Papers

Although photomultiplier tubes (PMTs) are sufficiently sensitive for applications based on counting single photons, the thermionic emission of electrons from the photocathode is one of the dominant background sources. In this study, we modeled the dark count rate of a given PMT as a function of the temperature and external electric field based on the Richardson-Dushman equation and incorporated the Schottky effect. To validate the model, measurements were performed using an eight-centimeter Hamamatsu R14374 PMT equipped with a bialkali photocathode. The dark count rate was measured over a range of temperatures from 10 to 40 degree Celsius. An external electric field was applied to the outside surface of the optical window with the photocathode by varying the potential difference between the photocathode and the surrounding medium from 0 to 1100 V. The result confirmed that the influence of the external potential difference remained relatively small within a difference of 200 V, with the increase in the dark count rate remaining below 50 % across all measured temperatures. This behavior was incorporated into the proposed model by including an error function to predict the dark count rate under operating conditions with varying temperatures and external electric fields.

First law consistency alone does not determine the black hole state space of NUT-charged spacetimes, because several inequivalent macroscopic formulations can yield consistent thermodynamics. We develop a two-horizon sector diagnostic for the electrically charged Kerr-Newman-NUT family by organizing the inner- and outer-horizon entropies and inverse temperatures into sum ($\Sigma$) and difference ($\Delta$) sectors. The charged rotating geometry gives a more stringent test of the uncharged Taub-NUT sector result, since the mass $M$, ordinary electric charge $Q$, ordinary angular momentum $J$, NUT charge $N$, and the NUT secondary hair $J_N=MN$ all enter the same two-horizon thermodynamics. For the physically anchored minimal homogeneous state spaces defined and tested here, we find a clear sector separation: the $\Sigma$ sector closes with the charge-like variables $Q$ and $N$, whereas the $\Delta$ sector additionally requires the rotation-like variables $J$ and $J_N$. Natural reductions that eliminate either $J_N$ or $N$ fail to reproduce the first law coefficient fixed by the sector temperature, and their associated Bekenstein-Smarr relations do not close with the assigned scaling weights. Within this class, electric charge and ordinary rotation therefore do not absorb the NUT secondary response, and the charged rotating family supports the NUT bi-hair organization: $N$ has a charge-like sector role, while $J_N=MN$ is a rotation-like thermodynamic secondary hair. The latter is defined off shell in the homogeneous equation of state, not as a new metric parameter or asymptotic conserved charge.

Primordial black holes (PBHs) can generate the Baryon Asymmetry of the Universe (BAU) through asymmetric capture of baryon-charge-carrying particles, but previous realizations of this mechanism typically yield an asymmetry well below the observed value because the relevant CP-violating scattering asymmetry is loop suppressed. We show that this limitation can be overcome through resonant CP violation in a mixed system of two nearly degenerate unstable fermions, $Y_{1,2}$, whose mass splitting is comparable to their decay widths. Rare production of the coherent $Y_1$–$Y_2$ state, followed by CP-asymmetric return and loss decays, generates an $\mathcal{O}(0.1)$ difference in integrated decay probabilities while preserving the global baryon charge at the Lagrangian level. Embedding this resonant source in the PBH-capture transport system yields the observed baryon asymmetry. We first reproduce the mechanism in a zero-temperature, sudden-evaporation treatment, which gives $\eta_B^{T=0}\simeq2.37\times10^{-10}\simeq2.72 \eta_B^{\rm obs}$. We find that after including thermal corrections and continuous PBH evaporation and entropy production, the resulting BAU becomes $\eta_B = 8.72\times 10^{-11}$ in agreement with the observed value. An interesting finding of the model is that even if PBH absorption remains active, we would still have BAU $\eta_{B}^{\text{no evap}} \sim 9.1 \times 10^{-12} \sim 0.105 \eta_B^{\rm obs}$. We further investigate gravitational-wave signatures associated with the primordial fluctuations responsible for PBH formation. The corresponding scalar-induced gravitational-wave spectra peak at $f \sim 0.16\text{--}0.17~\mathrm{MHz}$, with $h^2\Omega_{\rm GW}^{\rm peak} \sim (3\text{--}7)\times 10^{-8}$. Under idealized sensitivity assumptions, U-DECIGO can achieve signal-to-noise ratios above 10 for the benchmark spectra.

