Materials Science
Two-Dimensional Hexagonal BX3 (X = P, As) Monolayers as High-Capacity, Fast-Charging Anode Platforms for Lithium- and Sodium-Ion Batteries
Jakkapat Seeyangnok, Joongjai Panpranot and Udomsilp Pinsook
The rapid advancement of alkali-metal ion batteries demands robust anode platforms combining high specific capacities with rapid charge-discharge kinetics. Using first-principles density functional theory (DFT), we systematically evaluate two-dimensional (2D) hexagonal BX3 (X = P, As) monolayers as high-performance dual-use anodes for lithium-ion (LIBs) and sodium-ion batteries (SIBs). Both metallic host architectures display strong thermodynamic affinities for Li+ and Na+ adsorption, favoring the hollow H3 site through synergistic ionic charge transfer and orbital hybridization. Climbing image nudged elastic band (CI-NEB) calculations reveal low direct H3 -> H3
diffusion barriers: 0.40 eV (BP3) and 0.26 eV (BAs3) for Li+, and 0.26 eV (BP3) and 0.19 eV (BAs3) for Na+, confirming exceptional high-rate kinetics. Thermodynamic convex hulls establish maximum stable lithiation at Li3BX3, yielding low average operating potentials of 0.39 V (BP3) and 0.35 V (BAs3) alongside theoretical specific capacities of 775 mAh/g and 341 mAh/g, respectively, with BP3 doubling commercial graphite (372 mAh/g). For SIBs, multi-layer sodiation expands storage up to Na15BP3 and Na12BAs3, delivering ultrahigh capacities of 3875 mAh/g (BP3) and 1365 mAh/g (BAs3) at low voltages of 0.18 V and 0.15 V. Crucially, projected density of states (PDOS) analyses confirm that both frameworks preserve intrinsic metallic conductivity throughout all charging stages. These combined properties establish 2D BX3 monolayers as outstanding, structurally resilient anode candidates for next-generation LIB and SIB energy storage technologies.
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Physics and Society
An exact N-strain epidemic model using bond percolation
Peter Mann, V. Anne Smith, John B.O. Mitchell et al. (+1 more)
In this paper we examine the emergent structures of random networks that have undergone bond percolation an arbitrary, but finite, number of times. We define two types of sequential branching processes: a competitive branching process - in which each iteration performs bond percolation on the residual graph (RG) resulting from previous generations; and, a collaborative branching process - where percolation is performed on the
giant connected component (GCC) instead. We investigate the behaviour of these models, including the expected size of the GCC for a given generation, the critical percolation probability and other topological properties of the resulting graph structures using the analytically exact method of generating functions. We explore this model for Erdos-Renyi and scale free random graphs. This model can be interpreted as a seasonal N-strain model of disease spreading.
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All authors Peter Mann, V. Anne Smith, John B.O. Mitchell, Simon Dobson
High Energy Physics (Theory)
Claudia de Rham
Massive
gravity is one of the most natural proposals for modifying
gravity at large distance scales. First proposed to tackle the cosmological constant problem, it has the potential to simultaneously maintain theoretical consistency and agreement with current observational constraints. The development of Lorentz-invariant ghost-free massive
gravity resolves long-standing obstacles associated with interacting massive
spin–2 fields. Central to this development is a highly constrained nonlinear interaction structure that propagates exactly five degrees of freedom. The same interaction structure raises the strong-coupling scale to its maximal value, which organizes the theory as an effective field theory. Phenomenological consistency with local tests of
gravity is ensured by nonlinear screening through the Vainshtein mechanism, which is automatically built in. Recent developments have shown how to formulate the theory in a manifestly well-posed way within some limits and beyond. From an effective field theory perspective, unitarity, analyticity, and causality impose powerful constraints that strongly single out the ghost-free theory as a distinguished infrared realisation of massive
gravity. We further discuss these results in light of recent consistency analyses, which we put in context. Interestingly, massive
gravity has recently been invoked in discussions of black-hole
entanglement entropy and spacetime regions known as `islands'. The theory is also shown to emerge as an exactly solvable $T \bar T$ deformation in both two dimensions and for special cases in higher dimensions, opening up valuable insights into its UV behaviour. Massive
Gravity thus serves as a valuable theoretical laboratory for exploring the interplay between phenomenology and UV completions in infrared modifications of General Relativity.
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Chemical Physics
A Mesoscopic Ginzburg–Landau Model for Vibrational Strong Coupling Enhanced Rayleigh Scattering in Molecular Liquids
Wenxiang Ying and Abraham Nitzan
Recent experiments by Sandeep et al. [Angew. Chem. Int. Ed. 65, e16917 (2026)] suggest that vibrational strong coupling (VSC) in molecular
liquids can generate mesoscopic phenomena beyond single-molecule observables, including resonantly enhanced Rayleigh scattering, abrupt concentration thresholds, and thermal collapse. Motivated by these observations, we construct a mesoscopic Ginzburg–Landau model with two coupled fields: a cavity-controlled collective vibrational polarization $P$ and a secondary structural field $m$ whose long-wavelength susceptibility is renormalized by the collective vibrational polarization intensity $P^2$, assumed to govern long-wavelength density/dielectric fluctuations. With calibrated parameters, the model captures the observed Rayleigh enhancement, collective scaling relations, and threshold-like behavior, while explaining why polaritonic/IR signatures may persist when Rayleigh scattering disappears. The model further predicts enhanced long-wavelength density/dielectric correlations, enlarged mesoscopic correlation lengths, and slowed structural dynamics in the regime with strong Rayleigh enhancement, providing direct experimental tests through small-angle X-ray/
neutron scattering and dynamic light-scattering probes.
