Atomic Physics
Parts-per-million-accurate determination of the K${\alpha}$ photoionization resonance of Be-like oxygen with resolution of its $^{16}$O-$^{18}$O isotopic shift
Jonas Danisch, Marc Botz, Chintan Shah et al. (+15 more)
We determine with high accuracy the energy of the inner-shell transition $1s^2 2s^2~{}^1\mathrm{S}_0 \rightarrow 1s~2s^2~2p_{3/2}~{}^1\mathrm{P}_1$ ${}^{16}\mathrm{O}_{K\alpha}^{4+}$ at $554.372(3)~\mathrm{eV}$ ($\lambda$ = $22.36480(12)~\unicode{x212B}$) as well as its small shift of $2.2 \pm 1.3~\mathrm{meV}$ ($\Delta \lambda$ = $0.089(52)~\mathrm{m}\unicode{x212B}$) for the ${}^{18}\mathrm{O}$ isotope. This transition blends with a $K_\alpha$ line of $\mathrm{O}^{5+}$ used in astrophysical diagnostics, potentially affecting its reliability. In contrast to our experimental uncertainty of $\pm 3~\mathrm{meV}$, advanced electronic structure predictions for this four-electron system, including
quantum electrodynamic (QED) corrections on the order of $100~\mathrm{meV}$, still scatter by more than $\pm 250~\mathrm{meV}$. Ions generated and stored in an electron beam ion trap were excited at the ELETTRA synchrotron facility with monochromatic soft x rays, with
photon energies corrected by an additional spectrometer. Upon resonant excitation of $\mathrm{O}^{4+}$ and subsequent autoionization, we separate the photoions of each isotope by a time-of-flight measurement. This way, we resolve soft x-ray isotopic shifts of a few meV, obtain very accurate data on an essential astrophysical ion, and test calculations down to the level of QED contributions.
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All authors Jonas Danisch, Marc Botz, Chintan Shah, Moto Togawa, Joschka Goes, Dominic Hache, Filipe Grilo, Pedro Amaro, Vladimir A. Yerokhin, Steffen Kühn, Awad Mohamed, Roberta Totani, Monica de Simone, Stefano Orlando, Thomas Pfeifer, Fabrizio Nicastro, Marcello Coreno, José R. Crespo López-Urrutia
Mesoscale and Nanoscale Physics
Exceptional points in dissipative coupling polaron-polaritons
A. J. Vega-Carmona, D. A. Mendoza, A. Camacho-Guardian et al. (+1 more)
Understanding how strong correlations and dissipation combine to shape collective
quantum excitations is a central challenge in many-body physics. We investigate the effect of dissipative light-matter coupling on strongly interacting
exciton-polaritons in the presence of a biexciton resonance, which gives rise to polaron-polariton quasiparticles. We show that the interplay between many-body correlations and non-Hermitian coupling generates anomalous dispersion relations and exceptional points in the polaron-polariton spectrum. The location and coexistence of exceptional points are controlled by the dissipative coupling and the relative decay rates of the excitonic and photonic constituents, allowing them to emerge across different polaron-polariton branches. These results identify dissipative polaron-polaritons as a versatile platform for exploring non-Hermitian many-body physics with tunable light-matter quasiparticles.
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All authors A. J. Vega-Carmona, D. A. Mendoza, A. Camacho-Guardian, M. A. Bastarrachea-Magnani
Mesoscale and Nanoscale Physics
Magnon-polaron mediated spin Seebeck effect in altermagnets
Ilia Moghayer, Ritesh Das and Yaroslav M. Blanter
Altermagnets, distinguished by compensated antiparallel
spins yet nondegenerate
magnon spectra, bridge the gap between ferromagnets and antiferromagnets. Although several probes such as anisotropic transport and spectroscopic measurements have been proposed to identify altermagnetic order, experimentally accessible transport signatures remain highly desirable. Here, we show that in altermagnets subject to an external
magnetic field, the
spin Seebeck effect exhibits pronounced directional anisotropy. Specifically, the
spin Seebeck coefficient differs significantly along in-plane directions, and this anisotropy increases with field strength. Magnetoelastic interactions further produce resonant peaks whose positions with respect to an applied
magnetic field reflect the intrinsic
magnon band anisotropy, and provide localized features that enhance the distinguishability of the altermagnetic response. The peaks provide a robust experimental signature of altermagnetic order. Our findings serve as signatures of altermagnetic order while laying the groundwork for their application in spintronic devices.
