分类： 光学 >> 量子光学 提交时间： 2023-07-10
摘要： 原子系统有反射对称，有宇称，原子受激辐射，经平行平面谐振腔放大，可以产生宏观光子纠缠态[4]。 它是有确定宇称，总动量为零，确定能量，确定角动量的2N光子的量子纠缠态。观测它在时间、空间位置具有不确定性、随机性。根据海森堡测不准原理，其能量（频率）、动量完全确定。测量精度可以达到海森堡量子极限，具有量子2N增强效应（2N为纠缠光子数）。 通过实验测量它的几率分布P2N （t），以及它的傅里叶变换P2N （w-w0 ），实验结果与理论预期符合。并观测了宏观光子纠缠态的寿命，同样具有一个2N增强因子，实验结果与理论预期符合。
分类： 光学 >> 量子光学 提交时间： 2023-06-25
摘要： 多光子纠缠是量子通讯、光量子计算的核心技术。现在普遍使用的纠缠光源是自发参量下转换产生的两光子纠缠，虽已取得很大的成就，但离量子计算等的应用需求还很远，需要从理论和实验两个方面探索新路。 本文研究了受激辐射射基础过程，受激辐射的机理，发现此过程最初产生的两光子态的量子性质与受激辐射物质的对称性密切相关。如果受激辐射物质的电子态有宇称，它的波函数也有宇称，如原子、有对称中心的分子、有反演对称的晶体等，这类物质的电子态都有宇称和反射对称性。有宇称的物质的受激辐射过程遵守宇称守恒，受激辐射产生的两光子态有宇称，是迭加纠缠态。这样的两个纠缠光子经过平行平面谐振腔的作用，再通过受激辐射，不断重复这个过程，最终产生多光子纠缠。 本文主要结果和结论是：有宇称的物质的受激辐射产生多光子纠缠态。激光器物质的电子态如有宇称，则激光器谐振腔内（平行平面腔）的受激辐射产生的多光子态是纠缠态，并可从对称结构的双向单模激光器输出。 理论给出多光子纠缠的表示式。研制成一台对称结构双向输出单模He-Ne激光器，进行了多光子纠缠态的实验验证，实验结果与理论预期相符。
分类： 光学 >> 量子光学 提交时间： 2023-02-25
摘要： We study the open XXZ spin chain with a PT-symmetric non-Hermitian boundary field. We find an interaction-induced scale-free non-Hermitian skin effect by using the coordinate Bethe ansatz. The steady state and the ground state in the PT broken phase are constructed, and the formulas of their eigen-energies in the thermodynamic limit are obtained. The differences between the many-body scale-free states and the boundary string states are explored, and the transition between the two at isotropic point is investigated. We also discuss an experimental scheme to verify our results.
分类： 光学 >> 量子光学 提交时间： 2023-02-25
摘要： Space-time wave packets can propagate invariantly in free space with arbitrary group velocity thanks to the spatio-temporal correlation. Here it is proved that the space-time wave packets are stable in dispersive media as well and free from the spread in time caused by material dispersion. Furthermore, the law of anomalous refraction for space-time wave packets is generalized to the weakly dispersive situation. These results reveal new potential of space-time wave packets for the applications in real dispersive media.
分类： 光学 >> 量子光学 提交时间： 2023-02-25
摘要： Optical focusing through scattering media has important implications for optical applications in medicine, communications, and detection. In recent years, many wavefront shaping methods have been successfully applied to the field, among which the population optimization algorithm has achieved remarkable results. However, the current population optimization algorithm has some drawbacks: 1. the offspring do not fully inherit the good genes from the parent. 2. more efforts are needed to tune the parameters. In this paper, we propose the mutate greedy algorithm. It combines greedy strategies and real-time feedback of mutation rates to generate offspring. In wavefront shaping, people can realize high enhancement and fast convergence without a parameter-tuning process.
