Materials that exhibit reversible field-tunable responses to electric and magnetic stimuli enable adaptive modulation of mechanical, dielectric, and magnetic properties. This review focuses on electro-magnetorheological (EMR) hybrid materials that concurrently exploit electric polarization and magnetization-induced structure formation, with particular emphasis on protocol-dependent, non-additive behavior under superimposed fields. The underlying electrorheological (ER) and magnetorheological (MR) response mechanisms are analyzed from classical dipolar models to advanced descriptions that incorporate interfacial polarization phenomena, effective (microstructure-mediated) magnetoelectric coupling, and nonlinear structural dynamics. Microscopic interaction mechanisms are consistently linked to the macroscopic rheological and functional behavior of EMR fluids, gels, and elastomers, with an emphasis on viscoelastic properties, electrical conductivity, and cross-field coupling effects. The impact of field orientation, application sequence, and driving frequency on emergent material behavior is critically evaluated. The design and synthesis concepts for bifunctional particles and hierarchical composites are summarized. Key challenges related to colloidal and structural stability, response reproducibility, scalable manufacturing routes, and environmental sustainability are also discussed. Emerging multiscale and data-driven modeling frameworks are highlighted as enabling tools for predictive material design and optimization of EMR materials. Standardization needs in measurement protocols and reporting practices are addressed. The focus is on synchronized in situ structural characterization combined with dielectric and electrical measurements. These methods are used to rigorously discriminate additive superposition of ER and MR responses from genuinely non-additive cross-field coupling. Finally, perspectives on applications and device-integration strategies for EMR-based components and systems are outlined.
The Casimir effect, a fundamental manifestation of quantum vacuum fluctuations, has evolved from a curiosity between idealized metallic plates to a versatile probe of quantum and material properties in structured and time-dependent media. This review traces the progression of Casimir force research from its classical formulation in noble metals like gold (Au) to cutting-edge developments involving metamaterials and time crystals. Beyond surveying recent experimental and theoretical advances, we provide a unifying framework that bridges Casimir physics with essential solid-state principles—including band theory, dielectric response, and temporal periodicity—critical for understanding forces in real and engineered materials. Special attention is given to non-equilibrium and dynamically modulated systems, where time-periodic structures can profoundly alter vacuum-induced interactions. By synthesizing insights from quantum field theory and condensed matter physics, this review offers a comprehensive perspective on the rich interplay between quantum fluctuations, material response, and temporal symmetry breaking.
Primordial black holes (PBHs) may have formed in the early Universe and may account for all or part of the dark matter. In this review, we summarize the current observational constraints on PBHs across the full mass range, highlight potential evidence for their existence, and outline the prospects for future searches, particularly with gravitational-wave observatories. We also discuss different PBH formation scenarios, identify the corresponding mass functions, and present the observational constraints in each case.
Different platforms and sensors have been exploited since the start of the space era, with the aim of improving the knowledge of the gravity field of our planet. Then, since the beginning of this century, dedicated missions were designed and launched, providing a wealth of data that have helped estimate more and more accurate gravity field models, improving both spatial and temporal resolution. In recent years, the focus of these missions has been the determination of the temporal variations of gravity field, which are an important source of information for studies of global change phenomena. Thus, gravity field observations from space can give a significant contribution to the determination of many essential climate variables which help explaining phenomena that are changing the world we live in: climate change, distribution of water resources, flooding, melting of ice masses, global sea level rise, etc. In this paper, the basic concepts of gravity field observation from satellite missions will be presented. A short history of satellite missions exploited or specifically designed for the observation of the Earth gravity field will be outlined, coming to the most recent satellite missions and to the planned ones (including the novel concept based on quantum sensors) which will further our insight on several geophysical phenomena. In the final part of the paper, some results will be presented for different mission scenarios analyzed by applying the so-called space-wise approach in the frame of recent studies on future satellite gravimetry or gradiometry missions.
String theory relies on spacetime supersymmetry to guarantee the existence of stable vacua. In this review, we survey two features of non-supersymmetric strings that challenge both aspects: appearance of tachyons and worldsheet tadpoles. We describe how tachyons arise, how to characterize their presence in closed strings and in their orientifold projections, and how off-shell approaches can be used to tackle them. We then turn to tachyon-free, non-supersymmetric strings. After introducing the simplest ten-dimensional models, we address the additional issues raised by tadpoles and the spacetime consequences of their cancelation. Finally, we discuss recent attempts to explore the non-supersymmetric string landscape.