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General Relativity and Quantum Cosmology
Gauge-Unfixed Hamiltonian Casimir and Static Torsionful Sector in the Katanaev-Volovich Model
J. Manuel-Cabrera and J. M. Paulin-Fuentes
Hamiltonian analysis of the first-order Katanaev-Volovich model of two-dimensional
gravity with torsion. The first-order action already singles out natural canonical pairs: the auxiliary Lorentz scalars are conjugate to the spatial connection and zweibein. An extended Dirac-Bergmann
embedding isolates an auxiliary second-class sector whose elimination recovers the canonical structure encoded in the first-order action and leaves the first-class constraints generating the local gauge
symmetries. An independent Faddeev-Jackiw reduction yields the same reduced brackets. The Katanaev/Poisson-Sigma Casimir is then recovered, up to normalization, directly from the reduced Dirac-Bergmann first-class constraint ideal, before imposing any gauge condition. This identifies the Casimir as a global label of the reduced canonical sectors; after the static normalization is chosen, it supplies the
Hamiltonian parameter of the torsionful branch. The same normalization is applied to that branch in dilaton gauge, whose field equations are verified on shell. In this static sector the Casimir-normalized radial field does not coincide with the metric Killing norm: the diagonal representative satisfies \(NB=e^{4\beta r}\). Consequently, torsion modifies the Killing temperature through the normalization of the Killing time, while the horizon
entropy retains its standard two-dimensional dilaton value and the Casimir-normalized first law holds.
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Quantum Physics
The Complexity of Dynamical Correlators: Operator Shadows and Exponential Learning Separations
Shao-Hen Chiew, Armando Angrisani and Zoe Holmes
Quantum platforms can realize many-body dynamics beyond classical simulation yet complete readout remains intractable: the cost of extracting accessible information scales exponentially with system size. Classical shadows and Bell sampling offer scalable, multi-observable estimation from randomized or
entanglement-assisted measurements. Here we aim to push these ideas beyond static snapshots to dynamical correlators, including out-of-time-ordered correlators (OTOCs) and two-point functions. In particular, we introduce the notion of the shadow of an operator, defined as the classical shadow of the vectorized time-evolved operator. Pauli operator-shadows enable simultaneous estimation of all local OTOCs, while Clifford operator-shadows enable efficient simultaneous estimation of all two-point correlators. Alternatively, Bell sampling allows one to simultaneously compute all diagonal OTOCs. We also prove information-theoretic lower bounds for learning OTOCs, fully characterizing their query complexities in many cases, and yielding exponential separations that formalize when the vectorized approach provides measurement-efficiency advantages.
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Medical Physics
Differentiable Cardiac Electrophysiology Simulations for Dynamical State and Parameter Estimation
Adarsh Pashikanti, Shrey Chowdhary, Alex Ho et al. (+3 more)
The heart's contractions are triggered by action potential waves, which propagate through the cardiac muscle and exhibit diverse spatio-temporal dynamics during different heart rhythms. The dynamics are modeled with partial differential equations (PDEs) in cardiac electrophysiology simulations. However, fitting such models to measurement data to develop digital twins or patient-specific computer models is challenging. Here, we introduce differentiable cardiac electrophysiology simulations that can be fitted automatically to spatio-temporal measurement data of action potential waves in cardiac tissue. By comparing the simulated dynamics with the observation data, we define a loss function that is minimized via gradient-based optimization. Backpropagating the loss gradient through the differentiable PDE solver enables us to learn the parameters and recover the full dynamics, even with sparse, noisy, or partial observations. Implemented using both the finite-difference and smoothed particle hydrodynamics methods, our simulation framework can be applied to pixel-, voxel-, or point-based data, such as 2D or 3D slabs, or arbitrary shapes, such as the heart's ventricles. Using this methodology, we locate early activation sites inside a 3D bi-ventricular simulation geometry and fit a phenomenological model to imaging data of a voltage spiral wave in a cardiac monolayer
cell culture. With experimental data, we employed a perceptual loss based on the
Video Joint-
Embedding Predictive Architecture, which enables fitting to noisy imaging data, and a generative
diffusion model to estimate initial conditions and constrain solutions. Differentiable cardiac electrophysiology simulations could improve the diagnosis of rhythm abnormalities in patients and facilitate the development of personalized models or digital twins of the heart.
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All authors Adarsh Pashikanti, Shrey Chowdhary, Alex Ho, Weizhen Li, Emilia Entcheva, Jan Christoph
General Relativity and Quantum Cosmology
Schwarzschild-like Black Holes Submerged in an Exponential Density Dark Matter Profile
Kuantay Boshkayev, Yassine Sekhmani, Soroush Zare et al. (+3 more)
We study a class of Schwarzschild black holes embedded in an exponential-spheroidal dark matter
halo, modelled by a phenomenological density profile $\rho(r)=\rho_0 e^{-r/r_0}$. By solving the Einstein equations for a static, spherically symmetric spacetime, we obtain an analytic solution for the lapse function that reduces to the Schwarzschild spacetime in the absence of the
halo and to a regular
halo configuration when the central black hole mass vanishes. Indeed, the two
halo parameters, $\rho_0$ and $r_0$, describe the strength and radial extent of the dark matter distribution. We analyse the
curvature structure, energy conditions, shadow observables, scalar quasi-normal modes and grey-body bounds of the resulting spacetime. The
Ricci scalar and the
Ricci square remain finite at the origin, whilst the Kretschmann scalar retains the usual central
tidal singularity in the presence of a black hole mass. The weak, null, and dominant energy conditions are satisfied, whilst the strong energy condition is violated on a finite radial interval. We also show that the
halo monotonically shifts the
photon sphere and the shadow radius, which allows us to derive approximate constraints from the EHT observations of M87* and Sgr A*. For scalar perturbations, the Padé-resummed WKB approximation yields stable quasinormal frequencies, while the standard WKB approximation becomes unreliable for higher overtones and strong-
halo configurations. Finally, the greybody bounds indicate that the
halo weakens transmission through the effective barrier, particularly at low frequencies.
