Papers

Motivated by the equivalent partial-trace formulations of Werner-state distillability [P. Costa Rico, Lett. Math. Phys. 115, 47 (2025); S.-Y. Qi et al., Phys. Rev. A 110, 012406 (2024)], we prove a bipartite partial-trace inequality for every matrix of rank at most two. As applications, we prove the two-copy undistillability of NPT Werner states in arbitrary local dimension, thereby resolving this open problem highlighted in [P. Horodecki et al., PRX Quantum 3, 010101 (2022)]. We further prove a two-parameter extension of the matrix inequality and show that two individually one-copy-undistillable NPT Werner states cannot activate each other's one-copy distillability. We also resolve the singular-value maximization problem associated with the two-ququart case.

In this work, we introduce a multiconfigurational mixed quantum-classical many-body approach for simulating the finite-temperature correlated multi-exciton dynamics in the presence of phonon-induced static and dynamic disorder. In this mixed quantum-classical approach, the excitonic subsystem is described using a multiconfigurational wavefunction that extends beyond the mean-field limit, while the phonons are evolved quasi-classically. Using this approach, we simulate a multi-excitonic dissipative system and show how the interplay between phonon-induced dynamic disorder and exciton-exciton many-body interactions determines excitation-dependent excitonic transport and spatial correlations. Our results show that while the mean-field approach produces semi-quantitatively accurate diffusive dynamics, it does not capture the spatial correlations as expected. We find that a mean-field path approximation, where we generate pre-computed trajectories using our mean-field mixed quantum-classical approach and then perform multiconfigurational dynamics, can reproduce the spatial correlations to a good accuracy, positioning this approach as an efficient method for capturing spatial correlations in complex systems.

Quantum key distribution (QKD) provides information-theoretic security independent of computational assumptions, yet the bulk and cost of current systems hinder large-scale deployment. Although integrated photonic technologies have enabled highly integrated QKD chips, practical QKD transmitters are still predominantly implemented as rack-mounted systems. Here, we demonstrate a highly integrated standalone QKD transmitter that integrates all essential functionalities required for practical QKD operation within a compact platform built around a silicon photonic encoding chip. The transmitter occupies only $167 \times 56 \times 21~\mathrm{mm}^3$ ($\sim 0.2~\mathrm{dm}^3$), comparable in size to a half-height, half-width PCIe card and more than 30 times smaller in volume than a conventional 1U rack-mounted system. Paired with a conventional discrete-component receiver, it achieves a secure key rate of 219.1 kbps over 51.3 km of standard single-mode fiber, with performance comparable to that of conventional discrete-component implementations. This work bridges the gap between photonic chip integration and deployable QKD hardware, marking an important step toward transitioning QKD transmitters from conventional rack-mounted equipment to compact board-level platforms.

We analyze the conformational and dynamical properties of the kinetoplast DNA (kDNA), a massive sheet-like structure made from thousands of circular DNA molecules, found in the mitochondrion of certain parasites. The connectivity between circular DNA molecules is achieved by topological linking, hence, the kDNA may be regarded as a naturally occurring two-dimensional version of Olympic gels, whose physical properties are yet to be understood. We propose that the basic aspects in the large scale behaviors of kDNA could be described by the physics of polymerized membrane. Our analysis indicates the relevance of the hydrodynamic interactions in the dynamics of kDNA in aqueous solution. We demonstrate that the predicted dynamical scaling scenario captures various experimental data recently obtained from in vitro imaging experiments in a unified manner. We also provide an estimate for the in-plane elastic modulus of kDNA, whose magnitude agrees well with recent measurements.

