Quantum Physics
Learning sparse quantum states from single-qubit measurements
Su-un Lee, Liang Jiang and Kunal Sharma
We study the problem of learning a sparse
quantum state, an $n$-
qubit quantum state whose density
matrix has at most $s$ nonzero
matrix entries in an unknown product basis. While such states admit compact classical descriptions, they can carry long-range
entanglement that prevents reconstruction from local reduced density
matrices alone. Therefore, previous learning approaches addressed such long-range-entangled states using many entangling gates to extract the necessary information. In this work, we show that sparse states can nevertheless be efficiently learned using only single-
qubit measurements. Specifically, when the sparsity $s$ is constant, our
algorithm can learn sparse states from single-
qubit measurements with
polynomial sample complexity and classical computational complexity. When $s$ grows polynomially with $n$, sparse states can still be learned from single-
qubit measurements with
polynomial sample complexity, although efficient classical computation is not guaranteed in general. In this regime, however, the classical computational complexity becomes quasipolynomial when the state is sparse in an unknown basis that is a product of a known fixed finite set of single-
qubit bases (e.g., eigenbases of Pauli operators). These results establish efficient learning of sparse states with long-range
entanglement without entangling gates, and the single-
qubit measurement requirements make our
algorithms compatible with current
quantum devices.
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Materials Science · Cross-listed from cs.LG
Bounding Retraining Equivalence and the Deletion Floor in Materials Machine Unlearning
Can Polat, Mustafa Kurban, Erchin Serpedin et al. (+1 more)
In materials machine learning, closely related retained structures can sustain accurate property predictions even after removing a specific record, rendering post-deletion prediction error an ambiguous metric for machine unlearning. To resolve this ambiguity, we define the deletion floor as the expected target loss under a specified retraining procedure at the deleted request. Standard indistinguishability constraints yield a sharp interval bounding an update's target loss around this baseline reference. Theoretically, a conditional neighbor bound links a low deletion floor directly to retained fit, prediction regularity, and local label agreement, while an exact ridge identity isolates residual fit from the prediction change induced by record deletion. Empirically, controlled redundancy sweeps show an $\approx 8\times$ drop in median normalized retraining loss when one retained relative remains after deletion. Across two distinct fitting regimes in a paired Materials Project study, the lower-floor regime also exhibits a larger prediction change on more than 50% of the shared requests. Systematic comparisons against approximate updates and the original model decouple deliberate target suppression from preserved overall model utility. Consequently, request-level unlearning evaluations should report reference loss, prediction change, and retained utility together, interpreting post-deletion accuracy against what retraining itself leaves behind.
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All authors Can Polat, Mustafa Kurban, Erchin Serpedin, Hasan Kurban
Quantum Physics
Succinct Arguments for QMA from Collapsing Hash Functions
James Bartusek and Giulio Malavolta
We prove the existence of succinct arguments for QMA, assuming only the existence of collapsing hash functions. This is the first scheme that relies only on unstructured “Minicrypt” assumptions, which are not known to imply public-key encryption. Our main technical contribution is a
quantum-succinct claw-state generation protocol that allows us to bootstrap a small number of
quantum correlations into an arbitrarily large number of claw-state correlations, using classical communication only. This improves upon the work of [Zhang, STOC 2021], having better round complexity, a proof in the standard model, and being overall much simpler. This yields a
quantum-succinct blind delegation of
quantum computation protocol from one-way functions, which we plug into the communication-compression compiler of [Bartusek, Liu, and Malavolta, EUROCRYPT 2026] to obtain succinct arguments for QMA.
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Mathematical Physics · Cross-listed from math.DS
Uniqueness of four-body convex central configurations for all masses
Tejasvi Singh Tomar
We prove that for every choice of four positive masses and every cyclic ordering of the bodies there is exactly one strictly convex planar central configuration with that ordering, up to similarity. This answers Problem 10 in the list of Albouy, Cabral and Santos, which Santoprete calls the Simó-Yoccoz
conjecture. The main step is a uniform lower bound for the Hessian at convex central configurations: it is at least one quarter of its radial part, which vanishes only on translations and rotations. Dziobek's relations turn the indefinite part of the Hessian into a negative multiple of a square, and a Cauchy-Schwarz argument bounds this term by the radial part times the trace of an explicit $2\times 2$
matrix in which the masses do not appear. We prove that this trace is less than 3/4 by interval arithmetic on the three-dimensional set of normalized convex central configurations, in the coordinates of Corbera, Cors and Roberts. Uniqueness then follows by a covering argument from the case of four equal masses. The computation has been repeated with a second, independently written program. The Hessian bound and the uniqueness
theorem, including the computation, have been formalized in the Lean proof assistant and checked by its kernel, using only the standard axioms. As consequences, every degenerate four-body central configuration is concave, the convex central configuration depends analytically on the masses, and the known
symmetry theorems for kites, isosceles trapezoids and rhombi follow in a few lines. The analytic dependence and the
symmetry theorems are also formalized.
