Papers

Topological insulators host protected boundary states that are robust to disorder, making them attractive for applications and motivating their realization in engineered systems. Discrete-time quantum walks, which have been implemented in a variety of experimental platforms, can exhibit topologically nontrivial phases and their associated boundary states. Here, we introduce a class of topological quantum walks with variable step lengths that offer theoretical insights into the topological classification of such walks. For example, these walks can access higher winding numbers and support multiple edge states. They also provide context for the reduction of topological protection from a $\mathbb{Z}$- to $\mathbb{Z}_2$-valued invariant when time-reversal symmetry is broken. The topologically protected edge states are investigated using a transfer-matrix approach that describes their spatial profiles and spin structures. These predictions are in excellent agreement with numerical results and, where applicable, with the Jackiw–Rebbi zero-mode solution of the Dirac equation. Taken together, our analysis provides a roadmap for designing quantum walks with control over the number, spatial profile, and spin structure of their topological edge states.

Since the discovery of large elliptic flow at RHIC in the early 2000s, relativistic hydrodynamics has become a central framework for quantitative studies of the quark–gluon plasma (QGP). In parallel, increasingly sophisticated analyses have improved constraints on the initial state and the transport properties of the QGP. In this contribution, I overview the recent progress on bulk-property of QGP and light/strange hadron production.

Quantum applications increasingly execute as multi-stage quantum-classical pipelines, interleaving QPU computation with classical stages like circuit generation, transpilation, layout mapping, quantum error mitigation (QEM), and post-processing. These stages have diverse resource requirements and exhibit stochastic behavior under drifting hardware noises, yet existing workflow frameworks treat them as static, isolated components. We present LLQM (Low-Level Quantum Machine), a profiling-driven meta-framework for quantum-classical pipelines. LLQM decomposes pipelines into fine-grained tasks and continuously profiles their CPU/GPU, memory, QPU, and queue dependencies alongside real-time hardware states. This unified runtime abstraction captures cross-stage resource dependencies and reveals how classical and quantum decisions interact, enabling characterization of their impact on fidelity and resource consumption. We evaluate LLQM using QEM as a representative pipeline stage, on IBM 156-qubit Heron r2 processors with circuits up to 100 qubits and 1e7 transpiled gates. Our results show that continuous profiling exposes runtime bottlenecks and enables hardware-, fidelity-, and workload-aware optimizations.

We study the query complexity of estimating scalar summaries of zigzag bar lifetimes from snapshot-adjacency bits. For graphs $G_1,\ldots,G_m$ on $n$ labeled vertices, let $\ell_b$ be the snapshot lifetime of a degree-one bar $b$ of the intersection zigzag. For a probability generating function $\phi(x)=\mathbb{E}[x^R]$, the statistic $F_\phi=\sum_b\phi(\ell_b/m)$ includes normalized degree-$r$ total persistence and the mean generalized rank over a uniform time window. An exact identity underlies our algorithm: sample $R$ uniform times; the expected generalized rank between their minimum and maximum equals $F_\phi$. For graphs that rank is the circuit rank of an intersection graph, so a nonlinear barcode functional becomes an average of edge and component counts, and no barcode is computed. Without spectral-gap, homology-state, or QRAM assumptions, this gives a quantum estimator with additive error $\varepsilon n$ and $\widetilde O(\sqrt{m(K+n)}/\varepsilon)$ queries when a bound $K\ge F_\phi$ is supplied, against $\widetilde O(m\min\{n^2,(K+n)/\varepsilon^2\})$ classically, and an adaptive quantum variant with the same instance dependence. These estimators are optimal in two regimes. For every fixed power weight $x^r$, $r\ge2$, and for the uniform-window mean, the worst-case complexities are $\widetilde\Theta(n\sqrt m/\varepsilon)$ quantum and $\Theta(n^2m)$ classical. On sparse instances, under an explicit split-leakage promise met by power and binomial weights of logarithmic degree and the promise $F_\phi\le K$, they are $\widetilde\Theta(\sqrt{mK}/\varepsilon)$ and $\widetilde\Theta(m\min\{n^2,K/\varepsilon^2\})$. The classical lower bounds hold against fully adaptive algorithms, and fewer than $m$ such statistics cannot determine the positive-lifetime histogram. All bounds concern snapshot access; with an explicit update stream, near-linear full-barcode algorithms are known.

