Earth and Planetary Astrophysics · Cross-listed from eess.SY
A Floquet Mode LQR for Orbital Station-Keeping in Cislunar Space
António Nunes, Sérgio Brás and Pedro Batista
A linear optimal control law for orbital station-keeping in the Earth-Moon Restricted Three Body Problem (R3BP) is developed via Linear Quadratic Regulator (LQR) theory. First, the cost function is established considering a periodic state-weight
matrix, leveraging stability information of the target orbits retrieved through Floquet theory. Then, the resulting periodic Riccati differential equation is solved and local asymptotic stability guarantees are shown. Finally, the performance of the proposed LQR when tracking periodic orbits in the circular and
elliptic R3BPs is analyzed numerically.
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Strongly Correlated Electrons
SmoQyElPhQMC.jl: An open-source Julia package for efficient and scalable quantum Monte Carlo simulations of electron-phonon coupled models
Benjamin Cohen-Stead, James Neuhaus, Kipton Barros et al. (+2 more)
We introduce version 1.0 of the SmoQyElPhQMC.jl package, an open-source Julia code for performing scalable
quantum Monte Carlo simulations of electron-
phonon coupled model
Hamiltonians. SmoQyElPhQMC.jl is built upon the SmoQyDQMC.jl codebase and implements improved versions of the
algorithms presented in [B. Cohen-Stead et al., Phys. Rev. E 105, 065302 (2022)] to enable (near-linear) scalable simulations of a broad class of uncorrelated $e$-ph models both in system size and inverse temperature. By extending the functionality of the flexible scripting interface introduced in SmoQyDQMC.jl, the SmoQyElPhQMC.jl package continues to allow users to adapt it to different workflows and interface with other software packages in the Julia ecosystem. The code for this package can be downloaded from our GitHub repository at https://github.com/SmoQySuite/SmoQyElPhQMC.jl or installed using the Julia package manager. The online documentation, including examples, can be obtained from our documentation page at https://smoqysuite.github.io/SmoQyElPhQMC.jl/stable/.
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All authors Benjamin Cohen-Stead, James Neuhaus, Kipton Barros, Thomas A. Maier, Steven Johnston
Mesoscale and Nanoscale Physics
Strain- and doping-tunable optical resonance in Kekulé-Y graphene
Yawar Mohammadi
We investigate the optical response of Kekulé-Y
graphene under uniaxial strain and carrier doping. Using a low-energy effective
Hamiltonian, we show that strain reshapes the low-energy electronic structure of the Kekulé-Y phase and induces Van Hove singularities at energies well below those of pristine
graphene. Within the Kubo formalism, we calculate the optical conductivity and identify multiple anisotropic interband features, with a pronounced resonance arising from strain-induced Van Hove singularities. The pronounced resonance is strongly anisotropic and robust against moderate thermal broadening and disorder, providing a clear optical signature of Kekulé-Y ordering. We further derive analytical expressions for the low-energy optical conductivity and the Drude weight, providing a detailed characterization of the strain- and doping-dependent optical response. Our results establish strain engineering as an effective route for controlling valley-dependent optical properties in Kekulé-Y
graphene, originating from the Kekulé-induced coupling of the Dirac valleys, and suggest feasible optical probes for the experimental identification of the Kekulé-Y phase.
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Quantum Physics
Jones-matrix analysis of phase accumulation in a linear-optical multi-pass interferometer
Byoung S. Ham
Quantum information science has traditionally relied on nonclassical resources, such as entangled
photon pairs and squeezed states, to achieve measurement performance beyond classical limits. Here, we revisit the multi-pass photonic scheme reported in Nature 450, 393 (2007) to clarify the physical origin of the observed superresolution and the associated claim of supersensitivity. Using a rigorous Jones-
matrix formalism, we show that the round-trip
evolution of the HQMQ linear optics unit is equivalent to the product of two reflections in polarization space, resulting in an effective rotation operator. This equivalence reveals that the accumulated phase arises from coherent polarization-state rotation on the Poincare'e sphere. The resulting phase accumulation is interpreted geometrically as a progressive realignment of the polarization state during successive forward and backward propagations. To validate the theoretical model, a classical-wave implementation is experimentally conducted, analyzed, and compared with the corresponding Jones-
matrix solution. Finally, the scaling behavior of the Fisher information is analyzed to examine the origin of the claimed supersensitivity. The results are further compared with a recently developed coherence de Broglie wavelength framework, which achieves identical superresolution through repeated coherent interactions in a cascaded interferometeric architecture.
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Quantum Physics
Quantum sensing through bosonic-fermionic Bell-state transitions in two-photon interference
Chahat Kaushik, Vimlesh Kumar and G. K. Samanta
Hong-Ou-Mandel (HOM) interference has become a central resource for
quantum sensing and metrology owing to its sensitivity to temporal delay and
photon indistinguishability. However, existing HOM-based sensing schemes generally rely on inserting a sample into one arm of the interferometer, making the measurement vulnerable to optical loss,
alignment instability, and bandwidth-dependent distortion of the interference profile. Here, we demonstrate a
symmetry-controlled
quantum sensing scheme based on continuous transitions between symmetric (bosonic-like) and antisymmetric (fermionic-like) Bell states in two-
photon interference. By imprinting a
geometric phase onto the classical pump beam and transferring it to polarization-entangled
photons generated via spontaneous parametric down-conversion, we coherently tune the exchange
symmetry of the entangled state without altering the temporal or spectral indistinguishability of the
photons. The HOM response evolves continuously from bunching to antibunching with a sine square phase dependence, producing a coincidence modulation of approximately 10 * 10^4 counts s^-1 counts/s. In contrast to conventional HOM sensing, the phase-modulation linewidth remains fixed at pi/2, independent of
photon bandwidth. Using a birefringent
crystal placed directly in the pump beam, we measure thermo-dispersive birefringence with a resolution of the order of 10^{-6} over a broad temperature range. Our results establish exchange
symmetry as a controllable resource for robust
quantum sensing and
symmetry-engineered photonic
quantum information processing.
