Accepted
,,Received Date:2024-05-22
Abstract +
Ultrasonic phase changes carry critical information about tissue structures, and phase weighting can enhance the sharpness of ultrasonic images. Addressed here are challenges, such as the faint scattering echoes from folds, substantial noise interference, and the lengthy processing time involved in time-domain corrected imaging. Processed in this work is a frequency-domain coherent imaging method based on the coherence factor of the phase imaginary part. Firstly, the phase information in the wavefield signal is extracted, and then the phase imaginary part matrix is extracted by using circular statistics. Subsequent construction of the phase imaginary coherence factor (PICF) involves multiplying this matrix with the original frequency-domain matrix used in phase shift migration (PSM) imaging. By incorporating the PICF into phase migration imaging and adjusting the PICF of the migrating wavefield at each layer, fibre texture information can be efficiently recovered by frequency domain signal multiplication. In this paper, this technique is applied to the 18-mm-thick carbon-glass fiber composite boards. The experimental outcomes indicate that without PICF weighting, phase shift imaging loses the fiber layout information at depths exceeding 10 mm and cannot detect defects in deeper areas. The PICF-weighted PSM imaging identifies three fibre folds with depths of 11 mm, 15 mm and 16 mm, respectively. This method improves the imaging clarity and textural detail of folding defects, while maintaining a detection error of about 10% for folding angles. The imaging time is only 1.5 s, and its computational efficiency is at least 8.67 times that of time-domain TFM imaging.
,,Received Date:2024-06-11
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In practical applications, flexibility, lightweight, and high performance are the characteristics that polymer-based electromagnetic shielding materials should have. At present, it is still a great challenge to prepare polymer-based electromagnetic shielding materials with excellent conductivity, electromagnetic shielding properties, and mechanical properties. Therefore, in this work, single-walled carbon nanotubes/polyetherimide composite films are prepared by electrostatic spinning and vacuum-assisted filtration through using single-walled carbon nanotubes and polyetherimide as raw materials. By regulating the surface density of single-walled carbon nanotubes, the conductivity of the composite film can be enhanced to 1866 S/cm. For the electromagnetic shielding performance, the total electromagnetic shielding efficacy of single-walled carbon nanotubes/polyetherimide composite film in Ku band (12–18 GHz) is in a range of 75.78–81.83 dB, which is higher than the electromagnetic shielding efficacy of pure single-walled electromagnetic shielding effectiveness of carbon nanotube films (65.19–69.81 dB). This is attributed to the formation of interfaces between the polyetherimide fibers and the single-walled carbon nanotubes, with more interfaces consuming more electromagnetic wave energy for a given range of single-walled carbon nanotube surface densities. For the mechanical properties, the maximum tensile strength and elongation at the break of the single-walled carbon nanotube/polyetherimide film are 1.13 and 1.5 times higher than those of the single-walled carbon nanotube film, with the values of 28.52 MPa and 7.91%, respectively. As the surface density of single-walled carbon nanotubes increases, the interaction between single-walled carbon nanotubes as well as the interaction between polyetherimide fibers and single-walled carbon nanotubes at the interface plays a role in enhancing the mechanical properties of the composite films. The single-walled carbon nanotube/polyetherimide composite films, as an excellent polymer-based electromagnetic shielding composite material, can be used in fields such as the protection of precision electronic instruments and wearable electronic devices.
