Cosmology and Nongalactic Astrophysics
Intrinsic Tidal Shear at the Largest Scales: Galaxy Multiplet Alignment in DESI DR2
C. Lamman, J. Aguilar, S. Ahlen et al. (+45 more)
We measure the intrinsic
alignment (IA) of
galaxy multiplets with the large-scale
tidal field traced by
galaxy positions in DESI Data Release 2. Using the BGS, LRG, and ELG samples spanning $0.01 < z < 1.6$, we optimize the scales which define multiplets in each sample to minimize measurement noise. We measure multiplet
tidal alignment $\mathcal{E}_+$ on scales beyond 100 $h^{-1}$Mpc in all samples, and detect
alignment over 200 $h^{-1}$Mpc, up to 4.5$\sigma$ in the highest LRG
redshift bin. We additionally present the multiplet shape-shape autocorrelation, $\mathcal{E}_{++}$, which is independent of
galaxy bias and provides a consistency check of our NLA (nonlinear
alignment) model. We do not detect a
baryon acoustic feature in the projected
estimator. We also find the
alignment strength of multiplets is correlated with
redshift and
galaxy morphology. Multiplet
alignment offers direct access to the
tidal shear field in all
galaxy samples, even where individual
galaxy alignment cannot, and extends IA detection to the largest scales yet probed.
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All authors C. Lamman, J. Aguilar, S. Ahlen, A. Aviles, D. Bianchi, D. Brooks, A. Carnero Rosell, F. J. Castander, T. Claybaugh, A. de la Macorra, D. Eisenstein, A. Font-Ribera, J. E. Forero-Romero, C. Garcia-Quintero, E. Gaztañaga, G. Gutierrez, K. Honscheid, M. Ishak, S. Juneau, T. Karim, D. Kirkby, O. Lahav, M. Landriau, M. E. Levi, M. Manera, A. Meisner, R. Miquel, S. Nadathur, H. E. Noriega, N. Palanque-Delabrouille, W. J. Percival, M. Perdomo, F. Prada, I. Pérez-Ràfols, C. Ravoux, A. J. Ross, G. Rossi, R. Ruggeri, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, M. Schubnell, J. Silber, M. Siudek, G. Tarlé, R. Vaisakh, B. A. Weaver
Instrumentation and Detectors
A Deep Neural Network based Level-1 Trigger for the Magnetic Monopole Search in the SCEP Experiment
Changqing Ye, Yunhan Wang, Yifan Qiao et al. (+4 more)
The Search for
Cosmic Exotic Particles (SCEP) experiment proposes a multilayer
magnetic monopole (MM) detection array with a target exposure of O(10^4) m^2 year. Continuously recording the raw waveforms at this scale would generate approximately O(10) EB of data per year, making full waveform storage impractical. A Level-1 trigger is therefore required to reduce the stored-data volume while retaining rare MM signals. MM waveforms vary with particle velocity and trajectory, so a single filter kernel cannot match all possible signals. A mismatch between the kernel and the signal waveform can reduce the detection probability. This work therefore develops a compact template-bank construction method for MM detection. Each incoming waveform is filtered with all kernels in the bank, and the best-matched kernel is identified from their responses. A multilayer perceptron (MLP) trigger is further developed to combine all template responses and improve signal detection. With a 31-sample window and a stored-data fraction of 10^(-3), the MLP increases the mean net acceptance P_net from 6.72% for the conventional template-bank trigger to 8.79%, a relative improvement of 30.8%. The network is then implemented on a Xilinx AC701 board equipped with a field-programmable gate array (FPGA) to process a 20-bit input waveform sampled at 1 MHz using 200 MHz trigger logic. At the target stored-data fraction, the fixed-point implementation reduces P_net by only 3/(3.2 x 10^6) relative to the floating-point reference. On-board tests reproduce the bit-accurate reference trigger outputs and sustain continuous 1 MHz processing without dropped input samples, verifying the functional correctness and real-time operation of the FPGA-based Level-1 trigger.
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All authors Changqing Ye, Yunhan Wang, Yifan Qiao, Zhe Cao, Beige Liu, Qing Lin, Lei Zhao
Solar and Stellar Astrophysics
SN 2026dix: a nearby, transitional Type IIb/Ib supernova consistent with a warm supergiant progenitor
Tamás Szalai, Schuyler D. Van Dyk, Dominik Bánhidi et al. (+20 more)
Understanding the final
evolution stages of (very) massive
stars and their explosive outcomes, stripped-envelope
supernovae (SESNe), represent a long-term challenge for astrophysics. The latest results support a continuous distribution within the traditional SESN subclasses (IIb, Ib, Ic). The nearby ($D \approx 17.5$ Mpc) SN 2026dix seems to be another member of the recently identified group of transitional Type IIb/Ib explosions. A point source is located at the SN position within the uncertainties on multiple pre-explosion HST images. Together with post-explosion photometry and spectroscopy, it provides a good opportunity to study a rare type of SN in detail. We carried out a thorough comparative light-curve (LC) and spectral analysis of SN 2026dix. We also constructed its bolometric LC and modeled it semi-analytically. In addition, we constructed the spectral energy distribution of the presumed progenitor and compared this to model
stellar atmospheres and binary
stellar evolution tracks. We infer that SN 2026dix arose from an explosion in an interacting binary system, consistent with the properties of a warm ($T_\textrm{eff} \approx 6750-$7750 K; spectral type F2 to A7), luminous ($\log(L_{\rm bol}/L_{\odot})\approx 4.9-5.3$) supergiant primary and a less luminous, less massive hot
dwarf companion. The nature of the identified progenitor closely resembles that of some other known cases of SNe IIb and also well aligns with both the results of our semi-analytical LC modeling and the comparison of the LCs and spectra of SN 2026dix with the output of radiative-transfer models of an exploding
star with $M_\textrm{ini}$ = 18 $M_{\odot}$.