Understanding the effects of doping on the crystal structure and optical properties of semiconductor materials is crucial for advancing next-generation semiconductor and photonic technologies. Although various studies have focused on doped hematite ($\alpha$-Fe$_2$O$_3$), the relationship between dynamical stability and optical properties remains insufficiently explored. This study presents a comprehensive first-principles investigation that simultaneously evaluates the phonon dispersion characteristics and frequency-dependent optical response of B-doped, Y-doped, and (B, Y)-co-doped $\alpha$-Fe$_2$O$_3$, providing deeper insights into the underlying mechanisms. We examined the finite-temperature vibrational properties, dielectric function, and optical characteristics to comprehend the lattice dynamics and light-matter interactions under electromagnetic radiation. Vibrational thermodynamics reveal that pristine and Y-doped hematite maintain dynamic stability, while B-doped hematite exhibits imaginary phonon modes indicating lattice instability due to distortions in the Fe–O framework. Notably, Y co-doping with B helps suppress these soft modes, restoring structural stability through lattice relaxation and improved interatomic forces. B doping enhances low-energy absorption by introducing additional states in the valence band, while Y doping alters orbital hybridization, leading to a broader dispersion. In the optical regime, doped hematite displays dominant interband transitions below $2$ eV and strong absorption between 1.80 eV and 4 eV. The (B, Y) co-doping combines the low-energy benefits with an improved optical response profile. In summary, doping significantly enhances lattice vibrations, light-matter interactions, and optical responses, providing an effective strategy for tailoring hematite for diverse applications in photoactive, optoelectronic, and photonic technologies.

Quantum data-center (QDC) architectures aim to scale distributed quantum computing (DQC) by interconnecting multiple quantum processing units (QPUs), but their performance depends strongly on how algorithmic communication patterns interact with entanglement generation, switch reconfiguration, and network topology. This paper studies the Quantum Approximate Optimization Algorithm (QAOA) as a graph-structured optimization workload for QDC-based distributed quantum computing. We adapt QAOA to SwitchQNet, a distributed quantum compiler framework that schedules communication and entanglement generation over switch-based QDC networks, by adding a routing generator that converts graph-dependent two-qubit cost interactions into remote-CX communication requests across QPUs. Using this extension, we evaluate QAOA instances across Clos, fat-tree, and spine-leaf topologies, measuring communication latency, EPR-pair overhead, EPR wait time, retry overhead, and sensitivity to buffer size, look-ahead depth, communication-qubit count, EPR latency, and EPR fidelity assumptions. The results show that QAOA obtains modest but consistent latency reductions, highlighting its value as a diagnostic benchmark for studying the interaction between algorithm structure, entanglement management, and quantum-network architecture.

Fluid removal from rubber-substrate interfaces is crucial for maintaining friction during walking and vehicle braking on contaminated surfaces. We study the transient friction of rectangular rubber blocks sliding against tile and glass surfaces lubricated with water, glycerol, mud, or silicone grease. Two block configurations with different lengths in the sliding direction were tested after different stationary waiting times. For water, stationary squeeze-out is nearly complete before sliding begins. For glycerol, both stationary squeeze-out and sliding-induced fluid removal are important. For mud and grease, the steady-sliding state is reached after a sliding distance of the order of the block length, with little dependence on the preceding waiting time, showing that sliding-induced scraping dominates fluid removal for highly viscous substances. Dividing the contact into shorter blocks accelerates fluid removal by reducing the drainage distance and increasing the number of leading edges. Stationary squeeze-out calculations based on the measured surface roughness are in reasonably good agreement with the glycerol experiments. The results provide design guidelines for rubber tread blocks with multiscale drainage channels and sufficient compliance to promote transient fluid removal.