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General Relativity and Quantum Cosmology
Dynamical tidal response of neutron stars via scattering amplitudes
M.V.S. Saketh, Suprovo Ghosh and Nils Andersson
A key challenge of gravitational-wave physics is distinguishing the nature of compact objects in binary coalescences, in particular whether they are black holes or
neutron stars.
Neutron stars are set apart by a stronger
tidal response, whose static and dynamical aspects are directly linked to their rich internal physics. Measurements of this response through gravitational-wave observations constrain the
neutron-
star equation of state and provide insight into the physics of high-density matter. However, defining the
tidal response in general relativity is difficult due to coordinate ambiguities and the complexity of connecting the
star's response to the binary dynamics and the associated waveforms. In this paper, we show how the dynamical
tidal response of a
neutron star can be systematically defined within the worldline effective field theory (EFT) framework, and relate it to the gauge-invariant amplitude for gravitational-wave scattering off an isolated
star. We compute this amplitude both within the EFT, using standard
quantum field-theory techniques, and within
stellar perturbation theory (the corresponding ultraviolet theory), solving the coupled metric and matter perturbation equations numerically in the
stellar interior and matching to the analytical Mano-Suzuki-Takasugi (MST) solutions in the
vacuum exterior. Matching the amplitude between the two theories fixes the dynamical
tidal response. The result is consistent with known expectations, including the static limit and the behaviour near the
star's resonant modes, and it recovers the imaginary part of the dominant oscillation mode induced by gravitational-wave dissipation. We conclude with a discussion of potential improvements within both the EFT and perturbation theory.
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Materials Science
Modifying Electrochemical Doping in Light-Emitting Electrochemical Cells with Gold Nanoparticles
Ajay K. Poonia, Anton Kirch, Joan Ràfols-Ribé et al. (+8 more)
Electrochemical doping offers dynamic control of the electronic properties of organic
semiconductors, and it is the enabling feature of a range of technologies, including electrochemical transistors, energy-storage devices, light-emitting electrochemical
cells (LECs), and bioelectronics. Electrochemical doping is commonly controlled by the selection of the constituents in the active material of the device or the applied voltage bias, but herein we report that the incorporation of Au nanoparticles (Au-NPs) at an electrode interface can constitute an alternative control parameter. The LEC features balanced p- and n-type electrochemical doping that forms a p-n junction doping structure in its active material, and we find that it is possible to reshape this doping profile by incorporating Au-NPs at an electrode interface. Specifically, we establish that the inclusion of neat non-capped Au-NPs at the anodic interface shifts the p-n junction (i.e., the emission zone) away from the anode. In contrast, the inclusion of Au-NPs capped with sodium citrate is found to reverse this behavior, so that the emission zone is instead moved towards the anode. We utilize this control parameter to shift the emission zone towards a position of constructive (destructive) interference, as manifested in a strong increase (decrease) of the LEC emission efficiency. Our findings establish an interfacial strategy for modulating the spatial profile of electrochemical doping and tuning device performance without altering the chemistry of the active material, relying instead on the surface modification of one electrode. This approach is important because it provides a versatile and minimally invasive route to optimize electrochemical devices while preserving the intrinsic properties and formulation of the active material.
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All authors Ajay K. Poonia, Anton Kirch, Joan Ràfols-Ribé, Lucrezia Catanzaro, Anish Rao, Karol Kołątaj, Vittorio Scardaci, Giuseppe Compagnini, Guillermo P. Acuna, Ludvig Edman, Nicolò Maccaferri
Solar and Stellar Astrophysics
Morphokinematic structure of the Planetary Nebula NGC 6563
Zahra Al, Federico Soto-Badilla, Yüksel Karataş et al. (+2 more)
We present a morphokinematic analysis based on high-resolution long-slit echelle spectroscopy of the \nii$\lambda6583$ line and narrowband imaging. Position-velocity diagrams reveal asymmetric expansion and localized kinematic features. We derive a systemic velocity of $V_{\rm sys}^{\rm LSR} = -25\pm1$\kms\ ($V_{\rm sys}^{\rm HEL} = -34 \pm 1$\kms) and a main shell expansion velocity of $V_{\rm exp} = 22 \pm 1$\kms. Three-dimensional modeling indicates an ellipsoidal main body surrounded by a thin shell, two ear-like protrusions, and additional small-scale structures. The corresponding kinematic ages are $3\,600 \pm 700$ yr for the ellipsoid and ring, and $7\,500 \pm 1\,000$ yr and $8\,800 \pm 1\,500$ yr for the two opposite ear-like protrusions, respectively, indicating that these outer structures predate the main nebular envelope. The kinematic asymmetry and enhanced emission regions suggest
evolution within a non-uniform ambient medium. At the same time, the presence of collimated ear-like structures is consistent with shaping influenced by binary interaction, where earlier
outflows preceded the ejection of the dense shell. NGC\,6563 therefore appears to be a dynamically evolved system shaped by the combined effects of episodic mass ejection and environmental interaction.
