Three-dimensional photonic crystal （PC） heterostructures with high quality are fabricated by using a pressure controlled isothermal heating vertical deposition technique. The formed heterostructures have higher qual...Three-dimensional photonic crystal （PC） heterostructures with high quality are fabricated by using a pressure controlled isothermal heating vertical deposition technique. The formed heterostructures have higher quality, such as deeper band gaps and sharper band edges, than the heterostructures reported so far. Such a significant improvement in quality is due to the introduction of a thin TiO2 buffer layer between the two constitutional PCs. It is revealed that the disorder caused by lattice mismatch is successfully removed if the buffer layer is used once. As a result, the formed heterostructures possess the main features in the band gap of constitutional PCs. The crucial role of the thin buffer layer is also verified by numerical simulations based on the finite-difference time-domain technique.展开更多
By carrying out the two ideas of asymmetrical confinement and asymmetrical response into the photonic crystal （PC） structures that contain two or more nonlinear defects, we find that significantly unidirectional tra...By carrying out the two ideas of asymmetrical confinement and asymmetrical response into the photonic crystal （PC） structures that contain two or more nonlinear defects, we find that significantly unidirectional transmission can be achieved while the transmission for the positive launch direction maintains at large values. Our analyses are supported by the simulation results based on the finite-difference time-domain technique.展开更多
This paper demonstrates experimentally and numerically that a significant modification of spontaneous emission rate can be achieved near the surface of a three-dimensional photonic crystal. In experiments, semiconduct...This paper demonstrates experimentally and numerically that a significant modification of spontaneous emission rate can be achieved near the surface of a three-dimensional photonic crystal. In experiments, semiconductor coreshell quantum dots are intentionally confined in a thin polymer film on which a three-dimensional colloidal photonic crystal is fabricated. The spontaneous emission rate of quantum dots is characterised by conventional and time-resolved photoluminescence （PL） measurements. The modification of the spontaneous emission rate, which is reflected in the change of spectral shape and PL lifetime, is clearly observed. While an obvious increase in the PL lifetime is found at most wavelengths in the band gap, a significant reduction in the PL lifetime by one order of magnitude is observed at the short-wavelength band edge. Numerical simulation reveals a periodic modulation of spontaneous emission rate with decreasing modulation strength when an emitter is moved away from the surface of the photonic crystal. It is supported by the fact that the modification of spontaneous emission rate is not pronounced for quantum dots distributed in a thick polymer film where both enhancement and suppression are present simultaneously. This finding provides a simple and effective way for improving the performance of light emitting devices.展开更多
Application of the pressure controlled isothermal heating vertical deposition method to the fabrication of colloidal photonic crystals is systematically investigated in this paper. The fabricated samples are character...Application of the pressure controlled isothermal heating vertical deposition method to the fabrication of colloidal photonic crystals is systematically investigated in this paper. The fabricated samples are characterized by scanning electron microscope and transmission spectrum. High-quality samples with large transmissions in the pass bands and the sharp band edges are obtained and the optimum growth condition is determined. For the best sample, the transmission in the pass bands approaches 0.9 while that in the band gap reaches 0.1. More importantly, the maximum differential transmission as high as 0.1/nm is achieved. In addition, it is found that the number of stacking layers does not increase linearly with concentration of PS spheres in a solution, and a gradual saturation occurs when the concentration of PS spheres exceeds 1.5 wt.%. The uniformity of the fabricated samples is examined by transmission measurements on areas with different sizes. Finally, the tolerance of the fabricated samples to baking was studied.展开更多