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All authors Tamás Szalai, Schuyler D. Van Dyk, Dominik Bánhidi, Andrea P. Nagy, Réka Könyves-Tóth, Alexei V. Filippenko, Thomas G. Brink, WeiKang Zheng, Imre Barna Bíró, István Csányi, Zsófia Bora, Zsóka Horváth, Ágoston Horti-Dávid, András. P. Joó, Dávid Koller, Levente Kriskovics, Klára Lelkes, Katalin Nagy, Krisztián Sárneczky, Ádám Sódor, Róbert Szakáts, András Pál, József Vinkó
Superconductivity
Failure of Conventional Roughness Metrics in Assessing Field-Limiting Mesoscopic Topography in SRF Nb Films on Cu
Eric M. Lechner, Brandi Redman, Theodore S. Cahall et al. (+1 more)
A characteristic corrugated surface morphology of Nb films on Cu is identified, with mesoscopic features comparable to the London penetration depth and coherence length, and its impact on superconducting
radio frequency cavity performance metrics is examined.
Magnetic field enhancement factors and superheating field suppression factors are calculated within the London model for a representative corrugated geometry. These results demonstrate that roughness trends derived from buffered chemical polished and electropolished Nb cavities do not capture the impact of nanoscale surface morphology on SRF Nb thin film performance, as even surfaces that possess low average roughness can contain
geometric features that generate substantial local field enhancement and significantly suppress the Bean Livingston barrier. The influence of surface roughness on
impurity diffusion is also investigated, which highlights the roles of increased surface area and local
geometric confinement in modifying near surface
impurity distributions. Tracking the effect of
impurity diffusion on the
evolution of
magnetic field enhancement, we show that geometrically confined
impurity distributions can mitigate nanoscale
magnetic field enhancement substantially.
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All authors Eric M. Lechner, Brandi Redman, Theodore S. Cahall, Anne-Marie Valente-Feliciano
Statistical Mechanics
Non-negative differential mobility of one-dimensional underdamped Langevin dynamics: Proof via mapping to a marginally stable oscillator
Udo Seifert
For an underdamped particle driven by a constant non-conservative force across a periodic potential in one spatial dimension at finite temperature, numerical studies have shown that the differential mobility is non-negative. Here, an analytical proof will be given that is based on expressing the differential mobility by the long-time mean position of a marginally stable harmonic oscillator subject to noise in its stiffness.
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Optics
Performance of Capacitively Loaded RF Electrodes on SiO2/Si Substrates for High-Speed Electro-Optic Modulators
Ayed Sayem, Ting-Chen Hu, Mark Cappuzzo et al. (+3 more)
We experimentally investigate conventional and capacitively loaded traveling-wave RF electrodes fabricated on thermally grown SiO$_2$ on high-resistivity silicon substrates for high-speed electro-optic modulators. The capacitively loaded electrodes exhibit RF attenuation coefficients as low as approximately $0.23~\mathrm{dB/cm}/\sqrt{\mathrm{GHz}}$, comparable to values reported for electrodes fabricated on insulating quartz substrates, while retaining the silicon handle and avoiding substrate removal or undercut processing. By varying the SiO$_2$ buried-
oxide (BOX) thickness and the capacitive-loading geometry, the microwave effective index can be engineered over a broad range while maintaining low RF propagation loss. This enables microwave-optical velocity matching over a wide range of optical wavelengths, from the ultraviolet to the telecom C-band. These results demonstrate that thermally oxidized silicon provides a simple and scalable substrate platform for low-loss traveling-wave electrodes in thin-film lithium niobate and thin-film lithium tantalate electro-optic modulators, as well as for high-speed RF interconnects in integrated transceivers and co-packaged optical systems.
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All authors Ayed Sayem, Ting-Chen Hu, Mark Cappuzzo, Alaric Tate, Rose Kopf, Mark Earnshaw
Superconductivity
Topological properties and gap structure of the paired state in twisted TMD bilayers within a two-band effective model
Palash Saha and Michał Zegrodnik
We present a theoretical study motivated by the recent experimental results which demonstrate superconductivity emerging from flat topological bands of twisted transition metal dichalcogenide (TMD)
bilayers. To capture the non-trivial band
topology of the system, we employ an effective two-band Kane-Mele-like model and substitute it with Coulomb repulsion and inter-site pairing interactions treated at the Hartree-Fock mean-field level. Assuming a real-space pairing scenario, we analyze the resulting superconducting gap
symmetry and the stability of the paired state as a function of band filling and applied displacement field. Finally, we highlight the interplay between superconductivity and non-trivial
topology, detailing how interaction-induced effects and the
evolution of the density of states shape the resulting superconducting phase diagram.
