Quantum Beam Science

14 pages, 2587 KB

Open AccessArticle

Pressure-Driven Phase Transition in InPO₄: The Elastic Response of CrVO₄-Type, Scheelite, and Zircon Polymorphs

by Jesus E. Aviles-Coronado, Pricila Betbirai Romero-Vázquez and Sinhué López-Moreno

Quantum Beam Sci. 2026, 10(2), 14; https://doi.org/10.3390/qubs10020014 - 15 Jun 2026

Viewed by 219

In this work, we present a theoretical study of InPO₄ under pressure. Total-energy calculations based on density functional theory were performed to explore the crystal structure of InPO₄ in light of the recent X-ray diffraction characterization of this compound under pressure. [...] Read more.

In this work, we present a theoretical study of InPO₄ under pressure. Total-energy calculations based on density functional theory were performed to explore the crystal structure of InPO₄ in light of the recent X-ray diffraction characterization of this compound under pressure. A phase coexistence was observed above 10 GPa, involving the ambient-pressure CrVO₄-type structure and the high-pressure scheelite and zircon phases. Therefore, the previously performed analysis of InPO₄ behavior under pressure is extended by simulating X-ray spectra and interplanar distances for the three polymorphs. In addition, the elastic behavior of the three phases is analyzed to assess the elastic stability of InPO₄ under pressure and to compute the mechanical properties and elastic anisotropy. Our findings significantly extend previous experimental results on the compressibility of InPO₄, which were limited to the ambient-pressure phase. Moreover, our results unambiguously reveal a marked difference in the elastic properties of the scheelite and zircon phases under pressure, showing that the zircon phase is elastically unstable at high pressures. This suggests that the reported coexistence of phases may result from kinetic barriers or from non-hydrostatic conditions within the diamond anvil cell caused by the pressure-transmitting medium. Full article

(This article belongs to the Section Structure and Dynamics of Functional Materials)

► Show Figures

Figure 1

18 pages, 4963 KB

Open AccessReview

Advanced Neutron Focusing Optics for Pulsed Sources: Development and Prospects

by Taisen Zuo, Qing Chen, Hong Zhu, Zehua Han, Changli Ma, Chen Zhao, Long Tian, Tengfei Cui, Tianhao Wang and He Cheng

Quantum Beam Sci. 2026, 10(2), 13; https://doi.org/10.3390/qubs10020013 - 4 Jun 2026

Viewed by 207

Abstract

The evolution of neutron scattering from reactor-based steady-state sources to high-power pulsed spallation sources has necessitated a paradigm shift in neutron optics. While pulsed sources offer high peak brilliance and energy-resolved measurements via the time-of-flight (TOF) technique, the intrinsic divergence and broad wavelength [...] Read more.

The evolution of neutron scattering from reactor-based steady-state sources to high-power pulsed spallation sources has necessitated a paradigm shift in neutron optics. While pulsed sources offer high peak brilliance and energy-resolved measurements via the time-of-flight (TOF) technique, the intrinsic divergence and broad wavelength bandwidth of the incident beam pose significant challenges for focusing, particularly in the realm of very small-angle neutron scattering (VSANS, Q < 0.001 Å⁻¹). This review presents a comprehensive analysis of diverse focusing techniques, including converging multi-slit apertures, electrical and superconducting magnetic sextupole lenses, grazing-incidence focusing mirrors, compound refractive lenses with oscillation apertures, and a special multi-beam VSANS configuration. Special attention is given to the transition from permanent magnet systems to nested rotating sextupole permanent magnets (Nest-Rot-SPM) and modulated superconducting sextupoles (SSM), detailing the physical and engineering challenges involved. Furthermore, grazing-incidence reflective optics, notably toroidal Wolter mirrors, are discussed as an achromatic alternative. The integration of these technologies into world-leading pulsed neutron sources is reviewed to project the future landscape of extended Q-range coverage for SANS instruments. Full article

(This article belongs to the Topic Collaborative Innovation of Optical Fiber Communication, Optical Sensors, and Lasers: New Trends and Technologies)

► Show Figures

Figure 1

11 pages, 5631 KB

Open AccessArticle

Temperature-Dependent Performance Optimization of a Filtered ASE Source Employing Low-Concentration Erbium-Doped Fiber

by Wei Liu, Jianming Liu, Wei Xu and Jia Guo

Quantum Beam Sci. 2026, 10(2), 12; https://doi.org/10.3390/qubs10020012 - 22 May 2026

Viewed by 382

Abstract

Research on the thermal stability of amplified spontaneous emission (ASE) has mostly focused on broadband spectra. High-precision fiber optic gyroscopes (FOGs), however, require spectrally filtered sources. The impact of erbium-ion doping concentration on the temperature performance of such filtered sources remains relatively explored. [...] Read more.