We investigate the Fulling-Davies-Unruh effect in a local Lorentz-violating effective field theory, focusing on the quantum-field response of accelerated detectors. We canonically quantize a real scalar field exactly in the coefficients for Lorentz violation. The dispersion relation, Hamiltonian, and massless and massive Wightman functions are obtained. We determine the conditions under which the scalar dynamics preserves boost symmetry and distinguish these from the weaker conditions required for stationarity along a single accelerated worldline. The Wightman functions are used to construct the finite-time Unruh-DeWitt response for a uniformly accelerated detector. For generic coefficients the response is nonstationary and depends on both the duration and temporal location of the measurement. The spectrum, which is the resulting excitation rate as a function of the energy level difference in the detector, is obtained numerically. It shows discernable differences with the usual massive thermal spectrum for dimensionless coefficients on the order of $10^{-7}$. Experimental implications of the result are discussed. As an alternative viewpoint, we place Lorentz violation in the point-particle sector, derive the exact trajectory generated by a constant electric field, and study the proper-time Fourier response of a conventional scalar wave along the modified trajectory.

The anomalous Hall effect (AHE) is of fundamental importance for understanding spin-orbit coupling and magnetic transport in magnetic materials. Meanwhile, strain can significantly modify material properties, and the piezoelectric effect stands as a well-known representative. The piezo-Hall effect combines the two physical ingredients of AHE and strain. Specifically, the piezo-Hall effect describes a physical process in which the magnetic space group (MSG) of a magnetic material prohibits a net magnetic moment and suppresses the AHE in the pristine state but transforms into a new MSG upon strain application that permits a net magnetic moment, thereby enabling the emergence of the AHE. The underlying mechanisms cover strain-induced magnetic electronic state transition and strain tuning of magnetization direction. We take the $d$-wave altermagnetic metal as an example to analyze the piezo-Hall effect in detail, with first-principles calculations carried out on the specific material $\mathrm{RbCr_2Se_2O}$ to verify this scenario. A notable result is that under identical uniaxial strain applied along the $x$ and $y$ directions, the anomalous Hall conductivity exhibits opposite signs but equal magnitudes. Similarly, the piezo-magneto-optical effect can also be proposed, and if strain tuning is replaced by electric-field modulation, the electro-Hall effect and electro-magneto-optical effect can be also put forward accordingly. Even temperature can serve as an external field to introduce the temperature Hall effect. Our work advances the understanding of the coupling between strain and physical properties.

Traveling waves of activity in neural tissue can be halted by spatial inhomogeneity in synaptic coupling. We study an integrate-and-fire network in which each neuron fires once and the coupling decays exponentially. For this model the leading-edge firing map reduces exactly to a scalar equation for the wave speed in space, with a slow unstable and a fast stable homogeneous speed, $c_1$ and $c_2$, and a periodic modulation of the coupling enters this equation pointwise. Positive periodic waves terminate in folds. For slowly varying modulation the fold amplitude approaches a plateau set by the trough of the modulation, where the local bottleneck speed is $\sqrt{c_1 c_2}$; the approach to the plateau is set by the local geometry of the trough. For rapidly varying modulation the fold amplitude grows linearly with frequency, with a slope given by a full-amplitude average over the integrated modulation profile; a weak-ripple truncation of that average overestimates the slope about 2.5-fold at the default coupling. A perturbative recursion in the amplitude gives the speed profile explicitly. We distinguish loss of the periodic wave from failure of a particular launch, and the excitatory regime $\epsilon\le 1$ from its sign-changing extension. The results are checked against direct integration of the reduced equation and first-spike firing-map simulations of the network.

First-order phase transitions in neutron-star interiors can leave signatures in the polar quasi-normal-mode spectrum. We compute the complex quadrupolar $f$- and $p_1$-mode spectra in full general relativity for cold, nonrotating hybrid stars with a sharp hadron–quark interface. We model the equation of state by matching a hadronic SLy4 phase to a constant-sound-speed quark-phase. We compare slow phase conversion, in which fluid elements retain their phase and the interface moves with the fluid, with rapid phase conversion, in which matter changes phase as it crosses the boundary and the interface follows phase equilibrium rather than the fluid, together with an algebraic interpolation between these limits. On identical equilibrium backgrounds, the two physical limits produce a sizable separation in the real part of the $p_1$-mode frequency. This $p_1$ frequency separation is largest when the local tangential-displacement fraction of the eigenfunction changes rapidly across the interface. Across the surveyed EOS parameter space, rapid conversion generally lowers the $p_1$-mode frequency relative to slow conversion, with compactness-averaged separations reaching $\sim3.5\,{\rm kHz}$ on disconnected twin-star branches. The largest separations occur at relatively low transition pressures and large density discontinuities. By contrast, the $f$-mode is only weakly affected by the interface condition for individual stellar models. Across the sampled constant-sound-speed parameter space, departures exceeding the hadronic SLy4 reference residual occur mainly at low transition pressure, large density discontinuity, or both, with different boundaries for the real- and imaginary-part fitting variables. Thus, the $p_1$-mode probes the local interface response, whereas the tracked $f$-mode reflects the global departure of the hybrid sequence from the hadronic calibration.