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Materials Science
Multivalley 3D Electronic Structure of PbSe from Soft-X-Ray ARPES and First-Principles Calculations
Zefeng Cai, Valentine V. Volobuev, Jędrzej Korczak et al. (+7 more)
PbSe is a narrow-gap IV-VI
semiconductor, whose multivalley valence bands, with maxima at the L, $\Sigma$, and $\Delta$ points, underpin its intermediate-temperature thermoelectric properties. We combine soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES) with first principles simulations to study the valence band structure of bulk PbSe. High resolution measurements are conducted at
photon energies of 400-900 eV to map the valence
manifold along X$\Gamma$X, WXW, and K$\Gamma$K, and iso-energy surfaces are collected in the $k_z=0$ plane. Comparison to ARPES enables a rigorous assessment of the performance of density functional theory (DFT), using semi-local and hybrid functionals, as well as many-body perturbation theory within the quasiparticle self-consistent $GW$ approximation. We find that the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional and QP$GW$ reproduce the measured band dispersions to within 0.1-0.2 eV over the entire valence band. In contrast, the semi-local Perdew-Burke-Ernzerhof (PBE) functional compresses the band width and deviates from experiment by up to 0.6 eV. We further show that an accurate band structure and band gap are vital to obtaining a correct description of the dependence of the Seebeck coefficient of p-type PbSe on the hole concentration (Pisarenko relation). This has implications for computational efforts to discover thermoelectric materials.
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All authors Zefeng Cai, Valentine V. Volobuev, Jędrzej Korczak, Enrico Della Valle, Hantian Liu, Moritz Hoesch, Sergey M. Frolov, Tomasz Story, Vladimir N. Strocov, Noa Marom
High Energy Physics (Phenomenology)
LUX-ZEPLIN's Stairway to Hea$\nu$en: limits on elastic scatters of dark matter from solar capture
Debajit Bose, Thong T.Q. Nguyen, Akash Kumar Saha et al. (+3 more)
The recent report of xenon recoiling with about 250 keV energy at the LUX-ZEPLIN (LZ) dark matter direct detection experiment was interpreted by the collaboration as either a momentum-dependent elastic scatter or an inelastic scatter. In this study, we take elastic operators listed by LZ that fit the datum to better than 3$\sigma$, and perform a log-likelihood analysis using the reported significances to reverse-engineer their best-fit Wilson coefficients. We then estimate for each operator the rate of dark matter capturing in the Sun, and assuming self-annihilations of the captured population to various Standard Model final states studied by IceCube, we place limits on them from measurements at IceCube and Super-Kamiokande of the fluxes of
solar-direction and atmospheric
neutrinos. We show that large ranges of dark matter masses around the weak scale that explain the LZ event are ruled out in this scenario, with the strongest limits placed by direct annihilations to
neutrino-antineutrino final states.
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All authors Debajit Bose, Thong T.Q. Nguyen, Akash Kumar Saha, Nirmal Raj, Tarak Nath Maity, Ranjan Laha
Materials Science
Electrodeposited Co and Ni Hexacyanoferrates: Insights into Structure and Morphology
Larissa de O. Garcia, Michael Pohlitz, Mohammed F. Kalady et al. (+3 more)
Prussian blue (PB) and its analogues (PBAs) are interesting materials for electrochemical applications due to their tunable redox chemistry and open framework structure. In this study, hexacyanoferrates (HCF) containing iron (FeHCF), cobalt (CoHCF) and nickel (NiHCF) were synthesized via potentiostatic electrodeposition. Cyclic voltammetry revealed distinct redox behaviors. Morphological characterization (SEM, EDX) demonstrated uniform, pyramidal film growth for FeHCF and CoHCF. Otherwise, NiHCF presented a cracked film with cubic clusters on top due to residual stress. Despite this, homogeneous element distribution was found for all samples. Structural characterization (TEM and XRD) confirmed a cubic
lattice crystal structure for all films, with systematic
lattice contraction from Fe to Co to Ni due to decreasing atomic radius. Raman and XPS data revealed a shift toward Fe2+ dominant oxidation states and modifications in CN bonding with the influence of K+ and water occupancy in the PBAs framework. These findings illustrate how metal substitution and deposition parameters can tune the structural and electrochemical properties of PBA films, presenting a strategic route to design tailored electrodes.
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All authors Larissa de O. Garcia, Michael Pohlitz, Mohammed F. Kalady, Falk Röder, Axel Lubk, Daniel Wolfmand Christian K. Müller
General Relativity and Quantum Cosmology
Quantum Tunneling and the Emergence of Classical Spacetime in Einstein-Æther Quantum Cosmology
Germano A. Monerat, Alessandro O. Castro Junior, Eduardo V. Corrêa Silva et al. (+1 more)
We investigate a
quantum cosmological model within the framework of Einstein-Æther
gravity. The model consists of a positively curved FLRW Universe whose matter content is described by pressureless
dust, in the presence of a positive cosmological constant $\Lambda$. We first perform a classical
Hamiltonian analysis utilizing Schutz's variational formalism, constructing the phase space and deriving the dynamics of the scale factor. Notably, we identify specific initial conditions that lead to an inflationary expansion, which are extracted directly from the underlying
quantum dynamics. Subsequently, we quantize the model following Dirac's formalism, obtaining the Wheeler-DeWitt equation for the wave function of the Universe. We solve this equation numerically and investigate our results using the WKB approximation to compute
quantum tunneling probabilities $TP_{WKB}$ alongside an integrated tunneling probability $TP_{int}$, the expectation value of the scale factor coming from the many-worlds interpretation of
quantum mechanics, and the corresponding Bohmian trajectories. Finally, we analyze how these tunneling probabilities are influenced by variations in the fundamental parameters of the theory ($\Lambda, \sigma, \beta$) and the energy of the
dust fluid $E$. Our results indicate a higher probability for the
quantum birth of the Universe in a parameter regime characterized by larger values of $\Lambda, \sigma$, and fluid energy $E$, together with a smaller value of $\beta$.
