摘要：
We investigate collective radiant properties of two separated atoms in X-type quantum states. We show that quantum correlations measured by quantum discord (QD) can trigger and enhance superradiance and subradiance in the two-atom system even though in the absence of interatomic quantum entanglement. We also explore quantum statistical properties of photons in the superradiance and subradiance by addressing the second-order correlation function. In particular, when the initial state of the two separated atoms is the Werner state with nonzero QD, we find that radiation photons in the superradiant region exhibit the nonclassical sub-Poissonian statistics and the degree of the sub-Poissonian statistics increases with increasing of the QD amount, while radiation photons in the subradiant region have either the sub-Poissonian or super-Poissonian statistics depending on the amount of QD and the directional angle. In the subradiant regime, we predict the QD-triggered photon statistics transition from the super-Poissonian to sub-Poissonian statistics. These results shed a new light on applications of QD as a quantum resource.
摘要：
The propagation properties of anomalous vortex beams in strongly nonlocal nonlinear media are investigated. Two equivalent analytical expressions for the evolution of anomalous vortex beams are obtained. It is found that the input power plays a key role in the beam evolutions. Selecting a proper input power, the beam width can be broadened or be compressed periodically, even it can keep invariant during propagation. The beam order and the topological charge mainly influence the intensity evolution and the phase evolution, respectively. The evolution period, the beam width, the phase distribution and the intensity distribution are discussed in detail. The results can also be generalized to other equivalent physical systems, such as an optical fractional Fourier transform system or a medium with a quadratic graded refractive index distribution. (C) 2015 Elsevier B.V. All rights reserved.
作者机构：
[Zou, Changqing; Peng, Xiaojiang] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang, Peoples R China.;[Chen, Shifeng; Zou, Changqing; Lv, Hao] Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen Key Lab CVPR, Shenzhen, Peoples R China.;[Zou, Changqing] Univ Chinese Acad Sci, Shenzhen Coll Adv Technol, Beijing, Peoples R China.;[Fu, Hongbo] City Univ Hong Kong, Hong Kong, Hong Kong, Peoples R China.;[Liu, Jianzhuang] Chinese Univ Hong Kong, Hong Kong, Hong Kong, Peoples R China.
期刊：
IEEE Transactions on Visualization and Computer Graphics,2015年21(2):252-263 ISSN：1077-2626
通讯作者：
Zou, Changqing
作者机构：
[Zou, Changqing] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang, Peoples R China.;[Chen, Shifeng; Zou, Changqing] Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen 518055, Peoples R China.;[Fu, Hongbo] City Univ Hong Kong, Sch Creat Media, Hong Kong, Hong Kong, Peoples R China.;[Liu, Jianzhuang] Huawei Technol Co Ltd, Media Lab, Shenzhen, Peoples R China.;[Liu, Jianzhuang] Chinese Univ Hong Kong, Dept Informat Engn, Hong Kong, Hong Kong, Peoples R China.
通讯机构：
[Zou, Changqing] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang, Peoples R China.
关键词：
3D reconstruction;degree of reconstruction freedom;decomposition;line drawing;optimization-based
摘要：
This paper presents an approach for reconstructing polyhedral objects from single-view line drawings. Our approach separates a complex line drawing representing a manifold object into a series of simpler line drawings, based on the degree of reconstruction freedom (DRF). We then progressively reconstruct a complete 3D model from these simpler line drawings. Our experiments show that our decomposition algorithm is able to handle complex drawings which are challenging for the state of the art. The advantages of the presented progressive 3D reconstruction method over the existing reconstruction methods in terms of both robustness and efficiency are also demonstrated.
摘要：
Based on the angular spectrum representation of the Maxwell equations and the method of stationary phase, this paper presents the far-field analytical expression of a pulsed hollow Gaussian beam with constant waist width diffracted by the circular aperture, and the result can be simplified for the case of the paraxial propagation of pulsed Gaussian beam in the free space. Based on the analytical result, the influences of truncation parameter on the transverse intensity distribution of the pulsed beam are analyzed. Comparisons of normalized temporal intensity between the pulsed Gaussian beam and the fourth order pulsed hollow Gaussian beam are presented. We find that the spatial mode can induce the temporal shape changing. (C) 2014 Elsevier B.V. All rights reserved.