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All authors Zahra Al, Federico Soto-Badilla, Yüksel Karataş, Gerardo Ramos-Larios, Roberto Vázquez
Astrophysics of Galaxies
Lensed hot stars with HST in the 2030s
J.M. Diego
In the late 20th century, the Hubble Space
Telescope (HST) revolutionized astronomy, showing the Universe with a detail never seen before in the ultraviolet (UV), optical and infrared (IR) bands. In the early 2020s, the James Webb Space
Telescope started a similar revolution in the IR. The launch of Roman in late 2026 challenges the reign of HST in the optical band, but even after Roman's launch, HST will remain as the only
telescope capable of high-quality imaging in the UV band. In the optical bands, HST provides superior resolution than Roman for point sources. Although equipped with more sensitive MOS, Roman's sensors have a pixel size about 3 times larger than HST's CCDs, hence undersampling the point-spread-function, and resulting in a worse spatial resolution. The UV-capable and higher-resolution of HST in the UV and optical band, makes HST the best instrument for specific science cases. This paper responds to the "Building a Roadmap for Hubble science into the 2030s" call and focuses on science with lensed hot
stars at $z>0.5$ in the UV and optical bands, exploiting the features that makes HST the best instrument in the UV/optical until the launch of the Habitable World Observatory in the 2040s.
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Disordered Systems and Neural Networks
Local Coverage Governs Memorization in Diffusion Models
Claudia Merger and Sebastian Goldt
Memorization in
diffusion models is often treated as a global property of the model or
dataset. In practice, however, a single
diffusion model can simultaneously generate both memorized and novel samples. Which training samples are most likely to be memorized? In this work, we show that memorization is governed by local data coverage. Leveraging the connection between
diffusion models and kernel density estimation (KDE), we derive a theoretical criterion that predicts whether a point is memorized based on the density of training data in its neighborhood and the size of the training
dataset. In the high-dimensional limit, this leads to a sharp, local transition: regions of low coverage are dominated by isolated training samples, which are memorized, while dense regions support interpolation and generalization. We validate these predictions empirically, showing that memorization increases with local sparsity and that
diffusion models exhibit a coexistence of memorized and novel samples within the same model. Extending this framework to multi-class settings, we further show that classes with higher intra-class sparsity (and thus lower local coverage) are more strongly memorized. Our results provide a local view of memorization in
diffusion models, explaining when and where memorization occurs in terms of data geometry.
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Materials Science
The Future of Computing for Materials Science Challenges
Phalgun Lolur, Richard P. Padbury, George H. Booth et al. (+10 more)
Materials discovery increasingly relies on the coordinated use of theory, computation, experiment, data-driven methods, and emerging
quantum technologies, yet the full potential of these tools is realised only when they operate within workflows that reflect the complexity of real systems. This perspective summarises current capabilities, limitations, and opportunities across these domains, drawing on contributions from academia, industry, and national laboratories to identify the scientific and structural requirements for more reliable and efficient discovery. Classical simulations provide broad coverage across design spaces, while experimental measurements reveal degradation, heterogeneity, and kinetic processes that determine performance under realistic conditions. Machine learning accelerates exploration when supported by well-curated
datasets with clear provenance and uncertainty quantification, and
quantum computing offers promising routes into correlated electronic behaviour when aligned with properties that influence engineering decisions. Collectively, these insights highlight the need for reproducible workflows, shared data standards, realistic
benchmarks, and a research culture that prepares scientists to work across paradigms. By integrating these methodological and organisational elements, the community can move toward discovery processes that deliver robust predictions, support confident decision making, and shorten the path from conceptual design to deployable materials.
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All authors Phalgun Lolur, Richard P. Padbury, George H. Booth, Katherine Inzani, Nicole Holzmann, Thomas W. Keal, Joseph Montaya, Daniel F. Urban, Thomas Eckl, Emanuele Marsili, Wibe A. de Jong, Jonathan R. Owens, Julian van Velzen
High Energy Physics (Phenomenology)
High-scale Mirror Standard Model Dark Matter, Dark Phase Transitions and Gravitational Waves Implications
V.K. Oikonomou
We consider a scenario for dark matter in the Universe, according to which the dark matter sector is comprised by a dark Standard Model sector which interacts only gravitationally with the ordinary Standard Model sector. This dark Standard Model sector is assumed to have the same
symmetries as the ordinary Standard Model, with the couplings and the scale of the mirror Standard Model sector being different than the ordinary Standard Model sector. Specifically, the scale of the mirror Standard Model sector will be assumed to be quite higher compared to the ordinary Standard Model. Also the Yukawa couplings among the mirror
Higgs and the mirror
fermions are assumed to be different from those of the Standard Model and we examine the effects of the different scale and of the different Yukawas on the
evolution of the Universe. As we show, a mirror world phase transition occurs at high temperatures of the baryonic Universe, which can be first order or second order, depending on the scale of the Universe and the Yukawa couplings. These are dark phase transitions which occur quite earlier than the real world Standard Model electroweak phase transition. The case of a second order phase transition is quite interesting phenomenologically, since it can potentially have a direct imprint on the spectrum of
stochastic gravitational waves for frequencies probed by the future gravitational wave detectors. Also we examine whether this mirror dark matter world can form atoms and as we show in some scenario the high scale mirror dark matter can have both atomic and subatomic particle components. We also give an approximation of the total equation of state of high scale mirror DM and we discuss how high scale mirror DM can reconcile contradicting observations like the Bullet cluster and the Abell 520 cluster.