We investigate numerically and experimentally the modification of the spontaneous emission rate for micrometersized light sources embedded in a hollow-core photonic crystal fiber （HCPCF）. The diameter of the light s...We investigate numerically and experimentally the modification of the spontaneous emission rate for micrometersized light sources embedded in a hollow-core photonic crystal fiber （HCPCF）. The diameter of the light source is deliberately chosen such that they could be easily introduced into the central hole of the hollow-core photonic crystal fiber by capillary force. The photoluminescence from the microparticles is measured by using an inverted microscope in combination with a spectrometer. The modification of the spontaneous emission rate is observed in a wavelength region where there is no band gap. The experimental observations are consistent with the simulation results obtained by the plane wave expansion and finite-difference time-domain techniques.展开更多
In optical circuits, functional elements are often placed on waveguide junctions. We show that a junction in photonic crystals （PCs） possesses localized modes very close to the bandpass of waveguides. Their mode res...In optical circuits, functional elements are often placed on waveguide junctions. We show that a junction in photonic crystals （PCs） possesses localized modes very close to the bandpass of waveguides. Their mode reso- nances and field patterns can be controlled by modulating the PC waveguides. It is expected that functions such as switching and routing could be developed naturally by using junction modes without any special design of microcavities. Our calculation results can be explained by the coupled mode theory.展开更多
The derivations of several conservation laws of the generalized nonlocal nonlinear Schrodinger equation are presented. These invaxiants are the number of particles, the momentum, the angular momentum and the Hamiltoni...The derivations of several conservation laws of the generalized nonlocal nonlinear Schrodinger equation are presented. These invaxiants are the number of particles, the momentum, the angular momentum and the Hamiltonian in the quantum mechanical analogy. The Lagrangian is also presented.展开更多
We analyse a process of remote information concentration achieved by the W state. The result turns out to be neither as good as performed by the GHZ state nor as by the Smolin bound entangled state. Based on this part...We analyse a process of remote information concentration achieved by the W state. The result turns out to be neither as good as performed by the GHZ state nor as by the Smolin bound entangled state. Based on this particular phenomenon, the properties of the three entangled states are realized.展开更多
The fundamental and second order strongly nonlocal solitons of the nonlocal nonlinear Schrodinger equation for several types of nonlocal responses are calculated by Ritz＇s variational method. For a specific type of n...The fundamental and second order strongly nonlocal solitons of the nonlocal nonlinear Schrodinger equation for several types of nonlocal responses are calculated by Ritz＇s variational method. For a specific type of nonlocal response, the solutions of the strongly nonlocal solitons with the same beam width but different degrees of nonlocality are identical except for an amplitude factor. For a nonlocal case where the nonlocal response function decays in direct proportion to the mth power of the distance near the source point, the power and the phase constant of the strongly nonlocal soliton are in inverse proportion to the （m ＋ 2）th power of its beam width.展开更多
An improved nonlinear Schrodinger equation different from usual one of spinor Bose-Einstein condensates （BECs） in an optical lattice are obtained by taking into account a nonlinear term in the equation of motion for...An improved nonlinear Schrodinger equation different from usual one of spinor Bose-Einstein condensates （BECs） in an optical lattice are obtained by taking into account a nonlinear term in the equation of motion for probability amplitude of spins carefully. The elliptic function wave solutions of the model are found under specific boundary condition, for example, the two ends of the atomic chain are fixed. In the case of limit the elliptic function wave solutions are reduced into spin-wave-like or solitons.展开更多
The influence of multi-photon pulses on practical differcBtial-phase-shift quantum key distribution （DPS-Qt（D） is analysed. We have estimated the information which Eve obtained by PNS （photon-number splitting） at...The influence of multi-photon pulses on practical differcBtial-phase-shift quantum key distribution （DPS-Qt（D） is analysed. We have estimated the information which Eve obtained by PNS （photon-number splitting） attack and BS （beam splitting） attack. The result indicates that the PNS attack and BS attack will not limit the transmission distance as long as we select an appropriate mean photon number. Also, the maximum mean photon number under BS attack in practical DPS-QKD system and the set of practical assumptions about Eve＇s capabilities are presented.展开更多