We study the $\bar{K}^0d$ system using a new formulation of the fixed-center approximation that preserves elastic unitarity. The resulting scattering amplitude predicts a bound state below threshold, which can be interpreted as a $\Lambda(1380)N$ configuration complementary to the $K^-pp$ state associated with the higher $\Lambda(1405)$ pole. The interaction is attractive, with scattering parameters of the same order as recent $K^-d$ determinations. We further calculate the $\bar{K}^0d$ correlation function, which exhibits a characteristic structure associated with the bound state and provides a Coulomb-free observable that can be tested in future ALICE measurements. Results obtained with two different $\bar{K}N$ models are very similar, indicating the robustness of the predictions against the choice of the underlying interaction.

The positive-partial-transpose-squared (PPT-squared) conjecture asks whether the composition of two positive-partial-transpose (PPT) quantum channels must be entanglement breaking (EB). The problem remains open in general and, within the diagonal orthogonal covariant (DOC) class, the first unresolved deterministic dimension is four. A sufficient condition for PPT-squared composition is derived for DOC maps in arbitrary finite dimension. The proof isolates the quantum coherence data into two correlation matrices, mixes each with the identity until it lies in the convex hull of rank-one correlation matrices, and converts the resulting objects into an explicit triplewise completely positive (TCP) core. The remaining contribution is purely classical and is TCP whenever a simple entrywise mixing inequality is satisfied. For PPT DOC maps $\Phi_{A,B,C}$ and $\Phi_{D,E,F}$ on $M_d$, the entrywise bound $(AD)_{ij}\ge 2\lfloor\sqrt{d}\rfloor\sqrt{A_{ii}A_{jj}D_{ii}D_{jj}}$ for all $i,j$ guarantees that $\Phi_{A,B,C}\circ\Phi_{D,E,F}$ is EB. In dimension four the universal coefficient becomes four. A continuous family of bistochastic PPT channels is then constructed; every member with $a\ne1$ is not EB, while every pairwise composition within the family is proved to be EB. A rank-sensitive refinement shows explicitly how low coherence rank can improve the universal coefficient. The resulting certificate is sufficient rather than necessary and is complementary to factor-width and semidefinite-hierarchy approaches.

Electrostatic (ES) field enhancement at sharp conducting structures plays a central role in lightning protection, corona discharge, electrical breakdown in vacuum (for example in particle accelerators), and more generally in technological applications of field electron emitters. A canonical geometry for studying this ES effect is the hemisphere-on-cylindrical-post (HCP) model, in the regime where the structure stands on a planar conductor of large lateral extent, and a large gap exists between the structure and the counter-electrode. A parameter of major interest is the apex field enhancement factor (AFEF) (apex-ES-field/background-ES-field). For this (and other) structures, a formula for the AFEF can be written in the form AFEF = ASC x ASR, where the apex sharpness ratio (ASR) is given by the ratio (post-height/apex-radius-of-curvature), and the apex sharpness coefficient (ASC) depends on the post shape. For the HCP model, no exact analytical formulas for the ASC or the AFEF are currently known. (Quite possibly none exist.) This paper develops a compact analytical approximation for the ASC and hence for the AFEF. This compact formula has a logarithmic-style structure, rather than the power-style structure used in previous approximations. When compared with precise finite-element analyses of the HCP model, over the computationally accessible range 1 to 1000 for the ASR, this logarithmic-style formula has a maximum error-magnitude of 0.15 percent, which is significantly better than older approximations.