Development of a transmission X-ray nanometer-resolution microscope based on laboratory light source
,,Received Date:2024-05-24
Abstract +
Transmission X-ray microscope (TXM) is a high-precision, cutting-edge X-ray imaging instrument, which is a marvel of modern science and technology. It enables non-destructive imaging on a nanoscale, providing a powerful research tool for various scientific fields such as physics, life sciences, materials science, and chemistry. Although many synchrotron radiation devices at home and abroad have established nano-CT experimental stations with TXM as the core, currently only a few companies internationally can provide commercial TXM instrument based on laboratory X-ray sources. The primary reason is that this instrument involves numerous engineering challenges, including high-brightness laboratory X-ray sources, high-resolution X-ray optical elements, high-precision sample stage systems, high-sensitivity detectors, and extremely strict requirements for environmental factors such as temperature and vibration. In order to promote the development of high-end X-ray imaging instruments, it is necessary to overcome the technological bottlenecks encountered in the development of X-ray nano-CT. Discussed in this work mainly are the instrument design of a laboratory transmission X-ray microscope with working energy of 5.4 keV and the results of full-field imaging experiments. To start with, the design of the TXM instrument is introduced in detail. The TXM instrument is equipped with several key components, including laboratory X-ray source, condenser, sample stage module, zone plate, and imaging detector. The TXM instrument adopts a modular vibration isolation design and is equipped with a dedicated temperature control system. The main imaging magnifications of the TXM instrument are 50×, 75×, and 100×, and the optical path parameters and physical photos of the instrument under these three magnifications are introduced. The X-ray source used is a micro-focus X-ray source, operating in Cr target mode, with a focal spot size of 20 μm and a Ka characteristic spectrum brightness of
$ 5\times {10}^{9}{\mathrm{p}}{\mathrm{h}}{\mathrm{o}}{\mathrm{t}}{\mathrm{o}}{\mathrm{s}}/(\dot{}\dot{}) $
. The X-ray source provides illumination for the sample after being focused by an ellipsoidal condenser. The outer ring of the condenser's illumination ring corresponds to a numerical aperture (NA) of
$ {NA}_{2} = 3.196mrad $
, and the inner ring corresponds to a numerical aperture of
$ {NA}_{1} = 1.9086mrad $
. Under these conditions, the limit resolution of this TXM instrument is 22 nm. The zone plate has a diameter of 70μm, a focal length of 8.7mm, and 616 zones. The TXM instrument uses a high-resolution optical coupling detector equipped with a scientific-grade CMOS camera with an effective pixel size of 7.52μm. The optical coupling detector is equipped with 2× and 10× high numerical aperture objectives. When the TXM instrument magnification is 50×, the effective pixel size of the TXM instrument is 15 nm. In addition,a gold resolution test card is used as the sample to determine the imaging field of view of the TXM instrument by observing the size of the imaging area of the test card on the detector, and to determine the imaging resolution of the TXM instrument by observing the line width of the star-shaped target in the center of the test card. Experimental results show that the TXM instrument has an imaging field of view of 26μm and can achieve the clear imaging of characteristic structure with a line width of 30 nm. The radial power spectrum curve of the Siemens Star test card imaging results shows that the maximum resolution of TXM instrument is 28.6 nm. Finally, we draw some conclusions and present outlook. At present, imaging of 30-nm-wide line features has been realized, but the imaging of 30-nm half pitch line pair feature has not yet been achieved, and the limit resolution has not reached the design value, either. We will continue to explore the potential for upgrading the imaging resolution of the laboratory TXM in future work.
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Abstract +
In recent years, the use of discrete memristors to enhance chaotic maps has received increasing attention. The introduction of memristors increases the complexity of chaotic maps, making them suitable for engineering applications based on chaotic systems. In this paper, a fractional-order discrete memristor exhibiting local activity and controllable asymptotic stability points is constructed using multiband nonlinear functions. The locally active property of this memristor is demonstrated using the power-off plot and DC V-I plot. It is then introduced into the Henon map to construct a fractional-order memristive Henon map capable of generating an arbitrary number of coexisting attractors. Simulation results indicate that the number of fixed points in the system is controlled by the memristor parameters, correlating with the number of coexisting attractors, thus enabling controllable homogeneous multistability. The complex dynamical behaviors of this map are analyzed using phase portraits, bifurcation diagrams, Maximum Lyapunov Exponent (MLE), and attractor basins. Numerical simulations show that the fractional-order map can generate various periodic orbits, chaotic attractors, and period-doubling bifurcations. The system is then implemented on an ARM digital platform. The experimental results are consistent with the simulation results, confirming the accuracy of the theoretical analysis and its physical feasibility. Finally, a parallel video encryption algorithm is designed using the chaotic sequence iteratively generated by fraction-order memory Henon mapping, which mainly includes frame pixel scrambling and XOR diffusion. Comprehensive security analyses were conducted, proving the robustness and reliability of the proposed encryption scheme. The results show that the encryption algorithm can effectively protect video information. In the future, we will explore other methods for constructing chaotic or hyperchaotic systems with controllable multistability and study their circuit implementation, synchronization control, and chaos-based engineering applications.