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Soft Condensed Matter
Single Chain Expulsion from Diblock Copolymer Micelles with Dense Corona
Shuang Yuan and Jiajia Zhou
We use self-consistent field theory to investigate the free energy landscape for single-chain expulsion from a diblock copolymer micelle with a dense corona. Using the distance from the micelle center-of-mass to the hydrophilic-hydrophobic junction of the chain as the reaction coordinate, we compute the free energy landscape for chain exchange. Our results show that the expulsion free energy barrier scales linearly with both the hydrophobic block length and the solvent selectivity, consistent with recent experiments. To accurately resolve chain conformation, we introduce a second reaction coordinate: the distance between the junction and the free end of the hydrophobic block, and construct a two-dimensional free energy surface. Using the string method to identify the minimum energy path, we find that all pathways converge to a nearly degenerate reaction channel, irrespective of the initial path. Within this channel, the end-to-end distance of the hydrophobic block exhibits a broad distribution, yet the corresponding expulsion barriers remain nearly indistinguishable. Together, these findings establish a continuum-level theoretical foundation for understanding the hyperstretching mechanism and the transition state ensemble in micellar chain exchange.
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Strongly Correlated Electrons
Tensor network solvers for ultra-large tight-binding Hamiltonians: algorithms and applications
Tiago V. C. Antão, Anouar Moustaj, Yitao Sun et al. (+1 more)
Understanding
quantum materials at meso and even macroscopic scales requires tight-binding calculations on system sizes where explicit
matrix representations become prohibitively costly. This represents a major bottleneck to rationalize phenomena in moiré and super-moiré
heterostructures and quasicrystals. Here, we present a unified tensor-network methodology to solve tight-binding problems at exceptionally large scales, by mapping a system of $N = 2^L$ sites onto a many-body problem of $L$ pseudospin sites, which is subsequently solved with tensor network
algorithms. For
Hamiltonians with compressible real-space structure, the tensor network bond dimension remains modest, typically of order a few tens, independent of $N$. Tensor network representations of arbitrary hopping functions including long-range, spatially modulated, and twisted-layer couplings are built with quantics tensor cross interpolation, and all physical observables are evaluated entirely with tensor network
algebra without explicit
matrix storage or diagonalization. We demonstrate applications to spectral functions, momentum-space spectra via the tensor-network
quantum Fourier transform, real-space topological invariants, real-time dynamics, correlation induced
symmetry breaking with self-consistent mean-field calculations, non-Hermitian phenomena, and excitonic many-body physics. Our methodology enables routinely solving systems with billions of sites, by leveraging the tensor network compressibility of real-space structures, and establishing a flexible framework to study
quantum matter at ultra-large length scales. The methodology is implemented in the open-source Julia package TensorBinding.
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All authors Tiago V. C. Antão, Anouar Moustaj, Yitao Sun, Jose L. Lado
Materials Science
Substrate-dependent electrical transport in individual single-walled carbon nanotubes grown across SiO$_2$ and hexagonal boron nitride
Yuanjia Liu, Taiki Inoue and Yoshihiro Kobayashi
The electronic transport properties of carbon nanotubes (CNTs) are strongly affected by their surrounding environment, making the underlying substrate a critical factor for device performance. Here, we demonstrate enhanced carrier transport of individual single-walled CNTs on hexagonal boron nitride (hBN) by directly comparing CNT channels on SiO$_2$ and hBN within the same nanotube. This within-tube comparison removes tube-to-tube variability in chirality, diameter, and defect density, allowing the intrinsic substrate effect to be evaluated more reliably. The CNTs were synthesized using gas flow-directed growth, which yields long, well-aligned CNTs without transfer processes, allowing a single nanotube to extend across different substrate regions. Multichannel field-effect transistors fabricated along an individual CNT exhibit clear ambipolar characteristics. CNT channels on hBN consistently exhibit higher field-effect mobility than those on SiO$_2$. In contrast, temperature-dependent transport near the charge neutrality point exhibits thermally activated behavior with similar activation energies (15-20 meV) on both substrates, indicating that the intrinsic small bandgap of CNTs is largely unaffected by the substrate. These results provide direct evidence that hBN enhances low-field carrier transport in CNTs and establish a foundation for the fabrication of high-performance electronics based on hBN-supported CNTs.