分类： 光学 >> 量子光学 提交时间： 2023-02-25
摘要： In this letter, we present a simple and new idea to generate two types of novel integrable multi-L\'evy-index and mix-L\'evy-index (mixed) fractional nonlinear soliton hierarchies, containing multi-index and mixed fractional higher-order nonlinear Schr\"odinger (NLS) hierarchy, fractional complex modified Korteweg-de Vries (cmKdV) hierarchy, and fractional mKdV hierarchy. Their explicit forms can be given using the completeness of squared eigenfunctions. Moreover, we present their anomalous dispersion relations via their linearizations, and fractional multi-soliton solutions via the inverse scattering transform with matrix Riemann-Hilbert problems. These obtained fractional multi-soliton solutions may be useful to understand the related super-dispersion transports of nonlinear waves in multi-index fractional nonlinear media.
分类： 光学 >> 量子光学 提交时间： 2023-02-25
摘要： Coherent interactions between quantum emitters in tailored photonic structures is a fundamental building block for future quantum technologies, but remains challenging to observe in complex solid-state environments, where the role of decoherence must be considered. Here, we investigate the optical interaction between two quantum emitters mediated by one-dimensional waveguides in a realistic solid-state environment, focusing on the creation, population and detection of a sub-radiant state, in the presence of dephasing. We show that as dephasing increases, the signatures of sub-radiance quickly vanish in intensity measurements yet remain pronounced in photon correlation measurements, particularly when the two emitters are pumped separately so as to populate the sub-radiant state efficiently. The applied Green's tensor approach is used to model a photonic crystal waveguide, including the dependence on the spatial position of the integrated emitter. The work lays out a route to the experimental realization of sub-radiant states in nanophotonic waveguides containing solid-state emitters.
分类： 光学 >> 量子光学 提交时间： 2023-02-25
Yaqing Jin
Ye Yang
Huibo Hong
Xiao Xiang
Runai Quan
Tao Liu
Ninghua Zhu
Ming Li
Ruifang Dong
Shougang Zhang
摘要： With energy-time entangled biphoton sources as the optical carrier and time-correlated single-photon detection for high-speed radio frequency (RF) signal recovery, the method of quantum microwave photonics (QMWP) has presented the unprecedented potential of nonlocal RF signal encoding and efficient RF signal distilling from the dispersion interference associated with ultrashort pulse carriers. In this letter, its capability in microwave signal processing and prospective superiority is further demonstrated. Both the QMWP RF phase shifting and transversal filtering functionality, which are the fundamental building blocks of microwave signal processing, are realized. Besides the perfect immunity to the dispersion-induced frequency fading effect associated with the broadband carrier in classical microwave photonics, a native two-dimensional parallel microwave signal processor is provided. These demonstrations fully prove the superiority of QMWP over classical MWP and open the door to new application fields of MWP involving encrypted processing.
分类： 光学 >> 量子光学 提交时间： 2023-02-24
Zhen Wang
Qiang Wang
Hui Zhang
Simone Borri
Iacopo Galli
Angelo Sampaolo
Pietro Patimisco
Vincenzo Luigi Spagnolo
Paolo De Natale
Wei Ren
摘要： Photoacoustic spectroscopy (PAS) based gas sensors with high sensitivity, wide dynamic range, low cost, and small footprint are desirable across a broad range of applications in energy, environment, safety, and public health. However, most works have focused on either acoustic resonator to enhance acoustic wave or optical resonator to enhance optical wave. Herein, we develop a gas sensor based on doubly resonant PAS in which the acoustic and optical waves are simultaneously enhanced using combined optical and acoustic resonators in a centimeter-long configuration. Not only the lower detection limit is enhanced by the double standing waves, but also the upper detection limit is expanded due to the short resonators. As an example, we developed a sensor by detecting acetylene (C2H2), achieving a noise equivalent absorption of 5.7*10-13 cm-1 and a dynamic range of eight orders. Compared to the state-of-the-art PAS gas sensors, the developed sensor increases the sensitivity by two orders of magnitude and extends the dynamic range by three orders of magnitude. Besides, a laser-cavity-molecule locking strategy is proposed to provide additional flexibility of fast gas detection.