The decoherence of two initially entangled qubits coupled with a squeezed vacuum cavity separately is investigated exactly. The results show that, first, in principle, the disentanglement time decreases with the incre...The decoherence of two initially entangled qubits coupled with a squeezed vacuum cavity separately is investigated exactly. The results show that, first, in principle, the disentanglement time decreases with the increase of squeeze parameter r, due to the augmenting of average photon number of every mode in the squeezed vacuum cavity. Second, there appear entanglement revivals after the complete disentanglement for the ease of even parity initial Bell state, while there occur the entanglement decrease and the entanglement revival before the complete disentanglement for the case of odd parity initial Bell state. The results are quite different from those for the case of qubits in a vacuum cavity.展开更多
By adopting in-line lensless Fourier setup and phase-shifting technique, we recorded the phase-shifting digital hologram at short distance. As the Fresnel diffraction condition is no longer valid, the convolution appr...By adopting in-line lensless Fourier setup and phase-shifting technique, we recorded the phase-shifting digital hologram at short distance. As the Fresnel diffraction condition is no longer valid, the convolution approach is chosen for the reconstruction. However, the simulated reference wave for the reconstruction would suffer from severe undersampling due to the comparatively large pixel size. To solve this problem, sine-interpolation is introduced to get the pixel-size of the hologram reduced prior to the reconstruction. The experimental results show that an object image of high fidelity is obtained with this method.展开更多
In the paper （Phys. Rev. 2006 A 4 062320） Agrawal et al. have introduced a kind of W-class state which can be used for the quantum teleportation of single-particle state via a three-particle von Neumann measurement,...In the paper （Phys. Rev. 2006 A 4 062320） Agrawal et al. have introduced a kind of W-class state which can be used for the quantum teleportation of single-particle state via a three-particle von Neumann measurement, and they thought that the state could not be used to teleport an unknown state by making two-particle and one-particle measurements. Here we reconsider the features of the W-class state and the quantum teleportation process via the W-class state. We show that, by introducing a unitary operation, the quantum teleportation can be achieved deterministically by making two-particle and one-particle measurements. In addition, our protocol is extended to the process of teleporting two-particle state and splitting information.展开更多
In this paper,we explore whether a feature selection method can improve model performance by using some classical machine learning models,artificial neural network,k-nearest neighbor,partial least squares-discriminati...In this paper,we explore whether a feature selection method can improve model performance by using some classical machine learning models,artificial neural network,k-nearest neighbor,partial least squares-discrimination analysis,random forest,and support vector machine(SVM),combined with the feature selection methods,distance correlation coefficient(DCC),important weight of linear discriminant analysis(IW-LDA),and Relief-F algorithms,to discriminate eight species of wood(African rosewood,Brazilian bubinga,elm,larch,Myanmar padauk,Pterocarpus erinaceus,poplar,and sycamore)based on the laser-induced breakdown spectroscopy(LIBS)technique.The spectral data are normalized by the maximum of line intensity and principal component analysis is applied to the exploratory data analysis.The feature spectral lines are selected out based on the important weight assessed by DCC,IW-LDA,and Relief-F.All models are built by using the different number of feature lines(sorted by their important weight)as input.The relationship between the number of feature lines and the correct classification rate(CCR)of the model is analyzed.The CCRs of all models are improved by using a suitable feature selection.The highest CCR achieves(98.55...0.39)%when the SVM model is established from 86 feature lines selected by the IW-LDA method.The result demonstrates that a suitable feature selection method can improve model recognition ability and reduce modeling time in the application of wood materials classification using LIBS.展开更多
We propose a scheme for generating a genuine four-particle polarisation entangled state ｜χ^00） that has many interesting entanglement properties and potential applications in quantum information processing. In our ...We propose a scheme for generating a genuine four-particle polarisation entangled state ｜χ^00） that has many interesting entanglement properties and potential applications in quantum information processing. In our scheme, we use the weak cross-Kerr nonlinear interaction between field-modes and the non-demolition measurement method based on highly efficient homodyne detection, which is feasible under the current experiment conditions.展开更多
