Astrophysics of Galaxies
The multiwavelength structure of post-starburst galaxies at 0.5 < z < 3 with JWST PRIMER: compact morphologies and residual disturbances
David T. Maltby, Omar Almaini, Vivienne Wild et al. (+9 more)
We investigate the multi-wavelength structure of recently quenched post-starburst (PSB)
galaxies at 0.5 < z < 3, using photometrically selected samples from the Ultra Deep Survey (UDS). Leveraging deep eight-band JWST/NIRCam imaging from the PRIMER programme, we analyze ~120 PSBs across the rest-frame optical-to-near-infrared, and compare with a reference sample of ~3000 passive and
star-forming
galaxies. Structural parameters (effective radius Re and Sersic index n) are derived independently in each waveband, and reveal that PSBs exhibit minimal structural variation with wavelength, indicating negligible
stellar population age gradients or internal
dust obscuration. We confirm that PSBs follow the established
redshift-mass trends: at z > 1, massive PSBs (M* > 10^10 Msun) are compact spheroids resembling massive passive
galaxies, albeit significantly more compact, whereas at 0.5 < z < 1, PSBs are typically low-mass (M* < 10^10 Msun) compact, disc-dominated systems akin to low-mass passive discs. Furthermore, for the first time, we systematically quantify disturbance indicators (residual flux fraction RFF, asymmetry, residual asymmetry) across a large PSB sample. At all masses, PSBs exhibit low RFF and asymmetry values comparable to passive systems and consistent with smooth, largely undisturbed morphologies. However, at z > 1, massive PSBs (M* > 10^10.25 Msun) show enhanced residual asymmetry relative to the passive population, indicating a previously unrecognized level of structural disturbance masked beneath a smooth
stellar distribution. These results suggest that, while structural transformation is largely complete by the PSB phase, residual disturbances persist at high
redshift, supporting a scenario in which rapid quenching proceeds via two distinct pathways: highly disruptive events (e.g. major mergers) at high z and high mass, and comparatively gentle processes at later times.
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All authors David T. Maltby, Omar Almaini, Vivienne Wild, Elizabeth Taylor, Kate Rowlands, Thomas de Lisle, Guillaume Hewitt, Maya Skarbinski, James S. Dunlop, Adam C. Carnall, Anton M. Koekemoer, Derek J. McLeod
Astrophysics of Galaxies
Little Red Dots at z~2 in EIGER reveal a gentle decline with respect to their peak number density at z~5
Shrriya Kapoor, Jorryt Matthee, Alberto Torralba et al. (+10 more)
We report the discovery of a sample of little red dots (LRDs) at $z \approx 2$ identified from deep JWST/NIRCam imaging and wide-field slitless spectroscopy over $140$ arcmin$^2$ from the EIGER survey. With an improved blind broad-line identification
algorithm, we select 19 sources at spectroscopic
redshifts $z = 1.55-3.18$ identified via rest-frame near-infrared lines (Paschen-$\beta$, HeI+Pa$\gamma$ and OI). Based on a range of spectro-photometric criteria, we classify five of these sources as LRDs and the other 14 as classical active
galactic nuclei (AGNs). This classification is corroborated by some X-ray detections among the AGNs. Classical AGNs dominate the number counts above optical luminosities M$_{5100}<-22.5$, whereas the LRD fraction among broad-line sources reaches 100 % at M$_{5100}\approx-20$. The LRDs span the range in Balmer break strengths seen in the higher
redshift populations. Blue-shifted HeI absorption is detected in the two reddest sources. The HeI/Pa$\gamma$ ratio cleanly separates LRDs from classical AGNs and seems to anti-correlate with Balmer break strength, likely tracing HeI self-absorption at higher gas column densities. Our LRD sample has a similar optical luminosity range as their high-
redshift counterparts, corresponding to black hole masses of $\sim10^{6}$ M$_{\odot}$ at the Eddington luminosity. We measure LRD number densities of $\approx 7\times10^{-6}$ cMpc$^{-3}$ at $z = 1.9-2.5$, which indicates that LRDs represent $\lesssim 3$ % of the AGN population at these epochs. Our results confirm the previously reported decline in the LRD number density with respect to $z \approx 5$ based on photometric surveys, although we find the decline to be more gentle than earlier emphasized.
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All authors Shrriya Kapoor, Jorryt Matthee, Alberto Torralba, Ivan G. Kramarenko, Rongmon Bordoloi, Jenny E. Greene, Edoardo Iani, Daichi Kashino, Zhaoran Liu, Ruari Mackenzie, Sara Mascia, Rohan P. Naidu, Rob Simcoe
High Energy Physics (Theory)
Toward Hamiltonian simulations of Maxwell-Chern-Simons theory: constant modes and gauge field truncation
Andrea Bulgarelli, Maria Cristina Diamantini, Nico Dichter et al. (+6 more)
Maxwell-Chern-Simons (MCS) theory in $2+1$ dimensions provides a paradigmatic example of a topological gauge theory with both dynamical and topological degrees of freedom. Its Euclidean formulation suffers from a sign problem, making
Hamiltonian numerical approaches particularly attractive. As a first step toward the non-perturbative
Hamiltonian study of MCS theory, we investigate the constant mode sector on a spatial
torus. Being analytically solvable in the continuum, it provides an ideal
benchmark for understanding how the topological properties of the theory are encoded in a finite-dimensional
lattice Hilbert space. We construct a finite-dimensional discretization of the
torus of flat connections and show that the resulting
lattice problem maps onto a generalized Harper-Hofstadter model with twisted boundary conditions. We identify the commensurability conditions under which the finite
lattice exactly reproduces the
magnetic translation
algebra and the topological degeneracy of the continuum theory. A systematic analysis of gauge field truncation and its convergence toward the continuum limit is then presented.