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Instrumentation and Detectors
Electrothermal behavior of superconducting nanowires buried in a commercial CMOS process
Mohamed Gharib, Leonid Popryho, Salma Abdelzaher et al. (+14 more)
Superconducting films native to a commercial CMOS process enable co-integration of superconducting devices (high-kinetic-inductance elements and nanowire detectors) with cryogenic CMOS on one monolithic die. Such films are buried in the front-end-of-line, beneath the back-end-of-line metal stack, an environment that might quench a self-heated hot spot. Current-voltage characteristics are reported for titanium nitride (TiN) nanowires in the polycrystalline-silicon resistor layer of a 22 nm FD-SOI process, and measured retrapping currents are compared with thermal models for longitudinal conduction to the contacts and interfacial
phonon cooling into the stack. The wires are strongly hysteretic, with switching-to-retrapping current ratios I_sw/I_r of 7.4-9.8, sustaining a normal hot spot. For two wires of length ell = 50 micrometers and widths W = 0.50 and 1.00 micrometers, over bath temperatures T_b = 0.15-1.19 K, I_r follows the interfacial form (T_hs^n - T_b^n)^(1/2) with n = 4 (T_hs, the effective hot-spot temperature), and is strongly inconsistent with the (T_hs - T_b)^(1/2) constant-kappa longitudinal-conduction limit; free-exponent fits give n = approximately 4.8-5.0. An effective cooling coefficient Sigma_K = 7.9(3) W/(m^2 K^4) describes the data: 31(21) times below the acoustic- (diffuse-) mismatch value for a single clean interface, and approximately 12 times below the lowest previously reported comparable nanowire coefficient. The model-based film thermal conductivity is kappa = approximately 20 mW/(m K). Across lengths ell = 1-50 micrometers, I_r matches neither ell^(-1) of pure longitudinal conduction nor ell^0 of pure interfacial cooling; a two-channel model reproduces I_r(ell) with crossover length ell* = approximately 3.5 micrometers predicted, to an O(1) prefactor, from Sigma_K and kappa.
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All authors Mohamed Gharib, Leonid Popryho, Salma Abdelzaher, Tejas Guruswamy, Tomas Polakovic, Umeshkumar Patel, Orlando Quaranta, Thomas Cecil, Clarence Chang, Yu-Sheng Chen, Thomas H. Swift, Grayson M. Noah, Alberto Gomez-Saiz, John J. L. Morton, M. Fernando Gonzalez-Zalba, Antonino Miceli, Inna Partin-Vaisband
Earth and Planetary Astrophysics
JWST NIRSpec G395H Transmission Spectra of Two Similar Sub-Neptunes in the TOI-125 System
Yiwei Chai, Néstor Espinoza, Chloe Fisher et al. (+10 more)
The James Webb Space
Telescope (JWST) has enabled the first in-depth characterisations of sub-Neptune atmospheres, revealing a diversity of chemical compositions and cloud properties that challenge current models. Multi-
planet systems provide an opportunity to compare planetary atmospheres while controlling for formation conditions within the same protoplanetary disk. We present JWST NIRSpec G395H 3-5 um observations of two similarly-sized sub-Neptunes orbiting a sun-like
star within the TOI-125 system: TOI-125 b ($P=4.65$ d, $R_p=2.7~R_\oplus$, $M_p=10~M_\oplus$, $T_\mathrm{eq}=1100$ K) and TOI-125 c ($P=9.15$ d, $R_p=2.85~R_\oplus$, $M_p=6.8~M_\oplus$, $T_\mathrm{eq}=825$ K), comprising of one full transit of TOI-125 b but only 70% of TOI-125 c's transit due to larger than predicted TTVs. We obtain precise R~100 transmission spectra for both
planets, with median errorbars of 50 ppm for TOI-125 b and 85 ppm for TOI-125 c. Atmospheric
retrievals are compatible with a ~150x
solar metallicity atmosphere or clouds above ~3 mbar for TOI-125 b, and a ~100x
solar metallicity atmosphere or clouds above ~10 mbar for TOI-125 c. Our results may support recent evidence for metal enrichment in sub-Neptunes, while also further complicating the proposed trend in atmospheric feature size with
planet temperature. However, shorter wavelength follow-up observations of both
planets are needed to establish whether their spectra are truly muted or feature-rich, with implications for the nature of sub-Neptunes around sun-like
stars.
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All authors Yiwei Chai, Néstor Espinoza, Chloe Fisher, Erik Meier Valdes, Matthew Hooton, Brett Morris, Natalie H. Allen, Adam J. Burgasser, Brice-Olivier Demory, Amélie Gressier, Kevin Heng, Mercedes López-Morales, Meng Tian
High Energy Physics (Theory)
Symmetric Amplituhedra I: Spinor Helicity
Ran J. Tessler
For every pair of integers $0\leq k\leq N,$ and and every subgroup of $D_N\times\mathbb{Z}_2$, we construct the nonnegative symmetric Grassmannian, which is the subspace of the nonnegative Grassmannian fixed under that group, where the dihedral part acts on columns (with a sign correction to keep nonnegativity) and the $\mathbb{Z}_2$ factor exchanges a space with its orthocomplement (again, with a sign correction). This construction generalizes the earlier constructions of \cite{Karpman2018,Fraser2020,Shevchenko2025}. We study the geometry of this space. Then, when $k$ is further restricted to the range $[2,N-2]$ we also define a symmetric amplituhedron. We analyze its basic properties and its conjectural BCFW decomposition. The ABJM and reflected Lagrangian amplituhedra are the special cases corresponding to the groups $\{1\}\times\mathbb{Z}_2,$ and the group generated by a reflection combined with the exchange,
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Strongly Correlated Electrons
Chiral Weyl–Kondo semimetal and circular photogalvanic effect in a prototype Kondo lattice system
Yuan Fang, Kuan-Sen Lin, Mounica Mahankali et al. (+5 more)
Chiral Weyl–Kondo semimetals (cWKSM) provide a setting in which
chiral Weyl quasiparticles emerge in the immediate vicinity of the
Fermi energy from a Kondo-driven reconstruction of the strongly correlated electronic states in
chiral heavy
fermion systems (K.-S. Lin et al., arXiv:2602.22185). A defining characteristic of this strongly correlated topological state is the Kramers
chiral Weyl
fermions in the low-energy quasiparticle states. Recently, experiments in CeGaGe have emerged as a concrete realization of the proposed effect (Arushi et al., preprint). Motivated by these findings, here we go beyond the materials-specific effects by constructing a prototype Kondo
lattice model; it incorporates only the essential couplings that respect the associated tetragonal crystalline
symmetries. This simplification allows us to robustly demonstrate the
symmetry-enforced Kramers Weyl
fermions and related topological nodal states in the spectrum of heavy quasiparticles. Furthermore, the simplification provides a tractable setting to determine the salient features in the system's nonlinear optical response, the circular photogalvanic effect, in
chiral Weyl–Kondo semimetals. Both analytical and numerical calculations identify sharp peaks in the frequency domain as signatures of the Kondo-driven
chiral Weyl nodes; the sharpness of the spectrum reflects the resonant nature of the underlying strongly correlated electronic excitations. Thus, cWKSM provides a unique setting to spectroscopically identify topological
fermions that are induced by strong electron correlations. As such, our results are expected to bring about much needed new insights into the understanding of strongly correlated gapless topological matter.