The discovery of the accelerated expansion of the cosmos has sparked great interest in studying the nature of the mysterious force behind this effect, often called dark energy. Several theories were proposed to study the nature of dark energy, and holographic dark energy stands out among them due to the relation between dark energy density and the principles of quantum gravity and holography. Recent progress made in fractional cosmology has led to the addition of fractional correction terms to the definition of holographic dark energy. Based on such progress, in this study, we investigate the behavior of fractional holographic dark energy in forming exotic spacetimes, especially traversable wormholes, which represent intriguing solutions of Einstein's field equations connecting distinct regions of spacetime. In the present article, a new class of Morris–Thorne wormhole solutions is obtained under the consideration of fractional holographic dark energy as the source of the gravitational field with a varying redshift function in the context of Einstein gravity. To study the nature of wormholes, their geometry, viability, and thermodynamic behavior, a shape function is obtained, and the wormholes are analyzed in detail via embedding diagrams, throat geometry, active gravitational mass, compactness, exoticity factor, energy conditions, conservation law, volume integral quantifier, Kretschmann invariant, and complexity factor. Moreover, thermodynamic properties of the wormholes are studied via the examination of several parameters, including Hawking temperature, wormhole temperature, entropy, energy, work density, and heat flux, aiming to understand the influence of fractional holographic corrections on the stability and evolution of traversable wormhole structures.

A coordinated DIII-D campaign exposed and comparatively assessed 44 advanced plasma-facing materials from 12 institutions, including four public-private fusion partnerships, to support fusion pilot plant wall and divertor material down-selection. Samples were exposed using the Divertor Materials Evaluation System (DiMES) under Ohmic, L-mode, and H-mode conditions with edge-localized modes, at 0.2-2.5 MW m$^{-2}$ on flush geometries and 10-15 MW m$^{-2}$ on 10$^{\circ}$ angled geometries. Engineered tungsten architectures retained integrity; long-fiber Wf/W showed the clearest crack-arrest behavior. W-Re and K-doped W showed near-ITER-W-like responses, while additively manufactured W-Ta showed heat-flux-sensitive mass losses of 0.64 mg for the flat sample and 2.19-2.87 mg for angled samples. After irradiation to 0.3 dpa at 550$^{\circ}$C, neutron-irradiated ITER-grade W retained 2.8 times more deuterium than pristine W, while TiB$_2$ showed the lowest D$_2$ release in the Ohmic set. VTaHfMo was the most stable refractory multi-principal-element alloy. NbC and (Nb$_{0.5}$Ta$_{0.5}$)C retained integrity with 0.02-0.03 mg mass loss, whereas ZrC lost 7 mg. CVD SiC retained macroscopic integrity but exhibited an effective Si erosion yield of 0.5, about 5-10 times above prior DIII-D trends. Renewable boron pebble rods underwent controlled recession; 13% of released boron was ionized near the outer strike point and up to 50% was recovered locally. Initial in-situ chromium gross-erosion measurements yielded values of order $10^{-2}$. Together, these results provide cross-material benchmarks for fusion pilot plant down-selection and future AI/ML-assisted plasma-facing-material development.

We investigate the cosmological signatures of two-field dark energy with curved field-space geometry. We numerically solve the background and linear perturbation equations and assess the validity of the effective single-field description. We examine three distinct dark-energy clustering mechanisms: effective sound-speed suppression, dynamical excitation of the heavy mode, and tachyonic instabilities induced by field-space curvature, and explore their possible imprints on the matter power spectrum and cosmic microwave background anisotropies. Our analysis establishes multifield dark energy as a rich and testable extension of quintessence, with observable clustering signatures relevant to current and future cosmological surveys.

We use Monte Carlo data for the three-dimensional Ising model at the critical temperature to predict an emergent radial geometry of the bulk using machine learning. Specifically, we employ a differentiable solver for a probe field on an asymptotically $\mathrm{AdS}_4$ background, trained to reproduce the measured momentum-space two-point functions of the boundary operators ($\sigma$ and $\epsilon$). We find that a single metric cannot simultaneously serve both operators. Fitting each channel separately improves its own residual by a factor of three to five, but degrades the other by up to two orders of magnitude. We quantify this tension between the two operators and show that it survives changes to the momentum window and the lattice size. Our results numerically demonstrate that the bulk geometry of a theory with an $\mathcal{O}(1)$ central charge, such as the 3D Ising model, is not captured by a single classical metric.