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All authors Kuantay Boshkayev, Yassine Sekhmani, Soroush Zare, Hassan Hassanabadi, Shahin Mamedov, Yergali Kurmanov
Fluid Dynamics
Circulation Statistics in Rayleigh-Bénard Convection
Giovanni Saisse, Roshan J. Samuel, Luca Moriconi et al. (+2 more)
Important statistical properties of velocity circulation in homogeneous isotropic
turbulence (HIT) have been unveiled in recent years, raising the question of whether they persist, or are modified, in other classes of turbulent flows. Motivated by the dominant role of small-scale structures in the circulation fluctuations of HIT, we investigate their relevance in direct numerical simulations of Rayleigh-Bénard convection at a Rayleigh number of $10^9$ and Prandtl number of $O(1)$. Within the thermal boundary layer (TBL), the distribution of elementary
vortices is found to be strongly correlated with the temperature field, while the statistics of their core aspect ratios is significantly altered. Additionally, the probability distribution functions of circulation, computed for planar contours which are parallel to the walls, display salient features closely akin to those observed in HIT, with the Area Rule (a connection between circulation statistics and minimal surfaces) remaining particularly well satisfied – except for a possible transitional region at a distance of a few TBL thicknesses. Away from the TBL, as expected, the overall statistical behavior of these structures likewise resembles that of HIT, where the intermittent spatial distribution of small
vortex tubes is instead determined by the energy dissipation field.
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All authors Giovanni Saisse, Roshan J. Samuel, Luca Moriconi, Jörg Schumacher, Katepalli R. Sreenivasan
Plasma Physics
Dependence of Momentum Transport on the Dominant Turbulence Regime in the DIII-D Tokamak
C. F. B. Zimmermann, C. Chrystal, E. Perez et al. (+8 more)
Accurate prediction of toroidal
plasma rotation is essential for optimizing confinement and stability in future fusion devices. This work investigates turbulent core momentum transport in the DIII-D tokamak across a transition from ion-temperature-gradient (ITG)- to trapped-electron-mode (TEM)-dominated
turbulence. A momentum transport framework previously developed for ASDEX Upgrade is applied to modulated neutral beam injection experiments, separating diffusive, convective, and residual-stress contributions via
Fourier analysis of the rotation response. The
dataset spans low-rotation conditions, dominant electron heating, and background ExB shearing rates below
turbulence growth rates, accessing more reactor-relevant conditions. Gyrokinetic CGYRO and gyrofluid TGLF calculations confirm the scan covers an ITG-to-TEM transition. The analysis yields Prandtl numbers near unity. The pinch number shows no explicit dependence on the transition, instead ordering roughly with the logarithmic density gradient. The normalized residual stress, in contrast, exhibits a non-monotonic, V-shaped dependence across the transition: co-current in deep ITG and deep TEM regimes, near-zero or counter-current in the intermediate mixed-mode regime. This trend collapses onto an approximately linear dependence against electron kinetic profile gradients, suggesting residual stress generation by profile-shearing effects. Weaker background ExB shearing further shifts residual stress toward counter-current values. Linear CGYRO simulations for representative ITG and TEM discharges yield Prandtl and pinch numbers in good agreement with experiment, supporting gyrokinetic momentum-transport predictions in TEM-dominated regimes. These results indicate residual stress plays an important role in core rotation prediction for low-torque
plasmas and should be included in predictive models of future reactor scenarios.
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All authors C. F. B. Zimmermann, C. Chrystal, E. Perez, T. Tala, C. Angioni, S. Haskey, F. Khabanov, R. M. McDermott, G. McKee, A. Salmi, L. Schmitz
High Energy Physics (Phenomenology)
PBH formation and Gravitational Waves as Multi-messenger Signals of First-order Phase Transitions
Bhaskar Dutta, Cash Hauptmann, Peisi Huang et al. (+1 more)
The collapse of false-
vacuum domains during first-order phase transitions in the early Universe may lead to
primordial black hole (PBH) formation whose signatures form a multimessenger complement to gravitational wave (GW) production. We focus on PBH formation through the gravitational collapse of false-
vacuum domains, described using a junction condition formalism. This formalism develops the Schwarzschild collapse criterion dynamically, avoiding the usage of critical overdensity thresholds in a post-inflationary Universe, and is driven solely by the
vacuum energy enclosed within shrinking false-
vacuum domains without the assistance of particle or domain wall interactions in the false
vacuum. We study the parameter space of phase transitions and identify regions producing observable GWs, observable PBHs, or both simultaneously. We investigate this phenomenology in
polynomial and classically conformal scalar field potentials as model
benchmarks. We find that the scalar fields with
vacuum expectation values in the range of 1-100 MeV have the largest model parameter space available for these multi-messenger signals, which are testable with upcoming GW observatories, searches for Hawking radiation, and gravitational
lensing surveys.
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All authors Bhaskar Dutta, Cash Hauptmann, Peisi Huang, Adrian Thompson
Materials Science
exa-PD: A scalable high-performance workflow for multi-element phase diagram construction
Zhuo Ye, Feng Zhang, Maxim Moraru et al. (+4 more)
Exa-PD is a highly parallelizable workflow designed for the construction of multi-element phase diagrams (PDs). It uses standard sampling techniques, molecular dynamics (MD) and Monte Carlo (MC) as implemented in the LAMMPS package, to simultaneously sample multiple phases over a fine temperature-composition mesh for free-energy calculations. Parsl serves as the global workflow engine, coordinating large ensembles of MD and MC tasks to achieve massive parallelization with strong scalability. The resulting free energies of
liquid and solid phases are then fed to CALPHAD modeling via the PyCalphad package to construct multi-element PDs.
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All authors Zhuo Ye, Feng Zhang, Maxim Moraru, Weiyi Xia, Ying Wai Li, Yongxin Yao, Cai-Zhuang Wang
Instrumentation and Methods for Astrophysics
Hans Moritz Günther, Scott J. Wolk, Sean J. Gunderson et al. (+3 more)
Stars set the conditions for
planet formation,
planet evolution, and habitability – all major topics in astronomy today.