Artificial intelligence (AI) has profoundly transformed medical physics across its entire spectrum. Starting from data acquisition, AI has introduced innovations in the processing of imaging data, including denoising and image enhancement. It plays a key role in diagnosis by maximizing the informational content of medical data and supporting clinical decision-making, enhancing both interpretability and transparency through the emerging field of Explainable AI. AI has made significant contributions in areas such as radiotherapy planning optimization, real-time monitoring, and dosimetry, thereby accelerating simulations, reducing errors, and enhancing treatment precision. In the field of interventions, AI is guiding robotic-assisted surgery and intraoperative procedures, enhancing both accuracy and safety. Moreover, AI is streamlining hospital workflows, automating reporting, and enabling operational intelligence. Collectively, these advancements are improving efficiency, accuracy, and patient outcomes, while safeguarding the indispensable role of human care in medicine. This review tries to explore the key advancements enabled by AI in medical physics following the pathway from data acquisition to diagnosis, therapy, and intervention. Looking ahead, personalized care, enabled by digital twins, will make treatments more precise and less invasive. At the same time, generative AI will support healthcare professionals by automating routine tasks, allowing them to focus more on patient relationships and the human side of care.
We all know that the first laser device was realized by Theodore Maiman at Hughes Labs in 1960. Less known is that the very first computer simulations of the relaxation oscillations displayed by Maiman’s laser were also performed in 1960 on a digital IBM 704 computer. The reason is that lasers and almost all photonic devices are described by nonlinear equations that are more often than not impossible to be solved analytically, i.e., on a piece of paper. Since then the development and applications of lasers and photonic devices have progressed hand in hand with computer simulations and numerical programming. In this review, we introduce and numerically solve the model equations for a variety of devices, lasers, lasers with modulated parameters, lasers with injection, Kerr resonators, saturable absorbers, and optical parametric oscillators. Using computer simulations, we demonstrate stability and instability of nonlinear solutions in these photonic devices via pitchfork, saddle-node, Hopf and Turing bifurcations; bistability, nonlinear oscillations, deterministic chaos, Turing patterns, conservative solitons; bright, dark and grey cavity solitons; frequency combs, spatial disorder, spatio-temporal chaos, defect-mediated turbulence and even rogue waves. There has been a one-to-one correspondence between computer simulations of all these nonlinear features and laboratory experiments with applications in ultrafast optical communications, optical memories, neural networks, frequency standards, optical clocks, future GPS, astronomy, and quantum technologies. All of this has been made possible by ’novel insights into spatio-temporal dynamics of lasers, nonlinear and quantum optical systems, achieved through the development and application of powerful techniques for small-scale computing’ (2011 Occhialini Medal and Prize of the Institute of Physics and Societa’ Italiana di Fisica).
The application of X-ray methods (using conventional sources or synchrotron radiation) for investigating degradation phenomena in paintings has significantly increased in the last two decades. This rise is due to their ability to provide spatially resolved elemental, molecular, and structural information from the macroscopic to the nanoscopic levels. This review will focus on the application of latest-generation X-ray techniques, including X-ray fluorescence (XRF), X-ray absorption spectroscopy (XAS), and X-ray diffraction (XRD), to study the alteration processes of pigments in paintings. The first part outlines the fundamentals of XRF, XAS, and XRD techniques and then describes the corresponding instrumental set-ups used for non-invasive macro-scale mapping of paintings and synchrotron radiation-based X-ray analysis of paint micro-samples. Subsequent sections will cover advancements in X-ray data analysis software, workflow management systems, Open Science and FAIR data initiatives, alongside practical aspects of sample preparation and issues concerning X-ray-induced damage to paints. The final section will review degradation phenomena resulting from chemical changes of selected classes of pigments. This will involve describing key findings obtained from paintings, related micro-samples, and artificially aged paint mock-ups. The outcomes discussed in this review highlight their crucial role in developing effective monitoring and preventive conservation strategies for artworks highly susceptible to degradation within heritage sites and museums.
Recent advances in superconducting materials are giving renewed impetus to different power applications, some of which already existed based on previous superconductors with more modest properties while some others have been the symbiosis of new requirements in science and technology and better properties of the new superconductors. This paper constitutes a review of classical and new superconducting materials for power applications (the technological superconductors as they are frequently called) in terms of their structure and their engineering properties (electrical, mechanical and thermal) but also in terms of their manufacturability and scalability for possible scenarios where massive quantities may be required. The second and longer part of the paper is a state of the art of power applications of superconductivity related to energy (generation, transport and transmission), transport (airborne, waterborne and terrestrial) and industrial processes. Practically, all these applications are based on superconducting magnets, which are addressed in the article, including new technologies regarding their design, fabrication and operation. Particularly, these magnets can be the coils of superconducting electrical machines, also described in the paper, where different applications are presented following a scheme of problems to be solved versus the solution provided by superconductivity, including benefits regarding sustainability improvement associated with their better efficiency and power consumption reduction.