How can local multiplet signatures, collective core-hole screening, and an extended photoelectron be reconciled in Ce $L_3$ x-ray absorption near-edge spectra? Motivated by the question raised by Kvashnina [Chem. Eur. J. 30, e202400755 (2024)], we address this challenge using XSpectruplet, which couples local multiplet dynamics to continuum photoelectron propagation in self-consistent Kohn–Sham screening potentials. For Ce$^{4+}$ in CeO$_2$, our heuristic search identifies primary and secondary stationary screening states whose calculated white-line maxima lie about 7.3~eV apart after including their independently calculated total-energy difference, yet both retain the same effective local spectroscopic $4f^0$ sector. Their squared overlaps with the unrelaxed sudden reference give approximate statistical weights of 63% and 30%, respectively, within an independent-channel description. Their contrasting screening responses arise from collective rehybridization of occupied orbitals, rather than occupation of an additional localized $4f$ spectator, and produce contributions in both the main white-line and satellite regions. Ce$^{3+}$ in monazite CePO$_4$ provides the contrasting case of a localized $4f^1$ spectator participating explicitly in the multiplet dynamics. Independent relaxation of neutral $4f$ and white-line states gives a CeO$_2$ pre-edge–white-line gap of 10.51~eV, close to the experimental separation of approximately 10.7~eV. Its excess over the fixed-background spectral gap defines a net correction, which we transfer heuristically to CePO$_4$ without changing its local multiplet structure. This gives an estimated CePO$_4$ gap of 6.38~eV, compared with approximately 8.1~eV experimentally. Distinct spectral contributions can thus arise from collective screening without a change in the effective local configuration.

Phonon–magnon coupling has been extensively studied in ferromagnets, whereas its microscopic mechanisms in antiferromagnets remain less understood. Here, we combine first-principles calculations with spin–lattice dynamics to investigate phonon–magnon interactions and their impact on thermal transport in antiferromagnetic NiO and MnO, which are put in contrast to the ferromagnetic EuO with an identical crystal structure. Green–Kubo and spectral energy density analyses show that spin dynamics reduce phonon thermal conductivity and lifetimes, with the strongest effects in MnO. Comparison of the excitation spectra indicates that spin-induced phonon scattering depends sensitively on the relative phonon and magnon energy scales, while the contrasting behavior of MnO and EuO further highlights the role of magnetic order. A simplified phase-space model further illustrates that, for comparable phonon and magnon energy scales, the antiferromagnetic case can support a larger phonon–magnon scattering phase space than the ferromagnetic case, suggesting a greater number of kinematically allowed scattering channels. These results identify excitation energy scales and magnetic order as key factors governing phonon–magnon scattering in magnetic materials.

We investigate the growth of a circular domain in a phase-separating lipid membrane and its relation to the budding instability. We describe the in-plane dynamics with a conserved, time-dependent Ginzburg-Landau model under radial symmetry. Numerical solutions show a crossover of the domain size $D$ as a function of time $t$ from $D\sim t^{1/3}$ at early times to $D\sim t^{1/2}$ at later times, followed by saturation due to finite system size. The time-dependent line tension $\sigma(t)$, evaluated from the evolving concentration profile, rises rapidly before approaching the planar-interface value. This behavior distinguishes an early line-tension-dominated regime from a later domain-size-dominated regime. To estimate the budding instability, we combine $D(t)$ and $\sigma(t)$ with a quasistatic criterion for the loss of stability of a partially budded domain. The budding-instability time decreases with increasing membrane spontaneous curvature and increases near the critical point. Thus, the evolution of both domain size and line tension is essential for determining the time required for the budding instability.

We aim to derive convenient analytic estimations of magnetic inference errors, which can be used to inform and facilitate the creation of the science-traceability matrix of a polarimetric instrument. In order to do this, we study the general problem of the propagation of Poissonian noise in polarized light signals to derived data products of the Stokes profiles, namely integral moments of arbitrary orders and spectral derivatives of the intensity. In particular, we derive the errors on the longitudinal and transversal projections of the magnetic field inferred from the weak-field approximation (WFA) of the Zeeman effect. The propagated errors on magnetic inference are traced back to the signal- to-noise ratio (SNR) of the observations. The results can be used to quantify the contributions of different environmental and instrumental conditions (spectral line width, spectral resolution, line spread function, stray light) to the overall error on the inferred quantities. Our tests indicate that the integral-moment method of inference is comparable to the local derivative in a predictable way.

Spin pumping into superconductors is generally expected to become less efficient below the critical temperature $T_\textrm{c}$ because quasiparticle transport freezes out. Here we report a pronounced enhancement of the spin pumping-induced magnetic damping in Py/Nb heterostructures, confined to a narrow temperature interval immediately below the superconducting transition. The damping exceeds its normal-state value and therefore cannot be explained within the conventional quasiparticle picture of spin transport. The enhancement coincides with the finite-resistance vortex-creep regime of the Nb layers and disappears upon cooling into the pinned vortex state, indicating that mobile Abrikosov vortices provide an additional channel for spin-angular-momentum dissipation. These results establish ferromagnetic resonance as a sensitive probe of dissipative vortex dynamics in superconductors.

