Accepted Papers
Recent catalogue
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Vol.74 No.5
2025-03-05
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Vol.74 No.4
2025-02-20
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Vol.74 No.3
2025-02-05
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Vol.74 No.2
2025-01-20
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NUCLEAR PHYSICS
2025, 74 (5): 052401.
doi: 10.7498/aps.74.20241273
Abstract +
Lead is an important alloy material and nuclear fuel component. Lead-based eutectic alloys serve as important coolants and have been extensively utilized in the construction of lead-cooled fast reactor, such as the European lead-cooled System (ELSY) and the China lead-based Research reactor (CLEAR-I). These materials also play a significant role in research related to Generation-IV reactors. The study and calculation of lead nuclear data have important theoretical value and application prospects. 208Pb is the most stable and abundant isotope in lead nuclei, and high-quality description of 208Pb nuclear scattering data is important in achieving accurate theoretical calculations of nuclear reaction cross-sections in lead-based nuclear systems Based on the dispersive optical model, the nucleon scattering on 208Pb is described through the implementation of a dispersive optical potential in this work. The dispersive optical model potential is defined as energy-dependent real potential and imaginary potential. The dispersive contribution corresponding to the real potential is calculated analytically from the corresponding imaginary potential by using a dispersion relation, and the isospin dependence is reasonably considered by introducing an isovector component (i.e. Lane term) into the real part and the imaginary part of potential: the depth constant of the real Hartree-Fock potential $ V_{\rm{HF}}$ and the depth constant of surface imaginary potential $ W_{\rm{s}}$. Unlike K-D potential, which requires two different sets of parameters to describe neutron and proton induced scattering data. This optical potential uses the same set of parameters to simultaneously describe nucleon-nucleus scattering data. The derived potential in this work shows a very good description of nucleon-nucleus scattering data on 208Pb with energies up to 200 MeV. The calculated neutron total cross sections, neutron and proton elastic scattering angular distributions, and neutron and proton elastic analyzing powers are shown to be in good agreement with experimental data. Additionally, the difference in potential between neutrons and protons induced is described by an isovector term, achieving the reasonable and good prediction of quasielastic (p, n) scattering data.
NUCLEAR PHYSICS
2025, 74 (5): 052501.
doi: 10.7498/aps.74.20241640
Abstract +
We investigate the boundary effect of small-scale s quark matter and the self-similarity structure influence of strange hadrons in the hadron gas on quark-gluon plasma (QGP)-hadron phase transition. In this study, the multiple reflection expansion method is used to investigate the boundary effect of QGP droplets containing s quarks. The calculation reveals that under the influence of boundary effect, small-scale s quark matter exhibits that energy density, entropy density, and pressure are all lower. In the hadron phase, there exists a two-body self-similarity structure between K mesons and neighboring π mesons, subjected to collective flow, quantum correlations, and strong interactions. By using two-body fractal model to study the self-similarity structure of the K meson in meson and quark aspects, it is found that the self-similarity structure of the K meson exists in hadron phase, resluting in an increase in the energy density, entropy density, and pressure of the K meson. Furthermore, under the influence of self-similarity structure, the derived transverse momentum spectrum of K meson shows excellent agreement with experimental data (Fig. (a) ). This study predicts that in the HIAF energy region, the self-similarity structure factor of K meson $ q_{1} $ approaches 1.042. Additionaly, under the combined influence of boundary effects and self-similarity structure of K and π mesons, the phase transition temperature of s quark matter increases (Fig. (b) ). Morover, if the boundary of s quark matter is more curved, the increase of phase transition temperature becomes more pronounced compared to the effect of self-similarity structure alone.