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All authors Yuan Fang, Kuan-Sen Lin, Mounica Mahankali, Arushi, Kevin Allen, Sanu Mishra, Emilia Morosan, Qimiao Si
Quantum Physics
Low-Weight Canonical Logical Bases from Pair-Partition Codes
Koki Okada and Kenta Kasai
We construct complete canonical logical bases for
qubit CSS codes by assigning quaternary coefficients to binary circulant permutation
matrix pair-partition (CPM-PP) checks, constructing and normalizing logical representatives, and expanding the result into binary
matrices. When the two check systems have invertible submatrices on disjoint column sets, cofactor representatives are canonically paired by the inverse of a single pairing
polynomial. The resulting pairs span the entire logical space. When the pairing
polynomial is a cyclic-shift monomial with coefficient one, normalization preserves the binary weights of the representatives. We state the construction for general block dimensions and CPM size, work through a corresponding example, and report the parameters, check ranks, and basis weights of seven binary codes. Representative examples have parameters $[[320,80,14]]$, $[[448,112,18]]$, and $[[2048,512,24]]$. All three have maximum check weight 10 on both the X and Z sides. Their canonical logical representatives have binary weights 25, 27, and 27, respectively, on both the X and Z sides.
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Quantum Physics
Exponential lower bounds for low-degree strategies in position-based quantum cryptography
Isabel M. Moreno-Cuadrado, David Perez-Garcia and Carlos Palazuelos
Non-local
quantum computation (NLQC) consists on the implementation of a bipartite
unitary $U_{AB}$ by two cooperating distant players by means of a two-round protocol with a single intermediate round of simultaneous communication. It is a major open question to know whether there exists a
unitary $U_{AB}$ whose implementation in NLQC requires extra
quantum systems with dimensions ${\rm exp}(n^{\Omega(1)})$, where $n$ is the dimension of systems $A$ and $B$. This type of exponential lower bound is essential for security of position-based
quantum cryptography, since the capabilities of the adversaries are precisely described by NLQC. It has also been connected to many other problems, such as the optimality of universal
quantum simulators, or the expected properties of
holographic quantum gravity. Currently the best lower bounds are only sublinear in $n$. In this paper we consider the family of diagonal ${\pm 1}$ valued
unitaries $U_{\varepsilon}$, indexed by an element of the Boolean hypercube $\varepsilon \in \{\pm 1\}^{n^2}$, i.e. $U_{\varepsilon}|i\rangle_A|j\rangle_B =\varepsilon_{ij} |i\rangle_A|j\rangle_B$. We show that if $U_{\varepsilon}$ can be implemented in NLQC with constant accuracy for all $\varepsilon$, and the dependency on $\varepsilon$ in the first round of the associated strategy is a
polynomial of degree $O(n^{\frac{1}{4}-\delta})$, then the implementation of at least one $U_{\varepsilon}$ in NLQC requires resources scaling as $\exp\left(\Omega\left(\frac{n^{2\delta}}{(\log n)^2}\right)\right)$. The proof is based on
geometric properties of particular
Banach spaces, namely their type constants, together with random estimates of Boolean functions valued on them.
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Superconductivity
Periodic Trends and a Physics-Based Multistage Search for High-$T_c$ Hydride Superconductors
Tianran Chen and Taner Yildirim
Hydrogen-rich materials under pressure are candidates for conventional
phonon-mediated superconductivity, but first-principles electron–
phonon-coupling (EPC) calculations are computationally demanding. We develop an interpretable multistage workflow for prioritizing binary hydride
superconductors before full EPC calculations. Using controlled cubic $X_m$H$_n$ prototypes at 200~GPa, we introduce the spectral moment $A_1$ as an intermediate measure of electron–
phonon perturbation strength. In its linewidth-based construction, $A_1$ remains finite as harmonic
phonons soften, allowing related structures with imaginary harmonic modes to be screened; it does not establish superconductivity or physical realizability for unstable structures. For dynamically stable cubic systems, $A_1$ correlates strongly with the H-$1s$ density-of-states fraction at the
Fermi level, $\alpha$, a projected
Fermi-surface descriptor, $\beta$, and atomic number density, $\rho$. These trends are summarized heuristically by $A_1\approx h\alpha\beta\rho$, where $h$ is framework- and pressure-dependent; the descriptor is used for ranking, not as a universal $T_c$ predictor. We incorporate $\alpha\beta\rho$ and enthalpic competitiveness into a three-stage evolutionary search comprising multiobjective structural screening, harmonic-
phonon stability filtering, and coarse density-functional perturbation-theory (DFPT) EPC calculations. Application to more than 100,000 binary hydride structures at 50 and 200~GPa identifies candidates and prioritizes NaH$_6$ structural families. Higher-accuracy calculations show that $Pm\bar{3}m$ NaH$_6$ is dynamically stable down to 50~GPa and has a harmonic Allen–Dynes estimate of $T_c\approx230$~K. The framework combines electronic descriptors with progressively more expensive stability and EPC calculations for scalable hydride exploration.