The propagation behavior of light passing through a subwavelength metal slit structure is usually modeled by a Fabry-Perot （FP） resonant cavity based on the feature of transmission spectra. However, this mechanism b...The propagation behavior of light passing through a subwavelength metal slit structure is usually modeled by a Fabry-Perot （FP） resonant cavity based on the feature of transmission spectra. However, this mechanism belongs to a conjecture and it should be proven. We present a direct evidence from the numerical simulations of the amplitude distribution of the magnetic field by employing the time-domain simulation method. The light propagation behavior clearly shows a multi-reflection process inside a subwavelength slit as soon as it enters the slit. An analytical formula for calculating the field distribution involving the multi-reflection process is presented, and the theoretical calculations agree with the numerically simulated results. Our results provide explicit evidence that the FP model is reasonable to the description of the propagation process of light inside a subwavelength slit structure.展开更多
We present general and optimal schemes for local conversion of pure states, via one specific example. First, we give the general solution of the doubly stochastic matrix. Then, we find the general and optimal positive...We present general and optimal schemes for local conversion of pure states, via one specific example. First, we give the general solution of the doubly stochastic matrix. Then, we find the general and optimal positive-operator-valued measure （POVM） to realize the local conversion of pure states. Lastly, the physical realization of the POVM is discussed. We show that our scheme has a more general and better effect than other schemes.展开更多
The propagation and interaction of nonlocal incoherent white-light solitons in strongly nonlocal kerr media is investigated. Numerical simulations show that the interaction properties of nonlocal incoherent white-ligh...The propagation and interaction of nonlocal incoherent white-light solitons in strongly nonlocal kerr media is investigated. Numerical simulations show that the interaction properties of nonlocal incoherent white-light solitons are different from the case in local media. The interactions of nonlocal incoherent white-light solitons are always attractive independent of their relative phase, while the other parameters such as the extent of nonlocality and the input power have a great impact on the soliton interactions. Pertinent numerical examples are presented to show their propagation and interaction behaviour further.展开更多
This paper critically analyses and simulates the circuit configuration of the integral gated mode single photon detector which is proposed for eliminating the transient spikes problem of conventional gated mode single...This paper critically analyses and simulates the circuit configuration of the integral gated mode single photon detector which is proposed for eliminating the transient spikes problem of conventional gated mode single photon detector. The relationship between the values of the circuit elements and the effect of transient spikes cancellation has been obtained. With particular emphasis, the bias voltage of the avalanche photodiode and the output signal voltage of the integrator have been calculated. The obtained analysis results indicate that the output signal voltage of the integrator only relates to the total quantity of electricity of the avalanche charges by choosing the correct values of the circuit elements and integral time interval. These results can be used to optimize the performance of single photon detectors and provide guides for the design of single photon detectors.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 10674051)the Program for Innovative Research Team of the Higher Education of Guangdong Province,China (Grant No 06CXTD005)the Key Program of Extracurricular Research in South China Normal University (SCNU),China (Grant No 08GDKC02)
文摘Three-dimensional photonic crystal （PC） heterostructures with high quality are fabricated by using a pressure controlled isothermal heating vertical deposition technique. The formed heterostructures have higher quality, such as deeper band gaps and sharper band edges, than the heterostructures reported so far. Such a significant improvement in quality is due to the introduction of a thin TiO2 buffer layer between the two constitutional PCs. It is revealed that the disorder caused by lattice mismatch is successfully removed if the buffer layer is used once. As a result, the formed heterostructures possess the main features in the band gap of constitutional PCs. The crucial role of the thin buffer layer is also verified by numerical simulations based on the finite-difference time-domain technique.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60778032 and 10674051.