Acknowledging spin–orbit coupling (SOC) as a pivotal microscopic ingredient in quantum materials, this paper provides a comprehensive overview of spin–orbit-driven phenomena and effects in magnetic, non-magnetic and multiferroic materials. As for magnets, the review discusses SOC-induced magnetic anisotropy, exotic spin–spin interactions, and their implications on the emergence of complex spin textures. It also explores band-splitting effects in non-magnetic solids, with a focus on Rashba effects and spin-valley coupling. Additionally, the emergence of ferroelectric polarization from non-collinear spin textures in multiferroics is examined. The paper analyzes methods for estimating SOC-related quantities from first principles within the density functional theory, particularly exchange coupling tensors and magnetoelectric coupling tensors. Finally, it presents case studies on two-dimensional magnetic materials, including the characterization of peculiar Kitaev-like exchange coupling and the investigation of multiferroicity in NiI $$_2$$ 2 monolayers. Overall, the paper delves into the microscopic mechanisms related to SOC, by offering insights into the diverse effects and manifestations of SOC in the quantum materials world.
Topological materials, characterized by their symmetry-protected electronic properties, offer transformative opportunities to integrate solid-state topology and catalysis. When coupled with chirality, novel classes of chiral material systems emerge, including topological chiral materials and magnetic chiral materials, distinguished by their unique chiral-related phenomena. Investigating the role of structural and electronic chirality on chiral catalytic processes holds significant promise for designing advanced chiral catalysts. This review provides a comprehensive overview of intrinsic chiral materials with chiral space groups, accompanied by an in-depth analysis of their electronic chirality, including chiral spin angular momentum, chiral orbital angular momentum, chiral charge density waves, and chiral Weyl points. Moreover, we discuss various tuning knobs that induce chiral responses in topological materials. By offering fundamental insights into the interplay between chiral quantum phenomena and chiral catalytic efficiency, this review bridges chemistry and physics, offering strategies to optimize emerging chiral catalytic systems, such as spin-dependent catalysis and asymmetric synthesis.
The term diffusive media refers to all the media for which the photon diffusion equation provides an accurate description of light propagation. Indeed, this is the case for a plethora of natural media, such as biological tissues and agricultural products, when illuminated by red and near-infrared light. Diffuse Optics (DO) is the branch of Optics that studies how absorption and scattering phenomena affect light propagation in diffusive media. In this review paper, we present an introduction to time domain (TD) DO, a specific implementation of DO that employs picosecond light pulses, fast and sensitive photodetectors and timing electronics to record the distribution of photon time-of-flight (or photon path lengths) in diffusive media. By interpreting the TD DO signals with the physical model provided by the photon diffusion theory, it is possible to estimate the absorption and scattering properties of the medium that in case of biological tissues can be related to physiological and pathological conditions. We focus on the physical principles of TD DO, the building blocks of TD DO instrumentation, and the applications of TD DO targeting human biological tissues (such as the brain, breast, muscle, and others).
In this review, we discuss computational methods to study condensed matter systems and processes occurring in this phase. We begin by laying down the theoretical framework of statistical mechanics starting from the fundamental laws governing nuclei and electrons. Among others, we present the connection between thermodynamics and statistical mechanics using a pure statistical language, which makes it easier to extend the microscopic interpretation of thermodynamic potentials to other relevant quantities, such as the Landau free energy (also known as the potential of the mean force). Computational methods for estimating the relevant quantities of equilibrium and non-equilibrium statistical mechanics systems, as well as reactive events, are discussed. An extended Appendix is added, where we present artificial intelligence methods recently introduced. These methods can enhance the power of atomistic simulations, allowing to achieve at the same time accuracy and efficiency in the calculation of the quantities of interest.
Active Galactic Nuclei (AGN) are believed to be powered by accretion of matter onto a supermassive black hole. A fundamental ingredient in shaping our understanding of AGN is their variability across the entire electromagnetic spectrum. Variability studies have the potential to help us understand the geometry of the emitting regions (in various energy bands), their causal relations, and the physics of the accretion processes. This review focuses on the observational properties of AGN variability in the optical/UV/X-ray bands (where most of the AGN luminosity is emitted) and their dependence on the AGN physical parameters (i.e. mass, luminosity, accretion rate). We also discuss possible interpretations in the context of accreting compact systems, and we review the use of variability as a tool to discover AGN and trace their properties across cosmic time, using both ground and space facilities. Finally, we discuss the opportunities and challenges provided by current and next-generation optical/X-ray surveys, to use variability as an effective tool to probe the growth of super massive black holes in the Universe.