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Quantum Physics
QC-Stark: A Multi-Task Benchmark Revealing Capability Dissociations in LLMs Evaluated on Quantum Computing Tasks
Pranav Gupta
We introduce QC-Stark, a
benchmark for evaluating large
language models (LLMs) on 11
quantum computing (QC) tasks, spanning
circuit construction, debugging, compilation, error correction, and simulation. Across 2,750 evaluations (10 models $\times$ 11 tasks x 5 difficulty levels x 5 seeds), we find that overall rankings mask substantial per-task variation. The Spearman correlation between overall and per-task rankings is statistically insignificant for 4 out of the 11 tasks included in this
benchmark. A 2-parameter Item Response Theory (IRT) model validates measurement quality, and
prompt sensitivity analysis confirms ranking robustness across
prompt conditions. All tasks are auto-verifiable via execution, thus not requiring any manual evaluation. We make the code and data publicly available on Huggingface.
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Quantum Physics
Quantum Query Complexity Beyond the Worst Case
Srinivasan Arunachalam, Yanlin Chen and Amin Shiraz Gilani
Smoothed analysis is a central framework in classical
algorithms for explaining the performance of
algorithms beyond the worst case, often explaining why
algorithms perform well in practice. We initiate a systematic study of its
quantum counterpart and show the following results. $(1)$ We show that there is a total function whose smoothed
quantum query complexity is exponentially smaller than its classical query complexity. $(2)$ We give near-tight characterizations of smoothed randomized and
quantum query complexities for symmetric Boolean functions, unifying the worst-case complexity results of [Beals et al, FOCS'98] and average-case complexity results of [Ambainis and de Wolf, STACS'00]. $(3)$ We study string problems such as pattern matching and edit distance and, in various regimes, give
polynomial to superpolynomial
quantum speedups. Our main technical ingredients include a near-tight
quantum algorithm for $\varepsilon$-approximating the number of collisions between two non-repetitive strings, improving the result of Le Gall and Ng [QIC'22]. Together, our results show that smoothing can reveal larger
quantum speedups than worst-case analysis suggests, opening a path towards
quantum advantage on more realistic inputs.
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Materials Science
Density functional perturbation theory of meta-generalized gradient approximations using algorithmic differentiation
Bruno Ploumhans, Niklas Frederik Schmitz and Michael F. Herbst
Density functional perturbation theory (DFPT) is an established framework for the computation of derivatives in plane-wave density functional theory (DFT). We present an implementation of DFPT for exchange-correlation (XC) functionals $E_\mathrm{xc}(\rho,\tau)$ that incorporate an explicit dependence on both the density $\rho$ and the kinetic energy density $\tau$. This covers the popular class of semilocal meta-generalized gradient approximations (meta-GGAs) as well as broader nonlocal parametrizations. We sidestep the derivation of cumbersome XC second energy derivative expressions by recasting these derivatives as a Jacobian-vector product of the XC potentials, which we evaluate with algorithmic differentiation (AD) techniques. Integration with our previously developed AD-DFPT framework [N. F. Schmitz et al., npj Comput. Mater. 12, 6 (2026)] provides access to derivatives of arbitrary ground state quantities with respect to arbitrary perturbations. We employ AD-DFPT to compute a range of response properties for ZnO and BaTiO3, and find that the recent r2SCAN01 meta-GGA functional generally outperforms LDA and PBE. Finally, we showcase the optimization of a neural-network meta-GGA to self-consistently reproduce hybrid-DFT reference densities of bulk silicon, using AD-DFPT gradients. Overall, these results establish AD-DFPT as a versatile route for computing DFT derivatives at the meta-GGA level, be they common response properties or the unusual derivatives required for the gradient-based training of novel XC functionals.
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Materials Science
AI-Assisted Identification of Magnetic Orders and Skyrmions
Haowen Yang, Sophia Huerta and Yingying Wu
Exotic
magnetic orders in two-dimensional (2D) materials are attracting huge interest for energy-efficient spintronic applications, yet realizing robust high-temperature van der Waals antiferromagnets and topological
magnetic states remains challenging. In this work, we develop a machine-learning framework for identifying
magnetic orders and predicting magnetization using structural, compositional, and electronic information derived from the Materials Project. Fixed-length descriptors are constructed for two complementary tasks:
ferromagnetic (FM) versus
antiferromagnetic (AFM) classification and quantitative magnetization prediction.
Magnetic order is classified using a LightGBM model trained on structure-derived descriptors without explicitly including
magnetic descriptors. Five-fold cross-validation grouped by chemical system is used to reduce chemical leakage, together with hyperparameter and classification-threshold optimization. On an isolated test set, the classifier achieves a balanced accuracy of 93.6% in the testing set. Magnetization is predicted using a residual multilayer perceptron with compositional, structural, electronic, and task-specific initial-state descriptors. A logarithmic target transformation and robust weighted loss are used to account for the broad magnetization distribution, while three independently trained models are combined into a final ensemble. The model achieves a mean absolute error of 0.686 {\mu}B/formula unit. For selected
magnetic candidates, simulated
magnetic imaging and phase-reconstruction analysis are further used to investigate magnetization textures and skyrmion-like features through normalized magnetization profiles and topological charge. This framework provides an efficient approach for screening 2D
magnetic materials and prioritizing candidates for
antiferromagnetic and topological spintronic applications.