文摘By carrying out the two ideas of asymmetrical confinement and asymmetrical response into the photonic crystal （PC） structures that contain two or more nonlinear defects, we find that significantly unidirectional transmission can be achieved while the transmission for the positive launch direction maintains at large values. Our analyses are supported by the simulation results based on the finite-difference time-domain technique.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10974060 and 10774050)the Program for Innovative Research Team of the Higher Education in Guangdong,China (Grant No. 06CXTD005)
文摘This paper demonstrates experimentally and numerically that a significant modification of spontaneous emission rate can be achieved near the surface of a three-dimensional photonic crystal. In experiments, semiconductor coreshell quantum dots are intentionally confined in a thin polymer film on which a three-dimensional colloidal photonic crystal is fabricated. The spontaneous emission rate of quantum dots is characterised by conventional and time-resolved photoluminescence （PL） measurements. The modification of the spontaneous emission rate, which is reflected in the change of spectral shape and PL lifetime, is clearly observed. While an obvious increase in the PL lifetime is found at most wavelengths in the band gap, a significant reduction in the PL lifetime by one order of magnitude is observed at the short-wavelength band edge. Numerical simulation reveals a periodic modulation of spontaneous emission rate with decreasing modulation strength when an emitter is moved away from the surface of the photonic crystal. It is supported by the fact that the modification of spontaneous emission rate is not pronounced for quantum dots distributed in a thick polymer film where both enhancement and suppression are present simultaneously. This finding provides a simple and effective way for improving the performance of light emitting devices.
基金Project supported by the National Natural Science Foundation of China (Grant No 10674051)the Natural Science Foundation of Guangdong province, China (Grant No 06025082)+1 种基金the Program for Innovative Research Team of the Higher Education in Guangdong (Grant No 06CXTD005)the Program for New Century Excellent Talents (NCET) in University of China (Grant No ncet-04-0829)
文摘Application of the pressure controlled isothermal heating vertical deposition method to the fabrication of colloidal photonic crystals is systematically investigated in this paper. The fabricated samples are characterized by scanning electron microscope and transmission spectrum. High-quality samples with large transmissions in the pass bands and the sharp band edges are obtained and the optimum growth condition is determined. For the best sample, the transmission in the pass bands approaches 0.9 while that in the band gap reaches 0.1. More importantly, the maximum differential transmission as high as 0.1/nm is achieved. In addition, it is found that the number of stacking layers does not increase linearly with concentration of PS spheres in a solution, and a gradual saturation occurs when the concentration of PS spheres exceeds 1.5 wt.%. The uniformity of the fabricated samples is examined by transmission measurements on areas with different sizes. Finally, the tolerance of the fabricated samples to baking was studied.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10674051 and 10811120010)the Program for Innovative Research Team of the Higher Education of Guangdong, China (Grant No 06CXTD005)
文摘We investigate numerically and experimentally the modification of the spontaneous emission rate for micrometersized light sources embedded in a hollow-core photonic crystal fiber （HCPCF）. The diameter of the light source is deliberately chosen such that they could be easily introduced into the central hole of the hollow-core photonic crystal fiber by capillary force. The photoluminescence from the microparticles is measured by using an inverted microscope in combination with a spectrometer. The modification of the spontaneous emission rate is observed in a wavelength region where there is no band gap. The experimental observations are consistent with the simulation results obtained by the plane wave expansion and finite-difference time-domain techniques.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60778032, 61271117, and 10974060.
文摘In optical circuits, functional elements are often placed on waveguide junctions. We show that a junction in photonic crystals （PCs） possesses localized modes very close to the bandpass of waveguides. Their mode reso- nances and field patterns can be controlled by modulating the PC waveguides. It is expected that functions such as switching and routing could be developed naturally by using junction modes without any special design of microcavities. Our calculation results can be explained by the coupled mode theory.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10474023 and 10674050） and Specialized Research Fund for the Doctoral Program of Higher Education （Grant No 20060574006）.
文摘The derivations of several conservation laws of the generalized nonlocal nonlinear Schrodinger equation are presented. These invaxiants are the number of particles, the momentum, the angular momentum and the Hamiltonian in the quantum mechanical analogy. The Lagrangian is also presented.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10404007 and 60578055.
文摘We analyse a process of remote information concentration achieved by the W state. The result turns out to be neither as good as performed by the GHZ state nor as by the Smolin bound entangled state. Based on this particular phenomenon, the properties of the three entangled states are realized.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10474023 and 10674050） and Specialized Research Fund for the Doctoral Program of Higher Education （Grant No 20060574006）.