Stars are also important in their own right as the most visible component of
galaxies. In cool
stars, X-ray emission is powered by
magnetic fields, and so far our Sun is the only system in which those fields are spatially resolved. High-resolution X-ray (HiReX) imaging can track the origin and
evolution of those fields, see how they connect young
stars to their disks and
outflows, and measure the energy, mass, and momentum that radiation and coronal mass ejections (CMEs) carry into the circumstellar environment. This is crucial for understanding whether
planets can form and survive in young
stellar systems, whether life can develop on those
planets, and how the
star evolves over time. Intermediate-mass and high-mass
stars blow winds and eventually evolve into degenerate objects such as white
dwarfs,
neutron stars, and black holes. Their
evolution and death drive the chemical
evolution of
galaxies. High-resolution X-ray (HiReX) imaging can study the hottest components in those systems, such as the colliding winds of massive
stars,
accretion and nova explosions in CVs, and the shocks in
outflows that form planetary nebulae. All these cases have in common that the X-ray emission is tracing the hottest, fastest, and most energetic components of the shocks. HiReX observations can reveal the temperature, spatial structures, and elemental abundances of different system components that no other wavelength can. While
stars are physically small compared to more powerful objects such as accreting black holes and AGN, they are also much closer to us, allowing a HiReX mission to resolve a variety of physical phenomena fundamental to our understanding of how
stellar systems form, evolve, and interact with their environment.
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All authors Hans Moritz Günther, Scott J. Wolk, Sean J. Gunderson, Ruchi Pandey, Keivan G. Stassun, Lynne Valencic
Biological Physics · Cross-listed from math.DS
Ptolemy's Equant Equates to a Universal Dynamical Clock via Machine Learning
Jingdong Zhang, Luan Yang, Murilo S. Baptista et al. (+4 more)
Oscillatory dynamics arise ubiquitously in nonlinear systems, yet identifying a physically interpretable phase and phase dynamics in nonlinear, high-dimensional oscillations remains a central unresolved problem. Here we establish the principle of a universal dynamical clock, a physical perspective in which oscillations of arbitrary dimensionality and geometry are equivalently represented as uniform rotation through an equant-induced nonlinear viewing coordinate, inspired by Ptolemy's equant and formalised through an areal-uniformity principle reminiscent of Kepler's second law. Using a machine-learning framework, we demonstrate the existence of such an equant for a broad class of oscillatory dynamics and construct the associated dynamical clock and phase dynamics under additive forces, including noise, periodic perturbations, and coupling. Its value in uncovering new physical rules and phenomena is demonstrated by four findings: (i) collective oscillations in Escherichia coli populations obey a previously unexplained superlinear scaling law, resolving a long-standing open problem posed in 2004; (ii) the response mechanisms of engineered genetic
circuits to changes in gene expression and environmental conditions; (iii) a classical-mechanics counterpart of the Berry
geometric phase emerges naturally from the phase of the dynamical clock; and (iv) optimal equant non-uniformity provides a
geometric early-warning signal for critical transitions and enables prediction of critical parameters. By providing operational and system-agnostic phase dynamics that can be constructed directly from data, the dynamical clock enables principled classification, comparison, and control of oscillatory systems, and offers a new route to understanding how specific dynamical regimes support distinct functional behaviours in networked systems.
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All authors Jingdong Zhang, Luan Yang, Murilo S. Baptista, Zefeng Zhang, Qunxi Zhu, Wei Lin, Celso Grebogi
Astrophysics of Galaxies
A JWST, ALMA and VLA survey of the Ophiuchus-A star-forming region: Unveiling hidden dust mass and connecting infrared outflows to their radio origins
Isaac C. Radley, John D. Ilee, Gemma Busquet et al. (+18 more)
We present an infrared, millimetre, and
radio survey of 20 Class 0-III young
stellar objects in the Ophiuchus A L1688
star-forming cluster, combining high-resolution (7-25 au) VLA and JWST observations with archival ALMA data. We implement physically motivated models to derive
dust and ionised gas properties, spectral behaviour and their relative contributions through the millimetre-centimetre
radio spectral energy distribution. Our models reveal circumstellar
dust disks that are, on average, tens to hundreds of times more massive than millimetre-only estimates (subject to uncertainties arising from the choice of
dust opacity) and contain millimetre-sized grains even at the Class 0 stage. Owing to the VLA's high resolution we are able to connect
outflows to their origins, detecting protostellar jet emission on scales of 10s-1000s au. Our results represent a homogeneous characterisation of the
dust and ionised gas properties in Ophiuchus and present a potential solution to the long-standing 'missing disk mass' problem. However, our understanding is still limited by resolution and sensitivity at frequencies <40 GHz. Future facilities like the SKA and ngVLA are needed to provide the necessary capabilities to fully spatially resolve this emission (<0.18") even in one of the closest
star-forming regions.
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All authors Isaac C. Radley, John D. Ilee, Gemma Busquet, Hauyu Baobab Liu, Klaus M. Pontoppidan, Alvaro Ribas, Marc Audard, Eleonora Bianchi, Tyler L. Bourke, Claudio Codella, Audrey Coutens, Josep M. Girart, Melvin G. Hoare, Izaskun Jiménez-Serra, Doug Johnstone, Laurent Loinard, Olja Panić, Jaime E. Pineda, Linda Podio, John J. Tobin, David J. Wilner
Quantum Physics
Efficient routing and spectrum allocation in arbitrary flex-grid entanglement networks
Zachary Goisman, Matthew L. Stevens, Maxwell Goisman et al. (+7 more)
As practical
quantum networks approach large-scale deployment, the need for efficient user-to-user frequency allocation is increasing, yet current approaches only provide partial solutions to the routing and spectrum allocation problem for an arbitrary
quantum network. We address this challenge for repeater-less flex-grid
quantum networks based on hyperentangled
photons using an efficient three-stage pipeline combining leading tools in classical networking with recent advances in numerical optimization. First, double instantiations of Yen's
algorithm obtain low-loss route candidates between each pair of users and the
entanglement sources. Second, the advanced process optimizer (APOPT) obtains frequency channel allocations that maximize distribution rates under fidelity constraints. Finally, the constraint programming solver using satisfiability methods (CP-SAT) assigns specific frequency bins to each link, ensuring that there is no contention between frequencies from different sources. We numerically demonstrate this approach on a representative ring network and a Manhattan incumbent local exchange carrier
topology, realizing significant improvements over prior genetic
algorithm approaches in speed, accuracy, and scalability. Overall, this pipeline provides an efficient heuristic workflow for optimizing broadband
entanglement distribution, applicable to arbitrarily connected
quantum networks integrated within the existing lightwave infrastructure.