The constructive diagonal Ramsey problem asks, given adjacency-oracle access to an $N$-vertex graph, for a clique or independent set of the order guaranteed by Ramsey's theorem. We give a bounded-error quantum algorithm that, for every $K\ge2$ and $N\ge4^{K-1}$, finds and verifies a homogeneous $K$-set using $O\!\left(2^K K\log\frac K\eta\right)$ edge queries with failure probability at most $\eta$. At the Ramsey scale $N=2^n$, this yields a homogeneous set of order $\lfloor n/2\rfloor+1$ using $O(\sqrt N\log N\log(\log N/\eta))$ queries, improving on the $O(N)$ queries of the explicit classical recursion and giving, to our knowledge, the first sublinear worst-case algorithm for the Ramsey relation. We also derive an $\Omega(N^{1/12})$ quantum lower bound by a reduction from collision finding. The algorithm runs the constructive recursion over implicit candidate sets. Each set is represented by a short conjunction of adjacency constraints and sampled using capped unknown-solution quantum search, and a scale-aware concentration schedule balances estimation accuracy against the increasing cost of sampling deeper sets. We complement the upper bound with an $\Omega(N^{1-1/\sqrt2})$ randomized lower bound, transported from the random-Painter analysis of online Ramsey numbers, which holds on the uniform distribution $G(N,1/2)$. On that distribution a greedy quantum search uses only $\widetilde O(N^{1/4})$ queries, giving a provable polynomial quantum speedup for Ramsey search on random graphs. We also give an estimation-free size-biased recursion and extend it to every fixed number of edge colours.

The high-frequency (HF) band, ranging from 3 to 30 MHz, is widely used in a number of applications such as beyond-line-of-sight (BLOS) communications and over-the-horizon radar systems. The long-range propagation characteristics of the HF band rely on the Earth's ionosphere as a refracting medium to establish BLOS wireless links. However, traditional HF communications links often use channels with narrow bandwidths (typically 3 kHz), which limits the amount of data that can be transmitted. In this perspective article, we discuss the challenges of establishing wideband HF communications links with emphasis on the ionosphere, noise characteristics, antenna performance, and available bandwidth. Solar radiation drives ionospheric layering, where fluctuating electron densities determine usable frequencies that change with time of day, seasons, and latitude. Since background noise at HF decreases with increasing frequency, operating at the upper HF limit is advantageous. We present a noise prediction model following ITU Recommendation P.372-17 and highlight the role of high-directivity antennas such as Log-Periodic Dipole Arrays, in optimizing the signal-to-noise ratio of the link. Using ray tracing techniques, we model several representative wideband HF links that employ near-vertical-incidence skywave (NVIS) or long-range skywave modes over distances ranging from approximately 390 to 5,200 km. We examine the performance of these links for bandwidths up to 1 MHz and present their day and night ionograms, with transmitter and receiver locations spanning near-equatorial to high northern latitudes. The modeled maximum usable frequencies are corroborated against crowdsourced FT8 reception data and direct ionosonde measurements over the same period for links for which propagation data was available.