We exhibit two finite orthogonality hypergraphs that admit faithful orthogonal representations by rays in complex three-dimensional space but admit none in real three-dimensional space. Thus, although each orthogonality diagram is unchanged, its coordinatizability in dimension three depends on whether the scalar field is complex or real. The first hypergraph has 20 vertices and 12 contexts. The second hypergraph adds one vertex and two contexts. Phase-adjusted realification also gives explicit faithful orthogonal representations of both hypergraphs in real six-dimensional space.

We study the two-parameter static type-I vacuum black hole recently obtained from an electromagnetic seed by a nonlinear solution-generating map. Its parameter $B$ changes dimensionless horizon geometry, yet the Komar mass variation at fixed asymptotic time is incompatible with the entropy variation. Using the Iyer–Wald, Barnich–Brandt, and Lee–Wald constructions, we derive the surface-charge one-form throughout the regular solution space and show that it has a nonzero curl. The same obstruction is measured by symplectic flux through the limiting Weyl boundary. A field-dependent normalization of the stationary Killing field supplies an integrating factor; the resulting energy $H=m/(1+B^2m^2)^{3/2}$ is uniquely selected by Schwarzschild mass normalization within this class. Homothetic scaling leaves the fixed-$G$ phase space two-dimensional because its tangent carries nonzero exact-symmetry charges. In Weyl coordinates, spatial infinity at finite mass is a closed surface of revolution. Its Brown–York canonical response reproduces the Lee–Wald flux pointwise. The semi-infinite annular source of the massless background emerges as a nonuniform limit of this surface. Finally, with $y=Bm$, the mechanics takes the global form $\text{d} M=T\text{d} S+\Psi_y\text{d} y$. Thus $B$ labels a genuine geometric deformation while its variation acts as external-source work in the Hamiltonian associated with fixed boundary time.

Materials research advances through accumulated experience - scripts that work, protocols that are trusted, warnings attached to failed calculations or experiments, and judgement that links a new question to an old result. This experience is essential for reproducibility and knowledge transfer, yet it is usually fragmented across notebooks, repositories, job logs and individual memory, and it is rarely portable across artificial-intelligence agents. Here we argue that a lifelong AI partner for materials science can be designed around persistent memory rather than around a particular agent implementation. We introduce a self-evolving memory framework that stores scientific experience as inspectable facts and executable skills, so that observations, failure boundaries, protocols and validation checks can be retrieved, revised and migrated across models. We evaluate the idea in three computational settings that expose different layers of materials-research competence. In 49 real-world materials-tool-use questions comprising 138 executable subtasks, memory nearly doubles GPT-5.2 task success without model-parameter updates. In elemental-solid equation-of-state calculations, memory converts a wavefunction-initialization failure into a pre-execution guardrail, improving outcomes from 22/1/4 to 25/2/0 Correct/Partial/Error and avoiding 92% of repeated errors. In 13 practical material simulation workflows, remembered skills and failure facts halve the aggregate trace burden (tokens) and reduce tool calls by over a factor of two by the third round, while preserving physically meaningful outputs in band-gap, phonon, vacancy and work-function analyses. These results show that agent memory can serve as a durable scientific asset; a portable, self-improving record of materials-research experience that outlives any single model or agent stack.