文摘The fundamental and second order strongly nonlocal solitons of the nonlocal nonlinear Schrodinger equation for several types of nonlocal responses are calculated by Ritz＇s variational method. For a specific type of nonlocal response, the solutions of the strongly nonlocal solitons with the same beam width but different degrees of nonlocality are identical except for an amplitude factor. For a nonlocal case where the nonlocal response function decays in direct proportion to the mth power of the distance near the source point, the power and the phase constant of the strongly nonlocal soliton are in inverse proportion to the （m ＋ 2）th power of its beam width.
基金supported by National Natural Science Foundation of China under Grant No.10474022
文摘An improved nonlinear Schrodinger equation different from usual one of spinor Bose-Einstein condensates （BECs） in an optical lattice are obtained by taking into account a nonlinear term in the equation of motion for probability amplitude of spins carefully. The elliptic function wave solutions of the model are found under specific boundary condition, for example, the two ends of the atomic chain are fixed. In the case of limit the elliptic function wave solutions are reduced into spin-wave-like or solitons.
文摘The influence of multi-photon pulses on practical differcBtial-phase-shift quantum key distribution （DPS-Qt（D） is analysed. We have estimated the information which Eve obtained by PNS （photon-number splitting） attack and BS （beam splitting） attack. The result indicates that the PNS attack and BS attack will not limit the transmission distance as long as we select an appropriate mean photon number. Also, the maximum mean photon number under BS attack in practical DPS-QKD system and the set of practical assumptions about Eve＇s capabilities are presented.
基金supported by the National Natural Science Foundation of China (Grant No 60578055)the State Key Program for Basic Research of China (Grant Nos 2007CB925204 and 2007CB307001)
文摘The decoherence of two initially entangled qubits coupled with a squeezed vacuum cavity separately is investigated exactly. The results show that, first, in principle, the disentanglement time decreases with the increase of squeeze parameter r, due to the augmenting of average photon number of every mode in the squeezed vacuum cavity. Second, there appear entanglement revivals after the complete disentanglement for the ease of even parity initial Bell state, while there occur the entanglement decrease and the entanglement revival before the complete disentanglement for the case of odd parity initial Bell state. The results are quite different from those for the case of qubits in a vacuum cavity.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60747001 and 60467003)
文摘By adopting in-line lensless Fourier setup and phase-shifting technique, we recorded the phase-shifting digital hologram at short distance. As the Fresnel diffraction condition is no longer valid, the convolution approach is chosen for the reconstruction. However, the simulated reference wave for the reconstruction would suffer from severe undersampling due to the comparatively large pixel size. To solve this problem, sine-interpolation is introduced to get the pixel-size of the hologram reduced prior to the reconstruction. The experimental results show that an object image of high fidelity is obtained with this method.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10404007 and 60578055)the State Key Program for Basic Research of China (Grant No. 2007CB925204)
文摘In the paper （Phys. Rev. 2006 A 4 062320） Agrawal et al. have introduced a kind of W-class state which can be used for the quantum teleportation of single-particle state via a three-particle von Neumann measurement, and they thought that the state could not be used to teleport an unknown state by making two-particle and one-particle measurements. Here we reconsider the features of the W-class state and the quantum teleportation process via the W-class state. We show that, by introducing a unitary operation, the quantum teleportation can be achieved deterministically by making two-particle and one-particle measurements. In addition, our protocol is extended to the process of teleporting two-particle state and splitting information.