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All authors Zachary Goisman, Matthew L. Stevens, Maxwell Goisman, Taman Truong, Gayane Vardoyan, Don Towsley, Nicholas A. Peters, Nageswara S. V. Rao, Guoliang Xue, Joseph M. Lukens
High Energy Astrophysical Phenomena
Implications of the UV/optical Plateau of AT2018cow
Wenbin Lu and Anthony L. Piro
AT2018cow, the prototypical luminous fast blue optical transient (LFBOT), shows a slowly fading plateau in the UV/optical light lasting at least 5 years after the explosion. The plateau SED is blackbody-like with temperature $\gtrsim$ 2e4 K and an emission radius ~40 Rsun, which has been attributed to a geometrically thin
accretion disk around a compact object. Viscously powered disk models, however, require an unusually massive black hole $\gtrsim$ 200 Msun (for viscosity parameter $\alpha$ > 0.01). Moreover,
accretion onto such a massive black hole produces X-ray emission that is likely in tension with the XMM-Newton constraint, unless the X-ray is highly anisotropic or absorbed. We propose instead that the UV/optical emission arises from the photosphere of a super-Eddington wind launched from the inner disk, together with irradiation and reprocessing by the geometrically thin outer disk. Fitting the model to four-band HST photometry at t ~ 4 yr, we find that all accretors from 1.4 Msun
neutron star to ~100 Msun black hole produce similarly good fits. This degeneracy arises because the wind photospheric color temperature depends only weakly on the accretor mass. We also find that, at NIR-MIR wavelengths (1 to 10 um), wind free-free emission differs by an order of magnitude across the allowed mass range, providing a potential discriminant accessible to JWST. Another potential signature to differentiate the accretor mass and disk composition is the recombination line emission (HeII1640 or H$\alpha$) from the disk wind. The inferred disk parameters from our model are consistent with a micro-
tidal disruption event, either
tidal disruption or merger with a companion
star, in which an initially geometrically thick disk transitions to a thin phase within the first year and subsequently the thin outer disk evolves on the observed ~10 yr viscous timescale.
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Quantum Physics
Generation and detection of squeezed light on a single silicon photonic chip
Oliver M. Green, Bethany Puzio, Rowan A. Hoggarth et al. (+5 more)
The ability to generate and detect
quantum states of light on a single integrated photonic device is essential to scale
quantum photonics into useful
quantum technologies. Integrating the required capabilities into complementary-metal-
oxide-
semiconductor compatible monolithic chips can reduce cost and unlock new functionality through miniaturisation. In this work we demonstrate a single silicon-on-
insulator photonic integrated
circuit for the monolithic generation and detection of
quantum light on a commercially available platform that operates entirely at room temperature. Specifically, we leverage spontaneous four-wave mixing in silicon waveguides to produce squeezed light which is subsequently detected by photodiodes operating in a pulsed homodyne detector configuration on the same chip as the source. We directly measure $0.25(1)$ dB of squeezing, including contributions from waveguide propagation loss and detection inefficiency, and include a detailed analysis of the impact of nonlinear loss on the squeezing levels achievable using this platform.
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All authors Oliver M. Green, Bethany Puzio, Rowan A. Hoggarth, Rachel N. Clark, Edward C. R. Deacon, Alex S. Clark, Jonathan C. F. Matthews, Giacomo Ferranti
Strongly Correlated Electrons
Data-efficient reconstruction of critical quantum dynamics via blind fractional-envelope extrapolation
Hyunju Kim, Hyun-Yong Lee and Heung-Sik Kim
Simulating real-time dynamics of
quantum systems is often limited to short times by
entanglement growth. Finite-pole reconstructions such as linear prediction and related machineries extrapolate such data reliably when the spectrum is a finite set of excitations, but at criticality the low-energy spectrum is a power-law continuum $A(\omega)\sim|\omega|^{\alpha-1}$ – a branch cut whose real-time tail $G(t)\sim t^{-\alpha}$ finitely many poles cannot represent. Here we develop a fractional-calculus-motivated envelope extrapolation for such data. Its structure is motivated by a fractional form of Schwinger–Dyson (fSD) equation, in which the Laplace symbol $s^{\alpha}$ carries the branch cut analytically while the residual self-energy remains meromorphic. On real data we employ the corresponding operational alternative – the exponent $\alpha$ is selected blindly inside the fit window, the signal is detrended by $t^{\alpha}$, the residual is fitted by a stabilized finite-pole model, and the algebraic envelope is restored. On the critical XXZ chain this blind fractional-envelope method (fSD for short) extrapolates short-time data typically several-fold more accurately than finite-pole methods, with the exponent $\alpha$ identified blindly from the fit window alone and bracketing the closed-form Luttinger value at weak coupling. The same blind search finds the $z=2$ dilute-
magnon exponent $\alpha=1/2$ at the $\Delta=1$ saturation transition, and the advantage persists in the gapped free-
magnon phase with its sharp band edges. On noncritical dynamical mean-field spectra, whose low-frequency response is regular, fSD by contrast fails to select any stable fractional envelope and reduces to the standard pole result rather than manufacturing a spurious power law, making it an efficient and accurate route to
quantum critical dynamics when only short simulation times are accessible.