We experimentally explore the collective behavior of the nematode T. Aceti inside flexible boundaries showing the emergence of previously unreported states. These nematodes have been previously shown to be able to synchronize their body oscillations in a favorable condition of confined space. In this collective state, they are able to exert a strong pushing force which we exploit to study how their collective motion could deform a pliable boundary. Using a novel experimental technique, we were able to simulate a non-rigid border at a liquid-liquid-gas triple point. We discovered a state with periodic boundary deformations which are due to the synchronized oscillations of the nematodes. More interestingly, we found a novel state where the nematodes are able to form multiple protrusions in the border which oscillate, rotate, merge, and split. We propose a numerical model that is able to reproduce some of the observed parameters of this state as well as offer an analytical insight into protrusions dynamics. Our research opens a pathway for exploring the interaction between active matter and flexible interfaces with a new kinds of active matter agents forming dynamic non-chaotic border deformations.

Engineered dissipation corrects errors, yet a memory's phase decays. What the memory's gap measures is not settled. Here we show that when each jump resets one basis state, the wiring can set the gap time while the phase keeps its rate. Under dephasing the gap time spans two orders across wirings; the phase does not. In this class, a contrast on two or more qubits fades faster than a bare qubit at any distance; no such pump power substitutes. The ceiling is two over the qubits the contrast spans. A two-branch pump can escape it at distance three; a two-clock test runs on published data.

The effect of a porous coating on the water-exit dynamics of a circular cylinder is investigated experimentally. Cylinders comprising a $30~\mathrm{mm}$ solid core surrounded by a $10~\mathrm{mm}$-thick porous foam layer with pore densities of 10, 20, and 60 pores per inch (PPI) are compared with a smooth cylinder of the same outer diameter. Experiments are performed over $1.50\times10^{4}\leq Re\leq5.00\times10^{4}$ and $0.37\leq Fr\leq4.08$. Time-resolved particle image velocimetry characterizes the wake and reconstructed pressure field, while proper orthogonal decomposition (POD) examines its energetic organization. All porous cylinders reduce free-surface elevation relative to the smooth cylinder, with the largest reduction generally obtained for 60 PPI. The submerged wake, however, is not simply weakened. Porous cases generally develop larger circulation and vortex area, with a non-monotonic dependence on pore density and operating condition. The 10 PPI cylinder frequently produces the largest vortex region, whereas 60 PPI generates stronger negative pressure within the vortex and the largest integrated vortex-associated pressure deficit for $Fr=1.02$, $2.00$, and $4.08$. During the submerged approach to contact, this pressure deficit co-evolves strongly with circulation, with Pearson correlation coefficients typically between $0.90$ and $0.98$. POD shows that 9–18 modes recover 95% of the modal energy, with 20 PPI requiring only 9–10 modes. Overall, porous coating reorganizes wake strength, extent, pressure signature, and energetic structure while reducing the free-surface response.

Vision-language models (VLMs) are increasingly being used in scientific workflows, but their ability as agents to directly control laboratory experiments from visual feedback remains underexplored. This capability is important because many laboratory tasks do not naturally provide dense, pre-defined numerical objectives: informative signals can be sparse, intermittent, or visually ambiguous. A more general laboratory agent should instead be able to interpret visual observations, take actions to acquire useful feedback, and adapt its behavior based on the consequences of those actions. We study whether general-purpose VLMs can perform this kind of closed-loop scientific control using experimental optics as a testbed. We evaluate agents on three experimental systems that isolate distinct capabilities: a Michelson interferometer, a two-mirror cavity, and a four-mirror optical relay. The agents observe camera images, directly issue actuator and measurement commands, and retain their interaction history without receiving an engineered scalar objective during control. Across these experiments and matched simulations, we find that, given task-specific natural-language guidance, VLMs can estimate actuator-response relationships, resolve ambiguous observations through intervention, and actively create informative visual feedback when signals are sparse. These results suggest that pretrained multimodal models can serve as important decision-making agents within the experimental loop. Our work also establishes optics as a physically grounded testbed for visual reasoning and active perception in scientific agents.

The long-run statistics of chaotic dissipative partial differential equations are described by invariant measures, and when the equation carries a parameter these measures form a family whose members can differ in kind, from steady states to sustained spatiotemporal chaos. We ask whether a single generative model can cover such a family. We train a single conditional diffusion model once, on states of the Kuramoto-Sivashinsky equation at 160 values of its hyperviscosity, and evaluate it against held-out data at interleaved parameter values not seen in training, using a classifier two-sample test supported by spectral, geometric and tail statistics. Over most of the family, agreement improves as the dynamics become more chaotic. We identify a structural cause: the weakly chaotic members have invariant measures concentrated on low-dimensional sets, which a model with full support output cannot represent, and the target approaches full dimensionality as chaos increases. Restricting training to the strongly chaotic members reduces the classifier's excess over chance on those members by roughly 40%, and this restricted conditional model matches or exceeds models trained at single parameter values. On those members, generated samples reproduce energy spectra to within a resampling floor, with a small systematic deficit at the largest scales, and match the energy balance of held-out data.