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All authors Germano A. Monerat, Alessandro O. Castro Junior, Eduardo V. Corrêa Silva, Gil O. Neto
Earth and Planetary Astrophysics
JWST MEP - A World Under Spotty Starlight: Detection of CO2 and H2O in the Hot Saturn WASP-52b with JWST NIRSpec G395H
JWST GO 3969 Team: Yanbo Pan, Ryan J. MacDonald, Néstor Espinoza et al. (+20 more)
Exoplanets orbiting active
stars offer distinct challenges for atmospheric characterization with the JWST. Among such worlds, the hot Saturn WASP-52b (Teq $\sim$ 1300 K) orbits an active K-
dwarf that complicates transmission spectroscopy via
stellar contamination. Here, we present the first JWST NIRSpec G395H (2.8-5.2 $\mu$m) limb-averaged transmission spectrum of WASP-52b obtained through the JWST Morning/Evening Program (GO-3969), which aims to measure limb asymmetries across a sample of hot
giant exoplanets. Our spectrum reveals the first detection of CO2 in WASP-52b's atmosphere (ln B = 54 / >10$\sigma$), with a retrieved abundance of log CO2 = -5.09 (+1.09/-1.14), and confirmation of H2O (ln B = 5.9 / $\sim$3-4$\sigma$), with an abundance of log H2O = -3.41 (+1.04/-1.04). We find a steep near-infrared slope that cannot be explained solely by H2O absorption, necessitating unocculted starspots (ln B = 5.7 / $\sim$3-4$\sigma$), though with properties that vary across our data reductions. The shape and amplitude of the molecular bands additionally suggest high-altitude (<10 mbar) inhomogeneous clouds covering $\approx$40 $\pm$ 20% of the terminator (ln B = 1.9 / $\sim$2.5$\sigma$), which provides evidence for the morning-evening terminator differences that are consensus predictions of general circulation models. WASP-52b's atmospheric
metallicity can be sub-
solar,
solar, or super-
solar, due to order-of-magnitude uncertainties in the molecular abundances caused by degeneracies between compositions, clouds, and starspots. However, chemical
equilibrium retrievals provide a similar statistical fit while favoring a tighter constraint with a super-
solar metallicity (M/H = 14.8 (+12.1/-5.9) $\times$
solar). These results highlight that chemical detections and aerosol properties may still be recovered for
planets orbiting active
stars via transmission spectroscopy.
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All authors JWST GO 3969 Team: Yanbo Pan, Ryan J. MacDonald, Néstor Espinoza, Bibiana Prinoth, Zafar Rustamkulov, Luis Welbanks, Daniel Kitzmann, Nicolas Crouzet, Anna Walde, Diana Powell, Eva-Maria Ahrer, Adam J. Burgasser, Duncan A. Christie, Wolf Cukier, Carlos Gascón, Måns Holmberg, Thomas Kennedy, Mercedes López-Morales, N. J. Mayne, Dominic Samra, Arjun B. Savel, Maria E. Steinrueck, Christopher P. Wirth
Physics Education
"I don't have a good metric for what other people think:" Unpacking the double empathy problem in neurodivergent physics problem-solving
Liam G. McDermott, Frank T. Dachille, George R. Keefe et al. (+3 more)
Learning is a social act and requires communication between interlocutors. Learning also is a process that takes place in a socially constructed neuro-normative system. These neuro-normative systems can marginalize neurodivergent (i.e., autistic, dyslexic, epileptic) students, who oftentimes have non-normative socio-cognitive differences. In this paper, we investigate 3 neurodivergent physics students' experiences solving physics problems and in navigating physics culture. We use a Double-Empathy Problem lens to uncover how communication, particularly communication breakdowns, can manifest for neurodivergent students in physics. We find that the 3 neurodivergent students, experience communication breakdowns in their interactions with peers and instructors, and in interpreting problem statements. Furthermore, we find that participants experience fear of being misinterpreted or feeling as though they are viewed as stupid on account of communication breakdowns. We advocate for the need for a more neuro-inclusive physics culture and suggest actions that can be done by instructors to create more inclusive spaces in physics.
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All authors Liam G. McDermott, Frank T. Dachille, George R. Keefe, Mason D. Moenter, Daryl McPadden, Erin Scanlon
Cosmology and Nongalactic Astrophysics
FLUMEN: Neural Emulator of an Advanced Stochastic Weak Lensing Model
Galymzhan Baltabay and Ville Vaskonen
Weak gravitational
lensing by intervening structure magnifies distant sources and induces scatter in their luminosity distances. We develop an improved
stochastic model for the distribution of weak
lensing magnifications, $\textrm{d} P/\textrm{d}\mu$, that resolves individual lenses down to $10^7\,M_\odot$ and, besides field
halos and filaments, includes subhalos and large-scale clustering of the lens population. Both extensions broaden the distribution, and the resulting scatter in the luminosity distances agrees with the
halo-model prediction from the nonlinear matter power spectrum and exceeds that obtained from $N$-body ray tracing, which we attribute to the finite mass resolution and box size of the simulations. Building on this model, we develop FLUMEN, a conditional normalizing-flow emulator that predicts $\textrm{d} P/\textrm{d}\mu$ as a function of the source
redshift up to $z_s=12$ and six cosmological parameters $\{h,\Omega_M,\Omega_B,\sigma_8,n_s,z_{\rm eq}\}$. The emulator enforces the empty-beam cutoff and the fold-caustic power-law tail analytically, and reproduces the Monte Carlo distributions on held-out cosmologies with a median Kullback–Leibler divergence of $0.0048$ at negligible cost. Our results provide a fast and flexible framework for incorporating the full magnification distribution into cosmological analyses of standard sirens,
supernovae, and other point sources.