分类： 光学 >> 量子光学 提交时间： 2023-02-24
摘要： Benefitting from the excellent characteristics such as low cytotoxicity, functionalization versatility, and tunable fluorescence, nanodiamonds (NDs) have shown enormous application potentials in the biomedical field. Herein, we proposed, for the first time to our best knowledge, to integrate NDs on a plasmonic interface constructed on a side-polished fiber using drop-casting method. The added NDs engineers the plasmonic interface towards improving the sensing field, thus enhancing the sensitivity, which, moreover, is significantly dependent on the number of drop-casting cycles (DCs) and the used concentration of NDs dispersion solution. Experimental results suggest that properly increasing the NDs dispersion concentration is beneficial to obtain a higher sensitivity while using a fewer number of DCs, but the excessive concentration extremely deteriorates the resonance dip. Experimentally, using the optimal 0.2 mg/mL concentration and 3 DCs, we achieve the highest RI sensitivity of 3582 nm/RIU, which shows an enhancement of 73.8% compared to the case without NDs modification. The sensitivity enhancement in biosensing is also proved by employing bovine serum albumin as a demo. The behind mechanism is explored via characterizations and simulations. This work opens up a new application form for NDs, i.e. integrating NDs with a plasmonic interface towards high-performance biosensing.
分类： 光学 >> 量子光学 提交时间： 2023-02-23
摘要： In this article, we explore how cryogenic cooling of the Ti:sapphire laser crystal greatly reduces thermal lensing by over an order of magnitude because of two factors: (i) the increase in the thermal conductivity of the crystal, and (ii) the decrease in the temperature dependence of the refractive index. We obtained analytical expression of the focal length of thermal lens for the pump inside the laser crystal being a Gaussian beam. Through analysis of the laser cavity stability, we found that in order for the relative difference between the optimal laser cavity path lengths in the horizontal and vertical directions to be less than 0.1%, the focal length of thermal lens should be longer than 0.5 m. Such a requirement can be met if the laser crystal is cooled to temperatures below 100 K while being pumped at a power that is enough to produce 100 W output. Therefore, it is very likely that an output power of 100 W can be achieved on a single Ti:sapphire laser by cryogenic cooling of the laser crystal.
分类： 光学 >> 量子光学 提交时间： 2023-02-23
Yuzhe Xiao
Zhaoning Yu
Raymond A. Wambold
Hongyan Mei
Garrett Hickman
Randall H. Goldsmith
Mark Saffman
Mikhail A. Kats
摘要： Optical bottle beams can be used to trap atoms and small low-index particles. We introduce a figure of merit for optical bottle beams, specifically in the context of optical traps, and use it to compare optical bottle-beam traps obtained by three different methods. Using this figure of merit and an optimization algorithm, we identified optical bottle-beam traps based on a Gaussian beam illuminating a metasurface that are superior in terms of power efficiency than existing approaches. We numerically demonstrate a silicon metasurface for creating an optical bottle-beam trap.
分类： 光学 >> 量子光学 提交时间： 2023-02-23
摘要： Recently, the electronic analogy of the anomalous spatial shift, including Goos-H\"{a}nchen and Imbert-Fedorov effects, has been attracting widespread interest. The current research on the anomalous spatial shift in interface electronic reflection is based on the paradigm of linear approximation, under which the center position of the incident and reflected beams are obtained by expanding the phases of relevant basis states and scattering amplitudes to the first order of incident momentum. However, in a class of normal cases, the linear approximation can lead to a divergent spatial shift in reflection for certain incident angles even though the corresponding reflection possibility is finite. In this work, we show that such non-physical results are caused by an abrupt change in the number of the propagating states at critical parameters, and can be resolved by calculating the center positions of the scattering beams beyond the linear approximation. Moreover, we find that the beam width has an important influence on the spatial shift near the critical angles. We demonstrate our idea via concrete calculations of Goos-H\"{a}nchen and Imbert-Fedorov shift on two representative models. These results are beneficial for clarifying the scope of application of the linear approximation in the study of anomalous spatial shifts.
