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Integrated quantum photonic circuits are a promising approach to realizing future quantum information processing. To achieve large-scale quantum photonic circuits, as many quantum logic gates as possible are expected to be integrated on chips. This requires quantum logic gates to be as small as possible. Here, we report the implementation of super-compact universal quantum logic gates on silicon photonic chips by inverse design. The sizes for the fabricated optical controlled-NOT gate and single-qubit gates (Hadamard gate) on the chip are about one vacuum wavelength, which are the smallest optical quantum gates ever verified in the world. The quantum circuit by these cascaded fundamental gates is shrunk several orders compared to those previous quantum photonic circuits that perform arbitrary quantum processing. Our study paves the way for the realization of large-scale quantum photonic chips with integrated sources for practical quantum information processes.

We report on the first sub-60 fs pulse generated from a diode-pumped SESAM mode-locked Yb-laser based on a non-centrosymmetric Yb:YAl3(BO3)4 crystal as a gain medium. In the continuous-wave regime, pumping with a spatially single-mode, fiber-coupled 976 nm InGaAs laser diode, the Yb:YAl3(BO3)4 laser generated 391 mW at 1041.7 nm with a slope efficiency as high as 65.1%, and a wavelength tuning across 59 nm (1019 to 1078 nm) was achieved. By implementing a commercial SESAM to initiate and sustain the soliton type mode-locking, and using only a 1 mm-thick laser crystal, the Yb:YAl3(BO3)4 laser delivered pulses as short as 56 fs at a central wavelength of 1044.6 nm with an average output power of 76 mW at a pulse repetition rate of ∼67.55 MHz. To the best of our knowledge, this result represents the shortest pulses ever achieved from Yb:YAB crystal.

The good thermal stability of a phosphor is crucial for its practical applications. Unfortunately, in the past decades, only the Gurney–Mott equation was available to describe the relation between the luminescence properties of a phosphor and temperature, which is, however, phenomenological and not precise. In this work, we introduced a hypothesis that the lowering of the luminescence efficiency of a phosphor is caused by the heat generated during the luminescence process and can be reduced if the luminescence site dissipates the heat away. We verified this hypothesis by evaluating the thermal conductivities κ of their luminescence sites, the Eu atoms, in the three phosphors, SrLiAl3N4:Eu2+, Sr2Si5N8:Eu2+ and SrSiN2:Eu2+, as well as those of the Sr atoms in their hosts SrLiAl3N4, Sr2Si5N8 and SrSiN2. It is suggested that our new approach can be employed as a practical criterion to search for phosphor materials with efficient luminescence properties.

It has remained a big challenge to grow large crystals of compounds at very anisotropic crystal growth rates. GdPO4 is such an example, which usually grows into a needle-like shape. This work solved this problem by using Li+ ions, predicted by first-principles calculations, to adjust the crystal morphology of GdPO4. Based on the calculated surface energies and the polar properties of the surfaces, we identified two crystal planes, i.e. (−102) and (−111), which can be used to adjust the morphology of the GdPO4 crystal by using extrinsic cations in the flux system. With a predicted Li containing flux system, Li2O–MoO3–B2O3, a large crystal with a record size, 10.0 × 9.0 × 18.2 mm3, was grown by using the top-seeded solution growth (TSSG) method. Based on the grown large crystal and the polarized Raman measurements, four new Raman bands missing in early studies and other bands were unambiguously assigned. By introducing a new formula, the phonon–phonon interactions were shown to be weak in the temperature range from 83 to 803 K. Our study indicates that the crystal of GdPO4 can be used as a promising laser host material working under relatively high temperature conditions.

Monodisperse Tb-doped NaCeF4 nanocrystals were synthesized via a hydrothermal method. The morphology, and room temperature and temperature dependent luminescent properties were investigated. Excited at 254 nm, the emissions of Ce3+ at 270–370 nm and those of Tb3+ at 475–700 nm can be observed. The strongest visible emission was observed in NaCeF4:20 at% Tb with a quantum yield of 49%. The efficiency of energy transfer from Ce3+ to Tb3+ increases with the Tb3+ doping concentration and reaches 95% for NaCeF4:30 at% Tb. The ratio of Tb3+ emission to Ce3+ emission is sensitive to temperature, and the relative sensitivity was calculated to be 1.0% °C−1 at 60 °C. The mechanisms for this thermal dependence were analyzed in terms of non-radiative relaxation and energy migration.

