Despite its amazing quantitative successes and contributions to revolutionary technologies, physics currently faces many unsolved mysteries ranging from the meaning of quantum mechanics to the nature of the dark energy that will determine the future of the Universe. It is clearly prohibitive for the general reader, and even the best informed physicists, to follow the vast number of technical papers published in the thousands of specialized journals. For this reason, we have asked the leading experts across many of the most important areas of physics to summarise their global assessment of some of the most important issues. In lieu of an extremely long abstract summarising the contents, we invite the reader to look at the section headings and their authors, and then to indulge in a feast of stimulating topics spanning the current frontiers of fundamental physics from 'The Future of Physics' by William D Phillips and 'What characterises topological effects in physics?' by Gerard 't Hooft through the contributions of the widest imaginable range of world leaders in their respective areas. This paper is presented as a preface to exciting developments by senior and young scientists in the years that lie ahead, and a complement to the less authoritative popular accounts by journalists.
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Gerard 't Hooft et al 2024 Phys. Scr. 99 052501
S B Dugdale 2016 Phys. Scr. 91 053009
The concept of the Fermi surface is at the very heart of our understanding of the metallic state. Displaying intricate and often complicated shapes, the Fermi surfaces of real metals are both aesthetically beautiful and subtly powerful. A range of examples is presented of the startling array of physical phenomena whose origin can be traced to the shape of the Fermi surface, together with experimental observations of the particular Fermi surface features.
Jack Smith 2022 Phys. Scr. 97 122001
First conceptualised in Olaf Stapledon's 1937 novel 'Star Maker', before being popularised by Freeman Dyson in the 1960s, Dyson Spheres are structures which surround a civilisation's sun to collect all the energy being radiated. This article presents a discussion of the features of such a feat of engineering, reviews the viability, scale and likely design of a Dyson structure, and analyses details about each stage of its construction and operation. It is found that a Dyson Swarm, a large array of individual satellites orbiting another celestial body, is the ideal design for such a structure as opposed to the solid sun-surrounding structure which is typically associated with the Dyson Sphere. In our solar system, such a structure based around Mars would be able to generate the Earth's 2019 global power consumption of 18.35 TW within fifty years once its construction has begun, which itself could start by 2040 using biennial launch windows. Alongside a 4.17 km2 ground-based heliostat array, the swarm of over 5.5 billion satellites would be constructed on the surface of Mars before being launched by electromagnetic accelerators into a Martian orbit. Efficiency of the Dyson Swarm ranges from 0.74–2.77% of the Sun's 3.85 × 1026 W output, with large potential for growth as both current technologies improve, and future concepts are brought to reality in the time before and during the swarm's construction. Not only would a Dyson Swarm provide a near-infinite, renewable power source for Earth, it would also allow for significant expansions in human space exploration and for our civilisation as a whole.
Kaj Sotala and Roman V Yampolskiy 2015 Phys. Scr. 90 018001
Many researchers have argued that humanity will create artificial general intelligence (AGI) within the next twenty to one hundred years. It has been suggested that AGI may inflict serious damage to human well-being on a global scale ('catastrophic risk'). After summarizing the arguments for why AGI may pose such a risk, we review the fieldʼs proposed responses to AGI risk. We consider societal proposals, proposals for external constraints on AGI behaviors and proposals for creating AGIs that are safe due to their internal design.
Ulrik L Andersen et al 2016 Phys. Scr. 91 053001
Squeezed light generation has come of age. Significant advances on squeezed light generation have been made over the last 30 years—from the initial, conceptual experiment in 1985 till today's top-tuned, application-oriented setups. Here we review the main experimental platforms for generating quadrature squeezed light that have been investigated in the last 30 years.
Gerianne Alexander et al 2020 Phys. Scr. 95 062501
Sounds of Science is the first movement of a symphony for many (scientific) instruments and voices, united in celebration of the frontiers of science and intended for a general audience. John Goodenough, the maestro who transformed energy usage and technology through the invention of the lithium-ion battery, opens the programme, reflecting on the ultimate limits of battery technology. This applied theme continues through the subsequent pieces on energy-related topics—the sodium-ion battery and artificial fuels, by Martin Månsson—and the ultimate challenge for 3D printing, the eventual production of life, by Anthony Atala. A passage by Gerianne Alexander follows, contemplating a related issue: How might an artificially produced human being behave? Next comes a consideration of consciousness and free will by Roland Allen and Suzy Lidström. Further voices and new instruments enter as Warwick Bowen, Nicolas Mauranyapin and Lars Madsen discuss whether dynamical processes of single molecules might be observed in their native state. The exploitation of chaos in science and technology, applications of Bose–Einstein condensates and the significance of entropy follow in pieces by Linda Reichl, Ernst Rasel and Roland Allen, respectively. Mikhail Katsnelson and Eugene Koonin then discuss the potential generalisation of thermodynamic concepts in the context of biological evolution. Entering with the music of the cosmos, Philip Yasskin discusses whether we might be able to observe torsion in the geometry of the Universe. The crescendo comes with the crisis of singularities, their nature and whether they can be resolved through quantum effects, in the composition of Alan Coley. The climax is Mario Krenn, Art Melvin and Anton Zeilinger's consideration of how computer code can be autonomously surprising and creative. In a harmonious counterpoint, his 'Guidelines for considering AIs as coauthors', Roman Yampolskiy concludes that code is not yet able to take responsibility for coauthoring a paper. An interlude summarises a speech by Zdeněk Papoušek. In a subsequent movement, new themes emerge as we seek to comprehend how far we have travelled along the path to understanding, and speculate on where new physics might arise. Who would have imagined, 100 years ago, a global society permeated by smartphones and scientific instruments so sophisticated that genes can be modified and gravitational waves detected?