Under tight feature and compute budgets, classical threat detection pipelines often degrade on near-decision-boundary events. Small quantum processors are now available, but existing work inadequately shows whether quantum components improve end-to-end threat detection under the above resource constrained conditions. This paper tries to address this gap with a hybrid architecture that uses a compact multilayer perceptron layer to compress the information in data and then routes the processed features to a few qubit quantum heads implemented in quantum support vector machine (QSVM) and variational quantum circuit (VQC) models. On a simulation platform, we benchmark these hybrid models against classical models with comparable parameter budgets on two representative cybersecurity tasks, network intrusion detection on NSL-KDD dataset and spam filtering on Ling-Spam dataset. To validate their precision on real quantum hardware, we deploy the best 4-qubit QSVM model on an IBM Quantum device with noise-aware execution, evaluated on a smaller sub-dataset. In the results, shallow quantum heads consistently match, and on difficult near-boundary cases modestly reduce missed attacks and false alarms compared to classical models using the same features. Hardware validation results track the simulation behavior closely enough that the remaining gap is dominated by device noise rather than model design. Furthermore, we conduct adversarial attacks to test the robustness of one QSVM model. Taken together, the study shows that even on small, noisy devices, carefully engineered quantum components may function as competitive, budget-aware components in practical cyber threat detection applications.

Finite-temperature Bethe-Salpeter calculations of exciton-phonon self-energies in polar materials are bottlenecked by the Fröhlich divergence of the intra-1s scattering vertex. We show that for a bound electron-hole pair this divergence is analytically eliminated by electron-hole interference: the intra-1s vertex admits the exact factorization $V_{\mathrm{el}}(q)=q\,\mathcal G(q)$ with $\mathcal G(0)\propto(m_h-m_e)/(m_h+m_e)$, vanishing identically for equal masses (parity protection). A multipole interference factor $\mathcal I_n=\beta_e^{\,n}-(-\beta_h)^{n}$ determines where the singularity survives-only in dipole-allowed inter-state channels. We formulate a parity-selected truncation of the exciton-phonon self-energy in which the intra-1s channel is evaluated exactly at negligible cost, converging with $10^2$-$10^3$ fewer $q$-points. We find that the regularized intra-1s channel, previously obscured by numerical cutoffs, controls the temperature-dependent exciton shift in mass-asymmetric polar semiconductors.

Studying Gravitational Waves (GWs) provide a unique probe of the interplay between quantum matter and the dynamics of spacetime. We develop a QED framework for spontaneous emission in the presence of a weak classical GW by quantizing the electromagnetic field in a linearized gravitational background. We show that a passing GW dynamically phase-modulates vacuum electromagnetic modes, dressing photon states into a Floquet ladder of sidebands separated by the GW frequency. While the total spontaneous decay rate remains unchanged to first order in the GW strain, the emission pattern develops a characteristic spin-2 quadrupolar angular redistribution modulated with the GW phase. For finite interaction times, interference between the carrier and Floquet sidebands generates phase-dependent spectral asymmetries in the transient emission spectrum. To explore experimental observability, we formulate a cavity-QED master equation description and propose a differential cross-cavity detection protocol employing Rydberg ensembles or highly charged ions. These results establish cavity QED as a promising platform for exploring quantum electrodynamics in dynamical spacetime and for high-frequency gravitational-wave detection.

Establishing chemical design rules that simultaneously control the electronic structure and thermal transport is a long-sought goal for heat-management and energy materials. Here, we demonstrate that a single B-to-C substitution changes the electron count and simultaneously reconstructs the bonding network and crystal structure, driving a metal-to-semiconductor transition while concurrently enhancing the lattice thermal conductivity. Using density-functional theory (DFT) and machine-learned interatomic potentials (MLIPs), we investigate the electronic structure, lattice dynamics, and phonon thermal transport in cubic BaB3C3 and its B-to-C-substituted tetragonal BaB2C4 structure. The substitution donates one electron per formula unit to the B-C framework, thereby triggering the formation of strong C-C bonds and opening a bandgap of 0.33 eV. The Message Passing Atomic Cluster Expansion (MACE) model reproduces DFT energies and forces, yielding phonon dispersion and lattice thermal conductivity in excellent agreement with DFT benchmarks. Thermodynamically stable cubic BaB3C3 possesses an isotropic lattice thermal conductivity of 7.6 W/mK at 300 K. Substituting B with C hardens the phonon dispersion (evidenced by a frequency upshift from ~800 to ~900 cm^-1) and simultaneously boosts both phonon group velocities and lifetimes. Consequently, the lattice thermal conductivity surges to 18.7 W/mK, representing a remarkable ~2.5-fold enhancement of the in-plane component and a transformation from isotropic to anisotropic behavior, characterized by kappa_x = kappa_y > kappa_z. Our results demonstrate that minimal B-to-C substitution provides a viable strategy to modulate the electronic structure, thereby transforming the crystal from a metal to a semiconductor and concomitantly enhancing phonon thermal transport.

