Resonant modes and inter-well coupling in photonic double quantum well structures with single-negative materials

We investigate the resonance tunneling modes of photonic double quantum well made of two photonic crystals with two different single-negative materials. It is found that these resonance modes split pairs, due to a coupling between two photonic wells. It is observed that when two photonic quantum wells are far away from each other, resonance modes appear as a single peak. And the quality factors of the transmittance resonance peaks can be greatly improved by increasing the period number of the outer barrier. The effects of the losses coming from ENG and MNG materials on the resonance modes are also specifically explored.     

Experimental evidence for Raman-induced limits to efficient squeezing in optical fibers

We report new experiments on polarization squeezing using ultrashort photonic pulses in a single pass of a birefringent fiber. We measure what is to our knowledge a record squeezing of -6.8+/-0.3 dB in optical fibers, which when corrected for linear losses is -10.4+/-0.8 dB. The measured polarization squeezing as a function of optical pulse energy, which spans a wide range from 3.5-178.8 pJ, shows a very good agreement with the quantum simulations, and for the first time we see the proof experimentally that Raman effects limit and reduce squeezing at high pulse energy.     

Gap maps, diffraction losses, and exciton–polaritons in photonic crystal slabs

A theory of photonic crystal (PhC) slabs is described, which relies on an expansion in the basis of guided modes of an effective homogeneous waveguide and on treating the coupling to radiative modes and the resulting losses by perturbation theory. The following applications are discussed for the case of a high-index membrane: gap maps for photonic lattices in a waveguide; exciton–polariton states, when the PhC slab contains a quantum well with an excitonic resonance; propagation losses of line-defect modes in W1 waveguides, also in the presence of disorder; the quality factors of photonic nanocavities. In particular, we predict that disorder-induced losses below 0.2 dB/mm can be achieved in state-of-the-art samples by increasing the channel width of W1 waveguides.     

Resonant modes in photonic multiple quantum well structures with single-negative materials

A type of photonic multiple quantum well (PMQWs) structure made of two different photonic crystals (PCs) with two kinds of single-negative materials is investigated. It is demonstrated by transfer matrix method that omnidirectional resonance modes are generated. The number of the resonance modes can be controlled by adjusting the periodic structure of the constituents. The resonance tunneling modes are weak dependence on incident angle and the scaling of the barrier photonic crystals. When the losses are taken into account, the effects of the losses coming from ENG media and MNG media on the resonance modes are striking difference.     

Quantum simulation of zero-temperature quantum phases and incompressible states of light via non-Markovian reservoir engineering techniques

We review recent theoretical developments on the stabilization of strongly correlated quantum fluids of light in driven-dissipative photonic devices through novel non-Markovian reservoir engineering techniques. This approach allows one to compensate losses and refill selectively the photonic population so as to sustain a desired steady state. It relies in particular on the use of a frequency-dependent incoherent pump, which can be implemented, e.g., via embedded two-level systems maintained at a strong inversion of population. As specific applications of these methods, we discuss the generation of Mott Insulator (MI) and Fractional Quantum Hall (FQH) states of light. As a first step, we present the case of a narrowband emission spectrum and show how this allows for the stabilization of MI and FQH states under the condition that the photonic states are relatively flat in energy. As soon as the photonic bandbwidth becomes comparable to the emission linewidth, important non-equilibrium signatures and entropy generation appear, and a novel dissipative phase transition from a Mott Insulating state toward a superfluid (SF) phase is unveiled. As a second step, we review a more advanced configuration based on reservoirs with a broadband frequency distribution, and we highlight the potential of this configuration for the quantum simulation of equilibrium quantum phases at zero temperature with tunable chemical potential. As a proof of principle, we establish the applicability of our scheme to the Bose–Hubbard model by confirming the presence of a perfect agreement with the ground-state predictions both in the Mott insulating and superfluid regions, and more generally in all parts of the parameter space. Future prospects towards the quantum simulation of more complex configurations are finally outlined, along with a discussion of our scheme as a concrete realization of quantum annealing.     