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High Energy Physics (Phenomenology)
The Quantum Statistical Approach to Parton Distributions updated with recent experimental data
Claude Bourrely
The
Quantum Statistical Parton Model (QSPM) has been successful over the years to explain a important set of unpolarized and polarized experimental data on
proton parton distribution functions (PDFs). With the advent of the Marathon and SeaQuest experiments, an updated version of the
quark PDFs obtained in the framework of QSPM is presented. Moreover, in order to clarify the role of the thermodynamical potentials, the main parameters of the model, we examine the dependence of the nucleon
entropy on these potentials. We find that the values of these potentials lead to a maximal value for the nucleon
entropy.
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Astrophysics of Galaxies
Bar-driven secular evolution largely complete in a disk galaxy 7.6 billion years ago
Takafumi Tsukui, Zeyu Gao, Emily Wisnioski et al. (+4 more)
Disk
galaxies like the Milky Way are thought to evolve through internal dynamical processes: the
stellar disk forms a bar, the bar drives gas inflow that builds a
nuclear stellar disk, and the bar vertically thickens into an X-shaped bulge. Although this
evolution is thought to be slow, completing only at late
cosmic times, its timing remains poorly constrained. We report James Webb Space
Telescope imaging of a
galaxy at
redshift 0.92 (7.6 billion years ago) that already hosts an X-shaped bulge, a
nuclear stellar disk, and an extended
stellar disk, with geometry and inferred bar size indistinguishable from those of present-day barred
galaxies. The X-shaped bulge marks the completion of the major phase of bar-driven
evolution when the Universe was less than half its current age.
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All authors Takafumi Tsukui, Zeyu Gao, Emily Wisnioski, Joss Bland-Hawthorn, Satoru Iguchi, Themiya Nanayakkara, Karl Glazebrook
Chemical Physics
High-performance parallel implementation of high-order coupled-cluster theories
Yu Jin, Christopher Hillenbrand, Timothy C. Berkelbach et al. (+1 more)
High-order coupled-cluster theories with iterative triples (CCSDT), perturbative quadruples [CCSDT(Q)], and iterative quadruples (CCSDTQ) provide
benchmark-quality correlation energies, but their steep computational scalings, $O(N^8), O(N^9)$, and $O(N^{10})$, together with the large
memory requirements of high-order amplitude tensors, have historically limited their application to small molecules. In this work, we develop efficient open-source implementations of
spin-restricted CCSDT (RCCSDT), RCCSDT(Q), RCCSDTQ, and
spin-unrestricted CCSDT (UCCSDT) within the PySCF package. The shared-
memory implementation combines compact triangular storage of the highest-order amplitude tensors with the multithreaded tensor contraction backend pytblis, enabling efficient use of modern many-core CPU architectures. This design delivers near-ideal thread scaling up to 90 cores and achieves wall times shorter than or comparable to existing single-node implementations for representative
benchmark molecules. We further extend RCCSDT, RCCSDT(Q), and RCCSDTQ to distributed-
memory architectures using MPI-based
algorithms. By distributing compact high-order amplitudes across MPI ranks and overlapping communication with computation through nonblocking data transfers, the distributed implementation achieves near-ideal strong scaling on up to 32 nodes, corresponding to approximately 3,000 CPU cores. These developments substantially extend the practical reach of canonical high-order CC theory, enabling CCSDT(Q) calculations with approximately 100 correlated electrons in 450 orbitals and CCSDTQ calculations with approximately 50 correlated electrons in 115 orbitals. Applications to $\pi$-stacked noncovalent dimers, the CO dissociation energy of Cr(CO)$_6$, and the Cope rearrangement of semibullvalene demonstrate that canonical high-order CC
benchmarks are now feasible for chemically realistic molecular systems.