The attribution of the condition div A + (1/c^2) dPhi/dt = 0 has been under discussion since 1938 as a question of priority between Ludvig Lorenz and Hendrik Lorentz. This work argues that the problem is of a different nature, and that the discussion does not close because it has never been specified what is being attributed. Drawing on the three versions of the 1867 paper and on six further primary sources, it is documented that three separable acts have been designated under a single name: the obtaining of the relation between potentials, its imposition as a restriction on the admissible potentials, and its denomination as a gauge. It is further documented that in none of the three versions of the 1867 paper does the word potential appear, that the magnetic field does not figure in it as a quantity of the theory, and that the vocabulary in which that paper is described today enters the literature after it was written. It is concluded that the disjunction between the two denominations, posed without specifying which of the three acts is being attributed, is ill formed.

In situ adjoint training extracts parameter gradients directly from measurement, but has so far been limited to reciprocal or restricted systems. Here, we introduce the physical counterpart of the policy gradient theorem: a stochastic-adjoint gradient estimator that lifts these constraints by trading reciprocity for nondegenerate diffusion. As validation, we train a nonlinear resonator network, whose own dynamics supply the policy, against antagonistic temporal modulations with gradients from measured stochastic trajectories alone, without finite differences or a separate adjoint experiment.

We present TIC 160582982, an eccentric $\delta$ Scuti binary with a dynamically massive unseen companion. Six coherent high-frequency pressure modes used as pulsation clocks yield a phase-modulation orbit with $P_{\rm orb}=89.29\pm0.19$ d, $e=0.539^{+0.040}_{-0.037}$, and $a_1\sin i/c=145.6^{+3.7}_{-3.4}$ s, corresponding to $K_1=42.2^{+2.2}_{-1.8}$ km s$^{-1}$ and $f(M)=0.416^{+0.032}_{-0.028}\,M_\odot$. An independent frequency-modulation analysis of the two strongest modes gives a consistent orbital solution. Rotating MIST isochrones constrained by the atmospheric parameters and spectral energy distribution (SED) give $M_1=1.93\pm0.19\,M_\odot$ and $R_1=2.65\pm0.23\,R_\odot$. The mass function implies a formal edge-on minimum companion mass of approximately $1.80\,M_\odot$. Assuming a luminous main-sequence companion and including the non-eclipsing geometry gives $M_2=2.19^{+1.24}_{-0.34}\,M_\odot$ and $i=61.5^{+16.6}_{-19.6}$ deg. However, no clear evidence for the presence of a luminous counterpart is found, either photometrically or spectroscopically. This suggests the presence of a massive compact object, such as a neutron star or even a stellar-mass black hole, as the massive unseen binary companion. Future phase-resolved high-resolution spectroscopy will be crucial for obtaining an independent orbital constraint and clarifying the nature of the companion.

We develop a continuous event weighting framework for resonance searches that uses auxiliary event information without dividing the data into increasingly fine sensitivity categories. A hard selection is a binary weight, finite categories correspond to piecewise constant weights, and in the background dominated limit their fine partition approaches a continuous signal to background density ratio weight. The construction retains auxiliary discrimination in a single physically interpretable resonance spectrum, with calculable statistical variance and direct recovery of the selected signal yield. One million fully explicit event level pseudoexperiments using Gaussian, Gamma, and Beta auxiliary observables verify yield recovery, uncertainty propagation, and frequentist coverage while substantially improving discovery sensitivity. The method is further tested on publicly available CMS Run2016G and Run2016H diphoton Open Data as an independent real data benchmark, using detector level gluon fusion Higgs simulation only as the signal reference. This is a methodological test of the framework, not a CMS Higgs analysis. The results demonstrate a practical route to exploiting continuous auxiliary information without proliferating sensitivity driven event categories.

Hao, Huang, and Liu (STOC'26) recently showed that optimal quantum query complexity may require large workspace even for short-output problems, and asked whether a quantum query advantage over classical computation can itself require space. We resolve this question by exhibiting an explicit total Boolean function with quantum query complexity $Q=\widetilde{\Theta}(M)$, and randomized query complexity $R=\Theta(M^{21/20})$, whereas, for every fixed $0<\eta<1/100$ and $S\le O(M^{1/100-\eta})$, its $S$-space quantum query complexity satisfies $Q_S=\omega(M^{21/20})$. Consequently, $$ Q<R<Q_S, $$ so the unrestricted quantum query advantage disappears under sufficiently small workspace. The separation is obtained through a one-bit filtered-parity construction and a space-sensitive quantum lower bound based on compressed-oracle capacity and a new parity-to-capacity inequality, which may be of independent interest.