Research on the thermal stability of amplified spontaneous emission (ASE) has mostly focused on broadband spectra. High-precision fiber optic gyroscopes (FOGs), however, require spectrally filtered sources. The impact of erbium-ion doping concentration on the temperature performance of such filtered sources remains relatively explored. This work systematically compares low-concentration and high-concentration erbium-doped fibers (EDFs). The fibers are used in a bidirectional forward-pumped ASE configuration. This configuration integrates a 1530 nm Gaussian filter isolator. The optimized low-concentration EDF fully absorbs pump power over a longer length. Its gain-profile temperature shift partly compensates the filter passband shift. At the optimum fiber length of 10 m, this source shows a mean wavelength temperature drift of only 0.107 ppm/°C. In contrast, the commercial high-concentration EDF gives a drift of 0.136 ppm/°C. The power conversion efficiency of this source reaches 26.9%. The commercial EDF attains 24.5%. The results demonstrate that reducing the Er³⁺ doping concentration simultaneously improves the wavelength thermal stability and efficiency of filtered ASE sources. This finding offers important guidance for high-accuracy FOG design. Full article

(This article belongs to the Section Spectroscopy Technique)

► Show Figures

Figure 1

21 pages, 74312 KB

Open AccessArticle

Investigation of Spark-Plasma Erosion-Based Micro-Hole Drilling of SS316L and Ti-6AL-4V for Precision Biomedical Applications

by Pallab Sarmah, Promod Kumar Patowari and Kapil Gupta

Quantum Beam Sci. 2026, 10(2), 11; https://doi.org/10.3390/qubs10020011 - 5 May 2026

Viewed by 1132

Abstract

This research investigated the performance of spark-plasma erosion-based machining, also known as electrical discharge machining, for micro-hole drilling in SS316L and Ti-6Al-4V under various spark-plasma formation conditions, with 27 experimental combinations of capacitance, voltage, and electrode feed rate. Spark-plasma conditions at various discharge [...] Read more.

This research investigated the performance of spark-plasma erosion-based machining, also known as electrical discharge machining, for micro-hole drilling in SS316L and Ti-6Al-4V under various spark-plasma formation conditions, with 27 experimental combinations of capacitance, voltage, and electrode feed rate. Spark-plasma conditions at various discharge energies were found to play a major role in influencing machining time and overcut, which were considered two responses to evaluate machining performance. Increasing the voltage from 80 to 180 V at 100 pF decreased machining time from 2553 s to 564 s for SS316L and from 2608.2 s to 570.6 s for Ti-6Al-4V, but it increased overcut from 6 to 17.5 µm and from 8 to 22 µm, respectively. At 10,000 pF and 180 V, machining times of 51.6 s (SS316L) and 62.4 s (Ti-6Al-4V) were obtained, with maximum overcut values of 62.5 µm and 73.5 µm, respectively. Analysis of variance revealed that voltage strongly controlled machining time (~64%), while capacitance dominated overcut (64–69%). Ti-6Al-4V required 5–20% more machining time and exhibited a higher overcut due to its lower thermal conductivity and higher strength. The experimental observations indicated consistent plasma formation and favorable spark to achieve the required geometric accuracy and process productivity for the fabrication of high-quality biomedical components from SS316L and Ti-6Al-4V. Full article

(This article belongs to the Section Engineering and Structural Materials)

► Show Figures

Figure 1

20 pages, 6734 KB

Open AccessArticle

Time-Scale Mismatch as a Fundamental Constraint in Quantum Beam–Matter Interactions

by Abbas Alshehabi

Quantum Beam Sci. 2026, 10(2), 10; https://doi.org/10.3390/qubs10020010 - 8 Apr 2026

Viewed by 445

Abstract

Quantum beams-including X-rays, synchrotron radiation, electrons, neutrons, ions, and ultrafast photon sources-are indispensable tools for probing the structure, dynamics, and electronic properties of matter. The excitation time scale

τ_{e x c}

is defined operationally as the characteristic temporal interval governing externally imposed [...] Read more.