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High Energy Astrophysical Phenomena
Assessing the waveform systematics from parameter estimation to population inference with eccentricity
Muhammad Zeeshan, Richard O'Shaughnessy, Natalie Malagon et al. (+1 more)
While masses and
spins are routinely used to constrain compact binary formation channels, eccentricity provides an additional and potentially powerful diagnostic of binary origin, particularly for dynamically assembled systems. Recent advances in eccentric waveform modeling now make it possible to search for eccentric signatures in gravitational wave data; however, differences between waveform models can introduce systematic effects that may propagate into astrophysical population inference. In this work, we analyze 153 binary black holes, 2 binary
neutron stars and 7
neutron star black hole binaries from the GWTC-4 catalog. We compare the source and population level inferences obtained with two eccentric waveform models, SEOBNRv5EHM and TEOBResumS-DALI, as well as with quasi circular waveform analyses. We find that the two eccentric models give broadly consistent source parameter estimates for most events, but some events exhibit subtle and coherent differences. These small, systematic offsets can accumulate in hierarchical population inference, leading to differences in inferred population properties, most notably in the
redshift evolution and effective
spin distribution. Because coherent event level biases can grow approximately as $\sqrt{N}$ for a catalog of N events, waveform systematics become increasingly important as gravitational wave catalogs expand. We also introduce a synthetic data framework that generates eccentric populations and corresponding RIFT posterior samples, enabling injection studies that test the recoverability of eccentric population properties.
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All authors Muhammad Zeeshan, Richard O'Shaughnessy, Natalie Malagon, Katelyn J. Wagner
Physics Education
Computer-generated QIS tutorial feedback is valued by students, but does not replicate in-class collaboration
Josephine C. Meyer, Steven J. Pollock, Bethany R. Wilcox et al. (+1 more)
PER has consistently demonstrated the effectiveness of small-group tutorials in helping students develop conceptual understanding and fluency, but instructor uptake is limited by resource constraints. To test the effectiveness of out-of-class tutorials using computer-generated feedback as an instructor-friendly alternative, we conducted think-aloud interviews with students in a
quantum computing course who were randomly assigned to either a traditional validated small-group, pencil-and-paper tutorial on tensor products, or a solo computerized adaptation thereof. We found that while the computer-generated feedback was broadly considered useful by students, student engagement patterns were markedly different in the solo setting, with students demonstrating reluctance to use the interface's built-in help features and tending to internalize failure in unproductive ways counter to our intention of a formative learning environment. We discuss implications for curriculum design and directions for future research that may help to answer the longstanding question in PER of why tutorials work so well.
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All authors Josephine C. Meyer, Steven J. Pollock, Bethany R. Wilcox, Gina Passante
High Energy Astrophysical Phenomena
Triple radio flares from tidal disruption events: jet-wind collisions and the discovery of a third radio flare from AT2020vwl
Andrew Mummery, Adelle Goodwin, Colin Christy et al. (+2 more)
Radio flares from
tidal disruption events (TDEs) are observed on two distinct timescales:
prompt (around the time of optical peak) and delayed (hundreds to thousands of days after optical peak). A recent framework put forward to explain this diversity suggests that super-Eddington winds produce
prompt flares while jets launched during a disk state transition at low
accretion rates produce delayed
flares. A unique observational prediction of this framework is that individual sources showing both types of
flares may be expected to show a third
flare. This third
flare will occur when the (faster) jet catches up with the (slower) wind. The observational appearance of the third
flare depends on the system parameters. As the two shock fronts collide the (brighter) jet encounters a change in density, modifying its synchrotron-self-absorption frequency and observed flux. Here we discuss the observational appearance of such a scenario, and then show, in new long-term monitoring
radio observations of the TDE AT2020vwl, the discovery of a third
radio flare. This
flare is coincident with the time at which forward modeling of the first two
flares in a wind-jet framework predicts a collision between the two shock fronts. We make predictions for the long-term
radio evolution of two other TDEs showing double
radio flares: ASASSN-15oi (which may show a weak
flare or flattening of the lightcurve) and AT2024tvd (which is predicted to imminently undergo a third
flare).
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All authors Andrew Mummery, Adelle Goodwin, Colin Christy, Kate Alexander, Noah Franz
Cosmology and Nongalactic Astrophysics
Two-component large-scale radio emission in Abell 2244
M. Cianfaglione, F. De Gasperin, V. Cuciti et al. (+9 more)
Context. In recent years, clusters have been observed that host multi-component
haloes, both in non-merging and merging systems. The existence of these multi-component
haloes suggests that there is no clear distinction between the single components. Aims. Abell 2244 is an intermediate-mass cluster that hosts a double component diffuse
radio emission. The aim of this paper is to carry out a in-depth study of the diffuse
radio emission to constrain its origin and characterize its main
radio properties. Methods. In this work we present LOFAR HBA, MeerKAT UHF, and L-band observations of the cluster Abell 2244. We investigated the nature of the diffuse
radio emission, combining high sensitivity
radio data with XMM-Newton deep X-ray observations. We also used mock LOFAR observations to investigate contamination of the emission from faint
radio sources. Results. We find an integrated spectral index of $\alpha^{1279}_{144} = 0.9 \pm 0.1$ for both components, where only the
radio halo shows spectral steepening at higher frequencies. These values are comparable with the spectral indices observed in disturbed massive clusters. The outer component does not follow the same
radio X-ray correlation as the
radio halo, which suggests a different physical origin. Conclusions. By analysing the physical and morphological properties of the diffuse emission, we find that the characteristics of the outer component of the emission are intermediate between those of
radio haloes and of known megahaloes. Hence, we speculate that the source is either a morphologically disturbed
radio halo, caused by a minor merger interaction, or a megahalo but we cannot reach a final classification. From the mock observations, we find that it is unlikely that the emission is caused by faint sources at low resolutions.