Anton Zeilinger 2017 Phys. Scr. 92 072501
The quantum physics of light is a most fascinating field. Here I present a very personal viewpoint, focusing on my own path to quantum entanglement and then on to applications. I have been fascinated by quantum physics ever since I heard about it for the first time in school. The theory struck me immediately for two reasons: (1) its immense mathematical beauty, and (2) the unparalleled precision to which its predictions have been verified again and again. Particularly fascinating for me were the predictions of quantum mechanics for individual particles, individual quantum systems. Surprisingly, the experimental realization of many of these fundamental phenomena has led to novel ideas for applications. Starting from my early experiments with neutrons, I later became interested in quantum entanglement, initially focusing on multi-particle entanglement like GHZ states. This work opened the experimental possibility to do quantum teleportation and quantum hyper-dense coding. The latter became the first entanglement-based quantum experiment breaking a classical limitation. One of the most fascinating phenomena is entanglement swapping, the teleportation of an entangled state. This phenomenon is fundamentally interesting because it can entangle two pairs of particles which do not share any common past. Surprisingly, it also became an important ingredient in a number of applications, including quantum repeaters which will connect future quantum computers with each other. Another application is entanglement-based quantum cryptography where I present some recent long-distance experiments. Entanglement swapping has also been applied in very recent so-called loophole-free tests of Bell's theorem. Within the physics community such loophole-free experiments are perceived as providing nearly definitive proof that local realism is untenable. While, out of principle, local realism can never be excluded entirely, the 2015 achievements narrow down the remaining possibilities for local realistic explanations of the quantum phenomenon of entanglement in a significant way. These experiments may go down in the history books of science. Future experiments will address particularly the freedom-of-choice loophole using cosmic sources of randomness. Such experiments confirm that unconditionally secure quantum cryptography is possible, since quantum cryptography based on Bell's theorem can provide unconditional security. The fact that the experiments were loophole-free proves that an eavesdropper cannot avoid detection in an experiment that correctly follows the protocol. I finally discuss some recent experiments with single- and entangled-photon states in higher dimensions. Such experiments realized quantum entanglement between two photons, each with quantum numbers beyond 10 000 and also simultaneous entanglement of two photons where each carries more than 100 dimensions. Thus they offer the possibility of quantum communication with more than one bit or qubit per photon. The paper concludes discussing Einstein's contributions and viewpoints of quantum mechanics. Even if some of his positions are not supported by recent experiments, he has to be given credit for the fact that his analysis of fundamental issues gave rise to developments which led to a new information technology. Finally, I reflect on some of the lessons learned by the fact that nature cannot be local, that objective randomness exists and about the emergence of a classical world. It is suggestive that information plays a fundamental role also in the foundations of quantum physics.
S Pfalzner et al 2015 Phys. Scr. 90 068001
The solar system started to form about 4.56 Gyr ago and despite the long intervening time span, there still exist several clues about its formation. The three major sources for this information are meteorites, the present solar system structure and the planet-forming systems around young stars. In this introduction we give an overview of the current understanding of the solar system formation from all these different research fields. This includes the question of the lifetime of the solar protoplanetary disc, the different stages of planet formation, their duration, and their relative importance. We consider whether meteorite evidence and observations of protoplanetary discs point in the same direction. This will tell us whether our solar system had a typical formation history or an exceptional one. There are also many indications that the solar system formed as part of a star cluster. Here we examine the types of cluster the Sun could have formed in, especially whether its stellar density was at any stage high enough to influence the properties of today's solar system. The likelihood of identifying siblings of the Sun is discussed. Finally, the possible dynamical evolution of the solar system since its formation and its future are considered.