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All authors Yu Jin, Christopher Hillenbrand, Timothy C. Berkelbach, Huanchen Zhai
Astrophysics of Galaxies
The Milky Way Atlas for Linear Filaments III: Giant filaments and magnetic fields as evidence of a bubbly Galactic disk
Naval K. Bhadari, Ke Wang, Shu-ichiro Inutsuka et al. (+1 more)
Linear filamentary structures are fundamental constituents of the interstellar medium and play a central role in
star formation. Their relative orientation with respect to the ambient
magnetic field (B-field) provides key constraints on filament formation mechanisms. We investigate the relative orientation between Milky Way linear filaments (MWLFs) and the plane-of-sky B-field using polarization observations from the Atacama Cosmology
Telescope (ACT) DR6, complemented by Planck data. Filament orientations are compared with the local B-field and the
Galactic plane, while projection effects and statistical significance are quantified using Monte Carlo simulations of vector pairs in three-dimensions. We find no strong preferential
alignment between MWLFs and the ambient B-field. Although the B-field is preferentially aligned with the
Galactic plane with relative angles $\theta_{\rm BG} \sim0-25\deg$, filament orientations exhibit a bimodal distribution, being either parallel or perpendicular to the plane ($\theta_{\rm FG} \sim0-15\deg$ and $\sim75-90\deg$). Filaments located far from the
Galactic midplane ($|z|>90$ pc) preferentially show perpendicular
alignment with both the plane and the B-field, whereas those near the midplane exhibit a bimodal orientation. These results indicate that large-scale B-fields do not dominate the formation of MWLFs and instead favor a super-Alfvénic regime in which
magnetic forces are dynamically subdominant, as expected for filaments associated with
supernova-driven shells. Overall, our findings suggest that a face-on view of the Milky Way would resemble nearby disk
galaxies such as M74, as observed in JWST images, with its disk structured by a network of
supernova-driven bubbles (i.e., a bubbly disk).
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All authors Naval K. Bhadari, Ke Wang, Shu-ichiro Inutsuka, Mingke Sun
Earth and Planetary Astrophysics
Transmission Spectrum of the Benchmark Temperate Exo-Neptune TOI-1231 b
Subhajit Sarkar, Nikku Madhusudhan, Lorenzo Pica-Ciamarra et al. (+4 more)
The JWST is revolutionizing our understanding of the temperate sub-Neptune population through atmospheric spectroscopy. The nature of these
planets remains debated, as their bulk properties are compatible with a range of interior scenarios, including mini-Neptunes, hycean worlds, and gas
dwarfs, with different predicted atmospheric compositions. While theoretical studies have predicted compositional diagnostics for shallow- versus deep-atmosphere scenarios, there is a critical need for empirical constraints for a temperate
planet that is a priori known to possess a deep H$_2$-rich atmosphere. The temperate exo-Neptune TOI-1231 b provides one such
benchmark target. In this work, we present the JWST near-infrared (0.65–5.2 $\mu$m) transmission spectrum of TOI-1231 b, observed with NIRISS single-object slitless spectroscopy and NIRSpec G395H, representing the first for a temperate exo-Neptune. The density of TOI-1231 b requires a thick H$_2$-rich atmosphere, making the
planet a keystone reference case for testing mini-Neptune scenarios for sub-Neptunes. We report a strong detection of CH$_4$ ($\ln B = 54.5$-$69.6$) and moderate to strong evidence for CO$_2$ ($\ln B = 2.9$-$6.6$). We do not find significant evidence for any other prominent molecule, although we find high 95% upper limits on the mixing ratios of NH$_3$ and CO, both of which are expected in deep H$_2$-rich atmospheres. We also do not find any significant evidence for sulfur-bearing species that have been inferred for some temperate sub-Neptunes. This composition is consistent with expectations for a temperate Neptune possessing a deep H$_2$-rich atmosphere with no distinct surface. We discuss the implications of our results for the characterization of temperate sub-Neptunes.