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All authors Andrea Bulgarelli, Maria Cristina Diamantini, Nico Dichter, Lena Funcke, Tobias Hartung, Karl Jansen, Enrique Rico Ortega, Simran Singh, Lorenzo Spera
High Energy Astrophysical Phenomena
Decoding the Early-Time Light Curves of Type Ia Supernovae. II. Population Parameters of One Thousand ZTF Supernovae
Chang Liu, Adam A. Miller, Nikhil Sarin et al. (+13 more)
Early-time light curves of Type Ia
Supernovae (SNe Ia) encode critical information about their progenitor systems. We characterize the rise of normal SNe Ia using a volume-complete sample of 972 events from the Zwicky Transient Facility Data Release 2, an order of magnitude larger than any previous
dataset for similar analyses. Fitting light curves up to $30\%$ of peak flux with a power-law model under a hierarchical
Bayesian framework, we provide robust population-level constraints on the rise time ($t_\mathrm{rise}$; $\mu=18.55\pm0.08$ days, $\sigma=1.42\pm0.07$ days), rise index ($\alpha$; $\mu=2.10\pm0.04$, $\sigma=0.48\pm0.03$ in ZTF $r$), and $g-r$ color
evolution ($\alpha_g - \alpha_r$; $\mu=0.20\pm0.02$, $\sigma=0.17\pm0.02$). These power-law fits are sensitive to the chosen truncation epoch if data beyond $\sim$$40\%$ of peak flux are included, but generally converge when restricted to earlier epochs. The relation between rise morphology and light-curve width ($\texttt{SALT2}$ $x_1$ stretch) bifurcates into two distinct regimes: high-stretch SNe Ia show clear trends where a higher $x_1$ correlates with shallower rises and more persistent blue colors, whereas low-stretch SNe Ia lack such trends. While rise times correlate positively with $x_1$ overall, this relation flattens significantly within the high-stretch population. Searching for anomalies, we identify several normal SNe Ia with unusually long rise times, which potentially exhibit short-duration ($\lesssim$2 days) flux excesses over a smooth rise. Long-duration ($\sim$5 days) flux excesses appear common within the high-stretch population and are tied to the shallow rises and early blue colors, pointing to widespread outward $^{56}$Ni mixing. Multi-dimensional explosion models with more realistic progenitor setups are needed to fully reproduce the observed dichotomy in rise morphology and stretch.
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All authors Chang Liu, Adam A. Miller, Nikhil Sarin, Kate Maguire, Tomás E. Müller-Bravo, Ping Chen, L. Galbany, Young-Lo Kim, Jesper Sollerman, Eric C. Bellm, Joahan Castaneda Jaimes, Tracy X. Chen, Matthew J. Graham, David Hale, Mansi M. Kasliwal, Josiah Purdum
Earth and Planetary Astrophysics
White dwarf planets in star clusters: gravitational scattering versus mass-loss effects
Richard J. Parker and Dimitri Veras
White
dwarfs are unique laboratories for understanding the formation,
evolution and survivability of planetary systems. Post-main sequence mass-loss will change planetary orbital properties and stir up debris discs, leading to the observed pollution of white
dwarf atmospheres. However, to date, very few studies have investigated the impact of the
stellar birth environment on white
dwarf planetary systems. In this paper we simulate the
evolution of
giant planets around white
dwarf progenitors from their formation in a
star-forming region until 1Gyr, when the most massive
stars ($>$2M$_\odot$) have left the main sequence. Our simulations self-consistently model $N$-body interactions between
stars and
planets while
stars evolve into white
dwarfs within the cluster lifetime. We find that although scattering interactions in dense
star-forming regions create free-floating
planets, and alter the orbital properties of up to 20 per cent of the surviving
planets, the effects of mass-loss from the
star dominate the dynamics. This behaviour is independent of the
stellar density of the birth
star-forming region, and largely independent of the initial
planet orbital properties. Our simulations produce both captured
planets around white
dwarfs (potentially similar to WD 0806-661b), and triple systems with white
dwarfs and
planets (potentially similar to PSR B1620-26(AB)b), and our results yield a population synthesis of
giant planets from 1 - 100au that may be relevant to Roman,
Gaia and JWST observations.
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High Energy Physics (Theory)
QFT as a set of ODEs: higher dimensions
Fabiana De Cesare and Manuel Loparco
Correlation functions of local operators in
Quantum Field Theory (QFT) in Anti-de Sitter space (AdS) are completely fixed by the QFT data: the set of scaling dimensions $\Delta_i$ and OPE coefficients $C_{ijk}$ of the boundary operators, and the bulk-boundary (BOE) coefficients $b^{\hat\Phi}_i$ encoding how bulk fields decompose into boundary operators. In this work, we generalize the ordinary differential equations (ODEs) that govern the variation of the QFT data under a bulk relevant deformation, originally derived for AdS$_2$ \cite{Loparco:2026fki}, to the cases of AdS$_3$ and AdS$_4$. We demonstrate that these flow equations natively capture the mechanism of merger-annihilation when a boundary operator hits marginality, as well as level repulsion when different $\Delta_i$'s approach each other. Furthermore, we address the practical implementation of the framework: we propose substituting the ODE for the OPE coefficients with the crossing equation for greater efficiency, and we observe that Padé approximants dramatically improve the convergence of the sums over boundary operators, at least in free theories. Altogether, these advances lay the groundwork for the future application of the flow equations to the study of strongly coupled QFTs in AdS and their flat space limits.