Cherenkov radiation (CR) is the electromagnetic shockwaves generated by the uniform motion of charged particles at a velocity exceeding the phase velocity of light in a given medium. In the Reststrahlen bands of hexagonal boron nitride (hBN), hyperbolic phonon polaritons (HPPs) are generated owing to the coupling between mid-infrared electromagnetic waves and strong anisotropic lattice vibrations. This study theoretically and numerically investigates the generation of volume CR based on HPPs in hBN with super-large wavevectors. Results reveal that CR can be generated using free electrons with an extremely low kinetic energy of 1 eV—two orders of magnitude lower than that reported in extant studies. The findings of this investigation provide new insights into significantly reducing the electron energy required for CR generation and potentially open new research avenues in the fields of CR and HPP.

We demonstrate angle-insensitive spectral imaging in the wavelength range of 400 to 800 nm for average polarization based on topology-optimized plasmonic metasurfaces by optimizing the period and shape of the meta-atom.

We report on a diode-pumped mode-locked Yb-laser based on the non-centrosymmetric YAl3(BO3)4 host-crystal generating 56-fs pulses at 1044.6 nm with an average output power of 76 mW at a pulse repetition rate of ~67.5 MHz.

Photonic Ising machine is a new paradigm of optical computing, which is based on the characteristics of light wave propagation, parallel processing and low loss transmission. Thus, the process of solving the combinatorial optimization problems can be accelerated through photonic/optoelectronic devices. In this work, we have proposed and demonstrated the so-called Phase-Encoding and Intensity Detection Ising Annealer (PEIDIA) to solve arbitrary Ising problems on demand. The PEIDIA is based on the simulated annealing algorithm and requires only one step of optical linear transformation with simplified Hamiltonian calculation. With PEIDIA, the Ising spins are encoded on the phase term of the optical field and only intensity detection is required during the solving process. As a proof of principle, several 20-dimensional Ising problems have been solved with high ground state probability (0.98 within 1000 iterations for the antiferromagnetic cubic model, > 0.99 within 4000 iterations for two random spin-glass models, respectively).

We demonstrate a single-photon-sensitivity spectrometer based on metasurfaces and superconducting nanowire single-photon detectors with 1.5% ~ 9.5% total detection efficiency at 1100 nm ~ 1700 nm.

Based on a phase-modulated metallic nanoslit array, an angular momentum (AM) beam splitter has been demonstrated to distinguish both spin and orbital components carried by the light beam. With such a device, the AM modes could be coupled into nondiffracting surface plasmonic beams propagating toward different directions. According to the experimental results, the extinction ratio for spin AM beam splitting is larger than 10 and the spatial interval of adjacent orbital AM modes (with a topological charge interval of 2) is more than 1.1 μm. We believe that such a device would have great potential to achieve a highly compact photonic integrated circuit with the plasmonic beam.