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All authors Subhajit Sarkar, Nikku Madhusudhan, Lorenzo Pica-Ciamarra, Måns Holmberg, Frances E. Rigby, Julianne I. Moses, Megan Mealing
High Energy Physics (Phenomenology)
Yue Pan, Yipin Wang, Leyun Gao et al. (+2 more)
Diphoton systems, with
photon polarizations measurable at low energies, serve as ideal
qubits and were first used to demonstrate
quantum entanglement. However, due to the current absence of dedicated polarimeters at high-energy
colliders, the
entanglement properties of diphoton systems remain largely unexplored at the high-energy frontier. Studying
quantum entanglement at the high-energy frontier, where particle
colliders serve as a natural relativistic laboratory, helps us better understand the
quantum nature and seek new physics. In this letter, we propose a novel method to measure the
entanglement of diphoton systems at
proton-
proton colliders. The
photon spin analyzing power arises from the Bethe-Heitler process occurring in the tracker, where
photons scatter off
nuclei to produce electron-positron pairs whose joint angular distribution encodes the polarization of the diphoton system. Simulation results show that, under HL-LHC conditions, the statistical significance of
quantum entanglement in the
Higgs $\to \gamma\gamma$ process is $0.007\sigma$, while measuring the continuum diphoton process $q\bar{q} \to \gamma\gamma$ alone can reach about $1.5\sigma$.
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All authors Yue Pan, Yipin Wang, Leyun Gao, Qiang Li, Chen Zhou
Mesoscale and Nanoscale Physics
Modification of Damon-Eshbach magnetostatic mode spectra in ferromagnet/paramagnet bilayer
M. A. Kuznetsov
Using the magnetostatic approximation, we calculate the spectra of bulk and surface
spin waves in an in-plane magnetized ferromagnet/paramagnet
bilayer. Due to the dipolar coupling between the layers, the paramagnet becomes polarized, which in turn modifies the spectrum of the Damon-Eshbach magnetostatic modes. We assume that the paramagnet is characterized by a
magnetic susceptibility, $\chi \propto 1/(T-T_C)$, which reaches large values when the system temperature $T$ is close to the Curie temperature $T_C$. We find the conditions under which surface
spin waves become unidirectional, i.e., capable of carrying energy in only one direction, and determine the magnitude of their frequency nonreciprocity. We demonstrate the possibility of switching the unidirectional wave regime on and off by varying the external
magnetic field or temperature, making the ferromagnet/paramagnet system an attractive platform for tunable magnonic logic devices.
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High Energy Physics (Phenomenology)
Higher-order effects in amplitude-assisted polarisation extraction with machine-learning techniques
Juan M. Cruz-Martinez, Jakob Linder, Mathieu Pellen et al. (+2 more)
With increasing experimental precision, the prospect of extracting the polarisation of electroweak gauge
bosons is becoming particularly attractive. To this end, regression and classification procedures based on precise and accurate theoretical predictions are becoming increasingly important. In this work, we present the first amplitude-assisted regression procedure at next-to-leading-order accuracy in QCD, supplemented with parton-shower effects, using machine-learning techniques to extract the rate of longitudinal-
boson production in high-energy collisions. Several neural-network architectures are presented and benchmarked against a standard random-forest regressor, demonstrating the robustness of the results for di-
boson production at the LHC.
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All authors Juan M. Cruz-Martinez, Jakob Linder, Mathieu Pellen, Giovanni Pelliccioli, Emanuele Re
Quantum Physics
Bridging Quantum Computing Paradigms toward Semiconductor Yield: A Controlled CV-versus-DV Comparison on Wafer-Map Defect Classification
Yeonhong Kim, Jonghyeok Im, Monu Nath Baitha et al. (+1 more)
Realizing
quantum neural networks (QNNs) in industry requires knowing which
quantum computing paradigm suits which task. Motivated by AI accelerators and high-bandwidth
memory, where die stacking makes wafer-level defect screening central to yield, we study WM-811K wafer-map defect classification (eight classes), comparing the dominant paradigms, continuous-variable (CV) and discrete-variable (DV), under controlled conditions. To isolate the
quantum circuit as the sole variable, a shared convolutional backbone (~4.3M parameters) feeds interchangeable heads (classical dense, CV-QNN, or DV-QNN) as the only structural difference; each
quantum head is scaled over three sizes (3, 4, 8 qumodes/
qubits). The CV head consistently outperforms the DV head: at four qumodes/
qubits it reaches 79.7 +/- 1.8% accuracy versus 61.6 +/- 1.4%, a non-overlapping 18-point gap. The advantage is sharpest on the spatially localized Edge-Loc class, easily confused with Scratch, which CV recovers with recall 0.66 +/- 0.06 while DV fails at every size (<=0.05), showing the structured CV layer better captures fine spatial distinctions between defect types. Training curves show the DV limitation is a representational-capacity ceiling, not an optimization failure; at the Fock cutoff used here (d = 2) the CV advantage reflects two intrinsic properties, a structured, neural-network-analogue layer and continuous phase-space encoding, not
Hilbert-space dimensionality. On IBM hardware, DV accuracy holds at shallow depth, degrading only at the deepest
circuit. Both
quantum heads remain below the classical baseline (85.0%), but the controlled setting isolates where a structured head already helps and, as noise and scale improve, which paradigm can deliver practical advantage.