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Materials Science
Ultra-high vacuum Raman platform for in situ characterization of graphene nanoribbons
Jeong Ha Hwang, Amogh Kinikar, Lukas Rotach et al. (+9 more)
Atomically precise
graphene nanoribbons (GNRs) exhibit tunable electronic and
magnetic properties governed by edge
topology and finite-size effects, which make them versatile platforms for next-generation electronic and spintronic applications. However, the unpaired pi-electrons responsible for their
magnetic properties simultaneously make them highly susceptible to chemical degradation under ambient conditions. This intrinsic reactivity poses a central experimental challenge: accessing vibrational and electronic signatures of air-sensitive GNRs during synthesis and under controlled environments without breaking
vacuum. Once the material has been exposed to air, standard characterization techniques would probe oxidized or chemically modified species rather than the pristine form. Here, we overcome this limitation by developing a home-built ultra-high
vacuum (UHV) Raman platform designed to preserve sample integrity by preventing air exposure and to enable in situ investigation of material properties. The portable Raman
vacuum suitcase (RVS) integrates temperature control and precise gas dosing, allowing direct monitoring of growth kinetics,
lattice dynamics, and reactive-edge responses under well-defined thermal and chemical environments. Using this platform, we monitor the on-surface synthesis of 7- and 9-atom-wide armchair GNRs (7- and 9-AGNRs), quantify the
evolution of 7-AGNR Raman modes over a wide temperature range (162-748 K), and resolve chemical changes upon controlled O2 exposure that are consistent with oxidation at the reactive zigzag sites. These results establish UHV Raman spectroscopy with the RVS as a route to accessing the intrinsic vibrational signatures of low-dimensional
quantum materials under controlled environments.
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All authors Jeong Ha Hwang, Amogh Kinikar, Lukas Rotach, Andres Ortega-Guerrero, Carlo A. Pignedoli, Klaus Muellen, Thorsten G. Englmann, Xinliang Feng, Pascal Ruffieux, Roman Fasel, Mickael L. Perrin, Gabriela Borin Barin
Quantum Physics
Sublinear Copies Suffice for Fidelity Estimation with Pauli Measurements
Jayadev Acharya, Abhilash Dharmavarapu, Yuhan Liu et al. (+1 more)
We present a protocol that estimates the
quantum fidelity, up to precision $\varepsilon$, between a known target state and unknown lab-prepared state with sublinear, $o(d^{0.9908}/\varepsilon^2)$, number of Pauli basis measurements.
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All authors Jayadev Acharya, Abhilash Dharmavarapu, Yuhan Liu, Nengkun Yu
High Energy Physics (Phenomenology)
Heavy Quark Recombination Across Collision Systems: Meson and Baryon production
Vincenzo Minissale, Salvatore Plumari, Maria Lucia Sambataro et al. (+2 more)
Measurements of heavy-
flavor baryons in
nucleus–
nucleus and
proton–
proton collisions have provided strong evidence that heavy-
quark hadronization cannot be described solely in terms of
vacuum fragmentation. In particular, the large enhancement of the $\Lambda_c/D^0$, $\Xi_c/D^0$ and $\Omega_c/D^0$ ratios observed at RHIC and LHC energies has been successfully described within a coalescence plus fragmentation approach, supporting the relevance of recombination mechanisms in both large and small collision systems. Building on these results, we discuss recent developments in the coalescence hadronization framework. Particular emphasis is given to the production of multi-charmed
baryons, namely $\Xi_{cc}$, and $\Omega_{ccc}$, whose yields are predicted in a wide range of collision systems from PbPb to KrKr, ArAr and OO collisions. The strong sensitivity of these states, especially $\Omega_{ccc}$, to the underlying charm-
quark distribution makes them valuable probes of charm thermalization and non-
equilibrium effects in the QGP. We also present recent extensions of the model to the beauty sector, including predictions for $\Lambda_b/B^0$, $\Xi_b/B^0$ and $\Omega_b/B^0$ production. The results indicate sizeable recombination effects and a stronger
baryon enhancement than in the charm sector, highlighting the increasing role of coalescence for heavier
quarks. Finally, we briefly comment on ongoing developments toward a unified description of open and hidden heavy
flavor through the application of the same framework to quarkonium production in small collision systems.
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All authors Vincenzo Minissale, Salvatore Plumari, Maria Lucia Sambataro, Gloria Calà, Vincenzo Greco
Quantum Physics
Analysis of asymmetric errors in NISQ experiments
Gil Kalai, Tomer Shoham and Carsten Voelkmann
This paper continues our analysis of NISQ experiments and especially the Google 2019 “
quantum supremacy" experiment. In arXiv:2008.05177 we proposed statistical tools to analyze symmetric and asymmetric readout errors, and the symmetric case was extensively developed and studied in arXiv:2404.00935, where we used
Fourier methods combined with statistical tools. Here we extend and complement our earlier study and analyze asymmetric readout errors for data from experiments and simulations. Our study was further motivated by a paper by Fefferman et al. arXiv:2306.16659, who showed that the effect of amplitude damping gate errors is to have larger fractions of zeroes in the samples produced by the
quantum computer. We show that this effect of gate errors is not observed in the Google experimental data, where, for the entire range of the number of
qubits, $12 \le n \le 53$, the fraction of zeroes and ones reflects only the asymmetry of reported readout errors, and report on simulations with $n=12,14$ using IBM's and Google's simulators.