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High Energy Physics (Theory)
Exploring Line Bundle Standard Models with Transformers
Jacky H. T. Yip, Alessandro Mininno and Gary Shiu
We propose a
Transformer-based Reinforcement Learning architecture, "LB-Explorer", to search for heterotic line bundle standard models arising from compactifications on smooth Calabi-Yau (CY) threefolds. We focus on $E_8\times E_8$ heterotic string theory compactifications on CY with abelian line bundles to produce $\text{SU}(5)\times \text{S}(\text{U}(1)^5)$
symmetry, whose $\text{SU}(5)$ can be further broken to an MSSM-like gauge group using appropriate discrete Wilson lines. We test the LB-Explorer environment on complete intersection Calabi-Yau (CICY)
manifolds, though the neural network architecture naturally generalizes to any CY admitting a simplicial Mori cone and a freely-acting discrete
symmetry. The LB-Explorer efficiently learns constraints on the line bundle sums, guaranteeing the $E_8$ gauge
embedding, anomaly cancellation, poly-stability (supersymmetry), chirality of the spectrum, and the absence of exotic matter. Valid configurations can be subsequently filtered by imposing the missing constraints, such as the equivariant structure of the line bundle sum and further requirements on the particle spectrum. In this direction, we introduce a hybrid architecture incorporating CP-SAT solvers that aims to impose some of the conditions exactly by perturbing solutions found by the LB-Explorer. The versatility and scalability of the LB-Explorer make it a powerful tool for navigating the string landscape with a large number of
moduli. The code and tools necessary to reproduce our findings are available at https://github.com/alexmininno/LB-Explorer
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Astrophysics of Galaxies
Hot or Cold? Radial Redistribution of Stars in FIRE Simulations of Milky Way-Mass Galaxies and the Asymmetry of Inward versus Outward Migrators
Cecilia Steel, Andrew Wetzel, Rori Kang et al. (+3 more)
Stars can radially redistribute (migrate) within
galactic disks. The degree to which this occurs as dynamically `cold' (preserves orbital eccentricity) or `hot' (increases eccentricity) remains debated. Many models presume that radial redistribution occurs primarily via cold torquing, resulting in changes in angular momentum without dynamical heating. We test the net dynamical heating associated with redistribution over
stellar lifetimes using the FIRE cosmological zoom-in simulations of 12 Milky Way-mass
galaxies. We select
star particles today that underwent significant changes in orbital angular momentum, j_phi, since birth. We investigate net changes in their orbital eccentricity, e, and we quantify the `cold-torqued' fraction of
star particles with |Delta j_phi/j_phi,birth| > 0.2 that preserved eccentricity (|Delta e| < 0.1) since birth. The direction of radial redistribution is most critical: outward-migrating
stars experienced smaller net changes in eccentricity, whereas inward-migrating
stars almost always heat since birth. For
stars born on near-circular orbits (e_birth < 0.2), the cold-torqued fraction decreases rapidly with age today and is generally < 50% at ages >~2 Gyr.
Stars born on moderately eccentric orbits (e_birth ~ 0.4) are the most likely to preserve their birth eccentricity. However, the cold-torqued fraction is higher in earlier-forming and/or dynamically-colder disks. Significantly, we identify a population of
stars that dynamically `cooled', decreasing in eccentricity since birth: this is the primary way that
stars end up on near-circular orbits today. Overall, a
star's migration direction, its e_birth, and its age primarily determine whether it was dynamically heated, cooled, or unchanged. In general, radial redistribution in FIRE is typically not cold between birth and today.
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All authors Cecilia Steel, Andrew Wetzel, Rori Kang, Fiona McCluskey, Sarah Loebman, Kathryne J. Daniel
High Energy Physics (Theory)
Localization, Factorization and Dualities for Elliptic Kernels
Alessio Fontanarossa, Fabrizio Nieri and Antonio Pittelli
We study the exact partition function of 4d $\mathcal N=1$ supersymmetric gauge theories on a
torus times a cylinder $\mathrm{Cyl}=I\times S^1$, where $I$ is a finite interval carrying two boundary components. Each endpoint supports an independent Dirichlet or Robin-like boundary polarization, so that the partition function is a boundary-to-boundary
elliptic kernel. We construct the rigid supersymmetric geometry, determine the BPS locus, and compute the
chiral-multiplet 1-loop determinants for the four possible boundary polarizations via equivariant localization. The resulting elementary building blocks are theta functions dressed by cubic phases. We then prove rank-changing Seiberg-type dualities as identities of Jeffrey–Kirwan residues of these
elliptic kernels. We also discuss factorization into holomorphic-block cap wavefunctions represented by
elliptic Gamma functions, dimensional reductions to three and two dimensions, complete-intersection gauged linear sigma models, and
elliptic kernels for 4d $\mathcal N=4$ super Yang–Mills and the Klebanov–Witten theory, useful for
holographic applications.
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High Energy Astrophysical Phenomena
Decoding the Early-Time Light Curves of Type Ia Supernovae. I. A Hierarchical Bayesian Framework for Demographic Inference
Chang Liu and Adam A. Miller
Light curves of Type Ia
Supernovae (SNe Ia) in the days following explosion encode the diversity of progenitor systems and explosion physics. We present a hierarchical
Bayesian framework to robustly constrain the population-level light-curve morphology of SNe Ia by fitting a large light-curve
dataset simultaneously to power-law rises. Using a multivariate Gaussian population prior, this framework automatically down-weights sparsely sampled SNe and noisy measurements in the inference, obviating the need for restrictive quality cuts that introduce selection biases. Validation on simulated power-law light curves demonstrates that the population prior effectively suppresses the volume-projection bias from the asymmetric likelihood: compared to the classic two-step approach of fitting individual SNe and then aggregating the results, the hierarchical approach dramatically reduces the bias on the population-level parameters (mean, scatter, and correlation). When fitting the power-law model to light curves with more realistic morphologies, while the rise time can be mildly underestimated due to model misspecification, the recovered population scatter remains reliable. Furthermore, SNe with early flux excesses can emerge as outliers in the inferred parameter space, offering a potential diagnostic for identifying such events. Finally, we show that the inferred population distribution can also improve individual-event inference. Restricting the population prior to nuisance amplitudes, while preserving the complete correlation structure, regularizes fits to individual SNe without shrinking the physically meaningful rise time and rise index toward their population means.