Evaporation is a part of water cycle and a process of energy exchange between atmosphere and land surface, its variation reflects global change. Pan evaporation decreases with global warming is the phenomena named evaporation paradox, which exits in worldwide and spatio-temporal. Broad-scale observations between the 1950s and 2000s revealed that global pan evaporation (Epan) decreases with increasing quantity of clouds. However, in the Huaihe River Basin, both the total cloud quantity and Epan decreased during this period, and similar phenomena were observed in some other regions of the globe. A nonlinear second-order neutral-delay dynamic equation (NSNDE) of the change in the cloud quantity and Epan with time was constructed, encompassing different stages (formation, duration, waning, recurring) of the evaporation paradox. On the basis of this equation, a new model named "steamer" was proposed, encompassing a set of dynamic equations to explore the evaporation paradox. The effects of the total cloud quantity on factors that affect the sensible heat flux are investigated, revealing that actual evaporation (Ea) displays similar oscillation properties as Epan and the total cloud quantity, and their relationship is complimentary in some stages of the evaporation paradox. On the basis of the relation between the total cloud quantity and evaporation, an expression for global energy transpiration was established, and the time delay plays an important role in energy exchange between global spheres. This relation indicates the stability of atmosphere and surface.

In this comment on arXiv:2503.17307 (PRL, 136, 240202, 2026), a novel idea using flag states to transform complex state vector and operators to real ones is argued to effectively lead to a quantum mechanics that is complex in the disguised form of real. The claim that real-valued quantum mechanics cannot be falsified is conceptually flawed. A new criterion based on the geometric phases is suggested to compare real and complex versions of quantum mechanics.

We formalize side-channel detection in Gaussian-modulated continuous-variable quantum key distribution (CV-QKD) as a certificate-forgery hypothesis test and identify its detectability with an information-theoretic rate. Relative to a set $\mathcal{M}$ of trusted, real-time-monitored observables, the forgery- detectability rate $g_{\mathcal M}$ of a benign-statistics certificate is the missed-detection Stein exponent. We prove a dichotomy: $g_{\mathcal M}$ is monotone and strictly positive in the leaked Holevo information when the shot- noise unit is trusted, and identically zero otherwise, recovering local- oscillator and calibration attacks as the degenerate case. Monotonicity yields a certificate reusability rate bounding the Holevo leakage compatible with an undetected certificate over $N_{\mathrm{PE}}$ estimation rounds, via the non- asymptotic bound $\varepsilon_{\mathrm{PE}}\le\exp(-N_{\mathrm{PE}}\psi(r))$ whose near-threshold expansion matches the Gaussian confidence-interval scaling of standard finite-size analyses. We then give a composable finite-size key- length statement under collective Gaussian attacks, whose worst-case Holevo term is the reusability rate and whose parameter-estimation failure probability is bounded by the Stein exponent at every block length. Both results are unconditional in the trusted-correlation model, where strict monotonicity of the Holevo leakage in the excess noise follows from a noise-injection argument; for general $\mathcal{M}$ they hold under an explicit no-spurious-local-minima condition on the divergence landscape, verifiable by low-dimensional inspection. Convexity of the rate further assumes a numerically supported concavity of the Holevo bound, the sole numerical ingredient; proof status is delimited throughout.

We formulate minimal and dissipative Continuous Spontaneous Localization (CSL) dynamics in the functional Schrödinger representation for a non-relativistic bosonic field. In this framework, the Fock-space state is encoded in a wave functional, and fixed particle-number wave functions are obtained by sector projection. For the minimal CSL coupling to the smeared mass density, this projection gives the standard nonlinear stochastic dynamics in each \(N\)-particle sector, with the collapse operator acting on the total smeared density of the configuration. This makes the amplification mechanism transparent and allows us to discuss sector superpositions, local probability balance, and the status of Bohmian equivariance at the wave-function level. We then consider a dissipative extension in which the collapse operator includes a smeared current contribution. The one-particle sector reproduces the expected dissipative CSL energy balance, while fixed many-body sectors contain additional collective momentum shifts and pair-mixing terms that are not reducible, in general, to independent one-particle contributions. Within a leading compact closure, the collective pair friction produces a non-extensive stationary mean kinetic energy: in three dimensions and for weak dissipation, $T_N^{\rm comp}\simeq 2T_\beta/N$, whereas the corresponding dilute energy remains extensive.