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General Relativity and Quantum Cosmology
Sachs-Wolfe effect as a smoking gun for cosmological gravitational wave backgrounds
Giorgio Mentasti, Leon Vidal, Quentin Baghi et al. (+1 more)
The Sachs-Wolfe (SW) effect, arising from large-scale structures in the universe, modifies the frequencies of gravitational waves (GWs) sourced by a cosmological background. We show that for backgrounds with $\Omega_{\rm GW}\gtrsim 10^{-10}$, this effect imprints anisotropies and spectral distortions that can be detectable with a network of space-based interferometers (such as LISA + Taiji) and, if not taken into account, may bias the estimate of the theoretical model of the GW background. The effect is particularly enhanced in the high-frequency end of the spectrum. The SW-induced anisotropies and spectral distortions present in a GW background sourced at
primordial times will correlate with the SW signature present in the CMB. Any detection of a cross-correlation between the GW anisotropies and the CMB at large scales is therefore a smoking gun for confirming the
primordial nature of the background.
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All authors Giorgio Mentasti, Leon Vidal, Quentin Baghi, Carlo Contaldi
Materials Science
Multistate Manipulation of Charge-Spin Conversion in Two-Dimensional Ferroelectric Bilayers
Weiyi Pan, Xinyuan Jiang and Jaroslav Fabian
Achieving nonvolatile and multistate manipulation of charge-
spin conversion, including the Edelstein effect (EE) and
spin Hall effect (SHE), is crucial for high-density spintronic
memory. Here, we propose a mechanism to simultaneously control both EE and SHE in two-dimensional ferroelectric
bilayers, where interlayer-parallel and interlayer-antiparallel polarization configurations can coexist.
Symmetry analysis shows that in the interlayer-parallel states, reversal of the total polarization switches the sign of the EE, whereas changing to an interlayer-antiparallel configuration suppresses the EE to zero, enabling electrically switchable current-induced
spin accumulation among three distinct states, which could be used for ternary logic operations. Meanwhile, the magnitude of the SHE can be tuned by switching between two different classes of polarization configurations, namely interlayer-parallel and interlayer-antiparallel configurations. Using first-principles calculations, we demonstrate this mechanism in
bilayer metallic ferroelectric PtBi2, where both interlayer-parallel and interlayer-antiparallel polarization configurations are energetically stable. The EE coefficient in interlayer-parallel states, which can be reversed by polarization switching, arises from competing electron- and hole-pocket contributions near the
Fermi surface. The intrinsic SHE coefficients originate from
spin Berry
curvature that can be reshaped by polarization configuration variation and
Fermi-level tuning. Our results establish ferroelectric
bilayers as an all-in-one platform for electrically programmable charge-
spin conversion.
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Strongly Correlated Electrons
Bond-operator analytical approach for the $t$-$J$ model
A. V. Syromyatnikov
We present a bond-operator theory (BOT) for analytical consideration of the $t$-$J$ model and its extensions with longer-rage hopping terms. This technique is based on previously suggested representation of electron operators via localized
spins 1/2 and spinless
Fermi-operators of mobile holons which requires no constraint between them. We introduce a representation of operators of
spins, holons, and electrons in (extended) unit
cell containing several
lattice sites via a zoo of Bose- and
Fermi-operators acting in the
Hilbert space of all
quantum states of the whole unit
cell. BOT provides a regular expansion of physical quantities in powers of $1/n$ using conventional diagrammatic technique, where $n\ge1$ is the maximum number of introduced quasiparticles (
bosons and
fermions) which can occupy a unit
cell. The suggested representation reproduces commutation
algebra of all operators at any $n>0$ and allows to consider both magnetically ordered and disordered phases. Some elementary excitations described in the BOT by separate
bosons or
fermions appear in common approaches as bound states of conventional quasiparticles. In particular, there are two-hole bound states (Cooper pairs of two holes) which are described within the BOT by separate
bosons. We discuss in detail properties of the $t$-$J$ model on the square
lattice with no more than two holes (polarons). Although the expansion parameter $1/n$ is not small in the physically meaningful case of $n=1$, we obtain a good quantitative agreement with previous numerical findings at $n=1$ even in the first order in $1/n$ after taking into account a few simple diagrams. Self-consistent calculations in the first order in $1/n$ bring our results to a very good quantitative agreement with previous numerical findings of the ground state energy, staggered magnetization, and spectra of
magnons, polarons, and lowest-energy two-hole bound states.
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High Energy Physics (Experiment)
Machine-learned particle flow as a foundation model for collider physics
Farouk Mokhtar, Joosep Pata, Michael Kagan et al. (+1 more)
The workflow from particle collision to physics analysis passes through a series of reconstruction steps that are traditionally modular and disconnected, with no shared representation linking low-level detector data to high-level analysis tasks. We show that casting event reconstruction as a machine learning problem naturally produces such a shared representation. We repurpose a machine learning model trained for particle-flow reconstruction (MLPF) to perform three distinct analysis tasks: jet
flavor identification, jet energy regression, and missing momentum regression. By appending the per-particle latent representations learned during reconstruction as additional input features, we substantially improve over baselines that use conventional particle-level features alone. We further demonstrate that a single linear layer trained using only the latent representations achieves competitive performance against state-of-the-art baseline architectures, and outperforms the baseline for missing momentum regression with approximately 35 times fewer parameters. These results demonstrate that the latent representations learned during reconstruction encode essential physics information needed for downstream analysis, establishing MLPF as a foundation model and offering a concrete step toward an end-to-end pipeline from detector data to physics analysis.