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High Energy Physics (Theory)
Holographic Spread Complexity from Branes and Strings
Dimitrios Chatzis, Madison Hammond, Carlos Nunez et al. (+2 more)
We study Krylov spread complexity in
holographic theories using genuine string-theory probes. Building on the proposal that the growth rate of spread complexity is measured by a proper momentum in the bulk, we embed the falling-particle picture in top-down examples. We first analyse a D0 brane in the type IIA AdS$_4\times {\mathbb{CP}}^3$ background dual to ABJM theory, identifying it with a dressed monopole operator in the boundary CFT. For purely radial motion the proper-momentum prescription reproduces the expected quadratic growth of the complexity. When the probe carries momentum along an isometric direction, the naive prescription gives an apparent conflict with the short-time behaviour required of Krylov complexity. We propose that the correct fixed-charge description is obtained by Legendre transforming to the Routhian. We support the D0-brane interpretation through the regulated monopole two-point function, whose survival amplitude determines the Krylov moments, and we show that radial fluctuations give controlled corrections to the effective energy governing the complexity growth. We then extend the analysis to a rotating non-BPS D3 brane in AdS$_5\times S^5$, where angular momentum produces a centrifugal barrier and a sharp condition for radial in-fall. In the falling regime the Routhian prescription again gives the correct short-time behaviour. Finally, we consider a wound fundamental string in AdS$_5\times S^5$, which reduces to an effective massive falling particle. This clarifies the distinction between Noether charges, which require a fixed-charge Routhian treatment, and winding data, which enter through the effective mass. Our results provide a string-theoretic realisation of
holographic spread complexity for point-like and extended excitations, making manifest their dependence on field theory parameters.
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All authors Dimitrios Chatzis, Madison Hammond, Carlos Nunez, Alfonso V. Ramallo, Ricardo T. Santamaria
Cosmology and Nongalactic Astrophysics
Magneto-Thermal Instability in Galaxy Clusters – III. The Limit of Adiabatic Stratification
Lorenzo Maria Perrone and Henrik Latter
In the hot and dilute intracluster medium of
galaxy clusters, large-scale buoyancy instabilities can develop due to the transport of heat along
magnetic field lines. In particular, the peripheries of
galaxy clusters are unstable to the magneto-thermal instability (MTI), which may contribute to the observed levels of
turbulence. Recent theoretical and numerical work has revealed that the stable background
entropy stratification controls the nonlinear saturation of the instability, by setting the strength and the integral scale of the resulting turbulent state. However, observations of the periphery of
galaxy clusters show that the radial
entropy profiles near the virial radii $R_{500}$ may be flatter than predicted by models of smooth gravitational
accretion. This motivates us to investigate the saturation of the MTI in adiabatic (buoyantly neutral) atmospheres, using both phenomenological approaches and Boussinesq numerical simulations, carried out with the pseudospectral code SNOOPY. We find that the adiabatic MTI saturates in a state characterised by the formation of large-scale plumes and their destruction by shear instability, yielding a new scaling law for the saturated turbulent kinetic energy, $\sim$$\chi \omega_T$, as the adiabatic limit is approached, where $\chi$ is the effective thermal diffusivity and $\omega_T$ is the MTI frequency. This predicts that the MTI plumes may achieve near sonic speeds in cluster outskirts, thus providing significant turbulent pressure support, even in the face of suppressed thermal conduction.
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High Energy Physics (Phenomenology)
Precision Solar System Dynamics for Ultralight Dark Matter Search
Jonas Frerick, Hyungjin Kim and Felix Kling
Ultralight dark matter exhibits an order-one density fluctuation at the scale of its wavelength. This density fluctuation exists across the entire dark matter
halo and interacts with
stars and
planets, perturbing their motion via gravitational interactions. We investigate the possibility of using precision
solar system dynamics to search for ultralight dark matter. We examine this possibility with interplanetary
radio range measurements. We show that the precision of current range measurements can probe ultralight dark matter at masses around $10^{-15}\,$eV, had its density in the
solar system been $10^5$ larger than the so-called local dark matter density. This limit complements other constraints, such as the one from analyses of
pulsar timing observations.
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High Energy Physics (Theory)
Towards Equations for String Amplitudes
A.Morozov, K.Pushkin and M.Reva
Generic Feynman integrals are widely studied as solutions of Picard-Fuchs equations on
moduli spaces of their parameters, and this calls for consideration of this phenomenon at a more basic level - of string amplitudes which are integrals over true non-singular module space of Riemann surfaces and their various generalizations. The main puzzle here is that a single string amplitude involves mane different particle diagrams, corresponding to different parts of the same
moduli space, but different particle diagrams are usually believed to satisfy different equations, not unified into a common entity. We begin investigation of this problem, starting from Koba-Nielsen diagrams. While there is nothing interesting at this level for particles, the tree-level open bosonic string amplitudes satisfy non-trivial linear difference equations in kinematic variables. Moreover, the integration-by-parts on
moduli space, standing behind Picard-Fuchs equations for particle loops, for strings are operative already at the tree level. We construct a complete system of such equations for arbitrary n-point tree amplitudes, with the number of independent relations matching the kinematic parameters. In variance with the particle case equations are difference ones rather than differential. The low-energy limit $\alpha \to 0$ smoothly recovers the algebraic QFT structure.