ATOMIC AND MOLECULAR PHYSICS
2025, 74 (5): 053101.
doi: 10.7498/aps.74.20241522
Abstract +
Au/CeO2(111), as an important catalyst system, has demonstrated excellent catalytic performances in a variety of fields such as the catalytic oxidation and the water-gas shift reactions. In order to reveal in depth the Au/CeO2(111) catalytic mechanism, especially to understand the interaction of the active components on an atomic scale, in this work, the adsorption properties on the Au/CeO2(111) surface are investigated by calculating the adsorption energy, differential charge density, Bader charge, and the density of states by using density functional theory (DFT+U). First, five adsorption sites of Au/CeO2(111) are identified in the planar region of CeO2(111), and the most stable adsorption configuration is found to be located at the bridging position between surface oxygen atoms (the oxygen-oxygen bridging site), which suggests that Au interacts more closely with the oxygen-oxygen bridging sites. Further, the differential charge density and Bader charge reveal the charge transfer mechanism in the adsorption process. Specifically, the Au atoms are oxidized into Au+, while the Ce4+ ions in the second nearest neighbor of Au are reduced to Ce3+, and the adsorption process is accompanied by a charge transfer phenomenon. Au also exhibits a unique adsorption behavior in the CeO2(111) step-edge region, where a highly under-allocated environment is formed due to the decrease in the coordination number of atoms in the step edge, which enhances the adsorption of Au in a highly under-allocated environment. The adsorption of Au at the step edge is enhanced by the lower coordinated environment due to the reduced coordination number of the atoms at the step edge. By comparing four different types of step structures (Type I, Type II, Type II*, and Type III), it is found that the higher adsorption energy of Au at Type II* site and that at Type III site are both mainly due to the lower coordinated state of Ce atoms at these sites. Charge transfer is also particularly pronounced at the Type III sites. It is also accompanied by electron transferring from Au to Ce4+ ions, making Type III the preferred adsorption site for Au atoms. By constructing a more comprehensive Au/CeO2 model, this study breaks through the previous limitation of focusing only on planar adsorption and reveals the adsorption mechanism of Au/CeO2 at the edge of the step, which provides a new perspective for understanding in depth the catalytic mechanism of Au/CeO2(111).
ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
2025, 74 (5): 054201.
doi: 10.7498/aps.74.20241443
Abstract +
This work investigates the combination of two partially overlapping oscillating fields, aiming to analyze the effect of the separation distance between the fields on the production of electron-positron pairs in a vacuum. The process is simulated using computational quantum field theory (CQFT) method and the split-operator technique, which is based on the spacetime-dependent Dirac equation. The main focus is to analyze the influence of separation distance and frequency combination on the pairwise production rate and energy spectrum.The research results show that partially overlapping sub-critical oscillating fields can still effectively generate electron-positron pairs at small separation distances. The variation in separation distance along the overlapping direction significantly affects the pairwise production rate. For two oscillating fields with a fixed sum of frequencies, the separation distance has a notable effect on the pairwise production rate, with different frequency combinations exhibiting varying degrees of dependency.Further analysis of the energy spectrum reveals that the number and positions of spectral peaks are differently affected by the separation distance. Models with smaller frequency differences exhibit more concentrated energy distributions, generally presenting a single-peak structure. In contrast, models with larger frequency differences show more dispersed energy distributions, typically presenting a dual-peak structure. As the separation distance increases, the energy spectrum structure varies with different frequency combinations, especially for larger separation distances. In the case of larger frequency difference, the high-energy peak declines rapidly with separation distance increasing, leading to a lower proportion of high-energy electrons, while in the case of smaller frequency difference the change is relatively small. This phenomenon is further analyzed using energy transition probability distribution diagrams of particles.By analyzing the probability distribution diagrams of particle energy transitions, we obtain a preliminary understanding of the differences in various frequency combinations with respect to separation distance, and explain the changes in energy spectrum structure from the perspective of multiphoton transitions. Additionally, a more detailed analysis of these diagrams based on the law of conservation of energy, enables us to extract particle production trends corresponding to various multiphoton transition effects. It is found that for the same frequency combination, the trends of second- and third-order effects with varying separation distances are different, with higher-order effects decaying more rapidly.By analyzing the variation of probability of multiphoton transitions in a combined field with separation distance, as well as the variation of the probability of multiphoton transitions in a single field, we conclude that when the separation distance is small, the combined fields with larger frequency differences have advantages in the generation of electron-positron pair. However, when the separation distance is large, the combined fields with smaller frequency differences begin to play an important role and exhibit better stability, owing to their inherent multiphoton effects. For different cases under the combined influence of two fields, we conduct a more in-depth analysis of the differences between different orders within the same frequency combination and between the same order transitions under different frequency combinations. By proposing hypotheses and conducting computational verification, it is found that under the same conditions, the trend of normalized overlapping photon numbers changing with separation distances is consistent with the trend of corresponding particle production numbers, providing a more convenient method for testing the trend of particle production under separation distance.This study not only enriches our understanding of the generation of vacuum electron-positron pairs in strong fields, but also provides theoretical guidance and reference for designing experimental devices for generating pairs.
ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
2025, 74 (5): 054202.
doi: 10.7498/aps.74.20241664
Abstract +
Quantum entanglement is a key resource for performing quantum computing and building quantum communication networks. By injecting a microwave-optical dual-mode entanglement field into the system, as well as pumping the optical and microwave cavities, and by appropriately choosing the detuning relationship between the pumping field and the modes, it is shown in this work that microwave-phonon entanglement Eab and magnon-optics entanglement Ecm can be generated simultaneously in the cavity opto-magnomechanic system, and the entanglement can be in a steady state. Specifically, the model is based on a hybrid quantum system of magnons, where a microwave-light entanglement generated by an optically pulsed superconducting electro-optical device through spontaneous parametric down-conversion process is injected as the intracavity field, and a blue-detuned microwave field is used to excite the magnon modes to produce magnon-phonon entanglement. Through the interaction between an optomechanical beam splitter and microwave-magnon state-swap, steady microwave-phonon entanglement Eab and magnon-optics entanglement Ecm are successfully realized. The entanglement Eab and Ecm in the system are analyzed using the logarithmic negativity. The effects of several parameters of the system, such as environment temperature, coupling strength and dissipation rate, on the degree of entanglement are investigated. In particular, the entanglement Eab and Ecm generated in this system can exist both simultaneously and individually. Especially when gam = 0, the entanglement Eab and Ecm still exist. Moreover, directly injecting entangled microwave-light into the system can significantly enhance the robustness of the entanglement against temperature, which will have broad application prospects in quantum information processing in quantum networks and hybrid quantum systems. Notably, the entanglement Eab and Ecm exist even at a temperature of 1.3 K. Our research has potential value for applications in the fields of quantum information processing and quantum networks.
ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
2025, 74 (5): 054203.
doi: 10.7498/aps.74.20241659
Abstract +
Nanolaser (NL), as an important optical source device, has a significant influence on photonic integrated circuits and has become a research hotspot in recent years. In this work, the synchronization performance of a dual-channel laser chaotic multiplexing system is investigated based on NLs and an active-passive decomposition is used to enhance signal processing and multiplexing efficiency. By establishing a rate equation model, the synchronization characteristics of the system are analyzed, with a focus on two key parameters— Purcell factor (F ) and spontaneous emission coupling factor (β )—as well as the effects of system parameters, single-parameter mismatch, and multi-parameter mismatch. Numerical simulations show that with appropriate parameter configurations, the two master NLs can maintain low correlation, ensuring the "pseudo-orthogonality" of chaotic signals while achieving high-quality chaotic synchronization with their paired slave NLs. In this work it is found that both the Purcell factor (F ) and the spontaneous emission coupling factor (β ) significantly affect the synchronization performance of the system, and the optimal parameter ranges for achieving high-quality synchronization are identified. Additionally, the effects of feedback strength and frequency detuning are explored, revealing that frequency detuning plays a more critical role in the synchronization between the master NLs. The influence of parameter mismatches on system synchronization performance is also emphasized. The system exhibits robustness against single-parameter mismatch and has minimum influence on master-slave synchronization quality. However, multi-parameter mismatch gives rise to more complex effects. Compared with the traditional semiconductor laser systems, this system can maintain “pseudo-orthogonality” over a wider range of parameters, thus achieving higher security and lower channel interference. This research lays a theoretical foundation for chaos synchronization based on NLs and provides new insights for designing secure, stable, and efficient optical communication systems.
ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
2025, 74 (5): 054204.
doi: 10.7498/aps.74.20241174
Abstract +
In order to solve the problem that the measurement arm length needs to be obtained in real time when calculating the measurement angle in the process of Tolansky interference small angle measurement, a dual-arm Tolansky interference autocollimation angle measurement scheme is proposed, which not only maintains the function of Tolansky interference, but also integrates the principle of optical leverage. In the simulation study, it is found that the splitter with thickness in the scheme will lead to the lateral offset of the optical axis of the emitted light, which will change the position of the virtual point light source, and finally change the position of the center of the interference circle on the detector. In this work, in order to reduce the influence of the thickness of the beam splitter on the angle measurement accuracy of the angle measurement scheme, the optical path structure of the angle measurement scheme is redrawn, and the relationship between the center offset of the interference ring and the deflection angle, which contains the thickness factor and can accurately describe the optical path, is deduced. Therefore, the corresponding method is adopted as follows. Firstly, the measurement optical path of the splitter with a thickness factor is redrawn, the splitter is partially enlarged, and the original beam is replaced with the center line of the laser beam to draw the optical path. Then, the position of the virtual point light source under the influence of the thickness of the splitter is analyzed by using the single refraction spherical formula and the transition formula of geometric optics, and the relationship between the offset of the interference center and the deflection angle with the thickness of the splitter is established. Secondly, the coordinate information of the center of the interference ring under different thickness parameters of the splitter is obtained by using the virtual simulation experiment, which proves the correctness of the theoretical analysis. Then, simulation experiments such as simulation measurement of multiple sets of setting angles and angle measurement under different splitter thickness conditions are carried out, and the accuracy of the relationship including the splitter thickness factor deduced above is cross-validated. Finally, combined with the actual experiment, measurements are taken on the guide rail and calibrated autocollimator, and the influence of beam splitter thickness on angle measurement accuracy is investigated in detail. The research results are obtained below. Experiments show that the thickness of the splitter will affect the position of the initial center of the circle; with the increase of the thickness of the splitter, the error between the simulation measurement results and the relationship including the thickness factor is within ± 0.5 % at different angles, and the experimental data and theoretical results are in good agreement. At the same angle, as the thickness of the beam splitter increases, the difference between the established relationship and the approximate relationship gradually increases. With 1-mm-thick beam splitter, the relative error between the established relationship and the calculated value of the approximate relationship is only 0.22 % based on the data of the guide rail measured by the calibrated autocollimator. From these results, a conclusion can be drawn below. The utilizing a thinner spectroscope can effectively reduce the calculation and measurement errors, providing an important guidance for carrying out the in-depth research and development of this new autocollimator.
ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
2025, 74 (5): 054301.
doi: 10.7498/aps.74.20241286
Abstract +
Acoustic skyrmion modes are topological texture structures of velocity field vectors generated on the surface of acoustic structures. This protected vector distribution provides new opportunities for processing sound information, transmission, and data storage. In this study, a combined structure of waveguides and spiral structures is designed by using directional acoustic sources to excite waveguide mode transmission, thereby achieving selective excitation of localized acoustic skyrmion modes. Through theoretical analysis and numerical simulations, the pressure field distribution and velocity field distribution excited by spin acoustic sources, Huygens acoustic sources, and Janus acoustic sources in this structure are investigated, demonstrating the directional transmission properties of acoustic surface waves and the selectively excited acoustic skyrmion modes in the combined structure. Numerical calculations reveal that when the spin acoustic source excites acoustic surface waves propagating along the waveguide, the acoustic skyrmion modes in the helical structure in the direction corresponding to the propagation are selectively excited. When the Huygens source excites acoustic surface waves propagating along the waveguide, the acoustic skyrmion modes in the right or left direction are selectively excited. However, when the Janus source excites acoustic surface waves propagating along the waveguide, the acoustic skyrmion modes in the upward or downward direction are selectively excited. This selective excitation of acoustic skyrmion modes by a directional acoustic source provides a new way to design advanced acoustic information processing functional devices.
ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
2025, 74 (5): 054701.
doi: 10.7498/aps.74.20241678
Abstract +
In this paper, a three-dimensional numerical simulation of the motion behavior of bubbles in complex porous medium channels in a large density ratio gas-liquid system is conducted based on the lattice Boltzmann method. The Eötvös number (Eo), contact angle (θ) and Reynolds number (Re) are systematically discussed with emphasis on the law of their coupling effect affecting bubble velocity, morphological evolution and stagnation phenomenon. The results show that the increase of contact angle will reduce the bubble velocity but intensify the velocity fluctuations, making the bubbles tend flat, while the increase of Eo number significantly suppresses the influence of the contact angle, stabilizes the bubble velocity, and makes its shape close to a bullet head shape. When the contact angle is large (θ > 90°) and the Eo number is small (Eo < 10), the adhesion force is significantly enhanced and the bubbles will stagnate inside the porous medium. Re number and contact angle compete in the generation of resistance, and have mutually reinforcing effects on the average velocity of bubbles and interface evolution. The larger contact angle makes the deformation of the bubble tail intensify and becomes unstable, and as the Re number further increases, the tail tentacles are more likely to break, forming residual bubbles. It is also found in this work that the coupling between Eo number and Re number significantly affects bubble behavior in motion and morphological evolution. Under the conditions of high Eo number (Eo ≥ 25) and high Re number (Re ≥14), the bubble velocity increases with the Eo number rising, and the trend becomes more significant as the Re number increases; while under the conditions of low Eo number (Eo < 25) and low Re number (Re < 14), the speed change pattern is completely opposite. This phenomenon is due to the high instability of bubble morphology under the conditions of high Eo number and high Re number, which affects the buoyancy and speed performance. The research results provide important guidance for optimizing the flow behavior of bubbles in porous medium.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
2025, 74 (5): 055201.
doi: 10.7498/aps.74.20241586
Abstract +
To further explore the mechanism of self-pulsing discharge, a sandwiched microcavity cathode is used to study this phenomenon in argon. With the increases of discharge current, the discharge undergoes Townsend discharge, self-pulsing discharge and normal glow discharge. A complete self-pulsing discharge consists of the rising edge, the falling edge of the discharge current, and the waiting period of the discharge. The spatiotemporal dynamic characteristic of self-pulsing discharge is simulated by using a fluid model. The simulated results indicate that when the self-pulsing discharge current reaches its minimum value, the discharge is confined inside the cathode cavity. The electric field, electron density and electron generate rate are low, resulting in a Townsend discharge mode. As the discharge current increases, the discharge inside the cavity is strengthened, and the discharge gradually extends from the inside of the cavity to the outside. When the current reaches its maximum value, there exists a strong discharge outside the cavity, and an obvious cathode sheath is formed near the outer surface of the cathode, resulting in a high electron generate rate outside the cavity. When the discharge current decreases, the discharge shrinks from the outside to the inside of the cavity, and finally returns to the Townsend discharge mode. The simulated results also indicate that the ionization source varies depending on the stage of self-pulsing discharge, specifically, direct ionization is dominant when the current is high, and Penning ionization plays a major role in the pulse waiting period when the current reaches its minimum value. The experimental and simulation results indicate that the self-pulsing discharge in a micro-cavity cathode is essentially a process of mode transition between the Townsend discharge mode where the discharge is confined within the cavity and the normal glow discharge mode where the discharge region extends to the outside of the hole.
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