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All authors Farouk Mokhtar, Joosep Pata, Michael Kagan, Javier Duarte
Earth and Planetary Astrophysics
Dust and coma radicals in C/2024 E1 (Wierzchos): evolution of the activity
Irene Mariblanca-Escalona, Pedro J. Gutiérrez, Fernando Moreno et al. (+1 more)
We present multi-epoch R-band imaging and long-slit spectroscopy of the dynamically new comet C/2024 E1 (Wierzchos) during its pre-perihelion phase, spanning heliocentric distances from 4.5 to 2.3 au. The most prominent fluorescence emissions in the visible wavelength range are detected. We measure production rates of CN, C$_2$, and C$_3$, while no significant NH$_2$ signal is identified. In our
dataset, CN became detectable at 3.48 au, and C$_3$ and C$_2$ at 2.80 au. The mean ratios $\log\mathrm{C}_2/\mathrm{CN} = 0.00 \pm 0.07$ and $\log\mathrm{C}_3/\mathrm{CN} = -1.03 \pm 0.09$ place the comet in an intermediate taxonomic regime between typical and carbon-depleted populations.
Dust production rates, ejection velocities, and particle size distributions are constrained using a Monte Carlo
dust tail model that reproduces the observed coma morphology. The
dust population is characterized by a power-law size distribution with an exponent of $\sim -3.5$, and particle sizes ranging from 1~$\mu$m to 4~mm. The inferred initial ejection velocities span from $\sim$20$ m $s$^{-1}$ to $\sim$100$ m $s$^{-1}$. We use the empirical relation between CN and OH to estimate the water production rate and derive the
dust-to-gas mass ratio for heliocentric distances $r_{\rm{h}} \lesssim 3$ au, where water sublimation is expected to dominate the activity regime. The
dust-to-gas mass ratio remains consistently above unity, ranging from $\sim$1 to 3 depending on the choice of scale lengths and the CN–OH conversion factor. This result characterizes C/2024 E1 as a “
dust-rich” comet, where the mass loss is dominated by the refractory component rather than volatiles.
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All authors Irene Mariblanca-Escalona, Pedro J. Gutiérrez, Fernando Moreno, Luisa M. Lara
Soft Condensed Matter
Spherical metadensity functional learning for inhomogeneous classical fluids
Stefanie M. Kampa, Matthias Schmidt and Florian Sammüller
We develop classical density functional learning to address fluids with truncated pairwise interparticle interactions in three-dimensional spherical geometry. Simulation data for systems with randomized repulsive pair potentials provide the basis for supervised training of a neural metadensity functional, thereby making efficient use of results for radial distribution functions in the bulk fluid via the test particle route. Specifically, we develop spherical local learning in order to represent the one-body direct correlation functional in terms of a neural network, which captures spatial
curvature effects as well as the metadensity functional dependence on the thermally scaled pair potential. The framework yields efficient access to inhomogeneous structuring and related physical phenomena that occur in fluids and general solvents when adsorbed against curved solutes and confined inside of spherical and planar cavities. Test particle setups facilitate accurate prediction of the bulk fluid pair structure and verification of thermodynamic test particle sum rules via functional line integration. Applying the metadensity functional for Henderson inversion allows one to infer accurately the pair potential from the bulk radial distribution function. We address implications of the geometrical setup for two-body quantities and obtain the two-body direct correlation functional from automatic differentiation. For the hard sphere fluid, we confirm metadensity functional predictions against results from a standard neural density functional with fixed pair potential as well as to an analytic functional as given by fundamental measure theory. Simulation results provide further reference and corroborate reliable results of the spherical neural metadensity functional across a broad range of applications.
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Quantum Physics
Certification of the genuine resolution of photon number resolving detectors
Jef Pauwels, Towsif Taher, Roope Uola et al. (+3 more)
Photon-number-resolving (PNR) detectors are essential components of photonic
quantum technologies, yet thus far, no practical metric exists to certify how many
photons they can genuinely resolve in a single measurement. Here we introduce an operational framework for quantifying the capability of a PNR detector to distinguish between different numbers of
photons, i.e. its genuine resolution. In turn, we develop a practical and scalable protocol for certifying the genuine resolution of a detector, which is based on coherent state probes. We apply the method to a 28-pixel
photon-number-resolving superconducting nanowire single-
photon detector (PNR-SNSPD) and certify genuine four-outcome resolution. Our work highlights the critical requirements in terms of detector efficiency towards achieving high genuine resolution. This approach provides an operational
benchmark for PNR detectors and fills a crucial gap in the characterization of photonic
quantum devices.
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All authors Jef Pauwels, Towsif Taher, Roope Uola, Boris Korzh, Nicolas Brunner, Pavel Sekatski
High Energy Astrophysical Phenomena
Simulating observed point-symmetric core-collapse supernova morphologies with the jittering jets explosion mechanism
Jessica Braudo, Amir Michaelis, Muhammad Akashi et al. (+1 more)
We conduct two three-dimensional hydrodynamic simulations of the jittering-jets explosion mechanism (JJEM) of core-collapse
supernova (CCSN), launching three pairs of inclined opposite jets into the core of an enveloped-stripped
stellar model, and reproduce some morphological features of observed CCSN remnants (CCSNRs) that a single pair of jets or instabilities alone cannot reproduce. We launch the three pairs of jets within about a second, and follow the ejecta for more than 10 seconds until after shock breakout. Our main findings are: (1) Although the jets are choked deep inside the
star, they manage to form a pronounced multipolar (point-symmetric) morphology. (2) Instabilities and
vortices resulting from the jet-
star interaction form small clumps and narrow filaments, some of which form point-symmetric morphology, resembling some observed CCSNRs. (3) The most energetic jet of one simulation forms a large low-density blowout ahead of the ejecta, with filaments dragging behind it, resembling the blowout of the Cygnus Loop. (4) The inner ejecta presents two
symmetry axes along two of the three jet axes: one of a pair of rings and one of a pair of nozzles, resembling the structure of the point-symmetric SNR J0450.4-7050. (5) The three pairs of jets compress two dense blocks between their axes. The blocks exhibit a Doppler-shift bipolar
outflow highly inclined to the morphological axes along the jet axes. The inclined Doppler-bipolar
outflow and morphology axis resembles the CCSNRe W49B and SNR G292.0+1.8. Our study supports the claim that the JJEM is the primary explosion mechanism of CCSNe.