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High Energy Astrophysical Phenomena
An Analytical Toy Equation of State for Neutron Stars Consistent with Current Observations
Tian-Shun Chen, Xiao-Ding Zhou and Kilar Zhang
Fast analytic and semi-analytic studies of
neutron stars often require an equation of state that is convenient to evaluate while producing relativistic
stellar sequences compatible with current multimessenger constraints. We construct such a
benchmark by scanning a smooth double polytropic relation for the energy density as a function of pressure, $\hat\epsilon (\hat p)=a_1\hat p^{\Gamma_1}+a_2\hat p^{\Gamma_2}$. The parameters are selected with filters based on massive
pulsars,
tidal deformability from the binary-
neutron-
star event GW170817, and NICER mass-radius measurements. A single polytropic baseline scan finds no model passing all filters, whereas a double-polytrope scan identifies a viable region. A curve-integral score, evaluated against public NICER and GW170817 posterior data sets, is then used to choose
benchmark equations of state within this region. The selected representatives support $M_{\max}=2.44$–$2.49\,M_\odot$, with $R_{1.4}\simeq 11.3$ km and $\Lambda_{1.4}=485$–$512$, and remain causal on the stable branch. This compact analytic family provides reference cases for relativistic
stellar-structure tests at current observational scales.
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High Energy Physics (Phenomenology)
Simulation of Axion-Induced Electromagnetic Signal Detection Using Plasmonic Metasurfaces and Diamond NV Centers
James L. Webb
The
axion represents a strong candidate for weakly interacting dark matter. To date, high sensitivity lab based experiments and astrophysical observations have ruled out a substantial part of the
axion mass and
photon coupling parameter space. However, a challenge remains in searching for the presence of the
axion in the higher mass range 0.01-1eV corresponding approximately to
axion field oscillation at THz frequencies. This work investigates via numerical simulation the feasibility of a high sensitivity, lab-based
axion sensor operating in this range, based on plasmonic electric field enhancement by a nanostructured metasurface, combined with heterodyne detection and
quantum sensing via nitrogen-vacancy (NV) centers in diamond. Estimates of the sensor response to anomalous electromagnetic fields resulting from
axion coupling are given using Ti/Au nanopillars on LiNb at
axion mass corresponding to telecommunications wavelength ($\approx$0.8eV, 196 THz). Finally, the possibility of sensing in the lower
axion mass $<$10$^{-2}$ to 10$^{-1}$eV range is explored using alternative materials, with CdTe as an example.
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Quantum Physics
Spectral Geometry and Bosonic-Bloch Probes: Explorations in Quantum Learning
Santanu Ganguly, Xing Liang and Dimitrios Makris
This paper studies how spectral geometry emerges in
quantum learning models and how it can be diagnosed with physically grounded probes. In graph-regularized
quantum networks, training reorganizes the output similarity graph, increases the effective spectral dimension Delta S = +0.23, and reshapes the
Laplacian spectrum. Edge-resolved two-
boson interference directly probes this restructuring: the bosonic enhancement Delta P_uv correlates with the Fiedler edge split |Delta v_2| (r = -0.50), linking learned spectral partitions to interference signatures. A phase diagram shows a nonmonotonic dependence of performance on coupling strength gamma and noise delta, with graph regularization improving fidelity only in a restricted regime; hardware experiments confirm the predicted interference behavior within shot-noise uncertainty. We also analyze a hybrid
quantum autoencoder and introduce Bloch-space drift as a
geometric diagnostic of its latent representation. With an unsupervised benign-data threshold, the model achieves high ranking performance (ROC-AUC about 0.99) and negligible false-negative rates. Absolute Bloch drift strongly discriminates anomalies (ROC-AUC at least about 0.9), while consecutive drift is near random (ROC-AUC about 0.5), showing that detection arises from persistent state-space displacement rather than local fluctuations. Through the geometry of reduced single-
qubit states and associated
quantum Fisher information, these results show that learning-induced spectral organization appears as measurable
quantum-state structure, establishing a unified spectral-
geometric framework for diagnosing
quantum learning systems with bosonic and Bloch probes.
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Quantum Physics
Comment on "Ideal clocks – a convenient fiction" by K. Lorek et al
Vladimir Toussaint
We correct a subtle oversight in Eq.(19) of K. Lorek et al. [Class.
Quantum Grav. 32 175003 (2015)] concerning the decay probability of a uniformly accelerated
quantum clock. The original expression included unphysical cross-wedge term ($|\bar{\gamma}_{K 1}|^2$) violating the spatial separation of Rindler wedges. We derive the corrected probability using the paper's Rindler conformal coordinates $(\tau, \xi)$, retaining only causally consistent thermal terms, and discuss implications for relativistic clock models.
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Nuclear Theory
Finite-range EFT for the $E1$ strength distribution of ${}^6$He
Matthias Göbel, Hans-Werner Hammer and Daniel R. Phillips
Halo effective field theory (
Halo EFT) is a powerful tool to describe
halo nuclei and predict low-energy observables with quantified uncertainties. However, in the case that there is a leading-order interaction determined by two or more effective-range parameters, such as the $^2P_{3/2}$ $n\alpha$ interaction in $^6$He, the standard implementation in the dimer formalism leads to an energy-dependent interaction. This complicates the construction of a
Hilbert space of states, especially beyond the two-body problem. As an alternative, we propose the use of a finite-range formulation of
Halo EFT, which avoids these complications. For definiteness, we use separable interactions with Yamaguchi-like form factors, but other choices are possible. We solve for the ${}^6$He bound state in this finite-range EFT up to next-to-leading order (NLO) in the
Halo EFT power counting and calculate the ground-state $E1$ strength distribution of $^6$He at this order. The shape of the resulting distribution agrees with that obtained in the dimer formalism of the EFT, but finite-range EFT does not require the use of a non-standard wave function normalization condition. We also calculate the root-mean-square charge radius of $^6$He and find $2.06 \pm 0.35$~fm at LO and $2.00 \pm 0.09$~fm at NLO, in agreement with experimental data. To calculate the full $E1$ strength distribution final-state interactions must be incorporated. We approximate the full-three-body scattering operator first by single Møller operators and then by products of up to three Møller operators. The resulting NLO $E1$ strength distribution agrees with the experimental data within theory uncertainties.