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All authors Yeonhong Kim, Jonghyeok Im, Monu Nath Baitha, Kyoungsik Kim
Fluid Dynamics
Lock-exchange flow regimes under low air Froude number bubble curtains
Shravan K.R. Raaghav, Herman J.H. Clercx and Matias Duran-Matute
The flow and density field characteristics around a bubble curtain in a laboratory scale lock-exchange setup are investigated using two-phase large-eddy simulations. We study the detailed hydrodynamics and show that there are three qualitatively distinct (sub)regimes within the previously classified breakthrough regime. The occurrence of these regimes depends not only on air Froude number that characterises the relative strength of the bubble curtain and the
gravity current, but also on an additional non-dimensional parameter: the density ratio between the salt and fresh water. The dependence on this additional parameter is also observed in how effective bubble curtains are in blocking the transport of salt to the fresh part of the lock. Hence, it has important implications for the optimisation of bubble curtains in ship locks.
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Astrophysics of Galaxies
Projection-Enhanced Disk Breaks: Evidence from Deep Photometric Decomposition
Sergey S. Savchenko, Ilia V. Chugunov, Alexander A. Marchuk et al. (+5 more)
Radial brightness profiles of disk
galaxies often exhibit so-called breaks – locations where their exponential-scale length abruptly changes. Some
galaxies have downbending (Type II) breaks, where their brightness decays faster in outer regions, while other have upbending (Type III) breaks, resulting in more extended outer disks or envelopes. Disk radial profiles without any breaks (Type I) appear to constitute a minority. The exact fractions of different break types depend on many
galactic parameters – such as Hubble type,
stellar mass, spatial environment, and bar presence – and vary significantly across different studies. Another source of discrepancy is the orientation of
galaxies: projection effects may play an important role in break detectability. In this work, we utilize DESI Legacy DR10 imaging to perform photometric decomposition of a sample of 375 edge-on
galaxies and investigate their radial breaks. We find that the vast majority (~90%) of disks in our sample have Type II breaks, which is a considerably higher fraction than in many previous works (~50%). We carefully tested our results to check if observed breaks can be a result of flaring or two-disk composition. We showed that a high fraction of Type II breaks can be attributed to projection effects, which enhance the observed surface brightness of breaks in edge-on
galaxies.
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All authors Sergey S. Savchenko, Ilia V. Chugunov, Alexander A. Marchuk, Vladimir P. Reshetnikov, Matvey D. Kozlov, Dmitry I. Makarov, Aleksandra V. Antipova, Anastasia M. Sypkova
Earth and Planetary Astrophysics
Native-resolution retrievals of VHS 1256-1257 b spanning the JWST/NIRSpec wavelength range: Chemical composition of a partially cloudy atmosphere
S. de Regt, N. Whiteford, B. E. Miles et al. (+3 more)
The wide wavelength coverage and sensitivity offered by JWST enable detailed analyses of extrasolar atmospheres. At its highest resolution (R~2700), NIRSpec measures the absorption from atomic, molecular, and isotopic gases whose abundances reflect the chemical composition of accreted material, making them key tracers of the formation environment. Orbiting an inner M-
dwarf binary at a wide separation, the planetary-mass companion VHS 1256 b is one of the most variable sub-
stellar objects known, with flux variations of 10-30%. We analyse the 0.97-5.27 micron NIRSpec ERS spectra of VHS 1256 b, update the data reduction and employ petitRADTRANS for atmospheric
retrievals at the native spectral resolution. We model a partially cloudy atmosphere in chemical disequilibrium and fit directly for the elemental and isotopic abundances. Our best-fitting model closely matches the observations, bringing the residuals down to ~1%. The results are cautiously interpreted as degeneracies can bias some parameter constraints, most notably the mass and radius. Still, the
retrieval finds a partial cloud deck covering ~79% of the visible surface, with a clearer column dominating at short wavelengths. Small changes of 1-3% can account for the high observed variability. From the many detected gases, we infer a
metallicity, C/O ratio, and 12C/13C ratio in line with a
solar composition, while the 18O isotope appears depleted relative to the Sun and local ISM. The isotope abundances are significantly lower than previous studies suggested, underlining the importance of our updated spectra. The 18O-depletion defies our understanding of the likely top-down formation. Our interpretation of the retrieved composition is complicated further by the lack of host
star abundances. Nevertheless, this study demonstrates the value of panchromatic, native-resolution
retrievals for characterising complex extrasolar atmospheres.