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Fluid Dynamics
An improved periodic activation for PINNs reconstructing convective flows
Michael Mommert, Marie-Christine Volk and Christian Bauer
Architectures with periodic activation functions have already been shown to be beneficial in comparison to monotonic counterparts for a wide range of applications of physics-informed neural networks. Here, we investigate a network architecture which uses the complex exponential function, generating pairs of sine and cosine outputs as activation functions. Testing it against comparable, sine-activated multi-layer perceptrons for the task of temperature reconstruction from sparse velocity data for cubic Rayleigh-Bénard convection reveals significant improvements in the reconstruction quality without a substantial increase in computational cost per training step. Vice versa, the improved architecture enables reaching similar reconstruction qualities for a fraction of the expense. Analyzing the mathematical structure of these networks points to the improvements being rooted in the property of passing both a sine and cosine function forward. This way, the subsequent layer is able to adapt the phase of the provided latent periodic functions, and doing it individually for each of its
neurons.
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General Relativity and Quantum Cosmology
A computer assisted existence proof for a non-Schwarzschild black hole in Einstein–Weyl gravity
Kevin Goldstein and Vishnu Jejjala
Static, asymptotically flat, non-Schwarzschild black holes in four-dimensional Einstein–Weyl
gravity have previously been constructed by numerical shooting, while the local field equations admit horizon and asymptotic expansions to all orders. We give a computer assisted existence proof for a non-Schwarzschild solution whose dimensionless horizon radius is one in units of the massive
spin-two scale, with parameters close to the previously reported numerical branch. The exterior is divided into a convergent horizon series domain, a compact core enclosed by a parameter dependent Taylor model with directed rounding, and an infinite asymptotic domain treated as a centered stable
manifold fixed point problem. The resulting five-dimensional matching map between the core and tail is continuous on a rigorously specified box. After exact rational preconditioning, the signs on opposite faces satisfy the hypotheses of the Poincaré–Miranda
theorem and therefore certify a matching zero. The solution has a regular nondegenerate horizon, no additional exterior horizon, vanishing
Ricci scalar, and nonvanishing
Ricci tensor. The strict bounds also imply existence at every sufficiently nearby horizon radius and a local continuous family at fixed coupling. The proof establishes existence, but not uniqueness of the matching zero.
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Quantum Physics
Parameter-Decoupled Quantum Superresolution without Multiparameter Estimation
X.-F. Qian
Quantum superresolution promises to resolve closely spaced sources beyond the diffraction limit, but existing approaches generally rely on idealized source properties or require simultaneous estimation of multiple coupled parameters of realistic sources. Here we introduce a parameter-decoupled measurement that determines the separation of realistic passive sources without estimating their unknown brightness imbalance, mutual coherence, or relative phase. A complete four-parameter
quantum Fisher information analysis identifies the separation information that remains accessible in the presence of these nuisance parameters. We then construct a directly measurable log-probability invariant from projection channels whose conditional statistics depend only on the separation. Broad classes of channel pairs satisfy the resulting decoupling condition. For a Gaussian point-spread function, the lowest-order implementation asymptotically attains the four-parameter
quantum limit per incident signal in the sub-Rayleigh regime. This approach converts a realistic multiparameter imaging problem into an operationally single-parameter measurement, providing a practical route toward
quantum-enhanced resolution of passive spatial, temporal, and spectral signals.
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Fluid Dynamics · Cross-listed from eess.AS
Towards Physics-Informed Neural Networks for Stiff Guitar String Vibrations
Xinmeng Luan, Kensuke Okada, Ryoya Tabata et al. (+1 more)
Modeling stiff string vibrations is challenging due to their dispersive and high-frequency characteristics. This study investigates the effectiveness of Physics-Informed Neural Networks (PINNs) in simulating the transverse vibration of a one-dimensional linear stiff string with sharp initial conditions induced by plucking. The governing Partial Differential Equation (PDE), along with the associated initial and boundary conditions, is incorporated directly into the loss function of the neural network. For the reference measurements, a wire-breaking experiment was performed to excite the string, and its vibration response was captured using a
laser profiler. The comparison between experimental measurements, finite-difference time-domain (FDTD) simulations, and PINN-based simulations shows good overall agreement, highlighting the potential of PINNs for modeling stiff-string vibrations.