Roland E Allen and Suzy Lidström 2017 Phys. Scr. 92 012501
In The Hitchhiker's Guide to the Galaxy, by Douglas Adams, the Answer to the Ultimate Question of Life, the Universe, and Everything is found to be 42—but the meaning of this is left open to interpretation. We take it to mean that there are 42 fundamental questions which must be answered on the road to full enlightenment, and we attempt a first draft (or personal selection) of these ultimate questions, on topics ranging from the cosmological constant and origin of the Universe to the origin of life and consciousness.
Michael G Raymer and Ian A Walmsley 2020 Phys. Scr. 95 064002
We review the concepts of temporal modes (TMs) in quantum optics, highlighting Roy Glauber's crucial and historic contributions to their development, and their growing importance in quantum information science. TMs are orthogonal sets of wave packets that can be used to represent a multimode light field. They are temporal counterparts to transverse spatial modes of light and play analogous roles—decomposing multimode light into the most natural basis for isolating statistically independent degrees of freedom. We discuss how TMs were developed to describe compactly various processes: superfluorescence, stimulated Raman scattering, spontaneous parametric down conversion, and spontaneous four-wave mixing. TMs can be manipulated, converted, demultiplexed, and detected using nonlinear optical processes such as three-wave mixing and quantum optical memories. As such, they play an increasingly important role in constructing quantum information networks.
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Paulo H B Silva et al 2024 Phys. Scr. 99 055116
Seminal for the raising of the quantum information age and quintessential for a deep understanding of nature, Bell inequality violations are known for having provided a profound disruption to classical models of the physical world. Yet, their meaning is still debatable nowadays. An important point under dispute in this context concerns the relevance of realism. While some believe that a Bell inequality violation implies the manifestation of nonlocal aspects, others defend that it is the notion of realism that should be abandoned. The purpose of the present work is to shed some light on the matter by employing a formal definition of (ir)realism. Our strategy consists of (i) rephrasing Bell's assumption of local causality in terms of more primitive hypotheses and (ii) assessing where the fundamental difficulties emerge when using the quantum formalism. We analyze the question posed in the title using two distinct approaches and assert that a positive answer is justifiable. Nevertheless, even in this scenario, it becomes evident that violations of locality cannot be avoided. As a byproduct of our approach, the connections of (ir)realism with both quantum steering and entanglement are also discussed.
Yuanbiao Li and Bo Yang 2024 Phys. Scr. 99 065208
In this paper, the Monte Carlo simulation method is used to investigate a generalized random walk model based on node2vec which is a popular algorithm in network embedding and has been widely applied in various domains such as link prediction, node classification, recommendation systems, etc. The aim is to quantitatively study the impact of the random walk parameters(including the number of walks per initial node r, the length of each walk l, the return parameter α, the common neighbor parameter β, and the outgoing parameter γ) on the embedding results. Specifically, the cross entropy is utilized as an observation to compare the difference between the frequency of nodes after random walks and the normalized degree sequence of nodes. The results show that the clustering coefficient significantly impacts the cross entropy. For networks with high clustering coefficient, the value of β should closely approximate that of γ, whereas for networks with low clustering coefficient, the value of β should be significantly smaller than that of γ. The value of α should be less than or equal to the minimum values between β and γ. Finally, the embedding effects of different random walk parameters are tested using node classification and link prediction tasks in real-world networks, and the results indicate that cross entropy can provide guidance for obtaining high-quality node embedding.
Lin Zhang et al 2024 Phys. Scr. 99 065103
The uncertainty relation is a fundamental concept in quantum theory, plays a pivotal role in various quantum information processing tasks. In this study, we explore the additive uncertainty relation pertaining to two or more observables, in terms of their variance, by utilizing the generalized Gell-Mann representation in qudit systems. We find that the tight state-independent lower bound of the variance sum can be characterized as a quadratic programming problem with nonlinear constraints in optimization theory. As illustrative examples, we derive analytical solutions for these quadratic programming problems in lower-dimensional systems, which align with the state-independent lower bounds. Additionally, we introduce a numerical algorithm tailored for solving these quadratic programming instances, highlighting its efficiency and accuracy. The advantage of our approach lies in its potential ability to simultaneously achieve the optimal value of the quadratic programming problem with nonlinear constraints but also precisely identify the extremal state where this optimal value is attained. This enables us to establish a tight state-independent lower bound for the sum of variances, and further identify the extremal state at which this lower bound is realized.