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All authors S. de Regt, N. Whiteford, B. E. Miles, S. Gandhi, D. González Picos, I. A. G. Snellen
Earth and Planetary Astrophysics
The Mid-Infrared Transmission Spectrum of the Temperate Sub-Neptune TOI-270 d
Måns Holmberg, Nikku Madhusudhan, Martin Binet et al. (+3 more)
Observations of temperate sub-Neptunes with JWST have ushered in a new era for atmospheric characterization of small
exoplanets. In particular, the MIRI instrument provides a unique opportunity to search for molecules that are not easily accessible in the near-infrared, as demonstrated by recent mid-infrared observations of K2-18 b. In this work, we present the first mid-infrared transmission spectrum of TOI-270 d observed using the JWST MIRI LRS (5-12 $\mu$m) instrument. By leveraging archival MIRI LRS data, we establish a new empirical relation between the detector settling timescale and the flux, which helps accurately model the spectral light curves and improve the precision of the transmission spectrum. We find that there is notable evidence of molecular features in the MIRI transmission spectrum of TOI-270 d, favouring the presence of atmospheric absorption at $\ln B$ = 2.8-5.3 when comparing physically plausible atmospheric models with and without molecular line absorption. The data show excess absorption beyond what could be attributed to CH$_4$ and CO$_2$ detected previously, in line with recent near-infrared results. Through an agnostic search for 203 species, we identify several candidate trace molecules, most of which are complex molecules, evaluate their physical plausibility, and compare them against inferences from near-infrared observations. We also compare the MIRI spectrum of TOI-270 d to that of K2-18 b and find that random or systematic noise is unlikely to explain these observations. Future follow-up observations are necessary to definitively identify the additional absorbers beyond CH$_4$ and CO$_2$. These observations demonstrate the unique capability of JWST MIRI for atmospheric characterisation of temperate sub-Neptunes.
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All authors Måns Holmberg, Nikku Madhusudhan, Martin Binet, Subhajit Sarkar, Frances E. Rigby, Julianne I. Moses
Quantum Physics
The Dynamical Lie Algebra of QAOA-MaxCut on the Complete Graph
Jonathan Allcock, Pei Yuan and Shengyu Zhang
We give an analytical expression for the dynamical Lie
algebra corresponding to the QAOA-MaxCut problem on complete graphs, and show that the variance of the associated loss function scales linearly in the number of
qubits. This solves an open problem from [ASYZ26] and confirms that such systems do not exhibit barren plateaus. The proof is based on projecting the dynamical Lie
algebra generators onto subspaces given by the Schur-Weyl duality between irreducible representations of the
unitary and symmetric groups.