分类： 光学 >> 量子光学 提交时间： 2023-02-23
摘要： In the highly non-Gaussian regime, the quantum Ziv-Zakai bound (QZZB) provides a lower bound on the available precision, demonstrating the better performance compared with the quantum Cram\'er-Rao bound. However, evaluating the impact of a noisy environment on the QZZB without applying certain approximations proposed by Tsang [Phys. Rev. Lett. 108, 230401 (2012)] remains a difficult challenge. In this paper, we not only derive the general form of the QZZB with the photon loss and the phase diffusion by invoking the technique of integration within an ordered product of operators, but also show its estimation performance for several different Gaussian resources, such as a coherent state (CS), a single-mode squeezed vacuum state (SMSVS) and a two-mode squeezed vacuum state (TMSVS). Our results indicate that compared with the SMSVS and the TMSVS, the QZZB for the CS always shows the better estimation performance under the photon-loss environment. More interestingly, for the phase-diffusion environment, the estimation performance of the QZZB for the TMSVS can be better than that for the CS throughout a wide range of phase-diffusion strength. Our findings will provide a useful guidance for investigating the noisy quantum parameter estimation.
分类： 光学 >> 量子光学 提交时间： 2023-02-23
Hai Hu
Na Chen
Hanchao Teng
Renwen Yu
Yunpeng Qu
Jianzhe Sun
Mengfei Xue
Debo Hu
Bin Wu
Chi Li
Jianing Chen
Mengkun Liu
Zhipei Sun
Yunqi Liu
Peining Li
Shanhui Fan
F. Javier García de Abajo
Qing Dai
摘要： Controlling the charge carrier density provides an efficient way to trigger phase transitions and modulate the optoelectronic properties in natural materials. This approach could be used to induce topological transitions in the optical response of photonic systems. Here, we predict a topological transition in the isofrequency dispersion contours of hybrid polaritons supported by a two-dimensional heterostructure consisting of graphene and $\alpha$-phase molybdenum trioxide ($\alpha$-MoO3). By chemically changing the doping level of graphene, we experimentally demonstrate that the contour topology of polariton isofrequency surfaces transforms from open to closed shapes as a result of doping-dependent polariton hybridization. Moreover, by changing the substrate medium for the heterostructure, the dispersion contour can be further engineered into a rather flattened shape at the topological transition, thus supporting tunable polariton canalization and providing the means to locally control the topology. We demonstrate this idea to achieve extremely subwavelength focusing by using a 1.2-$\mu$m-wide silica substrate as a negative refraction lens. Our findings open a disruptive approach toward promising on-chip applications in nanoimaging, optical sensing, and manipulation of nanoscale energy transfer.
分类： 光学 >> 量子光学 提交时间： 2023-02-23
Bingbing Zhu
Zongyuan Fu
Yudong Chen
Sainan Peng
Cheng Jin
Guangyu Fan
Sheng Zhang
Shunjia Wang
Hao Ru
Chuanshan Tian
Yihua Wang
Henry Kapteyn
Margaret Murnane
Zhensheng Tao
摘要： The high power and variable repetition rate of Yb femtosecond lasers make them very attractive for ultrafast science. However, for capturing sub-200 fs dynamics, efficient, high-fidelity, and high-stability pulse compression techniques are essential. Spectral broadening using an all-solid-state free-space geometry is particularly attractive, as it is simple, robust, and low-cost. However, spatial and temporal losses caused by spatio-spectral inhomogeneities have been a major challenge to date, due to coupled space-time dynamics associated with unguided nonlinear propagation. In this work, we use all-solid-state free-space compressors to demonstrate compression of 170 fs pulses at a wavelength of 1030nm from a Yb:KGW laser to ~9.2 fs, with a highly spatially homogeneous mode. This is achieved by ensuring that the nonlinear beam propagation in periodic layered Kerr media occurs in soliton modes and confining the nonlinear phase through each material layer to less than 1.0 rad. A remarkable spatio-spectral homogeneity of ~0.87 can be realized, which yields a high efficiency of >50% for few-cycle compression. The universality of the method is demonstrated by implementing high-quality pulse compression under a wide range of laser conditions. The high spatiotemporal quality and the exceptional stability of the compressed pulses are further verified by high-harmonic generation. This work represents the highest efficiency and the best spatio-spectral quality ever achieved by an all-solid-state free-space pulse compressor for few-cycle-pulse generation.