单负材料组成一维光子晶体双量子阱结构的共振模

通过传输矩阵方法, 计算模拟了两种单负材料组成一维光子晶体双量子阱结构的透射谱. 研究发现: 由于双量子阱结构双阱之间的相互耦合作用, 共振模发生双重劈裂, 共振峰之间的距离可以通过调节双阱之间的耦合强度控制, 共振模的品质因子可以通过调节外部障碍光子晶体的周期数控制. 并且, 共振模受入射角和光偏振模式的影响都比较小, 适合全方向滤波. 当考虑两种单负材料不同损耗的影响时, 研究结果表明, 电损耗对低频处的共振模影响大, 而磁损耗对高频和低频处的共振模影响都比较大.     

Effect of unbalanced and common losses in quantum photonic integrated circuits

Loss is inevitable for the optical system due to the absorption of materials, scattering caused by the defects, and surface roughness. In quantum optical circuits, the loss can not only reduce the intensity of the signal, but also affect the performance of quantum operations. In this work, we divide losses into unbalanced linear losses and shared common losses, and provide a detailed analysis on how loss affects the integrated linear optical quantum gates. It is found that the orthogonality of eigenmodes and the unitary phase relation of the coupled waveguide modes are destroyed by the loss. As a result, the fidelity of single-and two-qubit operations decreases significantly as the shared loss becomes comparable to the coupling strength. Our results are important for the investigation of large-scale photonic integrated quantum information processes.     

二维光量子阱共振隧穿光谱特性的改善

用时域有限差分法研究了光子晶体量子阱中的量子化能态.研究发现,开腔与闭腔光量子阱结构共振透射峰的数目相同,位置几乎不变,但闭腔光量子阱出射光强更强,透射率更大,频率选择性更好,品质因子Q值更高.同时计算了开腔和闭腔光量子阱光场分布,结果表明,开腔光量子阱为行波阱,闭腔光量子阱为驻波阱,充分证实了闭腔光量子阱更能束缚光场的设想,对其作用机理进行了探讨.     

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).     

不同晶格常数光子晶体构成的光量子阱中的共振模

用基于平面波的传输矩阵法分析由具有不同晶格常数的光子晶体材料构成的光量子阱结构中的共振模，发现湮没于垒层的阱层能带分离成共振模，且共振模的数目随阱层的厚度变化而改变。提出一种新型的非对称量子阱结构模型，由2块晶格常数不同的光子晶体材料和夹在光子晶体材料中间作为阱层的均匀介电材料构成，并对其中的共振模进行了分析。指出当阱层厚度达到构成垒层的光子晶体晶格常数的一半时出现一个共振模，若继续小量增加阱层厚度将使共振模频率出现红移。最后给出一种基于平面波的传输矩阵法，且对于不同晶格常数的光子晶体量子阱结构均有效的数值模拟方法，可用于研究由三维光子晶体材料或者色散材料组成的光子晶体量子阱结构。     

Quantum photonic network on chip

We provide an overview of quantum photonic network on chip. We begin from the discussion of the pros and cons of several material platforms for engineering quantum photonic chips. Then we introduce and analyze the basic building blocks and functional units of quantum photonic integrated circuits. In the main part of this review, we focus on the generation and manipulation of quantum states of light on chip and are particularly interested in some applications of advanced integrated circuits with different functionalities for quantum information processing, including quantum communication, quantum computing, and quantum simulation. We emphasize that developing fully integrated quantum photonic chip which contains sources of quantum light, integrate circuits, modulators, quantum storage, and detectors are promising approaches for future quantum photonic technologies. Recent achievements in the large scale photonic chips for linear optical computing are also included. Finally, we illustrate the challenges toward high performance quantum information processing devices and conclude with promising perspectives in this field.     

Electromagnetically induced exciton mobility in a photonic band gap

It is suggested that an exciton in the engineered vacuum of a photonic-band-gap-quantum-well heterostructure exhibits electromagnetically induced anomalous quantum dynamics. The exciton is dressed by coherent emission and reabsorption of virtual photons near the photonic band edge and captured in momentum space, lowering its energy by 1-10 meV and lowering its effective mass by 4-5 orders of magnitude. The photonic band gap simultaneously enables strong coupling to confined optical modes and long exciton lifetime.     