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Abstract +
This paper presents two innovative sliding mode control laws that are meticulously designed based on the reaching law convergence principle. These control laws aim to achieve both finite-time and fixed-time synchronization for a specific class of memristive chaotic systems, which are known for their intricate and complex dynamical behaviors. By leveraging these control strategies, we can effectively manage the synchronization process, ensuring rapid convergence. Firstly, for the finite-time synchronization issue, a novel power reaching law is devised. Compared with the conventional reaching law, the prominent advantage of this reaching law is that the chattering of the sliding mode control is reduced to a lesser extent and the speed of reaching the sliding surface is quicker. An upper bound on the stabilization time, which is dependent on the initial conditions of the system, is obtained and the stability of the system is proved. For the fixed time synchronization problem, a new double power reaching law is put forward to minimize the chattering and accelerate the convergence. Then, by utilizing the fixed time stability theory, the upper bound of the convergence time that remains invariant with the initial value of the system is derived. Finally, in order to verify the effectiveness and feasibility of the theoretical derivation in this paper, two sets of control experiments are set up in the numerical simulation part to compare the influence of the two control laws on the system synchronization state. The experimental phenomenon strongly proves the accuracy of the proposed theorem.
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ObjectiveWith advancements in optical technology, the investigation of light-field-particle interactions has gained significant momentum. Such studies find widespread applications in optical manipulation, precision laser ranging, laser gas spectroscopy, and related fields. In optical manipulation techniques, employing two or more laser beams proves more effective for capturing and manipulating particles compared to using a single beam alone. Furthermore, as the demand grows for manipulating particles with intricate structures, there is a need to delve into the radiation e force characteristics of double Gaussian beams on non-uniform chiral particles. This research aims to deepen our understanding of how optical fields influence particles, thereby offering fresh perspectives on manipulating and utilizing non-uniform chiral layered particles at both micro- and nano-scales.
MethodBased on the generalized Lorentz-Mie theory (GLMT) and spherical vector wave functions (SVWFs), the expansion of the total incident field of a double Gaussian beam is derived using the coordinate addition theorem. The incident field coefficients and scattering coefficients of each region of the multilayer chiral sphere are obtained by enforcing boundary continuity and employing multilayer sphere scattering theory. The radiation force acting on non-uniform chiral layered particles within a double Gaussian beam is then derived through application of the electromagnetic momentum conservation theorem.
Results and DiscussionsThe correctness of the theory and programs in this paper is proven by comparison with existing literature. The influence of various parameters on the radiation force is analyzed in detail, such as the incident angle, polarization angle, beam waist width, beam center position, and internal and external chiral parameters. The results indicates that compared to a single Gaussian beam, counter-propagating Gaussian standing waves exhibit significant advantages in capturing or confining inhomogeneous chiral layered particles, offering enhanced particle manipulation capabilities. Additionally, by selecting an appropriate polarization state of the incident light, a delicate balance can be achieved among these parameters, effectively stabilizing the capture of inhomogeneous chiral particles.
ConclusionsThis study employs the generalized Lorenz-Mie theory and the principle of electromagnetic momentum conservation to derive analytical expressions for the transverse and axial radiation forces exerted by dual Gaussian beams on multi-layered chiral particles propagating in arbitrary directions. The research provides an in-depth analysis of how standing wave beams affect the radiation force behavior of non-uniform chiral particles. Numerical analysis reveals significant influences of beam waist, particle size, chiral parameters, polarization angle and mode, as well as particle refractive index on both transverse and axial radiation forces. This research is crucial for analyzing and understanding the optical properties of complex-shaped multilayer biological cells and has significant applications in the micromanipulation of multilayer biological structures.
MethodBased on the generalized Lorentz-Mie theory (GLMT) and spherical vector wave functions (SVWFs), the expansion of the total incident field of a double Gaussian beam is derived using the coordinate addition theorem. The incident field coefficients and scattering coefficients of each region of the multilayer chiral sphere are obtained by enforcing boundary continuity and employing multilayer sphere scattering theory. The radiation force acting on non-uniform chiral layered particles within a double Gaussian beam is then derived through application of the electromagnetic momentum conservation theorem.
Results and DiscussionsThe correctness of the theory and programs in this paper is proven by comparison with existing literature. The influence of various parameters on the radiation force is analyzed in detail, such as the incident angle, polarization angle, beam waist width, beam center position, and internal and external chiral parameters. The results indicates that compared to a single Gaussian beam, counter-propagating Gaussian standing waves exhibit significant advantages in capturing or confining inhomogeneous chiral layered particles, offering enhanced particle manipulation capabilities. Additionally, by selecting an appropriate polarization state of the incident light, a delicate balance can be achieved among these parameters, effectively stabilizing the capture of inhomogeneous chiral particles.