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All authors M. Cianfaglione, F. De Gasperin, V. Cuciti, M. Balboni, R. J. van Weeren, C. Groeneveld, J. M. Boxelaar, M. Della Chiesa, A. Bonafede, G. Di Gennaro, F. Gastaldello, G. Brunetti
High Energy Astrophysical Phenomena
A Multiwavelength Study of a Long-Duration VHE Flare from BL Lacertae with VERITAS
Atreya Acharyya, Avery Archer, Priyadarshini Bangale et al. (+72 more)
We report the first observations of a long-duration very-high-energy (VHE; $E > 100$ GeV)
flare from BL Lacertae (VER J2202+422), taken with the Very Energetic Radiation Imaging
Telescope Array System (VERITAS). On October 15, 2022, the
Fermi-Large Area
Telescope (LAT) detected elevated GeV activity originating from this blazar. This triggered a multiwavelength campaign, which includes observations from VERITAS, Swift, NuSTAR, and select optical and
radio observatories. VERITAS observed the source for a total of $\sim 9.8$ hours between September 1, 2022 and December 1, 2022. An analysis of these data yields a $\sim 28 \sigma$ detection of the source. While previously observed VHE
flares from BL Lacertae have lasted on time-scales of minutes to days, VERITAS continued to detect flaring activity from the source for over a month ($\sim 40$ days) after the original flaring activity was detected with
Fermi-LAT. Broadband spectral modeling shows that a synchrotron self-Compton (SSC) model with an external inverse-Compton (EC) component is preferred over a one-zone SSC model.
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All authors Atreya Acharyya, Avery Archer, Priyadarshini Bangale, Joshua Bartkoske, Wystan Benbow, James Buckley, Yu Chen, Jodi Christiansen, Alisha Chromey, Anne Duerr, Manel Errando, Miguel Escobar Godoy, Juan Escudero Pedrosa, Abe Falcone, Sydney Feldman, Qi Feng, Simon Filbert, Lucy Fortson, Amy Furniss, William Hanlon, Olivier Hervet, Claire Hinrichs, Jamie Holder, Zach Hughes, Thomas Humensky, Weidong Jin, Madalyn Johnson, Philip Kaaret, Mary P. Kertzman, Maria Kherlakian, Tobias Kleiner, Nikolas Korzoun, Sanchari Kundu, Mark Lang, Matthew Lundy, Eileen Meyer, John Millis, Connor Mooney, Patrick Moriarty, Reshmi Mukherjee, Wenmeng Ning, Rene A. Ong, Ashwani Pandey, Martin Pohl, Elisa Pueschel, John Quinn, Pazit Rabinowitz, Kenneth J. Ragan, Paul Reynolds, Deivid Ribeiro, Leandro Rizk, Emmet Thomas Roache, Iftach Sadeh, Alberto Sadun, Lab Saha, Glenn Sembroski, Ruo Shang, Megan Splettstoesser, Donggeun Tak, Anjana Talluri, James Tucci, Janeth Valverde, David Williams, Sam Wong, Margo Aller, Masoud Asadi-Zeydabadi, Ryan Hickox, Svetlana Jorstad, Sebastian Kiehlmann, Piatra Lusen, Allen Marscher, Walter Max-Moerbeck, Philipe De La Parra, Anthony Readhead, Katie Riley
Quantum Physics · Cross-listed from cs.LG
From hyperplanes to hyperellipsoids: a pedagogical bridge from linear classifiers to single-qubit mixed-state classifiers
Kaitlin Gili
Quantum machine learning ideas are typically absent from traditional machine learning curricula and are instead introduced in upper-level courses on
quantum information processing and
quantum computing. We propose a route for bringing
quantum ideas into the standard machine learning classroom directly after the introduction of binary linear classifiers. Specifically, we develop a pedagogical bridge between linear classifiers and single-
qubit mixed-state classifiers by characterizing their
geometric model structure. This characterization reveals that a single-
qubit mixed-state model for binary classification can be viewed as the “ellipsoidal version” of a standard linear classifier: rather than learning a hyperplane that separates data, the model learns a hyperellipsoid.. We present this connection as an accessible bridge from familiar classical machine learning concepts to
quantum machine learning, and encourage instructors to use it as a natural entry point for introducing
quantum ideas in the undergraduate machine learning classroom.
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High Energy Astrophysical Phenomena
Uncovering Hierarchical Sub-Population of Binary Black Holes
Muhammad Zeeshan and Richard O'Shaughnessy
Enabled by improved instruments with increasing sensitivity, the ongoing gravitational wave census now contains 259 binary black holes, numerous enough to unveil trends, substructure, and subpopulations which may provide key clues to their underlying formation mechanisms. In this work, motivated by evidence for multiple formation channels including hierarchical formation, we build a natively multi component mixture model for the binary black hole population, in which each component has an independently recovered rate, mass,
spin, and
spin misalignment model. (The components share a common
redshift distribution.) Using a model carefully tuned to avoid parameter degeneracies, a powerlaw model plus five successively higher mass gaussians, we recover overall merger rates versus mass and trends versus
redshift which are consistent with previously published results. Too, we recover previously identified overall trends versus
spin: preferential
alignment and low
spin at low mass; large
spin and isotropic
spins at high mass. Critically, however, our multi-component model disagrees with previously published results, finding all components except the lowest mass are consistent with isotropy. Too, our multi-component model has a roughly hierarchical spectrum of gaussian mass peaks, but without the expected correlations between
spin and mass expected from naked hierarchical formation
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Quantum Physics
Performance Model for Hybrid Quantum-Classical Workflows
Pooja Rao, Dimitar Trenev, Jerome Gonthier et al. (+13 more)
Hybrid
quantum-classical workflows are expected to underpin practical
quantum computing applications, yet the
quantum and HPC communities lack a shared framework for
reasoning about where and when their integration requirements matter most. Such a framework must separate two distinct levels of analysis: the application level, where communication overhead affects runtime performance, and the real-time level, where it determines feasibility. To address this, we introduce a runtime model that decomposes workflow execution into
quantum compute, classical compute, and communication costs. At the application level, a communication-to-computation ratio from this decomposition quantifies whether a workflow is communication-bound or compute-bound; at the real-time level, a feasibility constraint determines whether timing requirements can be met at all, with the reaction time setting the logical clock speed of fault-tolerant computation once they are. Application of this model to representative workflows demonstrates that co-location of
quantum processors with HPC infrastructure offers negligible performance benefit for compute-intensive applications today, while tight integration remains crucial for real-time tasks such as
quantum error correction needed for large scale
quantum computations. However, we discuss how even at the application level these assessments may shift with hardware
evolution, illustrating how the model can identify specific crossover conditions, and how, under fault tolerance, the reaction time can set application-level performance.