Kinematic fitting is widely used in particle physics experiments as a powerful tool to improve experimental resolutions, to suppress background and to provide selection criteria for the identification of specific reactions. Kinematic fitting methods, however, typically assume that the fitted quantities follow Gaussian distributions; an assumption which does not always hold. This is particularly true for energy measurements from electromagnetic calorimeters. This issue can largely be overcome by performing a transformation of the non-Gaussian variables into variables which follow a Gaussian distribution. The new adapted kinematic fitting procedure allows to better account for the non-Gaussian nature of the measured calorimeter energies, at the same time improving the accuracy and robustness of the kinematic fit. This leads to improved pull and confidence-level distributions of the kinematic fit as well as improved invariant mass distributions and signal-to-background ratios in the final event sample.

Background and objective. Carotid Doppler ultrasound is the most widely available bedside probe of cerebral haemodynamics, and machine-learning classifiers fed carotid velocity spectra can localise intracranial occlusions—but at the price of black-box models, thousands of training samples, and fragility to anatomical variants. We ask whether the same information can be obtained from an interpretable physical model. Methods. We formulate a linear frequency-domain one-dimensional model of a 26-segment circle-of-Willis network in which each cardiac harmonic propagates on a Womersley transmission line and is scattered independently by a lesion. The model is validated against a nonlinear one-dimensional solver and three-dimensional stenosis computations at two severities, coupled to a physics-based synthetic spectral-Doppler pipeline, and used to generate a 9{,}600-case virtual cohort for occlusion-localisation classification with physics-guided features. Results. Mean flow divisions agree with the nonlinear solver to three significant figures, harmonic magnitudes within a ratio of 0.90–1.04, and carotid waveforms to 6.1\,% in relative $L_2$ norm after a single kinematic area correction. The benchmark reproduces healthy flow splits within 1–9\,%, collateral-channel flows within 11–16\,%, and the collateral-pathway hierarchy. Physics-guided harmonic-ratio features localise twelve lesion classes at 95.1\,% accuracy from five training samples per class—over an order of magnitude fewer than waveform-driven convoluted neural networks; augmentation partially restores robustness to measurement noise and anatomical variants. Conclusions. The framework explains the physical origin of the empirically discriminative 2–12\,Hz Doppler band and makes occlusion localisation interpretable and sample-efficient.

Interstitial flow plays a key role in drug delivery, angiogenesis, cancer, and edema. Recent studies have identified connected interstitial pathways that can transport material over long distances. However, the spatial scale of physiological interstitial flow remains unclear: despite the existence of connected pathways, flow may be dominated by nearby vascular filtration or extend over longer distances. Here, we identify organ-scale interstitial flow patterns in the chick yolk sac and elucidate the mechanisms that determine their spatial scale. The yolk sac contains an organ-scale interstitial region that enables large-scale flow patterns to be identified without truncation. Our approach combines experimental imaging with computational modeling of coupled blood and interstitial flow in the whole yolk sac. Scaling analysis identifies a hydraulic conductivity ratio that controls the transition from small-scale to organ-scale flow. In organ-scale patterns, we find interstitial flow speed to be substantially greater than the transvascular flow speed. Mechanistically, the organ-scale patterns arise from the spatial segregation of the leakage and drainage of interstitial fluid from the vessels. These findings have important implications for biological transport by interstitial flow, suggesting that flow-mediated cues may be sensed locally but generated nonlocally.