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Statistical Mechanics
Exactly solvable non-unitary conformal interfaces in unitary CFTs
Qicheng Tang, Zixia Wei and Xueda Wen
We construct directly on the
lattice a class of non-
unitary interfaces that are both exactly conformal and exactly solvable, and establish their corresponding boundary and interface conformal field theory (CFT) descriptions. The construction is obtained by analytically continuing the scattering data of known exact
unitary conformal interfaces on the
lattice, yielding an $SL(2,\mathbb C)$-parametrized family, which is non-compact and breaks probability-current conservation. Exploiting the exact
lattice-continuum correspondence, we derive the conformal boundary states in the folded picture. We show that a proper definition of the
Hilbert space in the closed-string channel requires the incoming and outgoing boundary states to be specified independently by boundary data associated with a pair of dual biorthogonal bases, in close analogy with the right and left eigenvectors of a non-Hermitian
Hamiltonian. This requirement determines a consistent CFT construction of non-
unitary boundaries and interfaces, and leads to a non-
unitary generalization of the conventional Cardy's condition for
unitary boundary CFT. Beyond their formal construction, these non-
unitary interfaces are shown to exhibit logarithmic
entanglement scaling governed by an effective central charge that is generally complex. For the $SU(1,1)$ subclass, the effective central charge remains real but grows without bound as the transmission coefficient increases. This result is demonstrated through analytical and numerical
lattice calculations, as well as an interface CFT analysis in the unfolded picture. Finally, we present a general CFT analysis of a class of global
quantum quenches whose initial states are prepared with non-
unitary boundaries. We relate their effective temperature to the conformal dimension of the boundary-condition-changing operators associated with non-
unitary boundary conditions.
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Quantum Physics
Simulation of Two-qubit Gate Variability and Fidelity of Spin Qubits Built on Nanosheet Technology
Trung Nguyen, Sarah Dweik and Hiu Yung Wong
Silicon
spin qubits are promising for large-scale
quantum-computer integration because they can fully leverage the well-developed
semiconductor infrastructure. However, the low fidelity of two-
qubit entanglement gates remains a key barrier to large-scale integrations. Recent simulations of silicon
spin-
qubit two-
qubit gates have been performed on silicon-on-
insulator (SOI) platforms, while nanosheet-based charge-
qubit work has been limited to single-
qubit operation using a two-dimensional Schrödinger approximation. In this work, we study silicon
spin-
qubit double
quantum dots built on nanosheet technology using the
Quantum Technology Computer-Aided Design (QTCAD) simulation suite to run three-dimensional Poisson and Schroedinger solvers, followed by a many-body solver to extract exchange interactions. We evaluate the exchange energy sensitivity to process and bias variations and then use QuTiP to solve the master equation for a two-
qubit gate. The results show that millivolt-level bias variations at the plunger and middle barrier gates can reduce the gate fidelity below 99%, a common threshold target for many fault-tolerant
quantum-computing
algorithms. Gate-referred 1/f charge-noise effects are also analyzed through the resulting coherence time.
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Fluid Dynamics
Flexibility as a Universal Nature-Inspired Mechanism for Thrust Enhancement
Roberta Santoriello, Francesco Viola and Vincenzo Citro
Nature has equipped jet-propelled swimmers with flexible nozzles that outperform rigid ones, yet the origin of this advantage has remained unexplained. By tracking where and when energy is exchanged between fluid and structure, three-dimensional numerical simulations resolve the underlying mechanism: a standing-wave response of the nozzle, in which the structure dilates and then
recoils synchronously, charging and releasing energy to enhance thrust. Outside of this regime, the structure exhibits a traveling wave response, with expansion and contraction coexisting along the nozzle, reducing the thrust gain. We propose a physics-based model that captures the boundary between standing and traveling responses in a closed form, showing that the optimum occurs when the natural period of the structure matches the pulse duration. Beyond this optimum the strain imposed by the nozzle
curvature required for steering selects the geometry observed across marine species. The propulsion and maneuverability are reconciled within a single framework that yields design principles for soft robotic propulsors.
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Atomic Physics
Cesium Based Laser-Atomic Oscillator
Saurabh Pandey, Roger Ding, George Burns et al. (+1 more)
We report the first demonstration of a
laser-atomic oscillator with cesium (Cs) atoms. A
laser-atomic oscillator (LAO) is analogous to an active mode-locked
laser with a self-excited modulator, i.e. atoms, at a ground-state hyperfine transition frequency. Therefore, a LAO can be configured as the simplest active atomic clock or a self-oscillating, earth-field atomic magnetometer that delivers oscillation signals both optically and electrically. With the current experimental Cs-LAO setup, when it is configured as an atomic clock using the 0–0 hyperfine transition, the short-term fractional frequency instability is around 10$^{-10}$ level. When it is configured as a self-oscillating magnetometer using a magnetically-sensitive hyperfine transition, the
magnetic field sensitivity is around 100 fT/$\sqrt{\rm{Hz}}$ at 60 Hz. The presented Cs-LAO uses a cavity length from $\sim6.5$ cm to $\sim11.4$ cm. Ultimately, the minimal length of a Cs-LAO device can be $\leq1.63$ cm. Our new efforts unlock the potential of building truly chip-scale atomic clocks and magnetometers.