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All authors Xinmeng Luan, Kensuke Okada, Ryoya Tabata, Gary Scavone
Geophysics
Determination of Physical Height Differences from Time Transfer via the ACES Mission – A Simulation Study
Klarissa Emma Lachmann, Jürgen Müller, Peter Vollmair et al. (+1 more)
The determination of physical height differences using highly stable atomic clocks has emerged as a novel approach in relativistic geodesy, exploiting the gravitational
redshift as a direct observable of geopotential differences. In this study, we investigate the feasibility of satellite-based clock comparisons using the Atomic Clock Ensemble in Space (ACES) onboard the International Space Station, which enables time transfer via microwave (MWL) and optical (ELT) links. Since operational optical data are not yet available, a comprehensive full-scale simulation of realistic ACES observation scenarios is performed, including detailed noise models of clocks and links. A slope-based estimation method is applied to time series of clock comparisons in order to extract the relativistic
redshift signal and derive height differences between the ground stations. The performance of the approach is evaluated for quasi-common view, non-common view, and split non-common view configurations, where the latter divides the observation period into shorter intervals. The results show that optical links enable faster convergence and can achieve height accuracies at the decimeter level within a few days and at the centimeter level over longer periods, while microwave links are more strongly affected by noise and bias contributions. Non-common view processing significantly increases observation availability with only minor loss in accuracy, and the split approach provides robust solutions for larger networks. These findings demonstrate the strong potential of satellite-based clock comparisons as a remote-sensing technique for determining physical height differences on a continental scale.
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All authors Klarissa Emma Lachmann, Jürgen Müller, Peter Vollmair, Anja Schlicht
Cosmology and Nongalactic Astrophysics
High Resolution Grid-based Simulations of the Warm-Hot Intergalactic Medium
Lile Wang and Renyue Cen
We present high-resolution cosmological hydrodynamic simulations of the Warm-Hot Intergalactic Medium (WHIM) using the GPU-optimized grid-based hydrodynamic code Kratos. Employing a uniform 4096^3 grid in a (100 h^-1 Mpc)^3 comoving volume, we achieve a spatial resolution of ~24.5 h^-1 kpc, sufficient to resolve the Jeans scale of gas at T ~ 10^4 K and n_H ~ 10^-3 to 10^-2 cm^-3. This calculation ranks among the largest grid-based cosmological hydrodynamic simulations performed to date. We find that ~23.4% of
cosmic baryons reside in the WHIM phase (T = 10^5 - 10^7 K) at z = 0, significantly below the 40-50% found in earlier, lower-resolution simulations. Through a suite of lower-resolution simulations, we demonstrate that spatial resolution plays a pivotal role in determining the WHIM fraction: resolving gas near its Jeans scale allows it to reach higher densities, where enhanced radiative cooling transfers a substantial fraction of
baryons out of the WHIM temperature range. The remaining WHIM resides predominantly in filaments and
accretion-shock structures in the vicinity of
halos, where hierarchical structure formation and ongoing hydrodynamic
accretion provide continued shock heating. Synthetic observations of Lyman-alpha, O VI, O VII, and O VIII emission reveal distinct morphological and kinematic signatures, with O VI tracing filament-
halo interfaces and the X-ray lines probing hotter gas associated with massive
halos. These predictions underscore the importance of current and future missions such as XRISM, ATHENA, and HUBS for mapping WHIM thermodynamics and kinematics.
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High Energy Physics (Theory)
A Split-Signature Type IIB Background on $\mathrm{AdS}_{5,\mathbb C}$
Brenno Carlini Vallilo
We construct a maximally supersymmetric Type IIB background in signature $(5,5)$ on the real ten-
manifold underlying complex $\mathrm{AdS}_5$. The spacetime is diffeomorphic to $T^*S^5$ and carries the invariant metric $G=\mathrm i(\bar q-q)$, where $q$ is the holomorphic constant-
curvature metric. The real five-form $F_5=(4\mathrm i/L)(\Omega-\bar\Omega)$, built from its normalized volume form, is self-dual, and its stress tensor supports this scalar-flat, non-Einstein metric. We derive these fields from the most general $\mathrm{SL}(4,\mathbb C)$-invariant metric and five-form ansatz: self-duality and the Einstein equation fix their phases up to the overall scale, orientation, and flux sign. The fields obey the reality conditions of the untwisted $\mathrm{IIB}_5$ theory. The holomorphic coframe makes the supercovariant
curvature cancellation explicit, and flat transport gives thirty-two global real Killing spinors. Their Killing superalgebra is the factor-exchanging real form of $\mathfrak{psl}(4|4,\mathbb C)$, and we identify the corresponding supercoset.
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Solar and Stellar Astrophysics
Stability Analysis of the Proton Hammerhead Distribution Observed by Parker Solar Probe: Linear Theory and Fully Kinetic Simulations under Idealised Conditions
L. Pezzini, J. L. Verniero, F. Bacchini et al. (+3 more)
The non-adiabatic heating of the slow
Solar Wind (SW) remains an open problem, with wave–particle interactions as a primary candidate mechanism. Novel in situ Parker
Solar Probe (PSP) observations reveal strongly perpendicular anisotropic velocity distribution functions (VDFs), called "hammerhead", correlated with intense wave activity. These VDFs are systematically measured at the Heliospheric Current Sheet (HCS), making the hammerhead an important kinetic signature of the slow SW. In this work, we employ a fully kinetic particle-in-
cell approach, complemented by a linear Vlasov solver to cross-validate the simulation results, to investigate the stability of these VDFs, the timescales over which they evolve, and their interaction with
plasma waves. Our main findings indicate that the hammerhead distribution is primarily susceptible to drift-type instabilities, while energy is nonlinearly transferred back to the
plasma through a combination of Landau and cyclotron resonances, resulting in net heating in the parallel direction, preferentially energizing the beam
proton population. Crucially, these nonlinear interactions do not drastically alter the morphology of the distribution. This suggests the possibility that the hammerhead may be generated locally within the HCS in the inner heliosphere and subsequently advected outward, where it is eventually measured by PSP. This work lays the ground for future investigations into the kinetic physics of the HCS.
