Journal of the Korean Physical Society最新文献

The paper explores the influence of raindrops on the phase precision of Mach–Zehnder interferometer when the coherent states and the squeezed vacuum states are introduced into its input ports. The probability of photon loss η increases as the rain rate R or traveling distance L increases. In the presence of moderate or heavy rain, the loss probability η ranges from 0.2 to 0.48, or from 0.48 to 0.96 when the traveling distance L is close to 1 km. The threshold value R_th corresponds to the rain rate R at which the phase precision falls below the shot noise limit(SNL). At high squeezing level ((r = arcsin h(sqrt {N/2} )), the light rain does not degrade the phase precision below SNL. We also calculate the threshold value of rain rate(R_th) at various low levels of squeezing and compare R_th for three low squeezing levels (15 dB,10 dB, and 6 dB) that can currently be achieved. The results show that, at the same traveling distance, R_th is larger for a 15 dB squeezing level compared to 10 dB and 6 dB squeezing levels. Even in the presence of moderate rain, the phase precision for 15 dB remains sub-SNL for long distances approaching 1 km. A feasible experimental proposal for investigating the influence of raindrops is put forward with the current technology.

The detection of weak features in spectra remains a challenge. Differentiation remains a standard method, but maximum-entropy filters provide an alternative. Using dielectric-function data for MoSe₂ as a test case, we compare the capabilities of two maximum-entropy filters, the original Burg version and its corrected offshoot, to detect the biexciton and determine its energy. In contrast to differentiation, both approaches detect the biexciton. However, neither provides accurate values of the excitonic transition energies in this spectral range, although the Burg version is somewhat better.

Deep learning-based convolutional neural networks (CNNs) have been proposed for enhancing the quality of digital tomosynthesis (DTS) images. However, the direct applications of the conventional CNNs for low-dose DTS imaging are limited to provide acceptable image quality due to the inaccurate recognition of complex texture patterns. In this study, a deep residual learning network combined with the Anscombe transformation was proposed for simplifying the complex texture and restoring the low-dose DTS image quality. The proposed network consisted of convolution layers, max-pooling layers, up-sampling layers, and skip connections. The network training was performed to learn the residual images between the ground-truth and low-dose projections, which were converted using the Anscombe transformation. As a result, the proposed network enhanced the quantitative accuracy and noise characteristic of DTS images by 1.01–1.27 and 1.14–1.71 times, respectively, in comparison to low-dose DTS images and other deep learning networks. The spatial resolution of the DTS image restored using the proposed network was 1.12 times higher than that obtained using a deep image learning network. In conclusion, the proposed network can restore the low-dose DTS image quality and provide an optimal model for low-dose DTS imaging.

We designed a detector for small animal positron emission tomography to achieve high resolution and sensitivity. By using a quasi-block scintillator, superior sensitivity was achieved compared to existing scintillation pixels. The scintillator was arranged in several layers to measure the location where gamma-ray interaction occurred. DETECT2000 simulation was performed to evaluate the performance of the designed detector. DETECT2000 is capable of simulating the movement, scattering, reflection, and absorption of light generated within a scintillator. Using these parameters, a quasi-block scintillation detector was designed, and light emitted by gamma-ray interaction was generated throughout the scintillator. Light generated by gamma-ray events in the entire area was acquired at 1 mm intervals as a light signal from optical sensors placed on the sides of four quasi-block scintillators, and a flood image was obtained using the light signal. As a result, images were confirmed to be separated without overlap in all areas except for the positions of gamma ray events generated at the corners and edge of the quasi-block scintillator. It is expected that the system spatial resolution of around 1 mm can be achieved by imaging the locations of all gamma-ray events occurring at 1 mm intervals.

Boundary effect is a widespread idea in many-body theories. However, it is more of a conceptual notion than a rigorously defined physical quantity. One can quantify the boundary effect by comparing two ground states of the same physical model, which differ only slightly in system size. This quantity, which we call a boundary effect function, restricts the correlation and entanglement that the ground state can accommodate. Here, we analyze the boundary effect function for an XXZ spin–(frac{1}{2}) model using density matrix renormalization group calculations. We find that the three quantum phases of the model manifest as different functional forms of the boundary effect function depending on the correlation length of the bulk. As a result, the quantum phase transition of the model is associated with a nonanalytic change of the boundary effect function. This work thus provides and concretizes a novel perspective on the relationship between bulk and boundary properties of ground states.