Huai-Yi Xie 2024 Phys. Scr. 99 065502
Dyadic Green's functions (DGFs) are developed for calculating electric fields induced by multiple sources in the presence of a topological insulator (TI) stratified sphere within the framework of axion electrodynamics. Generalizing our previous work, these sources can be placed at arbitrary locations rather than be limited outside the TI stratified sphere. Utilizing these DGFs, we explore the topological magneto-electric (TME) effect of the dipole–dipole interaction in the presence of composite structures of an alternating metal-TI stratified sphere, causing some modifications of the energy transfer (ET) enhancement spectrum. Furthermore, for the multipolar resonances of the metal shells, we find the TME-induced red-shifts of each bonding and antibonding mode in the ET enhancement spectrum are independent on the locations and orientations of the two dipoles but only depend on the configuration of these composite structures. These phenomenological findings provide some useful guidance with experimenters to design realistic experiments for exploring possible unique TME signatures via the energy transfer between molecules near/in TI multicoated nanoparticles in the near-infrared region.
Mohd Shakir Khan et al 2024 Phys. Scr. 99 062001
Efficient energy storage strategies have become a major priority in the last few years. Transition metal sulphides are popularly known as attractive electrode materials or supercapacitors due to their high theoretical capacitance, excellent electrical conductivity, and favourable redox properties. Through compositional and structural engineering, some transition metal sulphides like Mn, V, Co, Fe, Cu, Ni, Mo, Zn, W, and Sn have shown substantial improvements in electrochemical performance. Composite engineering and morphological control are two of the key strategies employed to improve the TMS electrode's electrochemical performance. Excellent electrochemical TMSs address the issues of slow kinetics, poor stability, and large volume expansions. This study reveal optimised TMSs potential to transform supercapacitor applications and provides viable approaches to conquer current hurdles to shape the forthcoming century's high-performance and low-cost energy storage technology. The effects of composite engineering and morphological control on the ultimate electrochemical performance of the electrode materials are the primary focus of this investigation. Challenges to the further advancement of transition metal sulphide-based electrode materials are also explored in this article. Critical approaches to resolving significant issues in our current understanding of the kinetic and mechanistic perspectives of charge storage processes, i.e., slow kinetics, poor stability, and volume expansions, are also highlighted. Ultimately, future potentials, challenges, and possible solutions to tackle these problems are broadly discussed.
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Mohd Shakir Khan et al 2024 Phys. Scr. 99 062001
Efficient energy storage strategies have become a major priority in the last few years. Transition metal sulphides are popularly known as attractive electrode materials or supercapacitors due to their high theoretical capacitance, excellent electrical conductivity, and favourable redox properties. Through compositional and structural engineering, some transition metal sulphides like Mn, V, Co, Fe, Cu, Ni, Mo, Zn, W, and Sn have shown substantial improvements in electrochemical performance. Composite engineering and morphological control are two of the key strategies employed to improve the TMS electrode's electrochemical performance. Excellent electrochemical TMSs address the issues of slow kinetics, poor stability, and large volume expansions. This study reveal optimised TMSs potential to transform supercapacitor applications and provides viable approaches to conquer current hurdles to shape the forthcoming century's high-performance and low-cost energy storage technology. The effects of composite engineering and morphological control on the ultimate electrochemical performance of the electrode materials are the primary focus of this investigation. Challenges to the further advancement of transition metal sulphide-based electrode materials are also explored in this article. Critical approaches to resolving significant issues in our current understanding of the kinetic and mechanistic perspectives of charge storage processes, i.e., slow kinetics, poor stability, and volume expansions, are also highlighted. Ultimately, future potentials, challenges, and possible solutions to tackle these problems are broadly discussed.
Chenyan Huang et al 2024 Phys. Scr. 99 052004
Noise pollution is an important problem affecting people's lives and work quality. In the current noise reduction materials, the porous sound absorption materials usually only haveagood sound absorption effect for medium and high -frequency sound waves, and the sound absorption effect for low -frequency sound waves is relatively weak. However, in recent years, the research on acoustic metamaterials has made a breakthrough which can effectively absorb or isolate low-frequency sound waves. Therefore, researchers propose to combine porous sound-absorbing materials with acoustic metamaterials to form a composite structure, that broadens the frequency range of noise reduction, so as to achieve the goal of full-frequency domain noise reduction. This paper first introduces the research progress of porous materials and acoustic metamaterials, and then introduces the research progress of composite structures that are made of porous materials and acoustic metamaterials. Finally, the application prospect of the composite field of porous sound-absorbing materials and acoustic metamaterials are summarized.