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All authors Pooja Rao, Dimitar Trenev, Jerome Gonthier, Taylor Patti, Sebastian Stern, Tyler Takeshita, Yuri Alexeev, Cedric Lin, Sam McArdle, Justin Lietz, Katherine Klymko, Ermal Rrapaj, Norm Tubman, Krysta Svore, Peter Komar, Elica Kyoseva
Chemical Physics
Electronic Structure Calculations from Occupation Numbers on Quantum Computers
Edison X. Salazar, Juan Felipe Huan Lew-Yee and and Mario Piris
We present a
quantum-classical
algorithm for electronic structure calculations that dramatically reduces the
quantum measurement cost of variational
quantum eigensolver (VQE) approaches. While conventional VQE methods require measurements scaling as O(M^4) with system size M, the proposed occupation-number VQE (ON-VQE) reduces this cost to O(M/2) by avoiding reduced density
matrix (RDM) measurements and relying exclusively on ONs. The method exploits only the diagonal elements of the one-particle RDM in the natural orbital representation, where occupations are obtained directly from computational-basis measurement outcomes. By restricting the variational ansatz to double excitations within orbital subspaces associated with electron pairs, the required measurements can be grouped into a small number of
qubit-wise commuting observables, yielding an efficient and scalable measurement strategy. The approach is validated through simulations and executions on
quantum hardware for the cubic H$_8$ cluster, demonstrating the feasibility of extracting accurate ONs from
quantum measurements and evaluating electronic energies within the natural orbital functional (NOF) framework. Across representative molecular systems, the extracted ONs enable accurate energy evaluation with state-of-the-art NOFs while maintaining a dramatically reduced measurement cost. These results establish a scalable route toward
quantum simulation of strongly correlated electronic systems, demonstrating that accurate electronic energies can be obtained from
quantum measurements of ONs alone.
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Atomic Physics
A termolecular reaction theory for gas-phase nucleation based on long-range intermolecular forces
Yu Wang, Arnab Choudhury, Felix Graber et al. (+2 more)
The birth of a new phase is usually described thermodynamically, but in the gas phase it begins as chemistry. Here, we show that gas-phase nucleation can be described as a termolecular reaction network controlled primarily by long-range intermolecular forces. In single-component mixtures, dimer formation emerges as a direct termolecular process, whereas in binary mixtures a chaperon mechanism can enhance nucleation, with the second component acting as a catalyst for cluster formation. By incorporating cluster evaporation, the same framework can be extended beyond the collision limit, providing a molecular route to nucleation in regimes where larger critical clusters become relevant. We test the theory against unary and binary nucleation of water, toluene, and butane, obtaining agreement in absolute rates within one order of magnitude across the explored temperature and density ranges. These results identify long-range intermolecular forces as molecular drivers of gas-phase nucleation and establish elementary termolecular chemistry as a predictive route to cluster formation.
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All authors Yu Wang, Arnab Choudhury, Felix Graber, Ruth Signorell, Jesús Pérez-Ríos
Materials Science
Ab initio time-dependent GW approach for nonequilibrium exciton-phonon coupled dynamics across momentum space
Zhenfa Zheng, Benran Zhang, Jiawei Ruan et al. (+10 more)
The dynamics of optical excitations in materials generally involves intertwined electron-hole (e-h) and electron-
phonon (e-ph) interactions out of
equilibrium. However, a full theoretical description of such nonequilibrium dynamics requires a systematic treatment of the coherent excitonic excitations and
exciton-
phonon interactions across the entire
crystal momentum space in real time, which remains a major challenge and out of reach for first-principles approaches. Here, we present a new ab initio time-dependent adiabatic GW methodology that incorporates full finite-momentum e-h and e-ph couplings, enabling real-time simulations of the coherently coupled
exciton-
phonon dynamics. The excitonic excitations are naturally described by the equation of motion of the interacting single-particle density
matrix, whereas their couplings to
phonons are formulated within a linear-response framework, hence the simulations can be efficiently carried out within a primitive unit
cell. We demonstrate the capabilities of this new approach by investigating the direct-to-indirect
exciton transitions in monolayer WSe2 in a pump-probe setup of time-resolved and angle-resolved photoemission spectroscopy. Our results reveal that the
phonon-mediated ultrafast intervalley dynamics of
excitons of this system is within ~0.5 ps, manifested as in-gap photoemission intensity transfer from the K-valley to the Q-valley. This work establishes a comprehensive and practical nonequilibrium Green's function framework for accurately simulating nonequilibrium and coherent excitations involving coupled
excitons and
phonons from first principles.
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All authors Zhenfa Zheng, Benran Zhang, Jiawei Ruan, Chih-En Hsu, Zien Zhu, Supavit Pokawanvit, Felipe H. da Jornada, Hung-Chung Hsueh, Ting Cao, Mauro Del Ben, Yang-Hao Chan, Steven G. Louie, Zhenglu Li