ConclusionsThis study employs the generalized Lorenz-Mie theory and the principle of electromagnetic momentum conservation to derive analytical expressions for the transverse and axial radiation forces exerted by dual Gaussian beams on multi-layered chiral particles propagating in arbitrary directions. The research provides an in-depth analysis of how standing wave beams affect the radiation force behavior of non-uniform chiral particles. Numerical analysis reveals significant influences of beam waist, particle size, chiral parameters, polarization angle and mode, as well as particle refractive index on both transverse and axial radiation forces. This research is crucial for analyzing and understanding the optical properties of complex-shaped multilayer biological cells and has significant applications in the micromanipulation of multilayer biological structures.
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In response to the technological requirements for miniaturized, multi-angle, multi-altitude, and rapid simultaneous acquisition of atmospheric pollutants, this study has developed an integrated, lightweight, and cost-effective airborne Differential Optical Absorption Spectroscopy (DOAS) system. This system is designed to be used on a rotorcraft unmanned aerial vehicle (UAV) platform for monitoring atmospheric pollutants. The composition of the hexacopter UAV platform and the airborne DOAS system is detailed in this paper. The system includes a MAX-DOAS spectral acquisition system, a control system, and a flight environment monitoring system. Commands are sent from a computer via serial communication to drive a gimbal, controlling the azimuth and elevation angles of the telescope, with a camera recording the light obstruction. The sunlight scattered by the atmosphere is collected by the telescope and transmitted via fiber optics to the spectrometer, which then transmits the data to the control computer. Additionally, the system captures data on altitude, temperature, humidity, and GPS location during flight, filtering out spectral data under abnormal flight conditions. Stability studies indicate that the mean angular deviations for yaw, roll, and pitch are 0.07°, -0.13°, and -0.12° respectively, meeting the requirements for monitoring stability. Comparative experiments with a commercial ground-based DOAS system show that the correlation coefficients between the monitoring data of both systems are greater than 0.92, confirming the reliability of the airborne system. During field flight experiments, the airborne DOAS system conducted observations at altitudes of 30m, 60m, and 90m, with the elevation angle set at 0° and the azimuth angle measured every 30° from 0° to 360°. The system successfully obtained the concentration distribution of NO2, SO2, and HCHO at different azimuth angles and altitudes. The results indicate that the concentrations of all three gases decrease with increasing altitude, with higher concentrations observed in the southeast direction, suggesting the presence of pollution sources in that direction. Further analysis considering altitude changes revealed that the rate of concentration decrease for NO2and SO2slows with increasing altitude, while the decrease rate for HCHO remains relatively constant. The findings demonstrate that this system effectively meets the technical demands for simultaneous rapid multi-angle and multi-altitude detection of atmospheric pollutants, providing essential support for detailed monitoring in complex urban micro-environments.
,,Received Date:2024-06-11
Abstract +
Most of the existing metropolitan quantum networks are implemented based on a single quantum key distribution protocol, and interconnecting metropolitan quantum networks implemented by different protocols are the development trend of large-scale quantum networks, but there are still some problems in the provision of inter-domain key services , such as low possibility of and mismatch between key supply and demand. To solve the above problems, this paper proposes two on-demand inter-domain key service provisioning strategies for multi-domain cross-protocol quantum networks, namely, on-demand provisioning strategy based on BB84 bypass first (BB84-BF) and on-demand provisioning strategy based on MDI bypass first (MDI-BF). Meanwhile, a service provisioning model for multi-domain cross-protocol quantum networks is constructed, and an on-demand inter-domain key service provisioning algorithm is designed. Moreover, numerical simulations and performance evaluation are carried out under two scenarios: high key rate demand and low key rate demand for two-domain and three-domain quantum network topologies. Simulation results verify that the proposed on-demand provisioning strategies have better applicability to different multi-domain quantum networks. In addition, for different key rate requirements, the MDI-BF strategy and BB84-BF strategys have different performance advantages under different performance indicators, For example, in terms of the success possibility of inter-domain key service requests, the MDI-BF strategy is more suitable for the low key rate requirements (~30% higher than the traditional strategies in two domain topologies), while the BB84-BF strategy is more suitable for the high key rate requirements (~19% higher than the traditional strategies under two domain topologies). In addition, compared with the traditional strategies, the proposed on-demand provisioning strategies can increase the balance between key supply and demand by more than one order of magnitude. Hence, the proposed strategies can reduce the cost of inter-domain key service provisioning and improve the realistic security level.