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All authors Saurabh Pandey, Roger Ding, George Burns, Yuan-Yu Jau
Quantum Physics
Efficient entanglement of three remote single-atom quantum-network nodes
Matthias Seubert, Leonardo Ruscio, Tobias Frank et al. (+6 more)
Entanglement distributed over a set of individually addressable
qubit nodes is the enabling resource for a plethora of applications ranging from tests of
quantum physics to secure and modular
quantum information networks.
Entanglement between two
memory qubits has been realized on various platforms, but extension to more nodes remains rare and formidably challenging. The principal bottleneck is the efficiency of the light-matter interfaces connecting the
qubit nodes to their communication channels. Here, we efficiently generate, distribute and store a three-
qubit entangled state across three independent laboratories containing single atoms coupled to optical resonators. We sequentially entangle the atoms pairwise, two by heralded photonic
entanglement swapping and two by heralded state transfer. We reach a three-
qubit entanglement fidelity of 77(1)% and an
entanglement lifetime above 200us. The observed
qubit correlations violate Mermin's inequality while closing the detection loophole. Our three-
qubit entanglement-generation efficiency is 0.16%. This unprecedented efficiency of our scheme establishes a clear route towards multi-node
quantum networks.
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All authors Matthias Seubert, Leonardo Ruscio, Tobias Frank, Philip Thomas, Maya Büki, Gianvito Chiarella, Pau Farrera, Olivier Morin, Gerhard Rempe
Quantum Physics
Spatially Coupled MacKay-Neal/Hsu-Anastasopoulos CSS Codes Achieve the Quantum-Erasure Hashing Bound by Seeded BP Decoding
Kenta Kasai
We study hard-erasure belief-propagation (BP), understood as the sum-product
algorithm on erasure messages, for a punctured MacKay-Neal/Hsu-Anastasopoulos (MN/HA) representation of Calderbank-Shor-Steane (CSS) codes. For every integer degree triple $2\leq j_Z<j_X<k\leq60$, we prove that the constituent potential thresholds are $j_Z/k$ and $1-j_X/k$. The proof combines classical HA-MN duality with a completed exact rational certificate for all 1711 MN degree pairs in this range. The certificate establishes strict positivity on every physical nontrivial fixed-point branch, at every erasure probability in $[0,1]$, and has an independent integer-arithmetic verifier. A reduction of the Z-side recursion and a fixed-channel vector-potential argument then prove seeded density-
evolution convergence below the smaller constituent threshold for sufficiently large coupling width and an ideal seed interval at least that wide. Under $j_Z+j_X=k$, this threshold equals the
quantum-erasure hashing-bound parameter determined by the CSS design rate. In particular, the degree triple $(4,8,12)$ has potential threshold $1/3$ without a positivity hypothesis. The numerical example at erasure probability $0.3325$ reproduces the resulting decoding waves. The
theorem uses an ideal auxiliary-message seed; its finite-code realization and logical block-error convergence are separate questions.
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General Relativity and Quantum Cosmology
Electromagnetic radiation from a point-like charge in a weak gravitational wave: a Shapiro-delay-motivated approach
Vladimir Epp, Konstantin Osetrin and Taya But
We investigate the field of a point-like electric charge freely falling in a gravitational wave. In the presence of a gravitational wave, the initially static Coulomb field of the charge becomes time-dependent and generates corresponding radiation. The gravitational wave is treated as a weak perturbation of the Minkowski metric. The electromagnetic four-potential of the charge is sought as a solution to Maxwell's equations in the gravitational wave metric, to first order in perturbation theory. The potentials of the point charge are found in quadratures throughout the space. To regularize the potentials, an approach motivated by the Shapiro effect for the time delay of radiation in a gravitational field is used. The potentials of the charge in the far zone are calculated explicitly for a monochromatic, arbitrarily polarized gravitational wave. The angular distribution of the electromagnetic radiation induced by the gravitational wave is obtained.
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High Energy Astrophysical Phenomena
Radiation-pressure instability is an artifact of constant-$\alpha$ closure. Implications for AGN disk tensions
M. H. Naddaf, M. Ghasemnezhad, H. Ghanbarnejad et al. (+2 more)
The standard $\alpha$-disk formalism parametrizes turbulent angular momentum transport through a dimensionless coefficient $\alpha$, assumed to be spatially and thermodynamically invariant. While analytically convenient, this assumption leads to the well-known thermal and viscous instabilities in radiation-pressure dominated (RPD) regions. We show that this instability is not the consequence of radiation pressure, but is due to enforcing a constant $\alpha$ across distinct thermodynamic regimes. Requiring the steady thin-disk (TD) to remain thermally stable and single-valued in the $\dot{M}$–$\Sigma$ plane yields a necessary condition on the stress response, expressed as $\eta_{\rm x} \equiv d\ln\alpha_{\rm x}\,/\,d\ln X > 4/7$, where $X \equiv P_{\rm gas}/P_{\rm rad}$. The resulting viscosity law $\alpha_{\rm x} \equiv \alpha(X)$ emerges directly from the internal consistency of TD equations, without modifying the stress law or invoking any additional physics. $\alpha_{\rm x}$ removes the RPD unstable branch. The disk structure becomes smooth and globally single-valued, with higher $\Sigma$ and $\tau$ in the inner RPD disk, while preserving the standard effective-temperature profile. This increases thermal and inflow timescales, offering a natural route to
accretion-state dependent variability without large-amplitude radiation-pressure limit cycles. It also motivates revisiting AGN disk tensions, including microlensing sizes and continuum reverberation lags with improved radiative-transfer modeling. The results show that the RPD instability, and possibly some associated AGN disk tensions, reflect an inconsistent viscosity closure.