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All authors L. Pezzini, J. L. Verniero, F. Bacchini, A. N. Zhukov, G. Arrò, R. A. Lòpez
Optics
When Integrated Photonics Should Be Wavy
Oliver R. Müller, J. J. Erik Maris, Yannik M. Glauser et al. (+2 more)
Increasing demand for high-performance optical devices drives the search for improved fabrication and design paradigms. While photonic
circuits have traditionally used structures with two discrete 'binary' height levels, grayscale 'wavy' interfaces, or optical
Fourier surfaces, have recently become possible. They provide precise control over the
Fourier components that govern the optical response. This capability raises the question: When does a wavy device improve performance and why? Here, we show that wavy integrated processors exhibit superior accuracy and efficiency to binary analogs. Inverse-designed wavy interferometers have the design freedom to minimize outscattering to free space and backreflections. They reach a five-fold lower transmission error than binary counterparts and enable bandwidths up to 300 nm. We formalize these findings for other distinct integrated devices, such as photonic
crystals, nanocavities, and beam emitters. A
Fourier-optics analysis identifies a trade-off: wavy profiles manipulate light more accurately, whereas binary profiles excel in interaction strength. As such, tailored wavy profiles emit high-quality beams. However, binary profiles remain preferable in photonic
crystals and nanocavities, where maximal index contrast is required and binarization-induced higher harmonics are benign. Thus, for
quantum information, optical computing, and sensing, optical
Fourier surfaces offer a route to miniaturized integrated
circuits with improved performance.
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All authors Oliver R. Müller, J. J. Erik Maris, Yannik M. Glauser, Sander J. W. Vonk, David J. Norris
Quantum Physics
Intrinsic Vectorial Gradiometry via Quantum Control of a Spin-based Sensor
Jaime García Oliván, Pablo Acedo, Oliver T. Whaites et al. (+1 more)
Gradiometry provides a versatile alternative to passive environmental shielding in quasi-static magnetometry, effectively suppressing background noise through differential signal extraction. Nevertheless, traditional implementations rely on multi-sensor architectures restricted to spatial gradients, where subtracting signals from independent detectors involves imperfect suppression of common-mode noise and artifacts, limiting their sensitivity. To overcome these limitations, we introduce a
quantum control sequence that enables intrinsic temporal and spatial vectorial gradiometry of
magnetic fields using a single
quantum sensor. Our method provides direct access to first and higher-order derivatives of the
magnetic field and extended applicability via auxiliary
nuclear spin memory. We showcase this protocol on an ensemble of nitrogen-vacancy (NV) centers in diamond and combine it with mechanical control to realize high-precision differential sensing. Through detailed numerical simulations, we demonstrate the performance of our scheme in two critical DC magnetometry applications: (i) vector
magnetic anomaly detection and (ii) non-invasive gradiometry of neuronal action potentials.
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All authors Jaime García Oliván, Pablo Acedo, Oliver T. Whaites, Jorge Casanova
High Energy Physics (Phenomenology)
AGN and DSNB Neutrino Oscillation in Dark Matter Background
Po-Yan Tseng and Yu-Min Yeh
The
neutrino-matter interaction cause the final
flavor compositions deviating from those expected in
vacuum. In this work we consider
neutrinos interact with ultra-light scalar dark matters $\phi$ ($m_\phi\ll 1\,{\rm eV}$). When the
neutrinos emitted from a distant source and propagate through the dark matter medium, the MSW potential in the
Hamiltonian is replaced by the hypothetical $\nu\phi$ effective potential. Two types of
neutrino sources are adopted in our calculations. The first is point-like
neutrino source, the Active
Galactic Nuclei (AGN), which produce $\mathcal{O}({\rm TeV})$
neutrinos primarily through charged pion decay, yielding an initial
flavor ratio of ($\nu_e,\nu_\mu,\nu_\tau$)=($1:2:0$). We focus on two specific AGNs, NGC 1068 and TXS 0506+056 in our analysis, whose distances from Earth are much larger than the
neutrino oscillation lengths. We consider the range of $\nu\phi$ coupling constant such that the adiabatic condition and mean free path can be satisfied. Hence, by assuming
neutrinos are produced randomly from their corona regions, we compute the averaged
flavor ratio at Earth with $m_\phi=10,1,0.1\,{\rm peV}$ and $m_\phi=1,0.1,0.01\,{\rm feV}$, generate the ternary plots of
neutrino flavors, and compare the results with the IceCube present and future sensitivities. The second source considered is the Diffuse
Supernova Neutrino Background (DSNB), it is an isotropic
neutrino source with energy $\mathcal{O}({\rm MeV})$. Applying the core-collapse simulation
neutrino temperatures to the DSNB flux, we repeat the similar analysis for the DSNB with $m_\phi=10^{-22}\,{\rm eV}$, and we estimate different
neutrino flavors lies in the HK/DUNE/JUNO combined sensitivities limit.