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Astrophysics of Galaxies
The abundance and emission of PAHs from the local to early Universe
Massimiliano Parente, Desika Narayanan, Paul Torrey et al. (+8 more)
We present the first large-volume cosmological simulation of
galaxy evolution with a model for the abundance and luminous emission of Polycyclic Aromatic Hydrocarbons (PAHs) across a wide range of
cosmic time ($0 < z \lesssim 6$). The simulation is built on a semi-analytic model (SAM) that includes a treatment of
dust size distribution, with PAHs being identified with the smallest carbonaceous grains ($< 15$ A) residing in the diffuse ISM of
galaxies. PAH emission is computed by post-processing the simulation output with the radiative transfer code GRASIL. In our model, where
stars only inject large grains, the PAH abundance emerges from the growth and shattering of
dust grains in the ISM, naturally reproducing the observed correlation between the PAH mass fraction ($q_{\rm PAH}$) and both
metallicity and specific
star formation rate (sSFR). We derive a relation to infer $q_{\rm PAH}$ from $L_{\rm PAH}$, $L_{\rm IR}$, and sSFR, with a relatively small scatter (a factor of $\approx 1.3$). Simulated PAH emission correlates well with key
galaxy properties such as SFR and molecular gas content, and reproduces observational constraints. Taken together, these results support the viability of a top-down formation scenario for PAHs. We extend our model predictions to higher
redshifts, which can be exploited for future missions such as PRIMA. This work is a significant step toward leveraging PAH observations as a tool for studying
galaxy evolution.
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All authors Massimiliano Parente, Desika Narayanan, Paul Torrey, Gian Luigi Granato, Brandon S. Hensley, Jed McKinney, Alexandra Pope, Gergö Popping, Irene Shivaei, Laura Silva, J.D.T. Smith
Fluid Dynamics
Conservative local grid refinement for the vectorial lattice Boltzmann method
S.A. Hosseini, R. Strassle and I.V. Karlin
We present a conservative local grid-refinement coupling for the vectorial
lattice Boltzmann method (VLBM), a kinetic-type scheme for
hyperbolic conservation laws in which each conserved field is carried by its own population rather than by moment truncation of a Maxwellian. Coarse and fine regions share a common link speed and are advanced with different time steps, sub-cycled at a fixed ratio; a mean-preserving reconstruction in time supplies the missing coarse-to-fine boundary data, and a matched, Berger–Colella-style reflux returns the fine-to-coarse data, together conserving mass, momentum, and energy exactly, independent of the equation of state, the local relaxation parameter, or the time step. In addition, we propose an adaptive mesh refinement extension through a conservative pair of splitting and merging operators that require no modification to the underlying coupling. The approach is validated on a sequence of increasingly demanding two-dimensional cases, in every case recovering exact conservation and the expected accuracy gains over an equivalent uniform grid.
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Astrophysics of Galaxies
Precise C-N-O Abundances of Individual Galaxies in the First Billion Years from Ultra-Deep, Rest-UV-to-Optical JWST Spectroscopy
Raunaq Singh Rai, Guido Roberts-Borsani, Ryan Sanders et al. (+8 more)
We present ultra-deep JWST/NIRSpec $R\sim1000$ spectroscopy of nine
star-forming
galaxies at $z=6.0-8.3$ in the GOODS-N field, drawn from the Origins of Metal Enrichment in
Galaxies at
cosmic dAwn (OMEGA) survey. Paired with ancillary ultra-deep G140M observations, the G395M integrations from OMEGA yield continuous rest-frame UV-to-optical coverage and the full suite of diagnostics needed for precise characterisations and measures of the chemical abundances of these systems. Crucially, the auroral [O\,{\scriptsize III}]\,$\lambda$4363 line is detected in every
galaxy, enabling the determination of electron temperatures and direct oxygen abundances of $12+\log(\mathrm{O/H})=7.14-8.18$, independent of strong-line calibrations that dominate systematics at these
redshifts. We couple direct oxygen abundances with measurements of rest-frame UV emission-line strengths and ratios to infer the physical properties of our sample. Most importantly, we trace the relationship between oxygen abundance and both C/O and N/O abundance ratios with high fidelity, demonstrating robustly that $z=6.0-8.3$
galaxies follow the local trend in C/O vs. O/H, and that inferences regarding N/O are sensitive to the choice of rest-frame UV (\niv] or \niii]) or optical ([\nii]) tracers. This pilot study demonstrates the power of combining ultra-deep JWST/NIRSpec $R\sim1000$ rest-frame UV and optical spectroscopy, which now requires statistical samples to uncover the nebular properties of the full population of $z\geq 6$
star-forming
galaxies.
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All authors Raunaq Singh Rai, Guido Roberts-Borsani, Ryan Sanders, Alice E. Shapley, Leonardo Clarke, Pascal A. Oesch, Daniel Schaerer, Rui Marques-Chaves, Romain A. Meyer, Emma Giovinazzo, Shreya Karthikeyan
Quantum Physics
Induced Coherence in Quantum and Classical Interferometry: Origin and Control
Balakrishnan Viswanathan, Ravi Kamal Pandey, Devendra Kumar Mishra et al. (+2 more)
The wave-particle duality that manifests in the Young's double-slit interferometry satisfying the well known Englert-Greenberger-Yasin inequality has recently been shown to obey a universal triality relation involving coherence, predictability and rather surprisingly
entanglement. In the present work, we explicitly demonstrate the persistence of the triality relation in the
quantum induced coherence interferometer and the classical configuration recovers the well known duality inequality. Furthermore, we explore the origin of coherence and
entanglement, in the induced coherence interferometer, and means to control them. We show that path indistinguishability (or intrinsic indistinguishability of the sources) in our setup plays a complementary role in influencing both interference and
entanglement. We bring out manifestly the nature of coherence in both classical and
quantum versions of induced coherence interferometers.