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All authors M. H. Naddaf, M. Ghasemnezhad, H. Ghanbarnejad, D. Hutsemékers, B. Czerny
Statistical Mechanics
Multifractal Scaling in Hi-C Maps
Seong-Gyu Yang, Lucas Hedström, Jan Smrek et al. (+1 more)
The three-dimensional organization of the genome exhibits rich, scale-dependent structure, as revealed by both chromosome contact maps (e.g., Hi-C maps) and chromatin density measured by microscopy. Recent studies have reported multifractal scaling in these data. Yet, the origin of this scaling behavior remains unclear: existing efforts describe it through postulated models. Here, we show that the multifractal structure of Hi-C maps is a direct consequence of the power-law contact probability $P(s)$, which is itself an empirical observable measured from Hi-C maps. Starting from $P(s)$ with a single exponent $\gamma$, we analytically derive the mass exponent $\tau(q)$, which characterizes how the $q$-th moment of contact density scales with box size $l$ used to coarse-grain the genomic coordinate. This multifractal behavior reflects the
geometric competition between intra- and inter-segment contacts. We find that the slope of $\tau(q)$ at large $q$ is given by $2 -\gamma$ when $\gamma <1$, and by $1$ when $\gamma \geq 1$. We further show that this behavior is robust to noise and consistent across diverse organisms, indicating that it is a universal feature of chromatin organization. We extend our analysis into double-exponent $P(s)$, and show the $l$ dependence in multifractal behavior. Taken together, these results provide a physical explanation for multifractal scaling and establish a direct link between the multifractality in Hi-C maps and
polymer contact statistics, with the large-$q$ slope of $\tau(q)$ mapping onto a known
polymer contact exponent.
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All authors Seong-Gyu Yang, Lucas Hedström, Jan Smrek, Ludvig Lizana
High Energy Physics (Phenomenology)
Quantum Information as a New Lens for Precision Neutrino Physics
Khushboo Dixit, Ritam Kundu, Papia Panda et al. (+2 more)
We present a
quantum-information-theoretic study of three-
flavor neutrino oscillations in long-baseline experiments by mapping
flavor states to
qubit-like representations and quantifying
quantum correlations through total concurrence. The local minima of this
entanglement measure identify energy regions where the
flavor state is closest to separability, enabling cleaner extraction of oscillation parameters. We explain how these local minima offer opportunities for precision measurements and provide insight into the accurate determination of
neutrino oscillation parameters. We then propose a strategy to improve parameter extraction by aligning the
benchmark oscillation regions of NO$\nu$A and T2K with the minimum
entanglement achievable in each experiment. This shifts the concurrence minima toward higher-event-count energy regions, leading to tighter constraints and reducing the tension arising from their different energy regimes. For normal ordering, we obtain $(0.581^{+0.0136}_{-0.0150},195^{+38}_{-32}\,^\circ)$ in the $(\sin^2\theta_{23},\delta_{\rm CP})$ plane and $(0.580^{+0.0140}_{-0.0153},2.515^{+0.0344}_{-0.0344}\times10^{-3}\,\mathrm{eV}^2)$ in the $(\sin^2\theta_{23},\Delta m^2_{31})$ plane, yielding improved joint constraints. Using GLoBES simulations together with real data, we assess how local minima of
quantum correlations influence leptonic CP-violation sensitivity, $\theta_{23}$ octant-degeneracy resolution, and mass-ordering determination. Our results show that minimizing
entanglement can significantly affect these key sensitivities, highlighting
quantum information measures as complementary probes of
neutrino flavor oscillations and offering new insight into the role of
quantum correlations in precision
neutrino physics.
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All authors Khushboo Dixit, Ritam Kundu, Papia Panda, Soebur Razzaque, Ramita Sarkar
Instrumentation and Methods for Astrophysics
The filter exchange system of the LSSTCam at the Vera C. Rubin Observatory
Alexandre Boucaud, Pierre Antilogus, Éric Aubourg et al. (+26 more)
The Filter Exchange System of the LSSTCam at the Vera C. Rubin Observatory is a critical subsystem enabling the Legacy Survey of Space and Time (LSST) by performing rapid, repeatable exchanges among five large-format filters within a highly constrained in-camera volume. Since the start of on-sky operations in April 2025, the FES has routinely performed up to 40 filter exchanges per night, completing each change in under 90 seconds with a positioning repeatability of 100 micrometers in the focal plane. Safety and reliability are ensured through a dedicated software architecture. Drawing on over a year of operational experience, we report on the in-situ performance of this sophisticated system within the observatory environment, characterize the key performance metrics, and discuss how specific design choices have influenced system behavior and reliability in practice.
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All authors Alexandre Boucaud, Pierre Antilogus, Éric Aubourg, Antoine Bernard, Johan Bregeon, Patrick Breugnon, Julien Cordian, Hervé Croizet, Guillaume Daubard, Kevin Fanning, Fabrice Gallo, Anthony S. Johnson, Claire Juramy-Gilles, Pierre Karst, Mile Kusulja, Eric Lagorio, Travis Lange, Didier Laporte, Juan-Carlos Lazarte, Margaux Lopez, Aurélien Marini, Stuart Marshall, Dmitry Onoprienko, Hannah M. M. Pollek, Max Turri, Yousuke Utsumi, Francis Vezzu, Françoise Virieux, Téo Weicherding