,,Received Date:2024-04-03
Abstract +
Hydrazone molecular switches have significant application value in supramolecular chemistry. A new type of hydrazone molecular switch, named isatin N2-diphenylhydrazone, has been synthesized. Owing to its cis-trans isomerization characteristics under visible light excitation, ease of synthesizing of derivatives, and sensitivity to external stimuli, it has important application value in the field of biochemistry. Because of its forward and backward visible light excitation characteristics, it is considered a class of compound that is very suitable for molecular switches, and it has a wide application value in fields such as biotechnology. In addition, the derivatives compound exhibits strong interactions with negative ions, which enhances its function as a molecular switch, making it a four-state molecular switch that can be achieved by a single molecule. However, the photo-induced isomerization mechanism of these new molecular switches is not yet clear, and whether there are novel phenomena in the isomerization process is also unknown. In this work, a semi empirical OM2/MRCI based trajectory surface hopping dynamics method is adopted to systematically study a photo induced isomerization mechanism based on the E-Z isomerization process of the isatin N2-diphenylhydrazones molecular switch. Optimization configuration and the average lifetime of the first excited S1state are obtained by using the semi-empirical OM2/MRCI method of molecular switch. It is found that the average lifetime of the S1excited state of the E-configuration molecular switch is about 107 fs, and the quantum yield of E-Z isomerization of the molecular switch is 16.01%. By calculating the photo induced isomerization process of the molecular switch, two different isomerization mechanisms of the molecular switch are identified. In addition to the traditional molecular switch isomerization mechanism revolving around the C=N bond, a new isomerization mechanism, i.e. the face-to-face twisting of the molecular switch rotor part is elucidated. By calculating the time-resolved fluorescence radiation spectrum, it is predicted that there may be a very fast fluorescence quenching phenomenon occurring in about 75 fs in the isomerization process, slightly faster than the S1average decay events (107 fs). The information about wavelength-resolved attenuation at different times is also calculated, which reflects the ultrafast fluorescence quenching process accompanied by fluorescence red shift, ranging from 2.1 × 104cm–1to 3.4 × 104cm–1. By comparing the calculated fluorescence spectra with the average lifetime of excited states, the existence of “dark states” is proposed, and possible explanations for the existence of “dark states” are provided, and those “dark states” may be related to lower quantum yields. The research results can provide theoretical guidance for the design and application of new molecular switches. The ease of synthesis and sensitivity to external stimuli of its derivatives make those compounds extremely valuable in molecular switching and light measurement applications.
,,Received Date:2024-05-27
Abstract +
Thin-film solar cells provide an opportunity to reduce the cost of converting solar energy into electricity by replacing expensive and thick silicon wafers, which account for more than 50% of the total cost of photovoltaic (PV) modules. However, many thin-film solar cell materials result in low PV performance due to enhanced recombination through defect states. Cu(In,Ga)Se2(CIGS) is a promising thin-film solar cell material due to its direct tunable bandgap, high absorption coefficient, low effective electron and hole mass, and abundant constituent elements. Among them, magnetron sputtering or selenization technology is widely used to catch up with the development of preparing large-area CIGS thin-film solar cells because of its uniform film composition and simple process. However, the use of toxic gases such as H2Se and H2S and the difficulty in forming gradient bandgaps limit their development. In this work, the “V” Ga gradient classification of the absorbing layer of CIGS solar cells is realized by sputtering CuGaSe2(CGS) thin layers of different thickness values in the room temperature layer by sputtering and selenium-free methods of quaternary target sputtering. Firstly, the microstructure of the film is characterized by SEM, XRD, Raman and XPS, and when the CGS layer is located in the middle of the low-temperature layer, the grain size of the film is the largest, the crystallinity is the best, forming a “V-shaped” structure of CGI on the back of the absorbing layer. Subsequently, IV and external quantum efficiency(EQE) tests show that the optimized cell efficiency is as high as 15.04%, and the light response intensity is enhanced in the 300 －1200 nm band. Finally, the admittance spectrum(AS) test shows that the defect energy level of the solar cell changes from InGadefect toVCudefect of lower energy level, and the defect density decreases from 7.04×1015cm–3to 5.51×1015cm–3. This is comparable to the recording efficiency of the current single-target magnetron sputtering CIGS solar cells, demonstrating good application prospects.