摘要：
In this paper, using the rotating coordinates, we take the anomalous hollow Gaussian beam as an example to investigate the evolution of an ellipse-symmetric beam in strongly nonlocal nonlinear media. A set of analytical expressions are obtained and some numerical simulations are carried out to illustrate the relation between the evolution characteristics and the rotation angle. It is found that the evolution properties, such as the critical powers, beam widths, and intensity distributions in x and y directions, are all variational with the rotation angle.
通讯机构：
[Tan, Yanliang] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang, Hunan, Peoples R China.
关键词：
Air exchange rate;Airborne sheltering factor;Indoor airborne deposition velocity
摘要：
The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan resulted in significant releases of fission products. While substantial data exist concerning outdoor air radioactivity following the accident, the resulting indoor radioactivity remains pure speculation without a proper method for estimating the ratio of the indoor to outdoor airborne radioactivity, termed the airborne sheltering factor (ASF). Lacking a meaningful value of the ASF, it is difficult to assess the inhalation doses to residents and evacuees even when outdoor radionuclide concentrations are available. A simple model was developed and the key parameters needed to estimate the ASF were obtained through data fitting of selected indoor and outdoor airborne radioactivity measurement data obtained following the accident at a single location. Using the new model with values of the air exchange rate, interior air volume, and the inner surface area of the dwellings, the ASF can be estimated for a variety of dwelling types. Assessment of the inhalation dose to individuals readily follows from the value of the ASF, the person's indoor occupancy factor, and the measured outdoor radioactivity concentration. (C) 2015 Elsevier B.V. All rights reserved.
摘要：
The purpose of this paper is to investigate the effects of quantum noises on entanglement localization by taking an example of reducing a three-qubit Greenberger-Horne-Zeilinger (GHZ) state to a two-qubit entangled state. We consider, respectively, two types of quantum decoherence, i.e. amplitude-damping and depolarizing decoherence, and explore the best von Neumann measurements on one of three qubits of the triple GHZ state for making the amount of entanglement of the collapsed bipartite state be as large as possible. The results indicate that different noises have different impacts on entanglement localization, and that the optimal strategy for reducing a three-qubit GHZ state to a two-qubit one via local measurements and classical communications in the amplitude-damping case is different from that in the noise-free case. We also show that the idea of entanglement localization could be utilized to improve the quality of bipartite entanglement distributing through amplitude-damping channels. These findings might shed a new light on entanglement manipulations and transformations.
摘要：
Within the framework of the kinetic energy driven superconducting mechanism, the dynamical spin response of cuprate superconductors is studied from low-energy to high-energy. The spin self-energy is evaluated explicitly in terms of the collective charge carrier modes in the particle-hole and particle-particle channels, and employed to calculate the dynamical spin structure factor. Our results show the existence of damped but well-defined dispersive spin excitations in the whole doping phase diagram. In particular, the low-energy spin excitations in the superconducting-state have an hour-glass-shaped dispersion, with commensurate resonance that appears in the superconducting-state only, while the low-energy incommensurate spin fluctuations can persist into the normal-state. The high-energy spin excitations in the superconducting-state on the other hand retain roughly constant energy as a function of doping, with spectral weights and dispersion relations comparable to those in the corresponding normal-state. The theory also shows that the unusual magnetic correlations in cuprate superconductors can be ascribed purely to the spin self-energy effects which arise directly from the charge carrier-spin interaction in the kinetic energy of the system. (C) 2014 Elsevier B.V. All rights reserved.