X-pinch is one of the efficient sources of radiation due to its capability to generate high-energy-density plasmas. While existing 3D magneto-hydrodynamics (MHD) codes could be utilized to model such plasma, conducting full 3D numerical simulations is often expensive and time-consuming. In this study, we present a numerical framework capable of flexible adoption of models, based on the concept of the fractional step method where we separated the solution methods for different parts of the system. Numerical schemes were chosen primarily for their generality and flexibility, independent of specific characteristics of the target system, such as strict hyperbolicity. Specifically, we adopt the explicit relaxation scheme of the advection part and the implicit TR-BDF2 method of the source part. The developed framework is applied up to the 2D (r, z) cylindrical coordinate system and validated against representative benchmark problems for the MHD system, including (1) the Brio and Wu shock tube in both ideal and resistive settings, (2) the Orszag–Tang vortex, and (3) the magnetized Noh problem. Finally, we present a preliminary simulation of X-pinch.

Template-based nanorods prepared by anodized aluminum oxide templates have been utilized in a variety of fields as hot spots for surface-enhanced Raman scattering, self-assembling components, molecular electronic junctions, and elements for plasmon coupling. An important requirement for nanorods used in these fields is that they are stably dispersed in solution. Despite the importance of this research, these properties have not been extensively studied either experimentally or theoretically. Herein, the required conditions (concentration and surface potential) for the stable dispersion of template-based nanorods were theoretically investigated using DLVO (Derjaguin–Landau–Verwey–Overbeek) theory, and experimentally examined for the nanorods with different radii (175 and 22.5 nm), but the same length (750 nm). Contrary to the results expected from DLVO theory, only the thin nanorods were stably dispersed in solution. The difference in stability between the thin and thick nanorods under the same conditions was explained by their different surface potentials, which resulted from the different degrees of surface coverage by the adsorbates (2-mercapto ethane sulfonate).

This study investigates the gas-phase ozone decomposition kinetics, crucial for optimizing ozone concentration in various industrial applications, particularly oxidation processes. Experimental investigations were conducted within a sealed stainless-steel chamber, varying airflow (0–300 m³/h), temperature (20–40 °C), and relative humidity (40–80%). A combination of one-factor-at-a-time experiments and response surface modeling was employed to analyze the interplay of these factors on ozone decomposition. Results indicate that ozone decomposition is slower at zero airflow, 20 °C, and 40% humidity. Ozone was generated using a dielectric barrier discharge (DBD) reactor. This research highlights the importance of these variables in ozone-based applications and identifies optimal conditions for enhanced ozone utilization. By comprehending these factors, industries can improve efficiency in various oxidation processes relying on ozone. This can lead to more effective utilization of ozone as a valuable resource across numerous industrial applications. In addition, these findings may prove beneficial for optimizing ozone use in air treatment processes.

We explore a population of coupled oscillators capable of movement in two-dimensional space, named swarmalators, focusing on the numerical long-term state patterns. The system is composed of two equal-size subsystems of their own coupling strength distributions that give the negative means of intra-subsystem couplings and that of inter-subsystem couplings as well. The mean of each subgroup is used as the control parameter. We numerically observe that four long-term states appear depending on the two control parameters. It is also observed that there is a pattern with sync-state subsystem, which is non-trivial for bare subsystem of zero or negative coupling-strength mean.

Manipulation of metal microstructures via welding technique has attracted many interests due to its various applications for microscopic electronic circuits and photo-electronic structures. Refilling deletion of structures is challenging in sculpting metal microstructure. We propose the micro-size gas tungsten arc welding (GTAW) technique to overcome these challenges. The welded area of ~ 10 s μm are achieved by using an etched 100 μm W wire with optimized arc current and voltage control. The spatial size and depth of the welded spot in the invar surface show dependency on the arc current and voltages under proper Ar gas flow. We believe that these results can provide technical intuition for developing many industrial applications.