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Abstract +
The construction of core-shell structures with different structural properties based on the epitaxial growth technique has become an effective technique for regulating the luminescence properties of micro/nanocrystals. In order to obtain richer spectral information, this work attempts to prepare NaYF4:50%Yb3+/2%Tm3+@NaYF4@ NaYF4:20%Yb3+/2%Er3+@NaYF4@NaYbF4:2%Er3+multilayered core-shell microcry- stals by using multiple epitaxial growth with the introduction of surface modifiers and controlling their reaction conditions. From the XRD and SEM results, it is evident that the core-shell microcrystals possess a pure hexagonal crystal structure in the form of a disk.The microdisk has a thickness of about 2.32 μm with a diameter of about 28.31μm. The upconversion luminescence characteristics of different single microcrystal structures were investigated by a confocal microspectroscopy system. In order to achieve the selective excitation and emission of a single microcrystal, the spatial distribution of luminescent ions can be controlled through the introduction of an intermediate isolation layer. Under 980 nm laser excitation, different excitation sites of the single microdisk exhibit different upconversion emission characteristics. The significant blue (450 nm and 475 nm), red (648 nm) and green (524 nm and 540 nm) emissions are observed, mainly originating from Tm3+ions and Er3+radiative transitions. Meanwhile, the red and blue upconversion emission intensities of the microcrystals were improved by using various shell layers. In addition, the luminescence and energy-transfer features of single microcrystals were explored by varying the excitation position. The experimental results demonstrate that the incorporation of NaYF4inert shells between luminescent layers can regulate luminescence and prevent ion interactions. By utilizing the spectral fingerprint data of dopant ions in various shell layers, we created customizable micro-nano photonic barcodes and employed them for optical anti-counterfeiting detection. This study explores the use of constructed core-shell structures with luminescent tunable micron core-shell structures to achieve diverse spectral information and maintain stability through their structural properties. Thus, this core-shell structure offers a novel approach for utilizing upconversion luminescent microcrystals in micro- and nanophotonics for anti-counterfeiting and display purposes.
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Abstract +
Objective:The optical information change of beams acted with biological tissue can get an insight into the new optical effects of tissue, even can provide a theoretical basis for the development of biphotonic medical diagnosis and therapy technologies. Polarization technology is also widely used in the field of biological detection own to its advantages of non-contact, rich information and without staining markers. In this work, the polarization behaviors of partially coherent screw-linear edge mixed dislocation beam transmitting in biological tissue have been analyzed and explored. Simultaneously, in order to gain a clearer and more intuitive understanding of the mixed dislocation beam, both the normalized intensity and phase distribution at source plane for different parametersaandbalso have been discussed. We hope that the obtained results will provide theoretical and experimental foundation for expanding the application of singularity beams in biological tissue imaging technology.
Method:By combining the Schell term with the field distribution of the screw-linear edge mixed dislocation beam at the source plane, and based on the generalized Huygens-Fresnel principle, the analytical expressions of the cross-spectral density matrix elements of partially coherent screw-linear edge dislocation beam propagating in biological tissues are derived. Adopting the unified theory of coherence and polarization, the polarization behaviors of the beams can be investigated in detailed.
Results:At the source plane, the intensity is non axisymmetric distribution, and there exists a coherent vortex with a topological charge size of 1 and a linear edge dislocation. The sign ofais related to the rotation direction of the phase singularity. The larger the value of b, the farther the linear edge dislocation is from the origin (Figs. 1-4). At the source plane, the degree of polarization and ellipticity between the same two points are independent of the four parameters, including dimensionless parametera, the off-axis distance of edge dislocationb, the spatial self-correlation lengthσyy, the spatial mutual-correlation lengthσxy(Figs. 5(a), 7(a), 8(a), 10(a), 11(a), 13(a), 14(a), 16(a)), the orientation angle is only independent of a andσxy(Figs. 6(a), 12(a)); the polarization of different two points is independent ofaandb(Figs. 5(b)-10(b)), but is related toσyyandσxy(Figs. 11(b)-13(b)). In transmission, the polarization degree and ellipticity of different two points fluctuate greatly (Figs. 5, 7, 8, 10, 11, 13, 14, 16) and the orientation angle displays less fluctuation (Figs. 6, 9, 12, 13). Finally, all the polarization state parameters tend to be a certain value, respectively.