Background In recent years, with the rapid development of public network, emotion analysis has always been a research hotspot in the field of natural language processing and data mining. The current research mainly focuses on various comments on the Internet, and there is relatively little analysis of the psychological activities of the characters and the emotional changes of the text in the novel. How to use computer technology to identify the emotional tendency and psychological activities of characters in literary works has important practical significance. Topics and Methods This paper uses complex network and wlda algorithm to analyze the mood of Norwegian forest. Using complex network is to preprocess the data, extract the information in the article by using word frequency statistics, then build a complex network according to word frequency, find out the key points of complex network according to the principle of structural hole, complex network, and analyze the emotional tendency to be expressed in the article. The wlda algorithm model is used to segment the data, remove the stop words, and then the algorithm is used to verify the emotional tendency of the novel. The corpus used in the experiment is Haruki Murakami's novel Norwegian forest. The emotion seed words used in the experiment are from the Chinese word set used for emotion analysis in the Internet HowNet. The algorithm parameters take the data commonly used in wlda model, where 50 is equal to 0.01, and the number of keywords to judge the subject's emotional tendency is C, which is equal to 100. Readers' emotion algorithm, this study uses the relevant scale to investigate. (1) Positive emotion scale. The Panas emotion scale developed by Wason et al. Is widely used to measure emotion. The scale includes two dimensions: positive emotion and negative emotion. There are 6 questions in this dimension. In addition, the boredom tendency questionnaire was used to investigate internet boredom. The boredom tendency questionnaire was prepared by Huang Shihua et al. In 2010. The research shows that the scale has high reliability and validity. The scale has 30 items and is scored by Likert 7 points (from 7 to 1 means “completely agree” to “completely disagree”, and 4 means neutral). The scale includes two sub questionnaires of external stimulation and internal stimulation. The external stimulus sub questionnaire includes four factors: monotonicity, loneliness, tension and restraint. The internal stimulation sub questionnaire contains two factors: self-control and creativity. The higher the questionnaire score, the higher the boredom tendency. Group learning burnout scale group learning burnout scale was compiled by Lian Rong et al in 2005. The research shows that the scale has high reliability and validity. The scale has 20 items and uses a 5-level scoring method (from 5 to 1 means “completely consistent” to “completely inconsistent”, and 3 means neutral). It includes three dimensions, including depression, improper behavior and low sense of achievement. Emotion regulation strategy scale emotion regulation style scale was compiled by gross et al in 2003. The Chinese version of the scale has been proved to have high reliability and validity. The scale has 10 items and adopts Likert 7-point scoring (from 7 to 1 means “fully agree” to “completely disagree”, and 4 means neutral). The scale includes two sub questionnaires: cognitive reappraisal and expression inhibition. Data Analysis Adopt spss16 0 and amos17 0 statistical software Line statistical processing. Results In the process of simplifying complex network, the frequency of low-frequency words was 1. Experiments show that the results of complex network and wlda algorithm model are basically consistent, and the effect of emotion analysis is obvious. Readers' emotional response and emotional effect are also basically the same. Conclusion Some high-frequency but meaningless stop words in the corpus have caused great interference to the reasoning of the model topic. Therefore, when analyzing the text, we need to preprocess the corpus and filter out low-frequency words, which affects the emotion extraction to a certain extent. In the process of simplifying complex networks, it is also necessary to adjust the threshold of filtered low-frequency words according to different work. The experimental results show that the negative tendency is greater than the positive tendency, and the whole text expresses the negative emotion, that is, the sadness and confusion of survival. Acknowledgements Supported by the doctoral startup Research (No.20rc15), the research on the influence of consumers' purchase intention of traceable agricultural products (No.20rc03), and the design of precision control system based on the Internet of things (No.202103001).

Passively Q-switched Er:Yb:LuAl

Medicine is a fast-moving field, and the number of medical publications has increased rapidly over recent years. How to find relevant information from this vast pool of research effectively and efficiently has therefore become highly challenges. Previous studies have demonstrated that data fusion can improve search performance if properly utilized. However, in most cases effectiveness is the only concern and efficiency is not considered. A fusion-based system is by nature more complicated and expensive computationally than other retrieval models such as BM25, because many component retrieval systems and an extra layer of fusion are required. The number of component retrieval systems involved is an important indicator of complexity of the fusion-based system. We aim to select the optimal k-subset of component retrieval systems for any given number k, to optimize both fusion performance and reduce the cost of data fusion. A clustering-based approach is proposed. First all the candidates are divided into clusters by the Chameleon clustering algorithm, then representatives from every cluster are chosen by Sequential Forward Selection for fusion. Evaluated with two datasets from TREC, the proposed method performs more effectively than the other baseline methods including the state-of-the-art subset selection method significantly. When either of the two typical fusion methods is used, an improvement rate of over 10% is observed for both measures Mean Average Precision and Recall-level Precision, and an improvement rate of over 5% is observed for both measures Precision at 10 document level and Mean Reciprocal Rank.

It has remained a big challenge to grow large crystals of compounds at very anisotropic crystal growth rates. GdPO

Diode-pumped continuous-wave and passively Q-switched pulse Yb:Ca3TaGa3Si2O14 lasers are reported. At an absorbed pump power of 5.4 W, a 1046.4 nm continuous-wave laser with an output power of 3.24 W and a slope efficiency of 63.4% was obtained. When a Cr4+:YAG saturable absorber with an initial transmission of 95% was used, a 1015.2 nm passively Q-switched pulse laser with a repetition frequency of 5.43 kHz, energy of about 73.6 µJ, duration of 35 ns, and peak output power of 2.1 kW was demonstrated.

The fluorescence quenching caused by Nd3+ clusters in Nd3+-doped crystals even at low Nd3+ concentration has restrained the performance of Nd3+ lasers. In this work, Nd3+:CaNb2O6 and Nd3+:La3+:CaNb...