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All authors Jessica Braudo, Amir Michaelis, Muhammad Akashi, Noam Soker
Quantum Physics
Quantum-Classical Hierarchical Equations of Motion
Amartya Bose
We develop a
quantum-classical hierarchical equations of motion (QC-HEOM) approach for simulating non-Markovian open
quantum systems. The method combines the ensemble-averaged classical path reference of the
quantum-classical path integral formalism with a hierarchy of auxiliary
quantum influence functionals. By incorporating thermal fluctuations through an ensemble average over reference trajectories, the hierarchy is required to represent only the residual
quantum memory associated with the imaginary part of the bath response function. Consequently, unlike conventional hierarchical equations of motion, QC-HEOM does not require Matsubara or Padé expansions of the thermal kernel and exhibits only weak temperature dependence of the hierarchy size. Furthermore, because thermal fluctuations are supplied through reference classical trajectories, the framework naturally extends beyond harmonic baths and enables the incorporation of anharmonic and molecular environments through externally generated trajectories. We derive the formalism and demonstrate its exactness for a harmonic bath. Applications to an asymmetric
spin-
boson model and the seven-site Fenna–Matthews–Olson complex illustrate the accuracy of QC-HEOM. It reproduces
benchmark quasi-adiabatic path integral and hierarchical equations of motion results while requiring substantially fewer auxiliary objects, particularly at low temperatures. These results establish QC-HEOM as an efficient framework for treating residual
quantum memory in
quantum-classical descriptions of open-system dynamics. The separation of thermal fluctuations from residual
quantum memory through the use of Wigner trajectories provides an approximate route toward hierarchical treatments of complex anharmonic environments that are inaccessible to conventional HEOM approaches.
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High Energy Physics (Experiment)
Search for dark photons from Higgs boson decays in the gluon-gluon fusion channel in proton-proton collisions at $\sqrt{s}=13.6$ TeV with the ATLAS detector
ATLAS Collaboration
This paper presents a search for semi-visible
Higgs boson decays in final states with a
photon ($\gamma$) and missing transverse momentum $p_T^{miss}$. The analysis is optimised for the
gluon-
gluon fusion production channel and exploits a novel trigger deployed in 2023, with reduced thresholds down to 50 GeV on the
photon transverse momentum ($p_T^{\gamma}$) and 70 GeV on the $p_T^{miss}$, in combination with a selection on the transverse mass of the $p_T^{miss}$-$\gamma$ system ($m_T$) above 80 GeV. The results are interpreted in terms of
Higgs boson decays into a $\gamma$ and a dark
photon $\gamma_d$ ($H \to \gamma \gamma_d$). The analysis is performed using 135 fb$^{-1}$ of Run 3 data collected by ATLAS in 2023 and 2024. A boosted decision tree is used to identify events with misreconstructed primary vertices, which can affect the $p_T^{miss}$ calculation. Data-driven methods are employed to estimate the backgrounds from jets and electrons misidentified as
photons, while the backgrounds with genuine
photons are taken from Monte Carlo simulations, normalised to data in control regions with
muons. A binned maximum-likelihood fit to the $m_T$ distribution is performed to evaluate the compatibility of the observed data with the Standard Model expectation. No significant excess is observed over the Standard Model prediction, and an observed (expected) upper limit on the branching ratio of $H \to \gamma \gamma_d$ of 1.4% (1.2%) is obtained at 95% confidence level. Combining this result with previous Run 2 searches improves the observed (expected) upper limit to 0.9% (0.9%).
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Solar and Stellar Astrophysics
Gravity-mode main-sequence pulsators in the open clusters NGC 3532 and NGC 2516: Instability strip, near-core rotation, and internal structure
Gang Li, Chenyu He, Joey S. G. Mombarg et al. (+2 more)
Context. Studying pulsating
stars in clusters opens a new window onto
stellar physics.
Gravity-mode (g-mode) pulsators in open clusters allow us to measure their near-core rotation rates and, together with cluster age and mass constraints, test angular momentum transport in
stars above about 1.5
solar masses. Aims. We aim to detect g-mode pulsations in member
stars of the young open cluster NGC 3532, about 300 Myr old, and to measure their near-core rotation rates and internal properties. Methods. We used TESS photometry to extract light curves of NGC 3532 members. The observed g-mode period spacings allow us to measure near-core rotation rates and the asymptotic period spacing, Pi0. We also fitted isochrones to the colour-magnitude diagrams of NGC 3532 and NGC 2516 to refine the cluster ages and obtain
stellar masses. Results. We constrain the observed instability region of young gamma Doradus members from a blue edge at about 7760 K to a red edge at about 7070 K, while some hotter g-mode pulsators are also seen. The near-core rotation rates show a rotation-mass relation similar to that in NGC 2516: below 1.6
solar masses, the rotation rate increases with mass, whereas above 1.6
solar masses the NGC 3532
stars reach a plateau at about 2.8 d^-1. This mass may mark a threshold between different rotational
spin-down mechanisms. Existing evolutionary models with angular momentum transport imply that these g-mode pulsators were born rotating above 55 percent of the critical value. Our simplified models, assuming spherical
symmetry, angular momentum conservation, and rigid internal rotation, suggest that either mass-dependent initial rotation rates are required, or that minor angular momentum loss still operates above 1.6
solar masses. Finally, our Pi0 measurements reveal a discrepancy with theoretical predictions for some pulsators, as also found in the younger cluster NGC 2516.
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All authors Gang Li, Chenyu He, Joey S. G. Mombarg, Dario J. Fritzewski, Conny Aerts
Quantum Gases
Modeling light-matter coupled systems with neural quantum states
Noe Salmeron, Marin Bukov and Markus Schmitt
Recent advances in cold atom manipulation enable the study of many-body systems where short-range interactions between neighboring atoms coexist with long-range interactions mediated by
photons. Such a combination of interactions makes a theoretical approach challenging beyond mean-field methods. In this work, we develop a neural
quantum state based approach to study these systems numerically. We introduce a neural-network architecture capable of handling hybrid
Hilbert spaces with large local bosonic dimensions in strongly interacting
spin-
photon systems. We
benchmark this approach on a model of a two-dimensional
lattice of Rydberg atoms coupled to a
photon mode. The superradiant ground states found in the large
spin-
photon coupling regime allow us to demonstrate the efficiency of the method in the presence of high
photon occupation. Furthermore, the ability to capture
spin-
spin and
spin-
photon correlations leads us to observe quantitative deviations in the ground state phase boundaries with respect to mean-field theory. The method extends to other systems with a similar hybrid
Hilbert space structure, such as
spin-
phonon systems, and provides a scalable framework for investigating their ground state properties.
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Lattice Field Theory
Finite-volume effects on smeared spectral densities
Francesca A. Bresciani, Mattia Bruno and Maxwell T. Hansen
Using two distinct approaches, we derive a universal expression for the leading finite-volume effects of the smeared vector-vector spectral density (proportional to the smeared hadronic $R$-ratio) in a periodic cubic spatial volume of side length $L$. First, building on the results of previous work for finite-volume effects on Euclidean two-point functions, we show that the $L$ dependence is exponentially suppressed for a certain class of smearing kernels, and that the leading effects can be expressed universally in terms of the pion form factor. The same representation is then derived starting from the Lellouch-Lüscher-Meyer expression for the spectral decomposition of the correlator. The results may prove useful for controlling the $L \to \infty$ extrapolation of smeared spectral densities, in particular by defining a scaling regime in which the finite-volume effects are dominated by the leading terms in a large $L$ expansion and thus can be reliably estimated. To illustrate this point, we also present numerical estimates based on various kernels and models of particle interactions. Despite focusing on the vector channel, our derivation defines a general framework applicable to other cases as well.
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Physics and Society
Detecting Historical Turning Points in Italian Media: A Complex Systems Approach to a Diachronic News Corpus
Dario Zarcone, Salvatore Miccichè and David Sanchez
Introduction: The increasing availability of large-scale textual corpora has opened new possibilities for data-driven, quantitative approaches to historical analysis using Natural
Language Processing (NLP). However, diachronic corpora with historical relevance from the pre-digital era remain scarce and often incomplete. Methods: We present a quantitative approach to historical analysis based on the reconstruction and exploration of a diachronic corpus of around 600,000 articles from the Italian newspaper "La Repubblica", covering all the articles published from the first of January 1985 to the 31st of December 2000 - a period of major political, social, and geopolitical change in Italy and globally. Using NLP techniques, we analyze the text at both lexical and semantic levels; we then apply tools from complex systems and statistical physics to trace shifts in media discourse over time. Results: The word usage in the corpus is bursty, with a heavy-tailed distribution of Fano factors that is robust across timescales. Changepoints in word salience and the block structure of semantic similarity allow us to detect key transition periods, such as the transition from the First Republic to the Second Republic in Italy, or major international conflicts like the Gulf War or the Kosovo War, without relying on prior labeling. Periods of war correspond to lower
entropy in the semantic space, indicating a more focused discourse. Discussion: The results show how combining computational linguistics with ideas from complex systems can offer new quantitative insight into historical changes, opening up new paths for studying the dynamics of media and society through large-scale textual data.
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Optics
Chirally-sensitive optical rectification by isotropic chiral media
Raju Adhikary, Luca Assogna, Ambaresh Sahoo et al. (+8 more)
Chiroptical sensing is central to gain fundamental insight into electronic, vibrational and rotational degrees of freedom of
chiral molecules, and is a cornerstone for nanomedicine and drug discovery platforms. Current
chiral sensing technologies to assess the enantiomeric imbalance of
chiral pharmaceutical compounds are sensitive to ml volumes but are time-consuming and cannot be integrated on a chip, thus creating a major bottleneck for drug discovery and nanomedicine. Here, we propose a novel chiroptical sensing approach based on optical rectification in a photonic micro-cavity filled by a drug solution with nl volume. We theoretically demonstrate that, upon optical excitation by intense pulsed
laser light, such a nonlinear effect produces a chirally-sensitive nV voltage burst at the electrically-gated micro-cavity boundaries, with sign depending solely on the drug enantiomeric imbalance. Our results shed light on the potential of optical rectification as a robust platform for innovative lab-on-a-chip devices enabling
chiral sensing with nl sensitivity.