Conclusions:The results show that whenbis smaller, the linear edge dislocation is paraxial and plays an important role in the polarization state change; whenbis larger, the polarization state changes of the screw-linear edge mixed dislocation beam will tend to be the pattern of spiral beams. The absolute value of the difference betweenσyyandσxyis also one of main factors of influencing the polarization state. The sign ofadoes not affect the change in polarization state, but its magnitude affects the changes speed. Due to more complex factors determining the correlation fluctuations between different points in the light field, the changes of different two points are more sensitive than those of the same two points in shallow biological tissue. Beams with different parameters can be selected for different application requirements.
Method:By combining the Schell term with the field distribution of the screw-linear edge mixed dislocation beam at the source plane, and based on the generalized Huygens-Fresnel principle, the analytical expressions of the cross-spectral density matrix elements of partially coherent screw-linear edge dislocation beam propagating in biological tissues are derived. Adopting the unified theory of coherence and polarization, the polarization behaviors of the beams can be investigated in detailed.
Results:At the source plane, the intensity is non axisymmetric distribution, and there exists a coherent vortex with a topological charge size of 1 and a linear edge dislocation. The sign ofais related to the rotation direction of the phase singularity. The larger the value of b, the farther the linear edge dislocation is from the origin (Figs. 1-4). At the source plane, the degree of polarization and ellipticity between the same two points are independent of the four parameters, including dimensionless parametera, the off-axis distance of edge dislocationb, the spatial self-correlation lengthσyy, the spatial mutual-correlation lengthσxy(Figs. 5(a), 7(a), 8(a), 10(a), 11(a), 13(a), 14(a), 16(a)), the orientation angle is only independent of a andσxy(Figs. 6(a), 12(a)); the polarization of different two points is independent ofaandb(Figs. 5(b)-10(b)), but is related toσyyandσxy(Figs. 11(b)-13(b)). In transmission, the polarization degree and ellipticity of different two points fluctuate greatly (Figs. 5, 7, 8, 10, 11, 13, 14, 16) and the orientation angle displays less fluctuation (Figs. 6, 9, 12, 13). Finally, all the polarization state parameters tend to be a certain value, respectively.
Conclusions:The results show that whenbis smaller, the linear edge dislocation is paraxial and plays an important role in the polarization state change; whenbis larger, the polarization state changes of the screw-linear edge mixed dislocation beam will tend to be the pattern of spiral beams. The absolute value of the difference betweenσyyandσxyis also one of main factors of influencing the polarization state. The sign ofadoes not affect the change in polarization state, but its magnitude affects the changes speed. Due to more complex factors determining the correlation fluctuations between different points in the light field, the changes of different two points are more sensitive than those of the same two points in shallow biological tissue. Beams with different parameters can be selected for different application requirements.
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Abstract +
Currently, Quantum Secret Sharing (QSS) schemes based on entangled states have not yet fully harnessed the potential of the probability amplitude of entangled states. However, the probability amplitude is a key characteristic of quantum information science and holds significant application prospects in the fields of quantum computing and quantum communication. It is worth noting that entangled states can be effectively represented by Matrix Product States (MPS). The representation of entangled states using MPS can precisely reveal the entanglement characteristics closely related to the probability amplitude.
This study first focuses on the representation of the W state using Matrix Product States (MPS), an approach that allows us to determine the key conditions for W state to achieve quantum advantage in Quantum Secret Sharing (QSS). Subsequently, this research demonstrates that by representing entangled states with MPS, a W state can be compressed into a single photon state and a simplified matrix form, presenting an innovative technical path.
Moreover, one of the most attractive features of our proposed QSS scheme is its ability to compress multiple different quantum states (represented by photons) into a unified state represented by a single photon. This characteristic endows our scheme with scalability and flexibility, meaning that the group of participants can be easily expanded or reduced according to their specific needs. The addition of new participants is managed by Alice, who is responsible for the distribution of quantum state shares. On the other hand, when a participant leaves the group, their old quantum state share can be simply ignored in the process of recovering the secret's quantum state, thereby simplifying the management process.
Through this strategy, we can not only efficiently utilize entanglement resources but also meet the diverse needs of the system, including but not limited to communication security, data transfer rates, and system scalability. This research provides new perspectives and possibilities for the field of quantum information science and may have a significant impact on promoting the development of the field.