Unitary designs provide efficient substitutes for Haar-random unitaries in quantum information processing, randomized measurements, and many-body quantum dynamics. We propose a protocol based on time evolutions of a single chaotic Hamiltonian interleaved with unitary perturbations to generate unitary designs. We derive the frame potential of the resulting ensemble in terms of those of the intermediate ensemble. The intermediate ensemble need not itself be Haar random or exhibit Haar-level frame potentials, provided that its trace moments and frame-potential growth are sufficiently suppressed. The nontrivial Pauli set and the Clifford ensemble are simple examples, whereas ensembles whose cardinality does not grow with the Hilbert-space dimension generally fail. We further establish a frame-potential correspondence between multi-Hamiltonian temporal protocols and one-Hamiltonian protocols interleaved with repeated fixed trace-suppressed perturbations, showing that two perturbations suffice to recover Haar-level frame potentials. For local Hamiltonians, we derive a lower bound on the space–depth control resource, while more generally we establish a universal finite-window bound that constrains the required temporal sampling range. Together, these results identify complementary spatial and temporal resource requirements for perturbation-assisted randomness generation.

We systematically introduce hyperdeterminant wavefunctions as a variational-wavefunction-based theoretical framework for strongly correlated quantum states of matter, together with practical numerical simulation algorithms. This framework generalizes previously known fermionic parton constructions, yields reliable microscopics with intuitive physical pictures, and allows direct access to the fractionalized degrees of freedom together with associated microscopic effective field theories. We demonstrate the applications of this framework to fractional Chern insulators and quantum spin liquids. We comment that the hyperdeterminant states belong to a more general class of variational wavefunctions: the fused Gaussian states.

Here we discuss the effect of gravitational repulsion on geodesic deviation in the Schwarzschild-de Sitter spacetime. In particular, the geodesic deviation shows different behaviour inside or outside a critical surface, which is the divider between attractive and repulsive regions of gravity. This in turn makes it possible to locate the critical surface and regions of gravitational repulsion and attraction from the behaviour of geodesic deviation.

The atomistic understanding of flash sintering (FS) remains speculative, despite its efficiency and versatility in materials processing. Employing first-principles calculations we demonstrate how charge compensation of a range of defects in the prototypical Y-stabilized cubic ZrO$_2$ (YSZ) shifts Fermi level E$_F$ up during FS, thereby accelerating cation migration for fast mass transport. The charge transition of Zr vacancy, V$_{Zr}^q$, reduces its bulk diffusion barrier in V$_{Zr}^{-4}$ during flash by 2 eV, relative to V$_{Zr}^0$ before flash, which is triggered by the charge equilibrium of nonstoichiometric defects. The substituent defect Y$_{Zr}$, released by annihilating O vacancy, V$_O$, in Y$_{Zr}$V$_O$Y$_{Zr}$ defect complex, acts as electron acceptor and favors V$_{Zr}^0$ before flash whereas excess V$_O$, as electron donor thermally generated at the FS onset, upshift E$_F$ and thus support V$_{Zr}^{-4}$. The proposed mechanism of Fermi-level mediated cation diffusion for YSZ is generalized to other flash-sintered ceramics and has considerable bearing on the general theory of FS techniques in oxide ceramics.

The largest machine learning models in particle physics are also the most expensive to train, yet the return on scaling a given architecture cannot be estimated before that compute is spent. Scaling laws have been fit for jets, but none has yet been shown to predict the performance of models it was not fit on. We show that, for a generic transformer pretrained on collider jets, it can be forecast. Fitting a joint model-and-data scaling law on small models alone, spanning three orders of magnitude of training compute, we predict the loss of models trained afterward with more than one hundred times more compute to within one percent. We then connect the forecast to downstream physics performance: across two standard tagging benchmarks, lower pretraining loss yields systematically lower fine-tuning loss and higher background rejection after fine-tuning. Within this model family and these tasks, a compute budget can therefore be translated into expected physics performance before any large model is trained. The final frontier model is consistent with the published numbers for current state-of-the-art physics-aware foundation models trained on the same corpus, on accuracy, AUC, and quark/gluon rejection, with a residual edge for the physics-aware model only in the high-purity tail of top tagging. We release five pretrained models spanning multiple sizes, together with the complete training recipe and code.