基金support from National Natural Science Foundation of China(No.62075011)Graduate Technological Innovation Project of Beijing Institute of Technology(No.2019CX20026)。
文摘In this paper,we explore whether a feature selection method can improve model performance by using some classical machine learning models,artificial neural network,k-nearest neighbor,partial least squares-discrimination analysis,random forest,and support vector machine(SVM),combined with the feature selection methods,distance correlation coefficient(DCC),important weight of linear discriminant analysis(IW-LDA),and Relief-F algorithms,to discriminate eight species of wood(African rosewood,Brazilian bubinga,elm,larch,Myanmar padauk,Pterocarpus erinaceus,poplar,and sycamore)based on the laser-induced breakdown spectroscopy(LIBS)technique.The spectral data are normalized by the maximum of line intensity and principal component analysis is applied to the exploratory data analysis.The feature spectral lines are selected out based on the important weight assessed by DCC,IW-LDA,and Relief-F.All models are built by using the different number of feature lines(sorted by their important weight)as input.The relationship between the number of feature lines and the correct classification rate(CCR)of the model is analyzed.The CCRs of all models are improved by using a suitable feature selection.The highest CCR achieves(98.55...0.39)%when the SVM model is established from 86 feature lines selected by the IW-LDA method.The result demonstrates that a suitable feature selection method can improve model recognition ability and reduce modeling time in the application of wood materials classification using LIBS.
基金supported by the National Natural Science Foundation of China (Grant No.60978009 )the National Basic Research Program of China (Grant Nos.2009CB929604 and 2007CB925204)
文摘We propose a scheme for generating a genuine four-particle polarisation entangled state ｜χ^00） that has many interesting entanglement properties and potential applications in quantum information processing. In our scheme, we use the weak cross-Kerr nonlinear interaction between field-modes and the non-demolition measurement method based on highly efficient homodyne detection, which is feasible under the current experiment conditions.
基金Supported by the National Basic Research Program of China under Grant No 2006CB302901, and the National Natural Science Foundation of China under Grant No 10874124.
文摘The propagation behavior of light passing through a subwavelength metal slit structure is usually modeled by a Fabry-Perot （FP） resonant cavity based on the feature of transmission spectra. However, this mechanism belongs to a conjecture and it should be proven. We present a direct evidence from the numerical simulations of the amplitude distribution of the magnetic field by employing the time-domain simulation method. The light propagation behavior clearly shows a multi-reflection process inside a subwavelength slit as soon as it enters the slit. An analytical formula for calculating the field distribution involving the multi-reflection process is presented, and the theoretical calculations agree with the numerically simulated results. Our results provide explicit evidence that the FP model is reasonable to the description of the propagation process of light inside a subwavelength slit structure.
基金Supported from the National Basic Research Programme of China under Grant No 2007CB307001, and the Natural Science Foundation of Guangdong Province under Grant No 06029431.
文摘We present general and optimal schemes for local conversion of pure states, via one specific example. First, we give the general solution of the doubly stochastic matrix. Then, we find the general and optimal positive-operator-valued measure （POVM） to realize the local conversion of pure states. Lastly, the physical realization of the POVM is discussed. We show that our scheme has a more general and better effect than other schemes.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10474023 and 10674050, and Specialized Research Fund for the Doctoral Programme of Higher Education under Grant No 20060574006.
文摘The propagation and interaction of nonlocal incoherent white-light solitons in strongly nonlocal kerr media is investigated. Numerical simulations show that the interaction properties of nonlocal incoherent white-light solitons are different from the case in local media. The interactions of nonlocal incoherent white-light solitons are always attractive independent of their relative phase, while the other parameters such as the extent of nonlocality and the input power have a great impact on the soliton interactions. Pertinent numerical examples are presented to show their propagation and interaction behaviour further.
基金Project supported by the State Key Development Program for Basic Research of China (Grant No 2007CB307001)Guangdong Key Technologies R&D Program (Grant No 2007B010400009)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No 2001CB309302)
文摘This paper critically analyses and simulates the circuit configuration of the integral gated mode single photon detector which is proposed for eliminating the transient spikes problem of conventional gated mode single photon detector. The relationship between the values of the circuit elements and the effect of transient spikes cancellation has been obtained. With particular emphasis, the bias voltage of the avalanche photodiode and the output signal voltage of the integrator have been calculated. The obtained analysis results indicate that the output signal voltage of the integrator only relates to the total quantity of electricity of the avalanche charges by choosing the correct values of the circuit elements and integral time interval. These results can be used to optimize the performance of single photon detectors and provide guides for the design of single photon detectors.