含Kerr非线性的一维光子晶体中的类孤子

研究了含Kerr非线性的一维光子晶体中的类孤子。计算了光子晶体中加入Kerr非线性材料后,类孤子和入射光强、Kerr系数以及线性势阱的关系。随着线性势阱的降低,对应于在线性带隙中开始出现类孤子本征模所需要的最小入射强度也降低,即降低了非线性阈值;尽管非线性是产生类孤子的根本原因,但非线性系数对产生类孤子及孤子环中环的影响不如线性势阱高度的影响显著。     

Possible realization of directional optical waveguides in photonic crystals with broken time-reversal symmetry

We show how, in principle, to construct analogs of quantum Hall edge states in "photonic crystals" made with nonreciprocal (Faraday-effect) media. These form "one-way waveguides" that allow electromagnetic energy to flow in one direction only.     

Resonant modes and inter-well coupling in photonic quantum well with negative index materials

The transfer matrix method was used to study the resonant modes in photonic quantum well by stacking different photonic crystals consisting of positive index materials and negative index materials. The eigenfrequency equation for the resonant modes is derived. It is found that these resonant modes are omnidirectional, and the number of resonant modes is equal to the period number of photonic quantum wells. Moreover, the resonant modes become N-fold splitting in the N photonic quantum wells. The splitting intervals increase with the deceasing of photonic barrier thickness due to the coupling among the wells.     

Imaging single quantum dots in three-dimensional photonic crystals

Performing fluorescence wide-field microscopy we have imaged single semiconductor quantum dots deep inside a 3-dimensional photonic crystal prepared from colloidal polymer beads. Exploring the emission diffraction patterns in defocused images of quantum dots we demonstrate that the direction-dependent photonic stop band imprints an anisotropy to the angular emission of a single quantum dot. Hence a single, quasi-point-like emitter is manipulated to radiate its photons only to certain well-defined directions by means of the anisotropic light propagation in photonic crystals. The experiments thus provide new routes to evaluate local, frequency selective optical properties in 3-dimensional photonic crystals employing single emitters.     

Fabrication of three‐dimensional photonic crystals in quantum‐dot‐based materials

Controlling spontaneous emission (SE) is of fundamental importance to a diverse range of photonic applications including but not limited to quantum optics, low power displays, solar energy harvesting and optical communications. Characterized by photonic bandgap (PBG) property, three‐dimensional (3D) photonic crystals (PCs) have emerged as a promising synthetic material, which can manipulate photons in much the same way as a semiconductor does to electrons. Emission tunable nanocrystal quantum dots (QDs) are ideal point sources to be embedded into 3D PCs towards active devices. The challenge however lies in the combination of QDs with 3D PCs without degradation of their emission properties. Polymer materials stand out for this purpose due to their flexibility of incorporating active materials. Combining the versatile multi‐photon 3D micro‐fabrication techniques, active 3D PCs have been fabricated in polymer‐QD composites with demonstrated control of SE from QDs. With this milestone novel miniaturized photonic devices can thus be envisaged.     

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.     

Resonant modes in quantum well structure of photonic crystals with different lattice constants

The resonant modes in a quantum well (QW) structure composed of three slabs of two dimensional (2D) photonic crystals with different lattice constants are analyzed with plane-wave-based transfer matrix method (TMM). It is found that the energy band of the well slab submerged into the band gap of barrier slab is discretized into quantized modes and the number of the resonant modes changes with the well slab thickness. A model structure of asymmetrical photonic QW consisting of two slabs of 2D photonic crystals with different lattice constants and one uniform dielectric slab in between is proposed and the resonant modes in it are investigated with the same method. A useful numerical simulation method for theoretical discussion as well as for practical application about photonic QW structure of photonic crystals with different lattice constants is proposed.     

渐变折射率光量子阱对束缚态能级的调整

在对称的均匀电介质材料光子晶体体系中插入另一折射率渐变的光子晶体可构成光量子阱结构.利用时域有限差分法计算了不同折射率分布光量子阱结构的传输谱.研究表明：束缚态是对处于垒光子晶体禁带中的阱光子晶体导通带的离散化,束缚态能级个数等于阱光子晶体结构单元的重复周期数；以渐变方式调整阱区折射率分布,可在特定频率范围内得到新的互不交叠的束缚态.这样在有限的禁带区域可以成倍增加光子束缚态而无需增大光量子阱结构的尺寸,使信道密度最大化、光波有效带宽的使用最优化.这种量子阱结构可用于制作超窄带滤波器和多通道窄带滤波器,有望在光通信超密集波分复用和光学精密测量技术中获得广泛应用. 关键词： 光量子阱 光子束缚态 渐变折射率 光子晶体