Sonal Santosh Bagade and Piyush K Patel 2024 Phys. Scr. 99 052003
To achieve efficient solar cells, an in-depth review on significance of diffusion length enhancement is presented in this research work. We have focused on globally-adopted strategy of increasing diffusion length. The experimental pathways followed by various researchers to realize this strategy are deeply explored in this paper. The total of nine key-parameters that control and facilitate diffusion length enhancement are identified. Moreover, total of four parameters which are primarily influenced by diffusion length enhancement are listed. The underlying cause-&-effect mechanism pertaining to each parameter is discussed in-depth in this article. Furthermore, the comparison is performed between impact of electron and hole diffusion length enhancement on the device performance. The way to potentially implement this study for appropriate absorber layer selection is presented. Finally, a comparative study is performed on extent of influence of diffusion length enhancement technique to that of the band-offset optimization technique to achieve higher device performance. This rigorous analysis leads to discovery of the fact that diffusion length enhancement raises solar cell efficiency seven times as compared to that obtained by band offset optimization. Hence, significance of diffusion length enhancement for the pinnacle performance of solar cell is vividly revealed in this paper.
Theivasanthi Thirugnanasambandan et al 2024 Phys. Scr. 99 052002
The development of advanced materials, new device architectures and fabrication processes will lead to more utilization of renewable energy sources like solar energy. Solar energy can be harvested more effectively using solar cells incorporated with advanced nanomaterials. Black phosphorus (BP) is a two-dimensional material in which the layers are stacked together through van der Waals forces. The electrical and optical properties of the material are much more suitable for use in solar cell applications. BP nanosheets have optoelectronic properties such as tunable bandgap (0.3 eV − 2.0 eV) and high carrier mobility that make them as suitable candidates for solar cells. Also, BP is able to absorb a wide range of light energy in the electromagnetic spectrum. Being a p-type semiconductor, BP finds applications in optoelectronic and semiconductor- devices. The optical absorption of the material is determined by its structural orientation. The material also possesses the high in-plane anisotropic band dispersion near the Fermi level in the Brillouin zone which results in a high direction-dependent optical and electronic properties. The major limitation of the material is its stability since it is degraded under the illumination of light. BP is used as an electron transport layer in solar cells similar to ZnO, TiO2 and graphene. BP can also be integrated with hole transport layers and active materials. Research efforts have shown that BP and its derivatives have more potential to produce high efficiency solar cells. The application of BP in various solar cells and the enhancement in the efficiency of solar cells such as organic solar cells, perovskite solar cells, dye-sensitized solar cells and silicon solar cells are discussed in this review.
Raghuraman V and Sampath Kumar T 2024 Phys. Scr. 99 052001
The laser powder bed fusion LPBF method in additive manufacturing for metals have proven to produce a final product with higher relative density, when compare to other metal additive manufacturing processes like WAAM, DED and it takes less time even for complex designs. Despite the use of many metal-based raw materials in the LPBF method for production of products. Maraging steel (martensitic steel) is used in aeronautical and aircraft applications in view of its advantages including low weight, high strength, long-term corrosion resistance, low cost, availability, and recyclability. A research gap concerns the selection of design, dimension, accuracy, process parameters according to different grades, and unawareness of various maraging steels other than specific maraging steels. In this comprehensive review, the research paper provides information about on LPBF maraging steel grades, their process parameters and defects, microstructure characteristics, heat treatments, and the resulting mechanical characteristics changes. In addition, detailed information about the aging properties, fatigue, residual and future scope of different maraging steel grades in LPBF for various applications are discussed.
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Abubakar et al
In this research, an eight-element dual-band modified T-shaped slot antenna array is presented for high-performance integration into smartphones. This advanced antenna system operates efficiently across two critical frequency bands, 3.37-3.61 GHz and 4.9-5.1 GHz, catering to the sub-6 GHz 5G spectrum. The
antenna elements are symmetrically arranged on the ground plane, measuring 20 x 11.8 mm2 (0.233 λ x 0.138λ). A notable design feature is the introduction of section Dx, with dimensions d1 and d2, strategically positioned between the ground-mounted antennas to enhance isolation among radiating elements by
effectively managing surface currents. The proposed design is fabricated and isolation levels below -14 dB is achieved, with an Envelope Correlation Coefficient
(ECC) lower than 0.05 in the lower frequency band and 0.02 in the higher band. It demonstrated impressive efficiency ranging from 48.5% to 63.7%, a channel
capacity of 38.8 bps/Hz, and a gain of 3.9 dBi.
Lakkaraju et al
Parity-time $(\mathcal{PT})$ symmetric quantum theory can broaden the scope of quantum dynamics beyond unitary evolution which may lead to numerous counter-intuitive phenomena, including single-shot discrimination of non-orthogonal states, faster evolution of state than the standard quantum speed limit, and violation of no-signaling principle. On the other hand, $\mathcal{PT}$-symmetric evolution can be realized as reduced dynamics of a subsystem in real experiments within the scope of standard QT. In this experimental setup, if one side of a composite system is evolved according to a $\mathcal{PT}$-symmetric way, a non-trivial information transfer can happen, i.e., the operation performed at one side can be gathered by the other side. By considering an arbitrary shared state between two parties situated in two distant locations and arbitrary measurements, we show that the $\mathcal{PT}$-symmetric evolution of the reduced subsystem at one side is not sufficient for this information transfer to occur. Specifically, we prove that the information transfer can only happen when the density matrix and the corresponding measurements contain complex numbers. Moreover, we connect the entanglement content of the shared state with the efficacy of information transfer. We find evidence that the task becomes more efficient with the increase of dimension. 



Yüksel et al
In this study, we present the design of a photonic crystal (PC) structure with a hexagonal lattice, where adjustments to the PC unit cell symmetry reveal an all-angle self-collimation (SC) effect. By optimizing opto-geometric parameters, such as the rotational angle of auxiliary rods and adjacent distances, we analyze the SC property, leveraging group velocity dispersion (GVD) and third-order dispersion (TOD) characteristics. We also investigate the relationship between symmetry properties and their influence on dispersion characteristics. Through symmetry manipulation, we gain a comprehensive understanding of the underlying mechanisms governing light collimation and confinement in the proposed configurations. The PC structure with a C1 symmetry group exhibits all-angle SC effect within the range of a/λ=0.652 and a/λ=0.668 normalized frequencies, with a bandwidth of Δω/ωc =2.4% Further breaking the symmetry, transforming from C1 to C2 group symmetry, enhances the SC bandwidth to Δω/ωc =6.5% and reveals the perfect linear equi-frequency contours (EFC) at two different frequency bands: all angle SC between a/λ=0.616 and a/λ=0.656 normalized frequencies in the 4th transverse magnetic (TM) band and between a/λ=0.712 and a/λ=0.760 in the 5th TM band. Here, GVD and TOD values of TM 4th band vary between 7.3 (a/2πc2) – 254.3 (a/2πc2) and 449.2 (a2/ 4π2c3) – 1.3×105 (a2/ 4π2c3), respectively. Also, GVD and TOD values of TM 5th band vary between 182.5 (a/2πc2) – 71.3 (a/2πc2) and -24380(a2/ 4π2c3) – -9619 (a2/ 4π2c3) for the TM 5th band values. Additionally, we propose a composite/hybrid PC structure resembling C2 group symmetry, where two auxiliary rods are replaced by rectangular photonic wires with the same refractive index and width equal to the diameter of auxiliary rods. This hybrid structure exhibits an all-angle SC effect with an operating bandwidth of Δω/ωc =11.7%, which displays near-zero GVD and TOD performance and offers enhanced robustness against potential fabrication precision issues.
Di Manici et al
Objective: Radiation therapy requires reliable dosimetry protocols to deliver successful treatments with high accuracy and precision. In this context, accurate knowledge of the beam's energy spectra is mandatory. The goal of this study was to validate the synchrotron X-ray spectrum of the ID17 beamline at the European Synchrotron Radiation Facility (ESRF). The modification of the synchrotron storage ring and beamline in recent years necessitates a new characterisation of the radiation spectra of the ID17 beamline. The validated spectra will be a starting point for possible future clinical applications.
Approach: The half value layer method was used to measure the attenuation of the X-ray spectrum in Al and Cu. Experimental data was validated against theoretical data produced using OASYS; an in-house developed software for calculating beamline spectra. Two different spectral configurations, "conventional" and "clinical", were investigated. The characterised spectra were used to perform dosimetric validation of depth dose profiles measured in a water-equivalent phantom. The dose profile was measured using two different detectors and compared with calculations generated using two different Monte Carlo algorithms.
Main results: The results showed good agreement between measured and predicted half value layers, with differences of less than 1%. Excellent agreement to within 3% was obtained, an agreement that satisfies the requirements in conventional radiotherapy for approvable treatment planning.
Significance: Accurate spectra have been defined and validated for the ESRF – ID17 Biomedical beamline. The validated spectra can be used as input for future dosimetric studies and treatment planning systems in the context of preclinical studies and possible future clinical trials.
. et al
In this communication, a two-port ceramic based array radiator at mm-wave frequency range is structured and analysed. 3-dB power divider based microstrip feed line is utilised to excite the rectangular aperture. The same aperture is used to feed the ceramic, which creates fundamental hybrid mode (HEM11δ) inside the dielectric resonator. Feeding structure is designed on RT Duroid substrate having thickness 0.254 mm and permittivity 2.2. The length and width of the substrate is 60.0 mm and 30.0 mm respectively. Alumina material is used to design the ceramic having permittivity 9.8. The exclusive feature of the proposed antenna design is to get highly directional pattern along with high gain (more than 13.5 dBi) in mm-wave frequency range with the assistance of 1*4 array structure. Orthogonal orientation of antenna ports adds the polarization diversity concept, which in turns improve the isolation level more than 50 dB. Measured results confirm that the designed antenna works effectively in between 31.5-32.8 GHz. Broadside radiation pattern and good value of Envelop correlation coefficient (less than 0.1)/Diversity gain (10.0 dB) make the designed antenna employable for n257 frequency band of 5G mm-wave applications.