We present an overview of transport phenomena in quantum systems induced by time-dependent driving. The emphasis is on steady-state transport (as opposed to transient effects). We introduce the main theoretical frameworks to study open quantum systems out of equilibrium that are useful to study quantum transport under time-dependent driving. Based on this, we discuss the fundamentals of key mechanisms leading to steady-state quantum transport induced by time-dependent driving, such as the periodic charging and discharging of a mesoscopic capacitor, dissipation, quantum pumping, noise, and energy conversion in quantum transport. Our primary focus is on electronic systems, where decades of research have established a rich theoretical foundation and a wealth of experimental realizations. Topics of interest include quantum optics with electrons, quantum transport spectroscopy, quantum electrical metrology, and the critical role of quantum fluctuations in transport and thermodynamics. We also extend the discussion to atomic, molecular, and optical systems, as well as to nanomechanical platforms, which offer complementary perspectives and are currently experiencing rapid experimental development. Finally, we briefly examine the intersection of time-dependent transport and topological matter. This review aims to bring together the diverse approaches and emerging trends that define the current landscape of quantum transport research under time-dependent conditions, bridging theoretical insights with experimental advances across multiple physical platforms.
In this review, we give a brief overview of quantum simulation as applied to the study of complex systems. In particular, we cover the basic ideas of quantum simulation, neuromorphic computation, the Sachdev–Ye–Kitaev model, as well as applications to quantum batteries.
Renormalized field theory is a most effective framework to carry out asymptotic analysis of non-equilibrium nearly critical systems, especially in high orders of perturbation theory. Here, we review some subtle, slippery and non-conventional aspects of this approach. We present construction of the field-theoretic representation of certain Langevin-type stochastic equations with additive and multiplicative random sources as well as master equations of various birth–death processes. Application of the field-theoretic renormalization group combined with the short-distance operator-product expansion to the analysis of asymptotic scaling behavior is reviewed for passive scalar fields advected by various velocity ensembles, including Kraichnan’s rapid-change model and the stochastic Navier–Stokes equation. Infinite sets of anomalous exponents were calculated within regular expansions up to third order. Effects of anisotropy, finite correlation time and compressibility are discussed. The representation of the Kolmogorov constant and the skewness factor suitable for perturbative renormalization-group calculation and the second-order results are presented in a reasonable agreement with experiments in fully developed hydrodynamic turbulence. The recent third-order results for the critical exponents for the directed percolation process are presented; paradigmatic models for irreversible reaction–diffusion processes are discussed with the account of advection in various random velocity fields.
The X(3872) could be a shallow DD̅^* bound state, a compact four-quark state, or a partially composite particle, i.e. a superposition of the two. We will review how these hypotheses could be tested experimentally, examining especially the cases in which the X is a pure bound state or a pure compact tetraquark. Data on X→ DD̅π decays are compared with the analysis of the X lineshape. The pure bound state hypothesis corresponds to a well-defined region in parameter space defined by the width of the D^* versus the binding energy of the X. As for the X lineshape, we observe that the currently available experimental analysis tests the compatibility with the compact hypothesis for the X. We propose how to extend the analysis to examine the molecular or the partially composite hypotheses. We also review the analysis on the radiative decays of the X including pion corrections confirming some conclusions reached in the literature on the use of the universal wave function description for the molecular X.
Tools of quantum and statistical field theories have been successfully applied to turbulence. Nonequilibrium field theory is employed for modeling of hydrodynamic turbulence (HDT), which has small viscosity. In HDT, viscosity renormalization yields wavenumber-dependent viscosity and energy spectrum. Field theory calculations also yield nonzero energy flux for HDT. These field-theoretic computations have been generalized to other systems, such as passive scalar and magnetohydrodynamics. In this review, I cover these aspects, along with a brief coverage of weak turbulence, intermittency, and equilibrium solutions of Euler turbulence.
In this article several typesetting mistakes were made.Section 3.5In equation 4, ϕ (psi) has been written instead of φ (phi).The correct equation in Latex form is: \begin{equation} \label{eq:4} \boldsymbol{P \frac{2\theta}{2\pi-\phi} \frac{2\theta}{\pi + \theta} \frac{4\sinˆ{-1}\frac{R-r}{R + r}}{\pi + 2\sinˆ{-1}\frac{R-r}{R + r}}} \end{equation}