This study first focuses on the representation of the W state using Matrix Product States (MPS), an approach that allows us to determine the key conditions for W state to achieve quantum advantage in Quantum Secret Sharing (QSS). Subsequently, this research demonstrates that by representing entangled states with MPS, a W state can be compressed into a single photon state and a simplified matrix form, presenting an innovative technical path.
Moreover, one of the most attractive features of our proposed QSS scheme is its ability to compress multiple different quantum states (represented by photons) into a unified state represented by a single photon. This characteristic endows our scheme with scalability and flexibility, meaning that the group of participants can be easily expanded or reduced according to their specific needs. The addition of new participants is managed by Alice, who is responsible for the distribution of quantum state shares. On the other hand, when a participant leaves the group, their old quantum state share can be simply ignored in the process of recovering the secret's quantum state, thereby simplifying the management process.
Through this strategy, we can not only efficiently utilize entanglement resources but also meet the diverse needs of the system, including but not limited to communication security, data transfer rates, and system scalability. This research provides new perspectives and possibilities for the field of quantum information science and may have a significant impact on promoting the development of the field.
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Abstract +
Comprehending the propagation characteristics of surface plasmon polaritons (SPP) holds paramount importance for designing and constructing on-chip integrated systems utilizing plasmonic effect. Accurately characterizing and flexibly controlling SPP on thin metal film are indispensable. Here, we theoretically derive the group velocity dispersion of SPP propagation on the surface of Au film with varying thicknesses. These results indicate that when the thickness of the Au film is less than 40 nm, group velocity dispersion of SPP decreases significantly as the film thickness increases. The decrease of group velocity dispersion become mild with the thickness increasing from 40 nm to 60 nm, then the dispersion keeps at extremely low value with a constant for the film thicker than 60 nm. Using the finite-difference time-domain method, temporal evolution of localized electric field of SPP is numerically simulated for various propagation distances. By comparing the field amplitude and the dispersion of SPP that excited by incident light pulse with different dispersion, group velocity dispersion of SPP on the Au film is obtained, which get a well consistence with the theoretical result. Moreover, we have demonstrated that by utilizing the tailored SPP to excite metal nanoantenna, selective excitation at different frequencies in femtosecond temporal scale can be achieved through localized surface plasmonic resonant effect. Manipulating the sign and amount of the dispersion from the incident pulse, active control of the switching sequence and switching time of electric field between the Au cylinders can be achieved. Manipulating the propagation distance of SPP, active control of the switching time of electric field between the Au cylinders can be achieved. It provides a promising avenue for realizing functionalities such as signal propagation, reception, adjustment, and encoding in on-chip interconnect circuits systems based on SPP. This work shows that the dispersion can be as degree of freedom for controlling the amplitude, phase and pulse width of SPP propagating on thin film, and it is significant importance for the design and control of on-chip integrated systems utilizing plasmonic effect, such as ultrafast frequency demodulators as well as nanoantenna in on-chip interconnect optical circuits.
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Abstract +
Current status and challenges of key physics related to high-confinement operational scenarios and energetic particle confinement are briefly overviewed, from the perspective of design and operation of tokamak-based fusion reactors. In the past few decades, significant progress has been made in the research of high-confinement mode physics, identifying the main stability and confinement constraints on operational window of a fusion reactor, and developing some control methods for tuning plasma kinetic profiles to optimize the performance. Several scenarios, including inductive, hybrid and steady-state scenariosetc, potentially applicable for future reactors, have been developed. In the condition with predominant fusion alpha particle self-heating and shear Alfven wave (SAW) instabilities potentially dominating fusion alpha particle transport, the SAW linear stability properties and excitation mechanisms are well understood, and extensive research has been devoted into the SAW instabilities nonlinear saturation, alpha particle transport, and impact on fusion profile through heating deposition and micro-turbulence regulation. The magnetically confined fusion research has been entering a new stage of ignition and burning plasma physics, and new challenges faced are addressed, including whether efficient self-heating of plasmas by fusion alpha particles can be achieved, how to maintain the plasma stability and high-confinement via active control of key plasma profiles under the condition of dominant alpha particle heating, and whether it is possible to establish accurate models to predict long time scale complex dynamical evolution of fusion plasmasetc. Solving these key issues will lay a solid scientific foundation for designing and operating of future reactors as well as promote the development of plasma science.
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