A Dy3+-doped NaBi(WO4)2 crystal was successfully grown by the Czochralski method. Spectroscopic properties of the crystal at room temperature were measured and analyzed. Peak absorption cross-sections of the 6H15/2 → 4I15/2 transition for the crystal are 1.4 × 10-21 and 2.3 × 10-21 cm2 with full widths at half maximum of 7.5 and 6.6 nm for σ and π polarizations, respectively, and at 454 nm for both polarizations. Meanwhile, the crystal exhibits a strong yellow emission at 574 nm corresponding to the 4F9/2 → 6H13/2 transition with peak cross-sections of 0.97 × 10-20 and 1.27 × 10-20 cm2 for σ and π polarizations, respectively. The fluorescence lifetime and quantum efficiency of the 4F9/2 multiplet were estimated to be 179 μs and 80%, respectively. It has been found that the cross relaxation plays an important role in the relaxation of the 4F9/2 multiplet. The results show that the Dy3+:NaBi(WO4)2 crystal may be a promising gain medium of the 574 nm yellow laser pumped by a blue laser diode at 454 nm.

A stoichiometric Sr3Tb2(BO3)4 crystal was successfully grown by the Czochralski method. Polarized absorption and fluorescence spectra of the crystal were measured at room temperature. The peak absorption cross-section at 486 nm corresponding to the 7F6→5D4 transition of Tb3+ ions for the E//Z polarization is 1.32 × 10–22 cm2. Based on the Judd-Ofelt theory, fluorescence branching ratios of the 5D4→7F5 and 5D4→7F4 transitions of Tb3+ ions were calculated to be 64.86% and 7.69%, respectively. The radiative lifetime of the 5D4 multiplet was calculated to be 2.93 ms. The yellow fluorescence band centered at 586 nm corresponding to the 5D4→7F4 transition is flat and the full width at half the maximum of this band is 8.5 nm. The fluorescence lifetime of the 5D4 multiplet was measured to be 2 ms and the fluorescence quantum efficiency was estimated to be 69%. Above results show that the Sr3Tb2(BO3)4 crystal is a potential gain medium for yellow laser.

A 2.02 at.% Dy3+-doped Sr3Y(BO3)3 crystal was successfully grown by the Czochralski method. Polarized spectroscopic properties of the crystal were investigated at room temperature. The absorption spectra were analyzed based on Judd-Ofelt theory. Then the spontaneous transition probabilities, branching ratios, and radiative lifetime related to the 4F9/2 multiplet of Dy3+ were obtained. The peak emission cross-sections corresponding to the 4F9/2 → 6H13/2 transition are 0.10 × 10−20 and 0.12 × 10−20 cm2 for σ and π polarizations, respectively, and at 576 nm for both polarizations. The fluorescence lifetime and quantum efficiency were estimated to be 0.82 ms and 57%, respectively. The analysis on the fluorescence decay curve of the 4F9/2 multiplet indicated that the cross relaxation induced by the electric dipole-dipole interaction plays an important role in the depopulation of the 4F9/2 multiplet. The results show that the Dy3+:Sr3Y(BO3)3 crystal may be a promising candidate for solid state yellow laser pumped by a blue laser diode around 454 nm.

Amorphous photonic structures (APSs) with short-range ordered arrangement have attracted great interest because of their wide view angles. However, the presented methods for the APSs color printing and 3D coating on different substrates and curvatures are lack of control. Here, APSs with angle-independent structural colors were fabricated by the self-assembly of SiO2@Fe3O4 core-shell nanostructures, which were prepared by the hydrolysis of Fe(acac)3 on the silica surfaces. The size of SiO2@Fe3O4 core-shell colloids can be controlled well through the tuning of SiO2 particle size, whereas the coverage of Fe3O4 on silica surfaces can be precisely tailored through altering the mass ratio between Fe3O4 precursor and SiO2. APSs with only short-range ordered structures, uniform noniridescent structural colors, and high color visibility can be obtained through the self-assembly of SiO2@Fe3O4 colloids of different particle sizes in a few minutes. They are mainly attributed to the weak electrostatic repulsion interactions between SiO2@Fe3O4 colloids because of the partial coverage of Fe3O4 on silica surfaces and absorption of the incoherent multiple scattering of visible light from Fe3O4. Moreover, SiO2@Fe3O4 colloids show good adhesion to various substrates, such as paper, glass, plastics, resins, ceramics, and wood, which facilitates the formation of uniform APSs on different substrates. Multicolor prints and 3D coating of APSs on substrates with different curves and roughness can be realized on the basis of the fast assembly of SiO2@Fe3O4 colloids.