分类： 光学 >> 量子光学 提交时间： 2023-02-23
摘要： We realize fractal-like photonic lattices using cw-laser-writing technique, thereby observe distinct compact localized states (CLSs) associated with different flatbands in the same lattice setting. Such triangle-shaped lattices, akin to the first generation Sierpinski lattices, possess a band structure where singular non-degenerate and nonsingular degenerate flatbands coexist. By proper phase modulation of an input excitation beam, we demonstrate experimentally not only the simplest CLSs but also their superimposition into other complex mode structures. Furthermore, we show by numerical simulation a dynamical oscillation of the flatband states due to beating of the CLSs that have different eigenenergies. These results may provide inspiration for exploring fundamental phenomena arising from fractal structure, flatband singularity, and real-space topology.
分类： 光学 >> 量子光学 提交时间： 2023-02-22
Xiaojie Zhang
Haiyang Huang
Xuexue Guo
Xingwang Zhang
Yao Duan
Xi Chen
Shengyuan Chang
Yimin Ding
Xingjie Ni
摘要： Metasurface lenses, namely metalenses, are ultrathin planar nanostructures that are capable of manipulating the properties of incoming light and imparting lens-like wavefront to the output. Although they have shown promising potentials for the future miniaturization of optics, the chromatic aberration inherited from their diffractive nature plagues them towards many practical applications. Current solutions for creating achromatic metalenses usually require searching through a large number of meta-atoms to find designs that fulfill not only phase but phase dispersion requirements, which leads to intensive design efforts. Besides, most designs are based on regular-shaped antennas driven by the designers' intuition and experience, hence only cover a limited design space. Here, we present an inverse design approach that efficiently produces meta-atoms with unintuitive geometries required for broadband achromatic metalenses. We restricted the generated shapes to hold four-fold reflectional symmetry so that the resulting metalenses are polarization insensitive. In addition, meta-atoms generated by our method inheritably have round edges and corners, which make them nanofabrication-friendly. Our experimental characterization shows that our metalenses exhibit superior performance over a broad bandwidth of 465 nm in the near-infrared regime. Our method offers a fast and efficient way of designing high-performance achromatic metalenses and sheds new insights for unintuitive design of other metaphotonic devices.
分类： 光学 >> 量子光学 提交时间： 2023-02-22
Zheng-Da Li
Ya-Li Mao
Mirjam Weilenmann
Armin Tavakoli
Hu Chen
Lixin Feng
Sheng-Jun Yang
Marc-Olivier Renou
David Trillo
Thinh P. Le
Nicolas Gisin
Antonio Acín
Miguel Navascués
Zizhu Wang
Jingyun Fan
摘要： Quantum theory is commonly formulated in complex Hilbert spaces. However, the question of whether complex numbers need to be given a fundamental role in the theory has been debated since its pioneering days. Recently it has been shown that tests in the spirit of a Bell inequality can reveal quantum predictions in entanglement swapping scenarios that cannot be modelled by the natural real-number analog of standard quantum theory. Here, we tailor such tests for implementation in state-of-the-art photonic systems. We experimentally demonstrate quantum correlations in a network of three parties and two independent EPR sources that violate the constraints of real quantum theory by over $4.5$ standard deviations, hence disproving real quantum theory as a universal physical theory.
分类： 光学 >> 量子光学 提交时间： 2023-02-22
Jin Chuan Zhang
Hong Yang Zhu
Xiao Mei Zhu
Yan Li Zhang
Zhao Wang
Fei Liang Chen
Ke Li
Xiao Feng Li
Wei Li Zhang
摘要： Whispering gallery mode (WGM) microcavities can efficiently store and manipulate light with strong light confinement and long photon lifetime, while coupling light into and from WGMs is intrinsically hindered by their unique feature of rotational symmetry. Here, a scattering-assisted liquid crystal (LC) micropillar WGM laser is proposed. WGM lasing at the surface of the micropillar is obviously enhanced by fluorescence scattering in the core of the micropillar. Besides, weak scattering of LC molecules also builds efficient coupling channels between the laser modes and the axial transmission modes of the micropillar-based waveguide, providing an all-in-one liquid WGM laser with functions of self-seeding and self-guiding. Furthermore, based on the hysteresis characteristics of the electrically anchored LC molecules under the interaction of thermal force, an erasable read-write liquid memory device is proposed, paving the way for the application of logic-controllable WGM lasers in optical storage and optical control.
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