In 1911 Einstein suggested that photons which pass close to the Sun are deflected by its effective mass which would apparently shift the positions of stars by up to one arcsecond, something that should be observable by astronomers during solar eclipses. Einstein`s ideas including the later doubling of the value due to relativistic space curvature met with enthusiastic responses from astronomers. The history of these efforts, their motivations and interactions with Einstein is presented here, beginning with the expedition that failed due to WWI of the young Erwin Freundlich in 1914 and ending with the unsuccessful Potsdam campaign to Öland (Sweden) in 1954. A newly found conference photograph from the first post-war meeting of the Astronomische Gesellschaft in 1921 shows Albert Einstein as a new member of the AG on the Telegraphenberg in Potsdam.

We propose a single-field mechanism that dynamically prepares the initial conditions required for exponential plateau inflation. The inflaton is decomposed into a coarse-grained mode and a high-occupancy, approximately Gaussian band of relativistic nonzero modes. Gaussian–Hartree averaging of the potential produces an exact variance-dependent minimum, which places the coarse-grained field high on the plateau when the excitation variance is large. Under a translation-invariant microcanonical measure, the available phase-space volume is exponentially concentrated near this minimum, while an order-one homogeneous kinetic-energy fraction is exponentially atypical. During expansion, the preparation modes redshift as radiation, $\sigma^2\propto a^{-2}$ and $\rho_\chi\propto a^{-4}$. Although the induced minimum rapidly moves toward the vacuum, the force acting on the coarse-grained mode is bounded by an exponentially small factor, yielding analytic upper limits on its velocity, displacement, and kinetic fraction. We derive a sufficient condition for the subsequent number of slow-roll e-folds and exhibit a benchmark with more than 60 e-folds. The mechanism also motivates correlated finite-onset signatures: large-scale power suppression with decaying oscillations and a variance-convolution bispectrum.

We will study in details the masses spectrum of bosons and usual fermions of the Minimal Supersymmetric $SU(3)_{C}\times SU(4)_{L}\times U(1)_{X}$ Model.

We present a density-dependent generalization of the van der Waals hadron resonance gas model (DD-HRG) for describing both the hot hadronic matter created in heavy-ion collisions and the cold, dense matter inside neutron stars. Non-resonant interactions are incorporated through a generalized excluded-volume prescription with a density-dependent available-volume fraction, supplemented by an arbitrary density-dependent mean field. With isospin-dependent interaction parameters constrained by empirical properties of nuclear matter, the resulting equation of state extends the causality range to include neutron-star interiors and supports two-solar-mass stars. It also improves the description of lattice QCD thermodynamics and conserved-charge susceptibilities at vanishing baryochemical potential, with lattice data favoring reduced repulsion among strange baryons. This DD-HRG framework is available within the latest version of the open-source Thermal-FIST package.

We propose an extended Texturized Two-Higgs Doublet Model (2HDM-Tx) where a discrete $D_4$ symmetry predicts a four-zero texture in the fermion mass matrices. In contrast to the standard ansatz where the underlying Yukawa matrices are assumed to be structurally identical, we introduce a novel configuration of non-equivalent matrices that complementarily generate a specific Hermitian four-zero mass structure. This framework naturally suppresses flavor-changing neutral currents and provides a structural rationale for the fermion mass hierarchy, while in addition including a dark matter candidate. As a concrete phenomenological application, we show that the model simultaneously accommodates the persistent neutral resonance excesses at $95\text{ GeV}$ and $152\text{ GeV}$, satisfies current \text{LHC} Higgs data, and is consistent with the stringent upper bounds from lepton flavor violation processes. These combined constraints severely restrict the parameter space of the scalar phenomenology. Finally, we study the prospects for the discovery of the lepton-flavor violating process $h \to \tau \mu$ at the High-Luminosity LHC.