摘要：
In this study, we propose a regression forests-based cascaded method for face alignment. We build on the cascaded pose regression (CPR) framework and propose to use the regression forest as a primitive regressor. The regression forests are easier to train and naturally handle the over-fitting problem via averaging the outputs of the trees at each stage. We address the fact that the CPR approaches are sensitive to the shape initialisation; in contrast to using a number of blind initialisations and selecting the median values, we propose an intelligent shape initialisation scheme. More specifically, a large number of initialisations are propagated to a few early stages in the cascade, then only a proportion of them are propagated to the remaining cascades according to their convergence measurement. We evaluate the performance of the proposed approach on the challenging face alignment in the wild database and obtain superior or comparable performance with the state-of-the-art, in spite of the fact that we have utilised only the freely available public training images. More importantly, we show that the intelligent initialisation scheme makes the CPR framework more robust to unreliable initialisations that are typically produced by different face detections.
期刊：
Journal of Materials Chemistry C,2015年3(13):3189-3197 ISSN：2050-7526
通讯作者：
Liu, Li-Min
作者机构：
[Tang, Zhen-Kun; Zhang, Yan-Ning; Li, Xi-Bo; Liu, Li-Min] Beijing Computat Sci Res Ctr, Beijing 100084, Peoples R China.;[Zhang, Deng-Yu; Tang, Zhen-Kun] Hengyang Normal Univ, Dept Phys, Hengyang 421008, Peoples R China.;[Zhang, Deng-Yu; Tang, Zhen-Kun] Hengyang Normal Univ, Dept Elect, Hengyang 421008, Peoples R China.;[Zhang, Yan-Ning] Chengdu Green Energy & Green Mfg Technol R&D Ctr, Chengdu 610207, Sichuan, Peoples R China.
通讯机构：
[Liu, Li-Min] B;Beijing Computat Sci Res Ctr, Beijing 100084, Peoples R China.
摘要：
In order to design the high-performance spintronics, it is rather critical to develop new materials, which can easily regulate the magnetism of nanostructures. In this work, the electronic properties of two dimensional (2D) square-pyramidal vanadium dioxide (S-VO2) are explored based on first-principles calculations. The results reveal that the monolayer S-VO2 is an ideal flexible platform to manipulate the magnetic properties by either biaxial compressive strain or surface modification. Although the ground state of the pristine S-VO2 is a direct semiconductor with antiferromagnetic (AFM) coupling between two nearest V atoms, the monolayer S-VO2 becomes ferromagnetic (FM) under a biaxial compressive strain. Furthermore, the monolayer S-VO2 can be tuned from a nonmagnetic semiconductor to a magnetic semiconductor and even to a half-metal through surface modification. The tunable magnetic properties of the monolayer S-VO2 make it a promising candidate for applications in spin-devices.
摘要：
By applying the variational approach, the analytical expression of dipole breathers is obtained in nonlinear media with an exponential-decay nonlocal response. The parameters of the width, the amplitude, the phase-front curvature, and the phase of the complex amplitude of the dipole breathers are all given in analytical expressions. It is found that the input power plays a key role in the evolution of dipole breathers, whose magnitude decides the change of the beam width (compressed or broadened) during propagation. The physical reason for the evolution of dipole breathers is analyzed in detail. Numerical simulations are also carried out, and the analytical solutions are in good agreement with numerical simulations.
摘要：
We investigate here a new class of optical beams: modified hollow Gaussian beams (MHGBs) in strongly nonlocal nonlinear media (SNNM). A set of analytical expressions for the propagation properties is deduced and some numerical simulations are also carried out to illustrate the propagation properties. It is found that the evolution of the MHGBs in SNNM is periodical, which is the result of the competition between nonlinearity and diffraction. The second-order moment beam width of the MHGBs can keep invariant during propagation like a soliton when the input power equals the critical power, otherwise it varies periodically like a breather. However, the patterns of transverse intensity are always changing with the propagation distance increasing, which is different from solitons or breathers. It is also found that the evolution curve of on-axis intensity may manifest itself in a concave, a platform, or a Gaussian-like shape depending on the input power.