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All authors Balakrishnan Viswanathan, Ravi Kamal Pandey, Devendra Kumar Mishra, Sibasish Ghosh, Prasanta K. Panigrahi
Instrumentation and Detectors
A high-flux electron detection system to measure non-linear Compton scattering at LUXE
Antonios Athanassiadis, Oleksandr Borysov, Florian Burkart et al. (+16 more)
This paper presents the development and testing of a high-flux electron detection system designed to measure the energy spectrum of more than $10^9$ electrons from
laser-electron collisions at the LUXE experiment, planned at DESY. The system is intended to enable precision measurements of non-linear Compton scattering in the strong-field regime of
quantum electrodynamics. It combines a scintillating screen observed by a camera system with a spatially segmented detector based on the Cherenkov effect. Prototype tests were conducted at two accelerator facilities, where the performance of the system was evaluated under realistic beam conditions. The results demonstrate the feasibility of the detector concept, characterize its current performance and limitations, and provide input for the optimization and final design of the detection system to be used in the experiment.
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All authors Antonios Athanassiadis, Oleksandr Borysov, Florian Burkart, Hannes Dinter-Habermeier, John Hallford, Beate Heinemann, Louis Helary, Luke Hendriks, Ruth Jacobs, Max Kellermeier, Willi Kuropka, Jenny List, Frank Mayet, Gudrid Moortgat-Pick, Evan Ranken, Stefan Schmitt, Ivo Schulthess, Thomas Vinatier, Matthew Wing
Mesoscale and Nanoscale Physics
Superfluid Spin Transport in the Van der Waals Antiferromagnet CrCl$_3$
Peisen Yuan, Xiaomin Guo, Vincent Flynn et al. (+3 more)
Over the past decade, the quest for
spin superfluidity has moved to the forefront of spintronics, driven by the promise of phase-gradient-driven, ultra-low-loss
spin transport. However, experimental investigations remain limited, primarily due to the lack of suitable material systems. Here, we report on the discovery and control of a superfluid
spin transport in the easy-plane van der Waals
antiferromagnetic (AFM)
insulator CrCl$_3$ by a nonlocal device structure. Combining nonlocal
magnon transport measurements with theoretical modelling, we demonstrate that
spin superfluidity emerges in CrCl$_3$ under canted AFM
spin configurations, where it gives rise to ultra-long range (around 90 $\mu$m), weakly decaying
spin transport. We also provide direct evidence that strong
magnetic fields and elevated temperatures suppress the superfluid state, restoring the rapid exponential decay with distance of incoherent
magnons. These findings underscore the potential of
spin superfluidity in two-dimensional
magnetic insulators and establish CrCl$_3$ as a promising platform for energy-efficient, long-distance
spin transport in next-generation spintronic applications.
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All authors Peisen Yuan, Xiaomin Guo, Vincent Flynn, Benedetta Flebus, Fèlix Casanova, Luis E. Hueso
Quantum Physics
How fast can a parent estimate the value of their children? A quantum algorithm for stochastic games
Marien Raat, Merlin Incerti-Medici, James R. Wootton et al. (+2 more)
We give a
quantum algorithm for
stochastic $2$-player games. Their game trees are the expectiminimax trees of classical game search: $m$
adversarial layers alternate with $m$ chance layers, every node has $deg$ children, and the leaf values lie in an interval of length $N$. The
algorithm estimates the value of the game to root mean square error $\epsilon$ with \[ O\!\left( K^{D}\, deg^{\frac{D}{4}} \, \frac{N}{\epsilon} \, D^{4D} \log\left( \frac{deg N}{\epsilon} \right)^{4D} \right), \qquad D = 2m \] queries to the leaf values, where $K$ is an absolute constant. If we treat the depth $D$ as a constant as is sometimes done in the literature, the bound is $\widetilde O(deg^{m/2}\epsilon^{-1})$ against the classical $\widetilde O(deg^{m}\epsilon^{-2})$. So the quadratic speedup in the branching factor known for
adversarial trees and the quadratic speedup in the accuracy known for a single expectation both survive when we nest one inside the other. We use a derandomised multilevel Monte Carlo
estimator for chance layers and a coherent binary search for
adversarial layers. The composition is done by introducing a conversion between root-mean-square and uniform error guarantees, and a composition to nest it with
quantum mean estimation. We state the
algorithm for
stochastic games, but it is valid for the following conditions: the value of a parent is a Lipschitz function of the values of its children and the value at a chance vertex is linear in its children, however the speedup is preserved only if the deterministic step has a
quantum subroutine with sublinear query complexity.