Chip-scale optomechanical devices are driving the miniaturization of inertial sensors and next generation fundamental physics experiments. However, precision at the theoretical limit is often unattainable due to extraneous vibrations. One solution is tailoring the device to isolate a degree of freedom from the environment while maintaining coupling to the signal of interest. To this end, we introduce a dual milligram-mass torsion oscillator, formed by mass loading a strained silicon nitride nanoribbon. The antisymmetric torsion mode suppresses vibrations by over an order of magnitude to achieve a thermally limited torque sensitivity of $10^{-18}$ Nm/$\sqrt{\rm Hz}$ while maintaining ultralow loss. We demonstrate the sensing ability by detecting an optical radiation pressure torque of $10^{-16}$ Nm over a 30 Hz bandwidth. We also characterize the device for frequency-based gravimetry, demonstrating $10^{-6}g_0$ ($g_0=9.8$ $\rm m s^{-2}$) precision in 30 seconds with an oscillation amplitude of only 100 $\mu$rad. This device demonstrates a technique for overcoming vibration noise, with broad implications for optomechanical sensing from commercial applications to fundamental physics experiments.

(abridged) In order for the universe to develop astrophysical structures and support life, the fundamental constants that determine the laws of physics and the cosmological parameters that specify cosmic properties must fall within a range of values. The goal of this review is to delineate these ranges. We start with the premise that multiple universes can exist and can sample different realizations of the laws of physics. This treatment focuses on the coupling constants that determine the strength of the fundamental forces $(\alpha,\alpha_G,\alpha_{\rm s},\alpha_{\rm w})$ and the masses of the particles $(m_u,m_d,m_e)$ that make up atomic matter. We also consider cosmological parameters, including the energy density parameter $\Omega$, the dark energy density $\rho_v$, the baryon-to-photon ratio $\eta$, the dark matter contribution $\delta$, the amplitude $Q$ of primordial density fluctuations, and the number ${\cal D}$ of spatial dimensions. These quantities are constrained by the need for the universe to emerge from its epoch of nucleosynthesis with an acceptable chemical composition, live for a long time, and ultimately produce galaxies, stars, and planets. Stellar lifetimes must be long enough and surface temperatures must be high enough to support life. These requirements place constraints on the fundamental constants and cosmological parameters. This overview discusses several classic instances of possible fine-tuning in stars, including the triple alpha reaction, stable diprotons, and unstable deuterium. Finally, we note that for universes with significantly different parameters, a variety of astrophysical processes can generate energy, drive nucleosynthesis, and potentially support habitability.

While a tremendous amount of theoretical work has been dedicated to time-varying photonics, practical implementation in the optical range has relied almost exclusively on transparent conductive oxides , which remain severely constrained by being slow and highly lossy. To bypass these limitations, I propose an alternative platform utilizing ultrafast second-order nonlinearities within an epsilon-near-zero semiconductor-silver metamaterial. Due to the relatively low loss in silver and polarization-selective pumping, ultra-low pump absorption prevents thermal degradation, while absorption of the probe is sufficiently low to simultaneously permit the multi-cycle interaction lengths necessary for signal detection. I find that with pump powers of 100s of GW/cm2 one can open a wide momentum bandgap of tens of percents and achieve net parametric gain in time, offering a robust pathway to realizing photonic time crystals in optical range.

Fanpy is a Python library for developing new wavefunction methods. It enables users to quickly convert mathematical expressions into working code through a modular design based on the Flexible Ansatz for N-electron Configuration Interaction (FANCI) theory. This architecture facilitates a straightforward extension of the codebase. Here we present version 2.0 of the Fanpy package. This release includes several new wavefunction implementations, including coupled- cluster-inspired geminal approaches. A new analysis module enables a more detailed inspection of computational results and lays the groundwork for future features. In addition, the PySCF interface has been redesigned, and an interface to the PyCI package has been introduced to offload computationally expensive components. Finally, we introduce an improved software development environment, including automated testing and issue tracking.

