electrons in the conductor, this paper focuses on triggered sources, which can generate on‐demand a single particle state. It first outlines the electron optics formalism and its analogies and differences with photon optics and then turns to the presentation of single electron emitters and their characterization through the measurements of the average electrical current and its correlations. This is followed by a discussion of electron quantum optics experiments in the Hanbury‐Brown and Twiss geometry where two‐particle interferences occur. Finally, Coulomb interactions effects and their influence on single electron states are considered.     

Ultra‐low loss waveguide platform and its integration with silicon photonics

Planar waveguides with ultra‐low optical propagation loss enable a plethora of passive photonic integrated circuits, such as splitters and combiners, filters, delay lines, and components for advanced modulation formats. An overview is presented of the status of the field of ultra‐low loss waveguides and circuits, including the design, the trade‐off between bend radius and loss, and fabrication rationale. The characterization methods to accurately measure such waveguides are discussed. Some typical examples of device and circuit applications are presented. An even wider range of applications becomes possible with the integration of active devices, such as lasers, amplifiers, modulators and photodetectors, on such an ultra‐low loss waveguide platform. A summary of efforts to integrate silicon nitride and silica‐based low‐loss waveguides with silicon and III/V based photonics, either hybridly or heterogeneously, will be presented. The approach to combine these integration technologies heterogeneously on a single silicon substrate is discussed and an application example of a high‐bandwidth receiver is shown.     

PDL free plasma enhanced chemical vapor deposition SiC optical waveguides and devices

Planar silicon carbide (SiC) waveguides are proposed for fabrication on a silicon substrate with an oxide isolation layer. Using post deposition annealing it is possible to achieve low polarisation-dependent loss (PDL) within optical SiC waveguides fabricated using a low temperature deposition technique. The proposed waveguides are optically characterised and successfully used in power splitters and vibration sensors. Results before and after annealing cycles for those devices are discussed. The interesting optical characteristics of SiC waveguides as well as the first passive components presented open the way for photonic sensing in harsh environment where SiC is a very promising material.     

On‐chip single photon sources using planar photonic crystals and single quantum dots

We review the basic light‐matter interactions and optical properties of chip‐based single photon sources, that are enabled by integrating single quantum dots with planar photonic crystals. A theoretical framework is presented that allows one to connect to a wide range of quantum light propagation effects in a physically intuitive and straightforward way. We focus on the important mechanisms of enhanced spontaneous emission, and efficient photon extraction, using all‐integrated photonic crystal components including waveguides, cavities, quantum dots and output couplers. The limitations, challenges, and exciting prospects of developing on‐chip quantum light sources using integrated photonic crystal structures are discussed.     

Quantum dots in photonic crystals: From quantum information processing to single photon nonlinear optics

Quantum dots in photonic crystals are interesting both as a testbed for fundamental cavity quantum electrodynamics (QED) experiments and as a platform for quantum and classical information processing. We describe a technique to coherently access the QD-cavity system by resonant light scattering. Among other things, the coherent access enables a giant optical nonlinearity associated with the saturation of a single quantum dot strongly coupled to a photonic crystal cavity. We explore this nonlinearity to implement controlled phase and amplitude modulation between two modes of light at the single photon level—a nonlinearity observed so far only in atomic physics systems. We also measured the photon statistics of the reflected beam at various detunings with the QD/cavity system. These measurements reveal effects such as photon blockade and photon-induced tunneling, for the first time in solid state. These demonstrations lie at the core of a number of proposals for quantum information processing, and could also be employed to build novel devices, such as optical switches controlled at the single photon level.     

Optical hybrid approaches to quantum information

This article reviews recent hybrid approaches to optical quantum information processing, in which both discrete and continuous degrees of freedom are exploited. There are well‐known limitations to optical single‐photon‐based qubit and multi‐photon‐based qumode implementations of quantum communication and quantum computation, when the toolbox is restricted to the most practical set of linear operations and resources such as linear optics and Gaussian operations and states. The recent hybrid approaches aim at pushing the feasibility, the efficiencies, and the fidelities of the linear schemes to the limits, potentially adding weak or measurement‐induced nonlinearities to the toolbox.     

Generation of a superposition of odd photon number states for quantum information networks

We report on the experimental observation of quantum-network-compatible light described by a nonpositive Wigner function. The state is generated by photon subtraction from a squeezed vacuum state produced by a continuous wave optical parametric amplifier. Ideally, the state is a coherent superposition of odd photon number states, closely resembling a superposition of weak coherent states |alpha > - |-alpha >. In the limit of low squeezing the state is basically a single photon state. Light is generated with about 10,000 and more events per second in a nearly perfect spatial mode with a Fourier-limited frequency bandwidth which matches well atomic quantum memory requirements. The generated state of light is an excellent input state for testing quantum memories, quantum repeaters, and linear optics quantum computers.     

Optical‐fiber microcoil waveguides and resonators and their applications for interferometry and sensing

In this work, recent progress in the theoretical and experimental studies of optical‐fiber microcoil waveguides and resonators, as well as their various applications are reviewed. In particular, the focus is set on sensing and interferometry applications. It is shown that due to its inherently low propagation and fiber‐coupling losses, fiber‐microcoil based sensors and interferometers offer substantial enhancement of sensitivity and compactness compared to other types of devices. Recent progress in the realization and experimental characterization of such structures is presented and the theoretical tools to analyze the impact of real‐world nonuniformities on the characteristics of fiber‐microcoil structures are provided.