We present new constraints on a candidate third companion in the 61 Cygni binary system-one of the closest neighbors to our solar system (3.5 pc), the first stars to have a measured parallax, and two of the most favorable targets for habitable zone exo-Earth searches with future direct imaging missions. Kervella et al. (2022) first identified the candidate based on a 4.4$\sigma$ tangential velocity anomaly in the system determined using Hipparcos and Gaia DR3 astrometry of the A and B components. We combine this astrometric evidence with constraints from Gaia DR3 RUWE, MMT/Clio Lp imaging, nearly four decades of radial velocity (RV) measurements (including $\sim$2 years of new NEID RVs presented here), and N-body dynamical stability calculations of both stars in a Monte Carlo framework to estimate the candidate companion's mass and semi-major axis. Our analysis reveals that all of the available data are compatible with an $\approx(8 \pm 3)\;M_{\rm Jup}$ super-Jupiter in an $\approx(8 \pm 3)$ au orbit, with a broad range of allowed eccentricities and mutual inclinations. Using the Sonora Flame Skimmer evolutionary models, given the system's mature age of $(6.0 \pm 1.0)$ Gyr, we estimate a companion effective temperature of $(282 \pm 55)$ K and radius of $(1.02 \pm 0.02)\;R_{\rm Jup}$. Finally, we evaluate the stability of terrestrial planets in the habitable zone (HZ) of 61 Cygni AB in the presence of the giant planet candidate using N-body simulations. A companion semi-major axis $\lesssim$5 au, irrespective of the planet-planet mutual inclination, and between $\approx$5 au and 10 au, for misaligned orbits ($40^o \lesssim i_{\rm mut} \lesssim 140^o$), severely disrupts the HZ. Our results highlight the need to confirm the planet candidate and characterize its orbit to inform future exo-Earth searches with missions such as SHERA, HWO, and LIFE.

Turbulent flows span a wide range of scales, making direct numerical simulation (DNS) prohibitively expensive at high Reynolds numbers. Large eddy simulation (LES) offers a pragmatic alternative by only resolving the large-scale motions, but its accuracy hinges on the subgrid-scale (SGS) model. We introduce the Tau-orthogonal (TO) framework to the lattice Boltzmann method (LBM) using a macroscopic-velocity forcing. The TO method shifts the modeling target from a high-dimensional SGS field to the time dynamics of a small set of spatially integrated quantities of interest (QoIs). Training data are generated by a predictor-corrector tracking procedure that nudges coarse simulations toward reference QoI trajectories. Lightweight linear regression models with stochastic, multivariate Gaussian residuals (LRS) then drive the LES autonomously. Compact convolution-based kernels replace the sharp Fourier filters of the original formulation, lifting its restriction to rectangular periodic domains. We first evaluate the closure on two-dimensional Kolmogorov flow, where TO-LRS yields stable, statistically accurate online LES. However, bounded high-frequency oscillations are observed in the solution fields. The decisive test is three-dimensional turbulent channel flow, simulated on a grid five times coarser in every direction than the high-fidelity reference. Here the plain BGK solver is unstable, and even calibrated Smagorinsky and WALE models over-dissipate the near-wall flow. TO-LRS, applied on top of an eddy-viscosity substrate and with the QoI set augmented by mean-profile QoIs, reproduces the reference distributions and holds the DNS mean velocity profile, at $40\times$ lower online cost per simulated time unit than the high-fidelity simulation. These results establish reduced, QoI-based closures as an interpretable and inexpensive alternative to high-dimensional neural SGS models for LBM.