In this paper, we realize an adjustable biphoton frequency comb and investigate its spatial quantum beating. Vector spontaneous four wave mixing processes in a piece of dispersion shifted fiber are produced by non-degenerate continuous wave pump lights with orthogonal polarizations to generate broadband biphoton states, and then a pulse shaper is used to realize the biphoton frequency comb with high-dimensional frequency-bin entanglement. The property of the biphoton frequency comb is indicated by the shape of the fringes of spatial quantum beating, which is also comb-like with a series of dips. The variations of the beating fringes show the changes of frequency bins in the comb by the setting of the pulse shaper. It can be expected that the adjustable biphoton frequency comb has great potential on high-dimensional quantum information processing and quantum communication based on the frequency degree of freedom.

Tunable coupled mechanical resonators with nonequilibrium dynamic phenomena have attracted considerable attention in quantum simulations, quantum computations, and non-Hermitian systems. In this study, we propose tunable mechanical-mode coupling based on nanobeam-double optomechanical cavities. The excited optical mode interacts with both symmetric and antisymmetric mechanical supermodes and mediates coupling at a frequency of approximately 4.96 GHz. The mechanical-mode coupling is tuned through both optical spring and gain effects, and the reduced coupled frequency difference in non-Hermitian parameter space is observed. These results benefit research on the microscopic mechanical parity–time symmetry for topology and on-chip high-sensitivity sensors.

We proposed a fully connected quantum communication network architecture based on multi-user entanglement distribution by space multiplexing and wavelength multiplexing technologies. A fully connected QKD network with 40 users was demonstrated experimentally.

A single longitudinal-mode passively Q-switched 1537 nm pulse microchip laser was realized in an Er:Yb:Lu

We demonstrate a comprehensive characterization of the diode-pumped Yb:Bi

An Er:Yb:Ba3Gd(PO4)3 crystal was grown by the Czochralski method. Spectral properties of the crystal associated with 1.5–1.6 µm laser operation were investigated, including the absorption and fluorescence spectra and the fluorescence decay at room temperature. The fluorescence quantum efficiency of the 4I13/2 level of Er3+ ions and energy transfer efficiency from Yb3+ to Er3+ ions were calculated. A CW diode-pumped Er:Yb:Ba3Gd(PO4)3 laser at 1.5–1.6 µm with output power of about 73.9 mW and slope efficiency of 16.3% was achieved for the first time in the Er3+/Yb3+ co-doped phosphate crystal.

We have proposed and demonstrated a scalable and efficient scheme for programmable unitary operations in orbital angular momentum (OAM) domain. Based on matrix decomposition into diagonal and Fourier factors, arbitrary matrix operators can be implemented only by diagonal matrices alternately acting on orbital angular momentum domain and azimuthal angle domain, which are linked by Fourier transform. With numerical simulations, unitary matrices with dimensionality of 3*3 are designed and discussed for OAM domain. Meanwhile, the parallelism of our proposed scheme is also presented with two 3*3 matrices. Furthermore, as an alternative to verify our proposal, proof of principle experiments have been performed on path domain with the same matrix decomposition method, in which an average fidelity of 0.97 is evaluated through 80 experimental results with dimensionality of 3*3., The manuscript includes abstract (about 150 words), text part (about 4700 words), 7 figures and 42 references

We reported an electro-optically cavity-dumped Q-switched Er:Yb:YAl

A simple and flexible scheme for high-dimensional linear quantum operations is demonstrated on optical discrete spatial modes in the transverse plane. Quantum-state tomography via symmetric informationally complete positive-operator-valued measures and quantum Fourier transformation are implemented with dimensionality of 15. The statistical fidelity of symmetric informationally complete positive-operator-valued measures and the fidelity of quantum-state tomography are approximately 0.97 and up to 0.853, respectively, while the matrix fidelity of quantum Fourier transformation is 0.85. We believe that our approach has the potential for further exploration of high-dimensional spatial entanglement provided by spontaneous parametric down-conversion in nonlinear crystals.

It is still a technical challenge to obtain a 1.55 µm passively $Q$Q-switched ${{\rm Er}^{3 + }}/{{\rm Yb}^{3 + }}$Er

One of the important effects of lattice vibration on spectral properties of active ions is the emission or absorption of phonon between the electronic energy levels without the emission or absorption of photon.

As mentioned above, many laser crystals have nonlinear optical properties and so can double, mixing, or transform the frequency of laser beam by second harmonic (SH) and stimulated Raman scattering (SRS) effects.