Fringe online message boards are often studied in the context of the extreme ideology that they produce. So far, however, not much of this research has focused on direct real-world harm in the all-too-common form of collective harassment. We directly analyze the complex dynamics of KiwiFarms, an online message board dedicated largely to the harassment of individuals from vulnerable communities. We conduct exploratory analyses of the hyperlink structure of the platform and linguistic changes over time, and prospective modeling of thread size. After establishing this broader picture of the complex traits of the system, we observe the temporal evolution of community-specific vocabulary, finding that the community's framing of their harassment targets persistently evokes more danger in the early 2020s than the late 2010s. We lastly find that early thread-growth behavior is predictive of longer-term thread virality. We discuss the implications for broader understanding of toxic online behavior and threat assessment, and make the case for studying fringe platforms as complex systems with significant societal impact.

Ultrafast phase transitions in correlated materials are often inferred from selected diffraction peak intensities or diffraction peak displacements, leaving the underlying three-dimensional atomic trajectories elusive. Resolving these trajectories is essential for identifying which atomic motions drive changes in electronic properties and how they couple to electronic degrees of freedom. We address this challenge in vanadium dioxide (VO2), a correlated oxide with a near-room-temperature transition between the insulating monoclinic (M1) phase and metallic rutile (R) phase. For this purpose, we introduce ultrafast three-dimensional electron diffraction, which enables refinement of the transient unit cell and internal V and O coordinates, revealing the V-V dimerization and zigzag motion during the phase transition. The refined atomic coordinates follow a linear trajectory in real space during the transition, in contrast to nonlinear or sequential transformation pathways inferred from more indirect observables in earlier work. Quantum many-body calculations treating each V-V pair as a correlated unit show that dimerization creates the level splitting responsible for the electronic gap, which is further enhanced by nonlocal electronic interactions between the paired V atoms. The gap collapses when dimerization is lost. This work turns time-resolved diffraction from order-parameter tracking into transient crystallography, directly connecting atomic trajectories to electronic mechanisms in correlated materials.

Quasiperiodic oscillations (QPOs) in gamma-ray intensity have been reported from a few gamma-ray bursts. These QPOs could be related to fundamental frequencies in the sources, which would lead to new insights about these systems. Here we report on our analysis of GRB~241030A, a several-minute-long burst with $\sim 10$ gamma-ray flares that have approximate periodicities at f ~ 0.04 Hz and f ~ 0.08 Hz. This quasi-periodicity is seen in X-rays with the Swift X-Ray Telescope (XRT) as well as in gamma-rays with the Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM). Compared with a power spectral model that has only red noise, the Bayes factor in favor of a Lorentzian-shaped QPO is more than $10^{200}$, even when the red noise is described by segments with up to four different slopes. However, the interpretation of this power spectral feature as a QPO rather than as a fluctuation in red noise is complicated by the low frequency of the feature as well as the extremely large number of counts, which amplifies differences from smooth power spectral distributions. After discussing the properties of the apparent QPO, we discuss a few processes that could plausibly modulate the flux at this frequency. Among the mechanisms considered, we find the most plausible explanation to be a GRB jet passing through regularly spaced shells of circumburst material, possibly produced by binary interactions near periastron in an eccentric progenitor system.

The Quantum Approximate Optimization Algorithm (QAOA) is a promising variational approach for solving Boolean satisfiability (SAT) problems. Existing SAT-to-QAOA workflows first translate Boolean formulas into penalty Hamiltonians before applying generic quantum compilation, thereby discarding SAT-specific information such as clause structure, logical operators, and variable dependencies. Consequently, subsequent compiler optimizations cannot exploit the underlying Boolean formulation. This paper presents SAQC, a SAT-aware compilation framework that introduces a SAT Intermediate Representation (SIR) to preserve Boolean structure during compilation. The proposed framework supports both CNF and XOR-extended CNF (eCNF) formulations and performs SAT-aware optimizations including clause rewriting, dependency analysis, and clause scheduling prior to quantum lowering. Building on the optimized SIR, SAQC provides a unified framework for both penalty Hamiltonian generation and direct clause-to-ansatz synthesis, together with ansatz optimizations based on relative-phase decomposition, ancilla-assisted synthesis, and dynamic uncomputation. Experimental results demonstrate significant reductions in circuit depth, two-qubit gate count, and compilation time compared with conventional Hamiltonian-based workflows while remaining compatible with existing quantum compilation frameworks.

Inverse design has emerged as a powerful strategy for realizing compact photonic devices; however, its application to logic operations remains constrained by challenges in physical interpretability, architectural generality, and experimental validation. This work introduces an experimentally validated, unified, and physics-driven inverse design framework that implements all fundamental Boolean logic gates within a single silicon photonic architecture. Devices are fabricated within a 2 x 2 um^2 design region on a silicon-on-insulator platform, representing one of the smallest areas reported for photonic logic elements. By integrating amplitude, phase, and energy conservation into a composite figure of merit, the proposed approach enables direct control over constructive and destructive interference. Consequently, all logic functions, including XOR and three-input NAND/NOR operations, are achieved using a standardized configuration with two logical inputs and a bias port. Experimental results exhibit good agreement with numerical simulations across the C-band, confirming both the predictive accuracy and fabrication robustness of the method. Performance benchmarking reveals competitive contrast ratios compared to previous implementations, while providing a unified and scalable design strategy. These findings establish a physically interpretable and experimentally validated paradigm for inverse-designed photonic logic, advancing the development of compact, integrated optical computing systems.

`Fermi-liquid behavior' is nowadays used as a shorthand for quadratic temperature dependence of the electrical resistivity. In a metal, for this to occur, electrons must be cooled well below the Fermi degeneracy temperature, $T_{\mathrm{F}}$. A departure from this behavior is observed at finite temperature. Here, we note that this departure has opposite signs in two distinct types of Fermi liquids. In weakly correlated ones, the upward departure implies a higher exponent of the inelastic resistivity, attributable to additional scattering by phonons. In contrast, there is a downward deviation in strongly correlated metals, which implies either reduced scattering or additional conduction, as in the case of normal liquid $^3$He, in which a distinct contribution to heat transport by a sound mode has been recently identified. Such a channel of conduction smoothly transforms across $T_{\mathrm{F}}$ to the one captured by the Bridgman formula for thermal conductivity of classical liquids. In three metals (UPt$_3$, Sr$_2$RuO$_4$, and heavily overdoped LSCO), according to the available experimental data, the normalized amplitude of excess conductivity at $T/T_{\mathrm{F}}\simeq0.02$ is comparable to what has been seen in $^3$He, suggesting, without establishing, a common origin.

It is difficult to identify unresolved triple and higher-order systems beyond the solar vicinity. Star clusters yield controlled environments with known physical parameters, providing a way to explore homogeneous stellar samples. Combining modern optical and near-IR surveys, our main goal is to explore the region of the color-magnitude diagrams located above the sequence of equal-mass binaries, which is inhabited by unresolved triple and quadruple systems. Specifically, here we aim to discover and characterize the presence of multiple systems in the aged open star cluster Trumpler 19. We selected cluster members using Gaia astrometry and photometry from the VVVX and DECAPS2 surveys. We made optical and near-IR color-magnitude diagrams to select stars located >0.75 mag above the cluster main sequence, including suitable unresolved triple and quadruple systems. We confirm previous results that there is a sizable sequence of unresolved binaries in Trumpler 19. We also report the discovery of a sequence of unresolved multiple systems in this cluster, and confirm some of these multiple systems via radial velocities measured by the ESO KMOS VVVX-GalCen spectroscopic survey. The fraction of multiple stars in this cluster is comparable to that of the solar neighborhood, with the caveat that the local sample probes deeper down the main sequence. The fraction of unresolved triples and quadruples is also three times higher than that of the open cluster M 67, which is of a similar age and chemical composition. The discovery of unresolved triple systems in Trumpler 19 leads to our main conclusion that these systems were able to survive within the cluster for nearly 4 Gyr. In addition, this cluster contains more multiple systems than M 67, which has a similar total present mass. Further investigations are needed to unveil if this is a primordial feature or the result of dynamical evolution.

Generative AI can produce perfect solutions to standard physics homework, weakening the connection between submitted work and knowledge a student can use independently. We report a redesign of the introductory nuclear and particle physics course at Ruhr University Bochum, in which AI was permitted and encouraged alongside traditional tools on unusually difficult, research-shaped assignments. We found that most students remained engaged with the assignments throughout the course and produced ambitious work, while the course did not reliably secure its foundational objective. We offer this mixed experience as a reference point for discussion.

We study state tomography when each measurement acts on at most $k$ fresh copies and no quantum memory is retained between blocks. We prove a lower bound matching the upper bound in [arXiv:2510.07788]. Thus the copy complexity of estimating an arbitrary $d$-dimensional state to trace distance $\epsilon$ is, up to absolute constant factors, $\max\{d^3/(\sqrt{k}\epsilon^2),d^2/\epsilon^2\}$ for every $k$ and all sufficiently small $\epsilon$. This removes the earlier restriction that $k$ be small as a function of the accuracy. The lower bound applies to arbitrary measurements within each block and adaptive choices between blocks. The lower bound already applies in a small neighborhood of any state whose smallest eigenvalue is of order $1/d$, even when the center is known. The main ingredient is a uniform Fisher information bound for one measurement block that depends only on the smallest eigenvalue of the state. The proof avoids the perturbative expansion responsible for the restriction in [arXiv:2402.16353]. Fano's inequality for metric balls and a log-Sobolev comparison between mutual and Fisher information then reduce the adaptive protocol to this block bound [arXiv:1607.00550, arXiv:1902.08582].

Photoinduced electric effects in plasmonic and magnetic materials under pulsed laser illumination exceed the prediction of the electromagnetic momentum-transfer mechanism by orders of magnitude. In order to get more information on the nature of the effect we study the kinetics of photovoltages in permalloy thin films at different photoexcitation configurations. The photoinduced electric signals consist of magnetically dependent and magnetically independent components which are of significant magnitude and mainly follow the temporal profile of the laser pulse. In contrast, the predicted contribution from the Anomalous Nernst Effect is much weaker and exhibits substantially slower kinetics. These observations suggest that ultrafast photoexcited hot electrons, rather than thermal mechanisms, play the dominant role in generating the observed photovoltage.

Generalized unitarity, Landau analysis, and cluster adjacency encode complementary aspects of scattering amplitudes. We use one-loop planar $\mathcal N=4$ SYM amplitudes in dimensional regularization, at arbitrary multiplicity and helicity, to make their interface explicit. The weight-two symbol decomposes into an LS part, in which maximal-cut leading singularities furnish the coefficients and Landau loci associated with nested cuts organize the ordered symbol entries, an algebraic four-mass sector, and residual terms. Cancellations of certain letters contributed by individual box integrals, as well as further simplifications, are explained by the two-mass triangle relations among box coefficients. We prove these relations using a BCFW-like application of the global residue theorem and show that they can be understood geometrically as different dissections of the same region in the tree amplituhedron obtained by projecting the loop geometry of a triple cut. We then prove that the full rational symbol, including its infrared-divergent part, obeys cluster adjacency in the flag cluster algebra $\mathrm{Fl}_{2,4;n}$ for all multiplicities and helicities. Within the sector depending only on momentum-twistor four-brackets, we conjecture a stronger cluster property in $\operatorname{Gr}(4,n)$ for all helicities and prove it for NMHV amplitudes: the amplitude admits a representation in which every pole of each coefficient is compatible with both symbol entries. Finally, we observe that the algebraic four-mass letters, although non-rational, exhibit a suggestive Sklyanin-bracket pattern.