Quantum beams-including X-rays, synchrotron radiation, electrons, neutrons, ions, and ultrafast photon sources-are indispensable tools for probing the structure, dynamics, and electronic properties of matter. The excitation time scale

τ_{e x c}

is defined operationally as the characteristic temporal interval governing externally imposed energy deposition events within the interaction volume, such as pulse duration, bunch spacing, or beam dwell time. Interpretation of beam–matter interactions has traditionally relied on steady-state or quasi-equilibrium assumptions, implicitly presuming that intrinsic material relaxation processes can accommodate externally imposed excitation. Recent advances in high-brightness synchrotron sources, X-ray free-electron lasers (XFELs), and pulsed electron beams increasingly operate in regimes where this assumption is strained, and systematic nonequilibrium effects, radiation damage, and irreversible transformations are reported even under routine experimental conditions. This work examines the role of time-scale mismatch between beam-driven energy deposition and intrinsic material relaxation as a governing constraint in beam–matter interactions. Analyzing the hierarchy of excitation, electronic relaxation, phonon coupling, and thermal diffusion time scales, the analysis introduces a dimensionless mismatch parameter

Λ = \frac{τ_{r e l}}{τ_{e x c}}

, which quantifies the competition between externally imposed excitation and intrinsic relaxation processes in beam–matter interactions. The resulting framework provides a unified physical interpretation of beam-induced damage, signal distortion, dose dependence, and nonlinear response across quantum beam modalities, framing these effects as consequences of forced nonequilibrium dynamics rather than technique-specific artifacts. Full article

(This article belongs to the Section Radiation Scattering Fundamentals and Theory)

► Show Figures

Graphical abstract

25 pages, 6783 KB

Open AccessArticle

Spectral, Angular and Polarizing Properties of Semiconductor Photodiodes Covering the Near-Infrared to Soft X-Ray Range

by Terubumi Saito

Quantum Beam Sci. 2026, 10(2), 9; https://doi.org/10.3390/qubs10020009 - 3 Apr 2026

Viewed by 672

Abstract

Some windowless semiconductor photodiodes can detect not only photons but also charged particles, cover a wide spectral range including a part of the ionizing radiation region and, thus, play important roles for synchrotron radiation experiments. To understand the spectral, angular and polarizing properties [...] Read more.

Some windowless semiconductor photodiodes can detect not only photons but also charged particles, cover a wide spectral range including a part of the ionizing radiation region and, thus, play important roles for synchrotron radiation experiments. To understand the spectral, angular and polarizing properties of semiconductor photodiodes, complex amplitude coefficients of transmittance or reflectance are calculated based on rigorous formulation using Fresnel equations with complex optical constants of the composing materials, whose validity was verified by comparison with experiments. Concrete examples of the behavior on the complex plane are shown as a function of complex optical constants, film thickness, angle of incidence and the wavelength. The results show that the optical properties of the layered system are sensitive to its layer thickness, the angle of incidence and the wavelength in the ultraviolet region where optical indices of the composing materials steeply change. It has been shown that oblique incidence photodiodes are useful as polarization-sensitive devices, and that the graphical technique using the amplitude coefficients expressed on the complex plane is effective and powerful to search for optimal conditions for complex optical constants, film thickness and/or angle of incidence. Full article

(This article belongs to the Special Issue Quantum Beam and Its Applications for Quantum Technologies)

► Show Figures

Figure 1

13 pages, 347 KB

Open AccessFeature PaperArticle

Vorticity of Twisted Electron Fields: Role of the Energy–Momentum Tensor

by Andrei Afanasev, Carl E. Carlson and Asmita Mukherjee

Quantum Beam Sci. 2026, 10(2), 8; https://doi.org/10.3390/qubs10020008 - 25 Mar 2026

Viewed by 655

Abstract

Electron fields (and more generally spinor fields) with a vortex structure in free space that allows them to have arbitrary integer orbital angular momentum along the direction of motion have been studied for some time. We point out that there are several ways [...] Read more.

Electron fields (and more generally spinor fields) with a vortex structure in free space that allows them to have arbitrary integer orbital angular momentum along the direction of motion have been studied for some time. We point out that there are several ways to calculate the local velocity of the electron field, defined as the ratio of momentum density to energy density, and that all but one show a singular vorticity at the vortex line. That one, using the Dirac bilinear current with no derivatives, is the only one so far (to our knowledge) studied in the literature in this context and we further show how to understand an apparent conflict in the existing results. The momentum densities corresponding to the three possible velocity fields give different physical results, in particular regarding the electron induced quantum superkicks given to small electron-absorbing test objects. Full article

(This article belongs to the Section Radiation Scattering Fundamentals and Theory)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Quantum Beam Sci., Volume 10, Issue 2 (June 2026) – 7 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI