Mathematical Physics
A quantum-like model of political consensus via non self-adjoint Hamiltonians
Fabio Bagarello and Gloria Liarda
We discuss here how non self-adjoint
Hamiltonians, and their related Heisenberg-like dynamics, can be used to model a political system consisting in a coalition $\C$ of different parties (forming a government) and by their (original) supporters $\Sc$. Our aim is to model how the opinion of these supporters changes depending on the efficiency, competence and coherence of the coalition $\C$, as these are perceived by $\Sc$ during their action while governing. After a rather general introduction we propose three specific models, and we describe and comment the dynamical behaviour of the { full} system, $\Sc\cup\C$. The role of the so-called balanced
Hamiltonians, recently introduced by the authors in connection with integrals of motion, is discussed in details.
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Instrumentation and Methods for Astrophysics
Embedding Equity, Diversity, and Inclusion in the WST Collaboration
Laurane Fréour, Anna Puglisi, Maria Cristina Fortuna et al. (+11 more)
The proposed Wide-field Spectroscopic
Telescope (WST) is a next-generation
telescope facility with a 12-meter primary mirror that may be operational in the 2040s. The project has a broad range of scientific goals and engages a large Community of more than 1000 members across multiple time zones, institutions, career stages, and professional roles. As for any large-scale scientific collaboration, building WST is therefore not only a technical and scientific challenge, but also a social and organisational one. This is particularly important in Astronomy and STEM disciplines more broadly, where marginalized groups remain underrepresented, particularly in leadership positions. In this paper, we describe the creation and first year of activity of the WST Equity, Diversity, and Inclusion (EDI) working group. We discuss how the group has worked to embed EDI considerations into the early phases of the Collaboration, and we present our ongoing and future projects aimed at broadening participation, accountability, and community sustainability, while delivering groundbreaking science. We also reflect on the challenges of sustaining EDI work in a large and rapidly evolving collaboration, including recognition of EDI contribution, uneven participation, communication across heterogeneous groups, and the need to connect facility-level initiatives with broader organisational and territorial responsibilities. We present our activities as a situated example of how EDI can be approached as part of the governance, communication, and community infrastructure required to build sustainable research environments.
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All authors Laurane Fréour, Anna Puglisi, Maria Cristina Fortuna, Fatemeh Zahra Majidi, Umberto Rescigno, Amelia Bayo, Francesca Primas, Sabine Thater, Laurence Tresse, Stephanie Escoffier, Letizia P. Cassarà, Roland Bacon, Sofia Randich, Vincenzo Mainieri
Mesoscale and Nanoscale Physics
From Localized Packets to Plane Waves: A Time-Domain Approach to Transport in Mesoscopic Systems
Andrzej Biborski
Quantum transport in mesoscopic systems is conventionally formulated within the Landauer–Büttiker scattering framework, where steady-state currents emerge from the transmission of plane waves representing propagating carriers. While highly successful, this description obscures the explicit time-domain dynamics of individual fermionic excitations and their role in establishing macroscopic transport. Here, we present an exact and self-contained time-domain construction of Landauer transport based on a discrete basis of orthogonal fermionic wave packets. Starting from a second-quantized formulation, we define packet creation operators via a continuous
Fourier transform over a finite transport energy window. By encoding the Pauli exclusion principle, which enforces a fundamental temporal spacing $\Delta t = h/eV$, the current is reproduced in terms of orthogonal wave packets that are used for the rigorous construction of the many-body fermionic state. In this representation, a noiseless current emerges as a deterministic sequence of charge-carrying events, yielding the Landauer conductance $G_0 = e^2/h$ without invoking momentum-space kinematics. We further demonstrate that this construction remains exact for arbitrary energy dispersion. Additionally, the underlying Fock space decomposition into finite disjoint energy sub-bands renders the numerical approach highly scalable for high performance computing platforms. Our results establish a direct and rigorous bridge between the continuous scattering description of
quantum transport and a discrete, time-resolved picture based on fermionic wave packets.
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Quantum Gases
Observation of anyonic thermodynamics and generalized Pauli principle
Fansu Wei, Chi Zhang, Zimeng Ye et al. (+4 more)
Anyons are quasiparticles with
quantum statistics interpolating between those of
bosons and
fermions. Two distinct manifestations of anyonic behaviour have been theoretically established: fractional exchange statistics where particle exchange can produce any phase, and generalized exclusion statistics which extends the Pauli exclusion principle. While anyons exhibiting fractional exchange statistics have been observed in diverse platforms, experimental realizations of generalized exclusion statistics and direct measurements of its thermodynamic signatures have remained elusive. Here, we realize an anyonic thermodynamic ensemble obeying generalized exclusion statistics and detect its anyonic thermodynamics in a one-dimensional strongly interacting
quantum gas. To achieve this, we exploit the bijective mapping between dynamical and statistical interactions in one dimension. By tuning interaction strength and temperature over a wide range, we measure the equation of state and identify clear departures from Bose-Einstein and
Fermi-Dirac statistics. These deviations are quantitatively captured by generalized exclusion statistics, providing direct evidence for the generalized Pauli principle. Independent probes of other thermodynamic quantities including pressure and the Tan contact further validate this framework. Our results establish a versatile platform for engineering anyonic exclusion statistics and open the door to thermodynamic applications of anyons in
quantum technologies.
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All authors Fansu Wei, Chi Zhang, Zimeng Ye, Dengbo Wang, Botao Wang, Xiaoji Zhou, Hepeng Yao
Instrumentation and Methods for Astrophysics
Characterisation of the NewAthena WFI's DEPFET Flight Production's Operational Parameters
Léonie Sommer, Johannes Müller-Seidlitz, Valentin Emberger et al. (+9 more)
NewAthena's Wide Field Imager (WFI) uses detectors made up from Depleted P-Channel Field Effect Transistor (DEPFET) pixels operated in rolling shutter mode. The Large Detector Array (LDA) contains a 2 $\times$ 2 array of 512 $\times$ 512 pixels Large Detectors (LDs) allowing for a field of view of 40' $\times$ 40' with a frame time of 2 ms while the 64 $\times$ 64 pixels Fast Detector (FD) can observe very bright X-ray sources due to a faster frame time of 0.08 ms. Prototype sensors (64 $\times$ 64 pixels) were used to analyse the sensor's operational range and to optimise the ASIC and DEPFET parameters i.e. current and voltage settings, as well as the DEPFET read-out timing parameters, resulting in an improved energy resolution, reduced noise and otherwise improved sensor characteristics.
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All authors Léonie Sommer, Johannes Müller-Seidlitz, Valentin Emberger, Robert Andritschke, Astrid Mayr, Annika Behrens, Günter Hauser, Peter Lechner, Christian Sandow, Anna Schweingruber, Jonas P. Reiffers, Elif Kutdemir Öncü
Mathematical Physics · Cross-listed from math.DG
Linear Hamiltonians in generators of the real Jacobi group on the extended Siegel-Jacobi space and equations of motion attached
Elena Mirela Babalic and Stefan Berceanu
Using the energy function on the extended Siegel-Jacobi upper half space of order $n$, $\tilde{\mathcal{X}}^J_n$, with $n\in \mathbb{N}$, the equations of motion in the variables $(x,y,q,p,\kappa)$ attached to linear
Hamiltonians in the generators of the real Jacobi group $G^J_n(\mathbb{R})$ are presented, where $x,y$ are symmetric
matrices in $\mathcal{M}(n,\mathbb{R})$ and $p,q$ are real $n$-vectors. The case $n=1$ is presented separately.
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Astrophysics of Galaxies
Searching for a superdisk in radio galaxy J0116-473
Ankur Sinha, Riya Rathore, Narendra Nath Patra et al. (+1 more)
Superdisks have emerged as an active area of research in recent years, and J0116-473 represents a promising target for studying this extended structure. Our primary objective was to search for HI absorption associated with the suspected superdisk. However, no such absorption feature was detected, suggesting a low, or absence of neutral hydrogen content in the superdisk. In addition, we examined a compact point source located near the
galaxy's core and the presumed plane of the superdisk, enabling us to search for HI absorption against this background continuum. We also present a detailed multi-band morphological analysis of the
galaxy using
Giant Metrewave
Radio Telescope (GMRT) observations in Bands 3, 4, and 5. A spectral analysis of both the
galaxy and the nearby point source was carried out using data from these three frequency bands. A systematic steepening of the spectral index is observed from the core toward the lobes, as expected for aging synchrotron-emitting
plasma. We also found that the northern inner lobe exhibits a significantly steeper spectrum than its southern counterpart, possibly reflecting environmental effects associated with the proposed superdisk. Since superdisks are expected to contain hot, ionized gas, we additionally examined archival X-ray observations from the XMM-Newton
telescope. Although diffuse X-ray emission associated with the
radio lobes is visible, no significant emission is detected from the region corresponding to the suspected superdisk.
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All authors Ankur Sinha, Riya Rathore, Narendra Nath Patra, Abhirup Datta
Fluid Dynamics
Intermittency in Shell Models of Turbulent Cascades: from Single-Branch to Multi-Branch
Flavio Tuteri, Sergio Chibbaro and Alexandros Alexakis
Intermittency is one of the central features of turbulent transfer: the multi-scale energy cascade is mediated by rare and intense fluctuations. We investigate this phenomenon in a multi-branch shell model, which combines quasi-local triadic nonlinear interactions with a branching structure that mimics the growth of degrees of freedom toward small scales. Comparison with the standard Sabra model shows that branching enhances intermittency, as measured by anomalous scaling exponents of energy-flux structure functions. We further use multiplier statistics and large deviation estimates to characterize the multiplicative nature of the cascade. Our results suggest that reduced descriptions of turbulent intermittency should retain both nonlinear dynamics and geometrical organization. Implications on Navier-Stokes
turbulence are discussed.
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Quantum Physics
Measurement-enabled online quantum processing with amplitude encoding
Giacomo Franceschetto, Pere Mujal and Rodrigo Martínez-Peña
We introduce a
quantum reservoir computing online protocol that realizes amplitude encoding on
quantum hardware. Our scheme combines mid-
circuit measurement and reset operations to implement the partial-trace dynamics underlying amplitude encoding, while an indirect measurement scheme provides access to reservoir observables without interrupting temporal processing. In contrast to other approaches, our method preserves online operation, avoids input buffering, and keeps the runtime linear in the number of time steps. We present the theoretical formulation of the protocol and a proof-of-principle implementation on
quantum hardware, and we evaluate its performance on two standard
benchmark tasks. Our results show that the reservoir dynamics can be monitored through both direct measurements of the input
qubits and indirect measurements of the
memory qubits, enabling observation of the full system while isolating the internal
evolution of the reservoir. This work provides a practical route toward scalable hardware implementations of amplitude-encoded
quantum reservoir computing and opens the door to systematic experimental studies of complex
quantum reservoirs.
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Medical Physics
Quantitative Multi-Modal Optical Coherence Photoacoustic Elastography
Ekaterina Sherina, Lisa Krainz, Wolfgang Drexler et al. (+1 more)
We present a novel multi-modal optical coherence photoacoustic elastography framework, which combines two imaging modalities, optical coherence
tomography and photoacoustic
tomography, to enable complementary absorption-scattering measurements for the extraction of quantitative tissue features via quasi-static elastography. For this, we develop a sophisticated hybrid inversion
algorithm for merging the complementary information layers contained in both optical coherence and photoacoustic-based elastography measurements, and perform systematic evaluations to assess the impact of hybrid elastography data on strain and stiffness reconstructions. An extension to a photoacoustic
tomography and optical coherence
tomography imaging system allows precise elastographic experiments. Studies on a silicone elastomer phantom demonstrate that the combined optical coherence - photoacoustic approach outperforms single-modality optical coherence elastography and photoacoustic elastography, yielding higher strain signal-to-noise ratios and improved stiffness estimates. These results establish the advantage of multi-modal complementary imaging and data merging for accurate, high-resolution elastographic strain and stiffness mapping in both scattering and absorbing materials.
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All authors Ekaterina Sherina, Lisa Krainz, Wolfgang Drexler, Otmar Scherzer
Cosmology and Nongalactic Astrophysics
From Evidence to Evident: Decisive Cosmological Evidence for the Normal Neutrino Mass Hierarchy
Raul Jimenez, Carlos Peña Garay, Fergus Simpson et al. (+1 more)
Cosmological data have reached the precision needed to turn the
neutrino mass ordering from a weak
Bayesian preference into a decisive model-selection test. We compute the evidence for the Normal and Inverted Hierarchies by combining DESI DR2 clustering with NuFIT oscillation data. In baseline $\Lambda$CDM, DESI DR2 plus Planck CamSpec gives $\Sigma m_\nu<0.0642\,{\rm eV}$ at 95% confidence, close to the normal-ordering floor, $\Sigma m_\nu^{\rm NH}\simeq0.059\,{\rm eV}$, but well below the inverted-ordering minimum, $\Sigma m_\nu^{\rm IH}\simeq0.099\,{\rm eV}$. Thus the inverted hierarchy lies in the tail of the cosmological likelihood. The Bayes factor $K=P(D|{\rm NH})/P(D|{\rm IH})$ exceeds $460$ even for a conservative reference prior, and remains strong, $K>40$, in baseline-model extensions. We show that this result is robust to the choice between a reference prior and a physically motivated logarithmic hierarchical prior, marking the transition from prior-sensitive evidence to likelihood-dominated exclusion of the inverted hierarchy within standard cosmology.
Embedding these priors in the two-dimensional design space of measure (logarithmic versus linear in mass) and structure (hierarchical versus non-hierarchical), we find that all four prior constructions give decisive evidence under DESI DR2, with residual prior dependence governed mainly by the measure – a factor $\sim\!10$ in $K$ – rather than by the hierarchy assumption. At the prior-family level, the evidence favors the SJPV prior predictive over HS by a Bayes factor above $4,700$ across each matched-support variation tested. The favored normal ordering pushes the effective Majorana mass to the few-meV regime, with median $m_{\beta\beta}=3.28\,{\rm meV}$ and 95% credible interval $0.95<m_{\beta\beta}<11.55\,{\rm meV}$, below the inverted-ordering target for upcoming neutrinoless double-beta decay experiments.
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All authors Raul Jimenez, Carlos Peña Garay, Fergus Simpson, Licia Verde
Mathematical Physics
A finite element-based eigenvalue analysis for predicting thermal runaway in Li-ion battery packs
Shailendra Rahi, Vinay Dhakal, Ankur Jain et al. (+1 more)
Thermal runaway remains a critical safety concern in battery systems and other thermally active devices, necessitating reliable methods for predicting the conditions under which thermal runaway may occur. In this work, we develop a finite element framework for assessing thermal stability in systems undergoing transient heat conduction with temperature-dependent internal heat generation. The formulation leads naturally to a generalized
eigenvalue problem, wherein the sign of the smallest
eigenvalue provides a direct criterion for determining the onset of thermal runaway. This approach enables direct prediction of thermal runaway thresholds in geometrically complicated problems without requiring computationally expensive transient analysis. The proposed methodology is validated through comparison with analytical solutions for a cylindrical Li-ion
cell, as well as with a pack of cylindrical
cells, demonstrating excellent agreement in both cases. Based on this model, the influence of material properties, boundary conditions,
geometric parameters, and spatially varying heat generation on stability limits is examined. A key advantage of this formulation is its effectiveness even for complex geometries where analytical methods become impractical. By providing a systematic and computationally efficient means to identify stability thresholds, the present work offers a practical tool for the thermal design and safety assessment of battery systems.
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All authors Shailendra Rahi, Vinay Dhakal, Ankur Jain, Manish Agrawal
Quantum Physics
Probing chaos and thermalization through out-of-time-ordered correlators in random field spin chains
C Jisha, Shivam Mishra and Ravi Prakash
Out-of-time-ordered correlators (OTOCs) have emerged as a diagnostic of information scrambling and
quantum chaos in many-body systems. We investigate the imprints of chaos in the dynamics of OTOCs in the Heisenberg
spin-$1/2$ chain with random fields. The system is parameterized to exhibit a crossover from integrable to chaotic dynamics. We demonstrate numerically that the approach to saturation of the OTOC can distinguish between integrable and chaotic regimes, with a power-law $(1/t)$ relaxation for integrable systems and a higher-degree power-law decay $(1/t^\alpha; \alpha \ge 1)$ followed by an exponential relaxation for the chaotic regime. We further show that long-range spectral statistics, such as the number variance, are more effective in characterizing
quantum chaos in the regime near saturation of OTOC. We also demonstrate that the relaxation and initial scrambling regimes exhibit distinct and universal features, with the former being sensitive and the latter being robust against different realizations of random-fields. The long-time saturation of OTOC also fluctuates with different realizations, and its exact expression is derived through the Eigenstate Thermalization Hypothesis.
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Cosmology and Nongalactic Astrophysics
On the robustness of the angular homogeneity scale $\theta_H$: a comparative analysis of computational approaches
Pedro Fanha, António da Silva, José Fonseca et al. (+2 more)
The assumption of large-scale homogeneity is a cornerstone of modern cosmology and underlies the validity of the FLRW framework. Testing the scale at which the Universe transitions to homogeneity remains a key observational challenge, particularly with the increasing precision of
galaxy surveys. We aim to assess the robustness of the angular homogeneity scale, $\theta_H$, by systematically comparing different computational approaches used in its estimation and by quantifying the impact of methodological choices and physical clustering scales. We analyse mock
galaxy catalogues from the MICE Grand Challenge simulation. The angular fractal dimension $D_2(\theta_H)$ is computed using the Landy-Szalay
estimator and direct pair-counting methods. We implement different approaches, including symbolic regression, to model $D_2(\theta_H)$ and determine $\theta_H$. Uncertainties are estimated using resampling techniques and alternative parametric error propagation methods. We find that the estimation of $\theta_H$ is sensitive to methodological choices in the analysis, such as survey area,
redshift bin, numerical implementation and fitting strategy. While its
redshift evolution is robust, its absolute value is sensitive to both modelling choices and the presence of local clustering features. Our results highlight the importance of methodological systematics in homogeneity studies, showing that the determination of $\theta_H$ depends not only on the data, but also on the adopted analysis strategy. Flexible approaches such as symbolic regression provide a useful framework to model these effects, but also emphasize the need for careful modelling and survey design. This has important implications for future large-scale structure analyses aiming to test the Cosmological Principle with high precision.
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All authors Pedro Fanha, António da Silva, José Fonseca, José Pedro Mimoso, Ziad Sakr
Strongly Correlated Electrons
Emergence of Resonating Valence-Bond Correlations in Stretched Graphene
Sam Azadi, A. Principi, T. D. Kühne et al. (+1 more)
Electronic correlations in
graphene are generally considered weak due to the large bandwidth of its $\pi$ electrons. Here we show that tensile expansion of the honeycomb
lattice provides a direct route to enhancing correlation effects. Using variational and
diffusion quantum Monte Carlo, we compare a conventional Jastrow-Slater determinant wave function with a resonating-valence-bond (RVB) Jastrow-antisymmetrized geminal product ansatz for a series of stretched
graphene lattices. We find that the energy gain of the RVB state relative to the single-determinant description increases with bond expansion up to a critical strain $\delta_{\mathrm{cr}}$, and decreases beyond it, revealing a nonmonotonic
evolution of electronic correlations. The crossover is found to occur in the range $15\% < \delta_{\mathrm{cr}} < 20\%$, in agreement with mechanical stability limits. This behavior indicates a transition from a weakly correlated Dirac semimetal to a regime with enhanced non-dynamic correlation and short-range singlet pairing. Our results provide direct many-body evidence that
lattice expansion drives
graphene into a regime where RVB-like correlations become energetically favorable, offering a simple route to tuning correlation effects in Dirac materials.
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All authors Sam Azadi, A. Principi, T. D. Kühne, M. S. Bahramy
Solar and Stellar Astrophysics
A Candidate Low-mass Disk-eclipsing Binary in the ~316 Myr Open Cluster UPK 13
Jiamao Lin, Yongkang Sun and Chengyuan Li
UPK~13-c2 is a candidate member of the $\sim$316~Myr open cluster UPK~13 and was previously classified as a white
dwarf + main-sequence (WD$+$MS) binary with 99.44% confidence. We present multi-band photometric evidence that it is instead more plausibly a late-K/early-M binary with a misaligned circumbinary disk. The photometry reveals a flat-bottomed eclipse at $P=36.71$~days with an approximately achromatic $\sim$40% flux decrement from the optical through $W1$, a reduced $W2$ depth, and a prominent mid-infrared excess at $W3/W4$. Two independent diagnostics strongly disfavor the WD$+$MS interpretation. First, the flat eclipse floor and 2.5-day ingress require complete occultation of an extended
stellar component; a white
dwarf would cross the disk edge in $\lesssim$2~hr and cannot naturally reproduce the observed multi-day trapezoid. Second, the difference spectrum is well fit by a single $\sim$4000~K thermal spectral energy distribution, favoring a late-K/early-M
dwarf over a white
dwarf as the occulted source. A decoupled SED decomposition yields a template-based late-K/early-M binary estimate of M1V+K9V with $M_{\rm tot}\approx1.4\,M_\odot$ and an overall systematic uncertainty of about 20%. Under a sharp-edge eclipse model, forward modeling of the light curve favors an eccentric, spatially localized occulting structure. The light-curve morphology places UPK~13-c2 in the same
geometric class as KH~15D and Bernhard-2. If cluster membership is confirmed, UPK~13-c2 may be the oldest known main-sequence disk-eclipsing binary.
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Materials Science
Projected altermagnetism by symmetry reduction at surfaces and in thin films
Sopheak Sorn, Charanpreet Singh, Lukasz Plucinski et al. (+3 more)
Altermagnets are a newly identified class of
magnetic materials that combine vanishing net magnetization within the unit
cell with
spin-split electronic states. Their theoretical description relies on
symmetry properties of the bulk band structure. Surfaces and thin films, however, inherently break these
symmetries. Here, we investigate the consequences of such
symmetry reduction for the electronic structure of bulk altermagnets near the surface and of thin films. When the surface coincides with a
symmetry plane of the bulk altermagnetic order, the resulting two-dimensional Brillouin zone exhibits
spin-degenerate bands, corresponding to conventional
antiferromagnetic behavior. In all other cases, the
symmetry of the altermagnetic order is reduced, leading to modified
spin splitting. Remarkably, we discover a thin-film geometry of a $g$-wave altermagnet with a particular surface orientation that enables a $d$-wave
spin splitting, which is commonly accompanied by the
spin-splitter effect, suggesting the functionalization of non-$d$-wave altermagnets by surfaces. Our findings demonstrate that
symmetry breaking at surfaces and in thin films fundamentally reshapes altermagnetic
spin textures, providing a tunable platform for controlling
spin-dependent electronic phenomena.
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All authors Sopheak Sorn, Charanpreet Singh, Lukasz Plucinski, Gustav Bihlmayer, Yuriy Mokrousov, Wulf Wulfhekel
High Energy Astrophysical Phenomena
The flash-ionised SN Ibn 2025kzr: H-free CSM formed during a precursor outburst 55 days prior to explosion
S. de Wet, G. Leloudas, D. A. H. Buckley et al. (+33 more)
Type Ibn
supernovae (SNe) are a class of interacting SNe characterised by narrow helium lines in their spectra. We present an extensive observational
dataset of the Type Ibn SN 2025kzr at 51 Mpc, including the discovery of a precursor outburst with a peak brightness of M_r~-13.6 mag beginning ~55 days before explosion. Our photometry indicates the SN was discovered within the first day of explosion, showing fast-rising, ultraviolet-bright emission peaking at M_r=-19.26+/-0.09 mag and a peak blackbody temperature of T~29000 K, consistent with shock breakout within a region of dense and confined circumstellar material (CSM). Our high-cadence spectroscopic
dataset spanning 1.9-58.5 days post-explosion shows flash-ionised emission features during the first 10 days. In our SALT spectrum at 3.8 days we observe a pronounced blueshift of the He II lines by 460 km/s compared to the He I lines at zero velocity, while a Pickering-decrement analysis reveals a CSM that is fully hydrogen-free. The timing of the disappearance of the flash features combined with the CSM velocity of 1500 km/s imply a mass-loss event ~66 days before explosion, in close agreement with the timing of the precursor observed 55 days before explosion and strongly suggestive of a physical link. We derive a CSM mass of 0.03-1.7 M_sun and a corresponding high mass-loss rate >~10^{-1} M_sun/yr. The precursor timescale and energetics suggest an extreme mass-loss event that might be explained by wave-driven mass loss during the late stages of
nuclear burning, in particular the oxygen-burning phase. Overall, we favour a single massive Wolf-Rayet progenitor with M_ZAMS~30-40 M_sun to explain SN 2025kzr, although a binary origin cannot be excluded.
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All authors S. de Wet, G. Leloudas, D. A. H. Buckley, N. Erasmus, P. J. Groot, E. A. Zimmerman, P. Chen, Y. Tampo, M. Pursiainen, T. Killestein, F. Stoppa, G. K. Jaisawal, A. Gal-Yam, K. Maeda, J. Anderson, T.-W. Chen, M. Gromadzki, C. P. Gutiérrez, E. Kankare, T. E. Müller-Bravo, T. Pessi, S. Smartt, J. Sollerman, L. Tartaglia, D. R. Young, M. R. Alarcon, K. W. Smith, H. F. Stevance, T. de Boer, K. Chambers, C.-C. Lin, T. B. Lowe, P. Minguez, M. Nicholl, G. S. H. Paek, R. J. Wainscoat
Instrumentation and Methods for Astrophysics
WST Multi-Object Spectrograph Fiber Positioners:Development of a 32,000-Unit Precision Robotic System
Sébastien Pernecker, Maxime Rombach, Malak Galal et al. (+13 more)
The Wide-field Spectroscopic
Telescope Multi-Object Spectrograph requires an unprecedented fiber positioning system comprising 30'000 low-resolution and 2'000 high-resolution positioners across a 3.1 deg squared field of view. Each robotic positioner must achieve 5um RMS positioning accuracy in a densely packed focal plane, representing a more than sixfold scale increase over current instruments like 4MOST and DESI. To mitigate risks associated with industrial-scale production of 32'000 precision mechanisms, WST is pursuing a multi-concept development strategy. Four distinct positioner architectures are being prototyped and tested by an international collaboration (EPFL, AIP, UKATC, AAO) using 6.2 mm pitch triangular modules of 63 units each or a new inline modular concept. Performance metrics including positioning accuracy, repeatability, reconfiguration speed, collision avoidance, and manufacturability are being systematically evaluated. Down-selection to one or two concepts is planned for 2026-2027 during the HORIZON Europe-funded conceptual study phase. Current prototype testing demonstrates feasibility of meeting specifications, supporting WST's path toward first light in the early 2040s as ESO's next major spectroscopic facility.
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All authors Sébastien Pernecker, Maxime Rombach, Malak Galal, Jonathan Wei, Oliver Pineda Suárez, David Lee, Steve Watson, Younes Chahid, Chris Waring, Anmol Goyal, Joseph W. Barrow, Will Saunders, Jon Lawrence, Aaron Omadutt, Roelof S. de Jong, Jean-Paul Kneib
Disordered Systems and Neural Networks
Suppression of Extrinsic Anomalous Hall Conductivity in Disordered Parity Anomalous Semimetal
Shi-Hao Bi, Bo Fu and Shun-Qing Shen
We present an analytical investigation of the extrinsic contributions to the anomalous
Hall conductivity in the context of the half-quantized
Hall effect observed in disordered parity anomalous semimetal emerged from semi-
magnetic topological
insulator thin films. The gapless Dirac cone surface state, which embodies the quintessence of the half-quantized
Hall effect, exhibits remarkable robustness against disorder scattering. Two primary extrinsic mechanisms, the side-jump and skew-scattering, are deemed irrelevant and make no contributions. These results establish the parity anomalous semimetal as a disorder-resilient
quantum phase, thereby providing insights into Dirac
fermion physics.
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Solar and Stellar Astrophysics
The Quiet-Sun DEM Under Kappa: Diagnostic Degeneracy and the Failure of the Conductive Closure
Victor Edmonds
For a
plasma whose electrons carry a $\kappa \approx 2.5$ suprathermal tail, the Spitzer-Harm conductive closure does not exist: the conductive flux is the tail-carried third velocity moment, and the local conductivity integral diverges across the entire $\kappa \in [2,3]$ range – the finite value the closed-form $\kappa$-conductivity returns at $\kappa = 2.5$ is an analytic continuation of a divergent integral, not a physical conductivity. Edmonds (2026a) places the quiet
solar corona (QS) in this regime. Taking that as premise, two failures follow for any
plasma in the class: the standard EUV-DEM diagnostic cannot resolve such a
plasma, and the conductive term of the standard QS energy budget has no valid form. The diagnostic failure is shown end-to-end. A single-T $\kappa = 2.5$ probe, a multi-T $\kappa = 2.5$ source, and a multi-T Maxwellian source, all run through the regularized DEM inversion of Hannah & Kontar (2012), recover $\log T$ widths inside the FWHM distribution the same pipeline returns from 80 real quiet-Sun AIA patches; the pipeline cannot distinguish them. Two structural features also emerge: a Fe XI charge-state crossover and an EUV continuum reversal. The ionization-gated diagnostic structurally returns the tail-weighted effective temperature $T_{\mathrm{eff}}$, while Spitzer-Harm takes the bulk-core $T_{\mathrm{core}} = (\kappa - 3/2)/\kappa \cdot T_{\mathrm{eff}}$ as input. The mismatch invites a temperature substitution yielding a budget reduction – mechanically correct and physically empty, because the coefficient it corrects has no convergent form: it is the
Fourier-law closure itself that fails, not its temperature input. Two QS pillars for impulsive heating – DEM-width multi-thermality and the conductive-budget gap – lose their structural assumptions, and the budget question shifts to non-local kinetic transport outside any fluid closure.
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Optics
Thermodynamic-Kinetic Decoupling Enables Stable Excitonic Emission in Defect-Tolerant Cu-Based Quantum Dots
Haoran Chen, Zhipeng Xu, Chunjian Li et al. (+7 more)
Colloidal
quantum dots that simultaneously offer room-temperature single-
photon purity and high photoluminescence
quantum yield are sought for
quantum optics, but remain elusive in environmentally benign materials. We introduce a thermodynamic-kinetic decoupling strategy that transforms defect-tolerant CuInS2
quantum dots into bright, narrowband, and photostable single-
photon emitters. Zn2+ alloying strains the
lattice, thermodynamically suppressing native copper vacancies and narrowing the emission from a broad defect band of approximately 300 meV to an excitonic line of approximately 120 meV. Ga3+ incorporation then kinetically pins the cation sublattice against Cu+ migration, preventing defect regeneration during ZnS shell growth. The resulting Cd-free core/shell dots achieve near-unity
quantum yield of approximately 98% while retaining narrow excitonic emission. Critically, room-temperature single-dot spectroscopy reveals homogeneous linewidths as low as approximately 58 meV, strongly suppressed blinking, and high-purity single-
photon emission with g2(0) = 0.06. This stabilized excitonic emission directly reduces reabsorption losses in luminescent
solar concentrators, yielding an external optical efficiency of 12.68%. Our work establishes a generalizable framework to unlock intrinsic excitonic photophysics in ion-mobile, defect-prone
semiconductors, opening a viable path toward high-performance heavy-metal-free emitters for
quantum light sources.
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All authors Haoran Chen, Zhipeng Xu, Chunjian Li, Lei Hou, Dechao Yu, Xiaobin Xie, Yue Liu, Bohua Dong, Lixin Cao, Chenghui Xia
Earth and Planetary Astrophysics
TransitNet: A Compact Attention-Augmented Deep Learning Framework for Low-SNR Transit Blind Searches
Xingchen Yan, Jian Ge, Qingtian Liu et al. (+3 more)
Motivated by the observational incompleteness of intermediate-to-long-period Earth-size
planets, we present TransitNet, a compact
attention-augmented deep-learning framework for low-SNR transit blind searches. To enable realistic method development and objective threshold calibration under blind-search conditions, we develop a unified
dataset construction, benchmarking, and threshold-selection framework. On recovery
benchmarks constructed from unseen Kepler targets, TransitNet attains 95.2 percent accuracy in the challenging SNR range of 6 to 8 and outperforms both TLS and BLS, achieving ROC-AUC and PR-AP values of 0.974 and 0.982, respectively. In an injected Earth-size and sub-Earth-size transit recovery experiment, TransitNet achieves a recovery rate of 93.0 percent, substantially exceeding those of TLS (63.1 percent) and BLS (60.0 percent). In addition to detection, TransitNet provides
attention-based estimates of transit windows and midpoints. On an independent evaluation set, 97.4 percent of injected transits are fully covered by the estimated transit window. Applied to real Kepler observations, the model successfully recovers all 34 selected confirmed Kepler
planets, with a mean absolute transit midpoint error of 1.24 hours. The model combines a compact footprint of about 1.5 MB with high inference efficiency, yielding speed-ups of about 12 to 25 times relative to CPU-TLS and about 4 to 5 times relative to CPU-BLS. These results demonstrate that TransitNet provides an accurate, scalable, and computationally efficient framework for low-SNR transit blind searches in the tested regime and motivate its extension to longer-period Earth-size
planet searches.
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All authors Xingchen Yan, Jian Ge, Qingtian Liu, Kevin Willis, Quanquan Hu, Jiapeng Zhu
Superconductivity
The electric-field-driven intermediate state of three-dimensional superconductors
Ion Cojocari, Enzo Andreani, Paola Verniere et al. (+5 more)
The coexistence of superconductivity and finite electric fields may enable access to intriguing forms of electronic states. We demonstrate the emergence of an intermediate state in which electric fields penetrate the system while superconductivity still persists. Our measurements reveal a nonclassical regime characterized by the simultaneous presence of supercurrent and dissipative charge transport. This state, realized in a pristine unpatterned three-dimensional system, arises from electric-field-driven order parameter fluctuations. It provides a platform to explore dissipative states of charged
quantum fluids far from
equilibrium.
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All authors Ion Cojocari, Enzo Andreani, Paola Verniere, Florian Pallier, Marc Gabay, Miguel Monteverde, Claire Marrache-Kikuchi, Shamashis Sengupta
High Energy Physics (Theory)
Higher-Trace Operators and Cut Diagrammatics in the Conformal Block Expansion
Mohammad Reza Khansari
We study four-point functions of identical scalar operators in conformal field theories with AdS duals in large-$N$ expansion. We analyze the appearance of higher-trace operators in theories dual to bulk $\phi^3$ and $\phi^4$ interactions, focusing on how these operators are required by crossing
symmetry. We compute part of the OPE data associated with these operators. We also introduce a diagrammatic framework for organizing the different terms in the conformal block expansion within the large-$N$ expansion. This framework refines the use of crossing
symmetry by allowing it to be applied to individual diagrammatic
topologies, rather than only to the full correlator. It further separates different contributions to the OPE data by associating them with different cut diagrams. In this
language, the emergence of higher-trace operators and their relation to lower-trace OPE data become more manifest.
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Instrumentation and Methods for Astrophysics
Advancing Control Electronics for Next-Generation Astronomical Fiber Robotic Positioners
Sebastien Pernecker, Jonathan Wei, Maxime Rombach et al. (+3 more)
Next-generation spectroscopic surveys require compact, high-density fiber robotic positioner systems achieving 5um precision, placing strict constraints on the size and the power budget of the control electronics. We present a compact control electronics architecture that drives 21 theta phi SCARA positioners (42 BLDC motors) on a single board, representing a significant increase in complexity compared to the electronics used in ongoing surveys such as SDSS V and DESI, where each positioner relies on dedicated hardware. The design integrates power distribution, CAN communication, and a synchronization line for simultaneous motion in high-density environments. Sensorless Field Oriented Control with collision detection and mechanical and
magnetic hard-stop calibration enables accurate positioning without
Hall sensors or encoders, reducing system cost and complexity. We describe the system architecture and performance validation, demonstrating that the module meets precision requirements while reducing the space required for control electronics and improving energy efficiency for future survey instruments.
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All authors Sebastien Pernecker, Jonathan Wei, Maxime Rombach, Oliver Pineda Suarez, Tarik Ibrahimovic, Jean-Paul Kneib
Fluid Dynamics
APU-Accelerated Large Eddy Simulation with the Discontinuous Galerkin Solver GALÆXI
Spencer Starr, Anna Schwarz, Justin Du Plessis et al. (+5 more)
The exascale computing era, driven by heterogeneous GPU architectures, requires a fundamental redesign of traditional CFD solvers to fully leverage those heterogeneous systems. The discontinuous Galerkin spectral element method (DGSEM) provides an ideal foundation for this transition due to its high-order accuracy and local computational stencil. This work presents recent advances in the development and application of the architecture-agnostic DGSEM framework GALÆXI by linking hardware optimization, software implementation, and physical validation. The performance of GALÆXI on the AMD MI300A Accelerated Processing Units (APUs) featured on the Hunter supercomputer is analyzed. Specifically, evaluations of the strong and weak scaling performance and the impact of the compute partitioning modes available on the AMD MI300As are performed. Second, the strategy used to integrate the
algorithms necessary for wall-modeled large eddy simulations into the GPU-accelerated framework is outlined. Validation of those
algorithms is presented in the form of a plane turbulent channel testcase. Finally, the solver is applied to a demanding flow problem in the form of a wall-resolved large eddy simulation of a transonic compressor cascade. The results from this investigation demonstrate the capabilities of GALÆXI to accurately capture complex shock-wave/turbulent boundary-layer interactions.
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All authors Spencer Starr, Anna Schwarz, Justin Du Plessis, Andreas Wanninger, Johanna Hintz, Rohan Kaushik, Patrick Kopper, Andrea Beck
Materials Science
Spin-orbit coupling renormalization of the natural optical activity of Pb5Ge3O11 from first-principles
Asier Zabalo, Massimiliano Stengel and Eric Bousquet
We present a first-principles study of the natural optical activity of the gyroelectric Pb$_5$Ge$_3$O$_{11}$
crystal, explicitly accounting for
spin-orbit coupling (SOC) effects. We derive a new analytical expression for the gyration coefficients within the recent framework of long-wavelength density-functional perturbation theory [Phys. Rev. Lett. 131, 086902 (2023)], which significantly improves computational efficiency by reducing the number of required response functions and includes
spin-orbit coupling effects. We use this implementation to investigate the
evolution of Pb$_5$Ge$_3$O$_{11}$'s optical rotation across the ferroelectric double-well, from the paraelectric $P\bar{6}$ phase to the ferroelectric $P3$ phase. Our results demonstrate that, in addition to the substantial renormalization of the double-well energy,
spin-orbit coupling contributions play an equally crucial role in the natural optical activity, largely through purely electronic contributions, while SOC-induced structural relaxation effects are minor.
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Quantum Physics
Exceptional-Point-Anchored Variational Quantum Eigensolver for Non-Hermitian Many-Body Phase Diagrams: Bridging Skin-Effect Topology and Entanglement Criticality on NISQ Hardware
Akoramurthy B, Surendiran B and Xiaochun Cheng
We introduce the Biorthogonal Variational
Quantum Eigensolver (B-VQE), a
quantum algorithm for simulating non-Hermitian many-body systems on noisy intermediate-scale
quantum (NISQ) hardware. Non-Hermitian
quantum matter exhibits exceptional points, parity-time
symmetry breaking, and non-Hermitian skin effects, yet existing
quantum algorithms often rely on costly post-selection procedures and are not designed to capture biorthogonal eigenstates. B-VQE employs independent variational
circuits to represent the left and right eigenstates of a non-Hermitian
Hamiltonian and optimizes a biorthogonal objective function that directly tracks non-Hermitian phase transitions. The framework incorporates an Exceptional-Point Detector (EPD) that identifies exceptional points through a hardware-native coalescence metric and a Non-Hermitian
Quantum Geometric Tensor (NH-QGT) readout that distinguishes state-topological and band-topological signatures in interacting many-body systems. To overcome the exponential overhead associated with conventional non-Hermitian simulation, we develop an importance-sampling mitigation strategy that removes the need for ancilla-based post-selection while retaining
polynomial computational scaling. We validate the approach on three representative models: a non-Hermitian Hubbard chain, a non-Hermitian XXZ
spin chain, and a two-dimensional non-Hermitian (t)-(J) model. B-VQE achieves relative energy errors below (5\times10^{-3}) and locates exceptional points with high accuracy on noise-free simulations while resolving phase boundaries associated with localization,
quantum scars, and skin-effect physics. These results establish B-VQE as a scalable NISQ methodology for constructing non-Hermitian many-body phase diagrams and exploring topological and critical phenomena in open
quantum systems.
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Instrumentation and Methods for Astrophysics
Testing of a 15-Positioner Module Based on the MPS Design for Stage-5 Telescopes
Jonathan Wei, Oliver Pineda Suárez, Malak Galal et al. (+6 more)
Assessing the performance metrics of theta-phi micro-robotic positioners is a key step toward understanding their operational behavior and ensuring that they meet the specifications of Stage-5 astronomical facilities, including the Chinese MUST, the American Spec-S5, and the European WST. A detailed examination of these metrics enables a clear evaluation of the system's current capabilities while also revealing aspects that require further refinement, which in turn guides improvements in design and manufacturing. In this work, carried out in collaboration with Micro Precision Systems (MPS) in Switzerland, we present the results of positioning performance and angular tilt characterization conducted on a 6.2-mm-pitch robotic positioner module developed for high-density fiber placement in next-generation spectroscopic instruments. The prototype unit evaluated in this study was produced by MPS. The measured metrics, including positioning repeatability, datum repeatability, backlash, non-linearity, and angular tilt, are compared directly with the nominal performance targets defined for Stage-5
telescope systems.
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All authors Jonathan Wei, Oliver Pineda Suárez, Malak Galal, Maxime Rombach, Sébastien Pernecker, Stefane Caseiro, Corentin Magnenat, Florian Boeckle, Jean-Paul Kneib