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Computational Physics
Dirac Cones in d-wave Altermagnets Enable High-Conductivity and High-Efficiency Spin Sources
Tianye Yu, Junwen Lai, Peitao Liu et al. (+2 more)
Low critical charge-current density and low energy dissipation are highly desired in
magnetic random-access
memories, requiring
spin sources to exhibit both high charge-to-
spin conversion efficiency (CSE) and high charge conductivity. Altermagnets with vanishing net
magnetic moment and
spin-splitting bands provide promising
spin-source candidates for
spin-splitting-torque
magnetic random-access
memories. However, achieving both high CSE and charge conductivity remains challenging in altermagnets. In this work, we introduce Dirac cones into two-dimensional d-wave altermagnets, where their intrinsically high carrier mobility enables tunable charge and
spin conductivities with high CSE. Dirac-cone anisotropy provides an effective means of enhancing both CSE and charge conductivity, with cone tilting serving as an additional degree of tunability. Guided by this design principle, we identify a maximum CSE of 92% in Cr2SeTeS. When the
Fermi level moves slightly away from the Dirac point, high CSE, high charge conductivity, and the resulting high
spin conductivity can be simultaneously achieved. Our study advances the understanding of time-reversal-odd
spin transport via Dirac-cone engineering and provides a practical route toward developing
spin-source materials that combine high charge conductivity with highly efficient charge-to-
spin conversion.
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All authors Tianye Yu, Junwen Lai, Peitao Liu, Xing-Qiu Chen, Yan Sun
General Relativity and Quantum Cosmology
Revisiting the Entangled Relativity gravity framework
Bertrand Chauvineau
One revisits the Entangled Relativity theory framework,
embedding it in a larger set of theories. From their scalar-tensor reformulation, these theories admit General Relativity spacetime solutions as solutions with the same matter content, if this matter obeys an "intrinsic decoupling" condition. One shows that a set of matter Lagrangians satisfying this condition is completely characterized by the way they depend on the metric tensor. One then shows that it is possible to define a perfect fluid Lagrangian fulfilling the intrinsic decoupling condition up to 1PN order. Specifying to weak field spherical
stars suggests that Entangled Relativity and its proposed generalization are worthy alternatives to General Relativity. Indeed, the obtained numerical values of the Eddington parameters abruptly satisfy the known observational constraints. However, the non strict compliance of the theory with conservation laws demands to reconsider the link between observational data and the parameters for a definitive clarification of this point.
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Materials Science
Complete Neural Electronic Initialization Accelerates Materials DFT
Felix Ærtebjerg, Jonas Elsborg and Arghya Bhowmik
We present the first complete machine learning method for accelerating plane-wave density functional theory (DFT) in materials under the projector augmented wave (PAW) formalism. We formalize seven criteria that a Complete Neural Electronic Initializer must satisfy for practical end-to-end PAW DFT acceleration. Applying these to prior work reveals two structure-dependent components, augmentation occupancies and
spin initialization, whose absence prevents existing acceleration methods from providing complete reference-free initialization. We show that omitting these components can eliminate or reverse the acceleration obtained via models that only predict the smooth valence density. We satisfy the missing requirements by introducing AugNet, a general equivariant model for PAW augmentation occupancies, and the first general
spin density model for materials, which predicts the smooth
spin-difference density and
spin-difference PAW augmentation occupancies using predicted
magnetic moments to constrain the global
magnetic state. Combined with existing valence density models, our full method satisfies all seven criteria and forms a fully reference-free electronic initializer for materials DFT, requiring no electronic quantities from a converged target calculation. We show that perfect initialization could cut PAW DFT wall time by 40-52%, and our method recovers up to 62% of this saving, reducing end-to-end DFT wall time by up to ~25% on unseen structures while preserving converged energies.
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Statistical Mechanics
Full macroscopic thermalization and the formation of Schrödinger's cats by unitary time evolution in the weakly perturbed Ising model - Applications of the Roos-Sugimoto-Teufel-Tumulka-Vogel theory
Hal Tasaki
We study macroscopic thermalization in the
ferromagnetic Ising model with a weak generic (highly nonlocal and many-body) random
quantum perturbation. We prove that a single typical perturbation makes every initial state $|\Phi(0)\rangle$ in a specified energy shell thermalize: a measurement of a large class of macroscopic observables in the time-evolved state $|\Phi(t)\rangle=e^{-i\widetilde H_Lt}|\Phi(0)\rangle$ yields their thermal
equilibrium values, within a prescribed precision and with overwhelming probability, at sufficiently large, typical times $t$. The result covers the full finite-temperature range, including the ordered phase, where we use plus boundary conditions. With periodic boundary conditions in the ordered phase, every energy eigenstate in the shell is shown to be an almost balanced macroscopic Schrödinger-cat state. Moreover, every pure initial state becomes such a cat at sufficiently large, typical times, with each branch in the corresponding macroscopic thermal
equilibrium. The proof combines the theory of Roos, Sugimoto, Teufel, Tumulka, and Vogel with rigorous Ising large-deviation estimates.
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General Relativity and Quantum Cosmology
Massive scalar's self-mass from gravitons in de Sitter
Dražen Glavan, Shun-Pei Miao, Tomislav Prokopec et al. (+1 more)
We compute the fully renormalized one-graviton-loop contribution to the self-mass of a massive scalar field in de Sitter space. The computation is performed using dimensional regularization and the divergences are absorbed by BPHZ counterterms. This self-mass can be used to study one-loop
quantum-gravitational corrections to the dynamics of massive spectator scalars in inflation.
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All authors Dražen Glavan, Shun-Pei Miao, Tomislav Prokopec, Richard P. Woodard