Measurements of Higgs boson production in the off-shell region are presented, using the four-lepton decay channel. Data from proton-proton collisions at the CERN LHC, collected by the CMS experiment and corresponding to an integrated luminosity of 138 fb$^{-1}$ at a center-of-mass energy of 13 TeV, are utilized. The first direct test of composite Higgs boson models is performed, with a lower limit on the compositeness scale $\Lambda_\mathrm{H}$ set at 870 GeV at the 95% confidence level. Tests of gluon-fusion production within the standard model effective field theory framework are performed. The first constraint on the Higgs boson self-coupling in the off-shell region is obtained. By combining on- and off-shell measurements, the analysis sets the tightest constraints to date on light-quark Yukawa couplings, while relaxing assumptions such as the bound on the Higgs boson coupling to vector bosons, thereby providing more model-independent results. Constraints on the Higgs boson width are provided while accounting for a range of beyond-the-standard-model effects, including both light and heavy particles in the gluon-fusion production loop, as well as modified couplings to vector bosons. A combined analysis of the H$\to$ZZ and PH$\to$WW channels is performed to improve sensitivity to the Higgs boson width, yielding $\Gamma_\mathrm{H}$ = 5.1$^{+2.0}_{-1.8}$ MeV. The scenario of no off-shell Higgs boson production is excluded at a confidence level exceeding 5 standard deviations.

The stacked kinetic Sunyaev-Zel'dovich (kSZ) signal probes the velocity-weighted projected gas momentum around galaxies, and is emerging as a powerful probe of gas fractions and baryonic feedback. Its interpretation, however, rests on several assumptions that we test in this pair of companion papers. Using the FLAMINGO hydrodynamical simulations and DESI-like galaxy mocks for luminous red galaxies (LRGs), the bright galaxy sample (BGS), and emission-line galaxies (ELGs), we identify the ingredients required to model the signal to better than $10\%$. This first paper focuses on velocities. We decompose the signal into a dominant bulk-flow term, proportional to the mean optical depth, plus non-linear terms arising from the small-scale gas momentum and its coupling to the stacking velocity. When the stacking velocities are reconstructed from linear information in real space alone – an idealisation which is not possible in practice – the non-linear terms cancel and the signal traces the mean optical depth to within a few per cent. When the stacking velocity instead retains non-linear information or is affected by redshift-space distortions, the non-linear terms suppress the signal by $10-20\%$: a $1-2\sigma$ effect for current data that is expected to be statistically significant for upcoming surveys, and one that depends only weakly on baryonic feedback. Our results reveal a trade-off: velocity estimators that retain small-scale information boost signal-to-noise but require simulation-based modelling, whereas conservative reconstructions simplify the interpretation at the cost of signal-to-noise.

We investigated how a magnetic topological defect affects the vacuum polarization of a charged massive scalar field in a flat $(3+1)$-dimensional space-time. The defect was modeled as an impenetrable to matter field finite-thickness tube with magnetic flux inside. We implemented the most general form of the Robin boundary condition on the surface of the magnetic tube, which enables a fully general analysis of the problem. We have found that in flat spacetime, the total vacuum energy generated by a magnetic topological defect depends on the curvature $\xi$, except for special cases corresponding to the Dirichlet and Neumann boundary conditions. By contrast, when Robin's general boundary conditions are imposed, the induced vacuum energy acquires an explicit dependence on the curvature coupling $\xi$, which is significant even in flat space-time. A detailed study of the dependence of the effect on the boundary condition parameter has been carried out. The obtained results highlight the nontrivial role played by boundary conditions in vacuum polarization phenomena.