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Jiafei Yao et al 2024 Phys. Scr. 99 065207
In this paper, a negative capacitance field effect transistor with thickness variable ferroelectric layer (TVFL NCFET) based on the fully depleted silicon on insulator (FDSOI) is proposed. The TVFL NCFET features the linearly increased ferroelectric layer thickness along the channel from source to drain. The gradient voltage amplification effect caused by the TVFL is analyzed according to the proposed capacitance model and simulation. Both of the model and numerical results indicate that the TVFL leads to a gradient increased electrostatic potential distribution along the bottom of the ferroelectric layer. The influences of gradient voltage amplification effect on the transfer characteristics, the output characteristic, the ratio between on-state-current (ION) and off-state-current (IOFF), the drain induced barrier lowering (DIBL) and the subthreshold swing (SS) are investigated. The results show that the TVFL NCFET achieves the SS of 53.14 mV/dec, which is reduced by 19% when compared to the conventional NCFET. Meanwhile, large ION/IOFF is also realized and up to 1012 at most.
Hassan Sani Abubakar et al 2024 Phys. Scr.
In this research, an eight-element dual-band modified T-shaped slot antenna array is presented for high-performance integration into smartphones. This advanced antenna system operates efficiently across two critical frequency bands, 3.37-3.61 GHz and 4.9-5.1 GHz, catering to the sub-6 GHz 5G spectrum. The
antenna elements are symmetrically arranged on the ground plane, measuring 20 x 11.8 mm2 (0.233 λ x 0.138λ). A notable design feature is the introduction of section Dx, with dimensions d1 and d2, strategically positioned between the ground-mounted antennas to enhance isolation among radiating elements by
effectively managing surface currents. The proposed design is fabricated and isolation levels below -14 dB is achieved, with an Envelope Correlation Coefficient
(ECC) lower than 0.05 in the lower frequency band and 0.02 in the higher band. It demonstrated impressive efficiency ranging from 48.5% to 63.7%, a channel
capacity of 38.8 bps/Hz, and a gain of 3.9 dBi.
Ilaria Di Manici et al 2024 Phys. Scr.
Objective: Radiation therapy requires reliable dosimetry protocols to deliver successful treatments with high accuracy and precision. In this context, accurate knowledge of the beam's energy spectra is mandatory. The goal of this study was to validate the synchrotron X-ray spectrum of the ID17 beamline at the European Synchrotron Radiation Facility (ESRF). The modification of the synchrotron storage ring and beamline in recent years necessitates a new characterisation of the radiation spectra of the ID17 beamline. The validated spectra will be a starting point for possible future clinical applications.
Approach: The half value layer method was used to measure the attenuation of the X-ray spectrum in Al and Cu. Experimental data was validated against theoretical data produced using OASYS; an in-house developed software for calculating beamline spectra. Two different spectral configurations, "conventional" and "clinical", were investigated. The characterised spectra were used to perform dosimetric validation of depth dose profiles measured in a water-equivalent phantom. The dose profile was measured using two different detectors and compared with calculations generated using two different Monte Carlo algorithms.
Main results: The results showed good agreement between measured and predicted half value layers, with differences of less than 1%. Excellent agreement to within 3% was obtained, an agreement that satisfies the requirements in conventional radiotherapy for approvable treatment planning.
Significance: Accurate spectra have been defined and validated for the ESRF – ID17 Biomedical beamline. The validated spectra can be used as input for future dosimetric studies and treatment planning systems in the context of preclinical studies and possible future clinical trials.
Ayten Özkan 2024 Phys. Scr. 99 055269
In this study, the fractional impacts of the beta derivative and M-truncated derivative are examined on the DNA Peyrard-Bishop dynamic model equation. To obtain solitary wave solutions for the model, the Sardar sub-equation approach is utilized. For a stronger comprehension of the model, the acquired solutions are graphically illustrated together with the fractional impacts of the beta and M-truncated derivatives. In addition to being simple and not needing any complicated computations, the approach has the benefit of getting accurate results.