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All authors Marien Raat, Merlin Incerti-Medici, James R. Wootton, Evert van Nieuwenburg, Daniel Bultrini
Materials Science
High-Throughput Imaging of Degradation-Inducing Microscopic Impurities in Perovskite Solar Cells
Sofiia Kosar, Anil R. Pininti, Vladyslav Hnapovskyi et al. (+6 more)
The scalable fabrication of high-quality, large-area perovskite thin films is hindered by microscopic inhomogeneities, particularly residual compositional
impurities formed during processing. Identifying these
impurities, understanding their impact on device operation, and enabling their rapid detection are essential for upscaling perovskite
solar cells (PSCs). Here, nano-
Fourier transform infrared spectroscopy combined with high-resolution optical and scanning probe techniques was used to identify detrimental
impurities in wide-bandgap perovskite films relevant to tandem
solar cells. Photo-stress experiments revealed that degradation of the perovskite layer initiates at
impurity-perovskite interfaces, demonstrating that
impurities act as failure nucleation sites. Leveraging these insights, a rapid, non-invasive, and high-throughput framework based on high-resolution reflected light microscopy and machine learning-supported image analysis was developed, enabling detection and quantification of harmful
impurities in as-prepared films within seconds. Films with higher
impurity density show accelerated early degradation, establishing this parameter as an early-warning metric for stability screening. Extending this framework to degradation tracking further reveals coupled photo- and thermo-chemical contributions to
impurity-mediated instability. Overall, this work establishes a practical chemically-validated diagnostic imaging framework for rapid pre-screening of perovskite films to enable stable and scalable PSCs.
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All authors Sofiia Kosar, Anil R. Pininti, Vladyslav Hnapovskyi, José P. Jurado, Subhashri Mannar, Lorenzo Mardegan, Anand S. Subbiah, Frédéric Laquai, Stefaan De Wolf
Instrumentation and Detectors
Event-by-event track imaging of charged particles with an ultrafast plenoptic camera
Till Dieminger, Marco Barbieri, Vincenzo Berardi et al. (+8 more)
Modern elementary particle detectors often require high-resolution three-dimensional particle tracking in large dense active volumes, which is difficult to achieve in standard devices without an extremely fine
segmentation. In recent work, a plenoptic camera instrumented with a single-
photon avalanche-diode array, called PLATON, demonstrated to image individual visible
photons generated in monolithic scintillating material and reconstruct their three-dimensional origin from a single-event exposure, opening a route to high-spatial-resolution detection of elementary particles in unsegmented scintillator. However, those tests aimed to address
photon sources of essentially zero
geometric extent. In this work we close the gap to the tracking regime. First, we calibrated the PLATON prototype using light tracks in an organic plastic scintillator induced by a femtosecond infrared
laser via two-
photon absorption and characterised its capability to reconstruct
photon-starved 3D lines with a novel
algorithm, achieving good agreement with custom Monte Carlo simulation. Finally, the PLATON prototype was exposed to a test beam of pions at the CERN
Proton Synchrotron. For the first time, a plenoptic detector system was successfully used to detect and reconstruct the 3D tracks of elementary particles from 2D
photon-starved images on an event-by-event basis marking a transformative approach to high-resolution measurements.
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All authors Till Dieminger, Marco Barbieri, Vincenzo Berardi, Saúl Alonso-Monsalve, Kodai Kaneyasu, Paul Mos, Tim Weber, Johannes Wüthrich, Claudio Bruschini, Edoardo Charbon, Davide Sgalaberna
High Energy Physics (Phenomenology)
Magnetic thresholds and spin-resolved spectral moments of $\phi$ and $K^{*0}$ in a hadronic model
Lang Yu, Tao-Tao Sui and Xinyang Wang
We study the
spin-resolved spectral functions of $\phi$ and $K^{*0}$ in a thermal hadronic model with a constant
magnetic field. We construct the rest-frame retarded propagators by combining real
vacuum matching with exact Landau levels, connection contacts, and thermal scattering terms. The resulting stable-daughter calculation is checked against independent collision kernels and published expressions in common limits. We find that closed transverse thresholds give rise to narrow peaks with eV-scale detunings, whose areas must be resolved in the calculation of small
spin spectral moments. We test the leading threshold estimate for the peak area by an independent integration of the full kernel. Using positive compact daughter spectra, we then investigate how a finite spectral spread changes the local threshold structure. The disappearance of zeros of the real part of the inverse propagator is controlled by the spread relative to the detuning, whereas the weight integrated over a finite patch can remain nearly unchanged. We relate this redistribution to smooth accepted moments through a weighted identity with a bounded Taylor remainder, and evaluate the complete-window response to three endpoint replacements, including the patch complement. For the stable-daughter $\phi$ spectra with a fixed smooth weight, the response at the two smallest sampled fields is negative and compatible with $b^2$ scaling. Hard-window results instead oscillate in sign, and pseudoscalar mixing substantially changes the smooth response coefficient. These results quantify the sensitivity to thresholds and spectral projection; microscopic daughter widths and source-matched experimental
spin alignment require additional input.
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General Relativity and Quantum Cosmology
Kasner critical scaling in Einstein–Maxwell–scalar black holes with nonlinear collapse and scalarization
Chihang He and Chao Liu
A critical scaling exponent of $1/2$ was numerically observed for the Kasner parameter of asymptotically flat scalarized black holes and conjectured to be universal [Phys.\ Rev.\ Lett.\ 136, 251402 (2026)]. In the same static, spherically symmetric Einstein–Maxwell–scalar setting, we show that this exponent is not universal. We develop a rigorous mathematical framework and construct couplings realizing exponents $1/(2m)$ for any integer $m\ge1$ by tuning higher-order terms at fixed quadratic coupling parameter $\mu$. Nonlinear interior collapse produces a spacelike Kasner singularity with $\beta_{\rm K}\propto\varepsilon^{-1}$, where $\varepsilon$ is the value of scalar field at the event horizon. An exterior branch satisfying $q/q_\star-1\propto\varepsilon^{2m}$, therefore, yields $\beta_{\rm K}\propto|q/q_\star-1|^{-1/(2m)}$, where $q$ is the charge-to-mass ratio and $q_\star$ its critical value. We also determine the prefactor explicitly. This recovers the $1/2$ law and establishes a hierarchy including $1/4$ and $1/6$.
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