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All authors Raju Adhikary, Luca Assogna, Ambaresh Sahoo, Matteo Venturi, Andrea De Marcellis, Massimiliano Aschi, Antonio Mecozzi, Jens Biegert, Davide Tedeschi, Carino Ferrante, Andrea Marini
Fluid Dynamics
Flow behind the Imperial Front Wing: comparison of results from volumetric PTV experiment and Nektar++ simulations
Isabella Fumarola, Alexandra I. Liosi, Parv Khurana et al. (+4 more)
High-fidelity simulations are increasingly adopted, due to advances in computational power and methods such as Direct Numerical Simulation (DNS) and hybrid Large-Eddy Simulation (LES). These approaches are particularly valuable for unsteady flows around complex geometries at high Reynolds numbers; however they still require careful experimental validation. Planar and stereo Particle Image Velocimetry (PIV) are widely used for measurements but limited by measurement-plane selection and their ability to capture
vortices shapes and trajectories. This motivates the growing interest in volumetric techniques, historically difficult to implement in industrial settings. Recent advances in Particle Tracking Velocimetry (PTV) for measuring flows over large volumes make this approach suitable for validating numerical simulations of complex flows.This study compares volumetric PTV measurements against high-fidelity LES to assess the capabilities and limitations for industrial flows. The aim is to establish a
benchmark PTV
dataset for motorsport aerodynamics using the Shake-The-Box
algorithm. The experiment was carried out in the 10x5 wind tunnel at Imperial College London equipped with a rolling road for ground effect simulation and capable of testing up to 50% scale F1 model. Volumetric PTV measurements were performed downstream of the open-source Imperial Front Wing (IFW) at Re=74896. Results are compared with planar PIV studies and implicit LES simulation using spectral h/p elements in Nektar++. This work addresses open questions in the literature concerning the wake of the IFW. Good quantitative agreement is observed in the wake
topology. A previously unreported
vortex is identified which has the key role of preventing the merging of other dominant structures. These results demonstrate the suitability of PTV and STB for industrial applications while providing a
benchmark dataset for the IFW.
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All authors Isabella Fumarola, Alexandra I. Liosi, Parv Khurana, Adam Meziane, Isaac Balbolia, Sherwin J. Spencer, Jonathan F. Morrison
High Energy Astrophysical Phenomena
Multiwavelength Analysis of the Einstein Probe X-ray Transient EP240305a
Ruican Ma, Ye Li, Lian Tao et al. (+32 more)
We report multiwavelength observations of EP240305a, an uncatalogued X-ray transient detected by the Einstein Probe on March 5, 2024. The source exhibits distinct characteristics across the X-ray, optical, near-infrared, and
radio bands. The soft X-ray observations show two significant
flares lasting ~100-250 s, accompanied by rapid flux decay in a few days, and the optical and near-infrared data reveal a faint, candidate counterpart. In contrast, the
radio observations expose a long-term spectral
evolution from a self-absorbed to an optically thin state within two months, implying discrete jet ejection. We compare EP240305a with known classes of X-ray transients and find that it is unlikely to be associated with long-timescale transients such as jetted
tidal disruption events or X-ray binaries. Its properties also disfavor a short-timescale
stellar flare origin. Although the absence of optical spectroscopy prevents a
redshift determination, the source exhibits properties similar to those of gamma-ray-dark gamma-ray burst-like transients, which may be associated with relativistic jets viewed off-axis or with choked jets. The discovery of EP240305a, along with other uncataloged transients detected by the Einstein Probe, underscores the scientific potential of highly sensitive X-ray survey
telescopes and rapid-response multiwavelength follow-up observations in exploring the nature of atypical astronomical transients.
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All authors Ruican Ma, Ye Li, Lian Tao, Tao An, Ailing Wang, Arne Rau, Roberto Soria, Huaqing Cheng, Jing Wang, Hua Feng, Yuanqi Liu, Seán Brennan, Jingran Xu, Dave Buckley, Philip Charles, YuPeng Chen, Francesco Coti Zelati, Sebastien Guillot, Long Ji, Chengkui Li, Jinzhong Liu, Yuan Liu, Pierre Maggi, Itumeleng Monageng, Yanan Wang, Yanjun Xu, Guobao Zhang, Qingchang Zhao, Diego Altamirano, Peter Jonker, Nanda Rea, Xiaofeng Wang, Xuefeng Wu, Weimin Yuan, Shuangnan Zhang
Quantum Gases
Mass-imbalanced two-dimensional Bose-Fermi mixtures with boson-fermion pairing
Cristiano Luigi Kosman Chiarappa, Pietro Bovini and Pierbiagio Pieri
We analyze a two-dimensional Bose-
Fermi mixture at zero temperature in the presence of a tunable Bose-
Fermi attraction. We adopt a diagrammatic T-
matrix approach and study the behavior of several thermodynamic quantities for the two species as functions of density, mass ratio, and coupling strength. These include the chemical potentials, the
boson momentum distribution function, the condensate density, and Tan's contact parameter. We analytically demonstrate that the present T-
matrix formalism recovers the correct second-order perturbative expansion of the chemical potentials in the weak-coupling regime, and test it numerically. The near-universal behavior of the condensate fraction already found in prior work for the mass-balanced case is confirmed for different masses and becomes even more accurate when the
boson mass is large. The mass imbalance emerges as an additional control parameter that qualitatively affects the bosonic momentum distribution. In particular, we found that it can be used to allow for the experimental observation of a peculiar peak in the
boson momentum distribution at finite momentum.
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