An improved algorithm to implement our previously proposed static quantum embedding method MPCC (J. Chem. Phys. 161, 164107 (2024)) is presented. It uses the density-fitting (DF) approximation for the electron-repulsion integrals (ERIs) across all layers of the embedding method: the low-level method, the screened interaction, and the high-level method. Additionally, an approximate factorized solution of the Sylvester equation is employed based on the Laplace transformation for the low-level method. To build the screened interaction, we have explored an approximate construction of it based on the distinguishable cluster approximation (DCA) by Kats and Manby (J. Chem. Phys. 141, 061101 (2014)), which amounts to neglecting certain higher-order exchange and ladder diagrams. Combining all these techniques, we have obtained an $\mathcal{O}(N^4)$ algorithm for the low-level method; a non-iterative $N_{\rm frag} \mathcal{O}(N^4)$ algorithm for the screened interaction; and an iterative $\mathcal{O}(N_{\rm frag}^6)$ algorithm for the fragment solver, where $N_{\rm frag}$ is the number of fragment orbitals and $N$ is the total number of orbitals. The resulting low-scaling implementation of the MPCC method is applied to trans polyacetylenes, that is, C$_{2n}$H$_{2n+2}$ molecules for chain lengths $n=1-8$, and the timing and accuracy of the method are compared to the original unfactorized implementation. Moreover, the approximations are further validated by applying the method to the potential energy surface of the \ce{O3} molecule. Finally, we apply the method to the selected molecules in the S22 dataset for which the performance of the MP2 method is known to be poor. The results demonstrate that the DF-based implementation of the MPCC method provides a significant reduction in computational cost while maintaining accuracy comparable to that of the original implementation.

A black hole horizon carries exactly one nat of information per Planck cell, without naming what the black hole is made of. Two inputs suffice: entropy is irreducible uncertainty (the configurations no observation can resolve at the Planck floor, an objective bound, not ignorance), and the horizon is a complete scrambler, so by the Ehrenfest time its Wigner function has folded below the floor and no cell can be certified empty. A single cell then holds unresolved filament crossings; a cell crossed $n$ times admits $n!$ orderings that scrambling erases, so cardinality $n$ carries weight $1/n!$ and its count is $\Omega_1=\sum_n 1/n!=e$, one nat. The $N=A/\ell_P^2$ independent cells give $\Omega=e^N$, hence $S=N$. Multiplied by the kinematic factor $\tfrac{1}{4}$ (the causally accessible fraction of the null phase space, established separately), this returns $S_{BH}=A/4\ell_P^2$. The derivation invokes no field equations, no microscopic theory, and no posited Hilbert space.

We construct exact, static, circularly symmetric charged regular AdS$_3$ black hole solutions in a three-dimensional scalar-vector-tensor theory obtained from regularized Gauss-Bonnet couplings. While the Maxwell-charged counterpart of this theory suffers from a logarithmic curvature singularity at the origin, we demonstrate that coupling the action to non-linear Born-Infeld electrodynamics cures this pathology. We obtain the metric function and show explicitly the regularity of the core. Depending on the choice of parameters, the solution exhibits various horizon structures, including single-horizon, double-horizon, extremal black holes, and horizonless regular geometries. Finally, we discuss the significance of this regular spacetime as a testbed for microscopic entropy calculations in singularity-free setups.

The first sentence of this abstract–and the introduction to these proceedings–was authored by a human, but the bulk of this document was generated by an agentic AI system. In this talk, I take stock of machine learning (ML) for the LHC physics program over the twelve months from May 2025 to May 2026. The corpus is the HEPML Living Review, split at May 2025 into 1,756 earlier papers and 569 later ones. An AI pipeline surveyed the 569 abstracts, ranked them by citations, recency, theme, and collaboration involvement, and read 103 papers in full (95 from after the split, plus 8 earlier baseline papers), producing a structured note for each. The notes were then synthesized into six claims about the state of the field, checked by independent reviewer agents, and re-verified against the source papers. The headline claim is that (1) ML for high-energy physics (HEPML) stopped being a research area that builds tools and became infrastructure that the LHC physics program depends on: ATLAS and CMS now publish physics results that depend on neural networks, and the archived ALEPH data have re-entered production. The other five claims are: (2) simulation-based inference and foundation models are two revolutions starting to merge; (3) AI agents are the genuinely new front, with 47 papers in twelve months and no adopted measurement yet; (4) "do we trust it?" is the fastest-growing agenda, with one recent paper in five about uncertainty, calibration, or interpretability; (5) what is slowing down is informative, since equivariance was absorbed into a tool and model-specific phenomenology ceded ground to model-agnostic searches; and (6) theory ML crossed a capability threshold in multiple research areas. I close with what is settled, what is incoming, and what is open, and briefly discuss the concerns raised by this way of working with AI.