V K Anand et al 2024 Phys. Scr. 99 055977
CeRh2Ga2, which crystallizes in CaBe2Ge2-type primitive tetragonal structure (space group P4/nmm), is known to exhibit Kondo lattice heavy fermion behavior and is proposed to be a potential candidate for Weyl-Kondo semimetal phase. Here we examine the effect of annealing, particularly on the electrical resistivity of polycrystalline CeRh2Ga2. A comparative study of the powder x-ray diffraction (XRD), magnetic susceptibility χ(T), heat capacity Cp(T) and electrical resistivity ρ(T) data of both as-arc-melted and annealed CeRh2Ga2 samples are presented. The XRD patterns of both as-arc-melted and annealed samples look similar. No marked effect of annealing could be clearly seen in the temperature dependences of χ and Cp data. However, the effect of annealing is clearly manifested in the T dependence of ρ, particlularly at low temperatures. At low-T the ρ(T) data of as-arc-melted CeRh2Ga2 follow a T2 temperature dependence (Fermi-liquid feature), whereas the ρ(T) data of annealed CeRh2Ga2 exhibit an upturn (semimetal-like feature).
Patricia Hernández-León and Miguel Caro 2024 Phys. Scr.
We present a new technique for visualizing high-dimensional data called cluster MDS (cl-MDS), which addresses a common difficulty of dimensionality reduction methods: preserving both local and global structures of the original sample in a single 2-dimensional visualization. Its algorithm combines the well-known multidimensional scaling (MDS) tool with the k-medoids data clustering technique, and enables hierarchical embedding, sparsification and estimation of 2-dimensional coordinates for additional points. While cl-MDS is a generally applicable tool, we also include specific recipes for atomic structure applications. We apply this method to non-linear data of increasing complexity where different layers of locality are relevant, showing a clear improvement in their retrieval and visualization quality.
Christopher R Martin et al 2024 Phys. Scr. 99 055609
This simplified model provides solutions for the current-voltage characteristics of a sheath in a dense flowing plasma when surface chemistry contributes secondary ions. The problem is motivated by the recent discovery that strong transient signals in industrial ion current sensors are caused by chemical reactions with carbon in the steel being cut or welded by oxyfuel processes. The one-dimensional model considers a quasi-uniform dense plasma flowing towards and stagnating on an absorbing surface, above which there is a source of secondary ions. Because the secondary ions are formed directly in the plasma sheath, they have strong impacts on the current-voltage characteristic. With ionic Reynolds number, R, and integral length scale, α, secondary ion formation rate, Ω, and length scale, β, saturation currents are simply R + βΩ until β ≪ 1, at which point, new electrons cannot escape the sheath, and secondary ions have no effect. Floating potential, ϕ∞, scales like , and secondary ions have little impact unless β2Ω > 1. Even then, floating potential is only weakly affected by secondary ion formation. The integral length scale, α, is not found to strongly affect the results.
Yong Wang et al 2024 Phys. Scr.
Cascaded arc plasma has been widely applied in linear plasma devices (LPDs) to produce high flux plasma for the study of plasma-material interaction. In this work, cascaded arc He plasma produced in an LPD with a compact arrangement is investigated by voltammetry and optical emission spectroscopy (OES). The results show that the cathode potential increases with the discharge current while it firstly decreases and then increases as increasing the gas flow rate. A local reverse electric field is observed at low gas flow rates between two cascaded plates (i.e. floating electrodes) near the cathode. The OES' results reveal that as the gas flow rate increases, the intensity of He I lines increases and the electron excitation temperature (Texc) decreases. As increasing the discharge current, the intensity of He lines exhibits various trends at different gas flow rates, showing a monotonic decline at 1.94 slm and a first increase followed by a reduction at 3.52 slm. The Texc increases with the discharge current. These findings could preliminarily shed light on the properties of cascaded arc of He plasma in the compact LPD and aid in the optimization of the device to generate the high-flux divertor-relevant plasma.
Y. B Ateş and Eser Olgar 2024 Phys. Scr.
The effect of isotropic velocity-dependent potentials on the bound state energy eigenvalues of the Kratzer, Mie and Hulthen potentials is obtained for any quantum states in the presence of constant form factor ε(r)=γρ_0. The corresponding energy eigenvalues and eigenfunctions are determined for any quantum numbers n and l in the framework of the well-known Nikiforov-Uvarov method. 
Andrew R Hogan and Andy M Martin 2024 Phys. Scr. 99 055118
Both the Jaynes-Cummings-Hubbard (JCH) and Dicke models can be thought of as idealised models of a quantum battery. In this paper we numerically investigate the charging properties of both of these models. The two models differ in how the two-level systems are contained in cavities. In the Dicke model, the N two-level systems are contained in a single cavity, while in the JCH model the two-level systems each have their own cavity and are able to pass photons between them. In each of these models we consider a scenario where the two-level systems start in the ground state and the coupling parameter between the photon and the two-level systems is quenched. Each of these models display a maximum charging power that scales with the size of the battery N and no super charging was found. Charging power also scales with the square root of the average number of photons per two-level system m for both models. Finally, in the JCH model, the power was found to charge inversely with the photon-cavity coupling κ.