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Biological Physics
Plant-On-a-Disc (POD): A Phytofluidic platform enabling In Situ Root Analysis
Kaushal Agarwal, Sumit Kumar Mehta and Pranab Kumar Mondal
Phytofluidic platforms have enabled controlled studies of plant roots, however, most existing systems either impose
geometric confinement without flow or introduce hydrodynamics in single-channel devices that limit throughput and disrupt downstream analysis. New experimental platforms are therefore needed to investigate how roots integrate mechanical confinement and hydrodynamic nutrient transport, two defining features of the rhizosphere that remain difficult to reproduce under controlled laboratory conditions. Here, we present the Plant-on-a-Disc (POD), a phytofluidic platform that enables the parallel cultivation of eight seedlings under controlled hydrodynamic conditions while allowing non-invasive, in situ
multimodal analysis of the intact root-shoot system. The device is fabricated in PDMS using a cost-effective wire-drawing technique to generate radial microchannels that converge into a central sump beneath an optical window. This design enables sequential bright-field, fluorescence, and Raman measurements using a single microscope objective without disturbing neighbouring seedlings. Dimensionless transport analysis and finite-element modelling confirm that the radial architecture equalizes hydraulic resistance across channels, establishing creeping laminar flow with convection-dominated nutrient transport under physiologically safe shear conditions. Using Brassica seedlings, we show that hydrodynamic flow drives coordinated root responses across multiple scales. Roots grown in flow condition exhibit accelerated elongation, substantial ROS generation and anisotropic cortical
cell expansion, accompanied by carotenoid signatures detected by Raman spectroscopy.
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Quantum Physics · Cross-listed from cs.SE
QPipe: LLM-Based Agentic Quantum Application Generation for Test Optimization
Ming Tao, Yuechen Li, Tao Yue et al. (+2 more)
Quantum computing is increasingly explored for software engineering (SE) optimization, but translating natural-
language (NL) task-level requirements into executable
quantum applications still demands substantial
quantum and programming expertise. We present QPipe, a large
language model (LLM)-based multi-
agent architecture that autonomously turns NL requirements into traceable
quantum-application workflows through specialized
agents for requirement parsing, formulation, code generation, review, execution, and verification. We evaluate QPipe on 20 NL requirements, each associated with a real-world
benchmark and a test-optimization problem. QPipe successfully completes the key stages of
quantum-application generation across requirements, achieving average rates of 100% for code compilation and 96.7% for application execution and final-result combination, with average generation costs of 260.1 seconds and 1.89M
tokens per requirement. Among the generated
quantum applications that execute successfully, the returned solutions outperform the offline genetic
algorithm baseline in most cases. Ablation results further show that QPipe's advantage depends on retaining code-generation skills, task knowledge, review feedback, and multi-
agent decomposition. These results indicate that agentic coordination can support generation of executable
quantum applications for tackling test optimization problems from real-world
benchmarks.
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All authors Ming Tao, Yuechen Li, Tao Yue, Man Zhang, Aitor Arrieta Marcos
Materials Science
First-principles calculations of spin-split bands in chiral hybrid organic-inorganic perovskites ($R$/$S$-PEA)PbI$_3$ and ($R$/$S$-NEA)PbI$_3$
Tetsuya Furukawa, Kazushi Nakano, Youta Suzuki et al. (+3 more)
Chiral hybrid organic-inorganic perovskites provide a promising platform for investigating the physics of chirality-driven
spin-split bands because they combine robust molecular chirality with strong
spin-orbit coupling from heavy inorganic ions. First-principles calculations including
spin-orbit coupling are performed for the one-dimensional
chiral perovskites ($R$/$S$-PEA)PbI$_3$ and ($R$/$S$-NEA)PbI$_3$ to compare their
spin-split band structures and to identify the factors controlling their differences. In ($R$/$S$-PEA)PbI$_3$, the lowest conduction bands predominantly consist of Pb orbitals, whereas in ($R$/$S$-NEA)PbI$_3$, they are formed by hybridization between Pb orbitals and the lowest unoccupied molecular orbital of NEA. Both compounds exhibit pronounced
spin splitting near the valence-band maximum and conduction-band minimum. The effective
spin splitting of the edges of the valence bands is stronger in ($R$/$S$-NEA)PbI$_3$, despite similar linear-in-$k$ splitting coefficients near the relevant high-
symmetry points. This enhancement originates from larger gaps induced by
spin-orbit coupling at high-
symmetry points and band (anti)crossings in the multiband structure. For a given molecular handedness, the PEA- and NEA-based compounds exhibit opposite
spin textures, consistent with the opposite
chiral distortions of the [PbI$_6$]$^{4-}$ octahedra and with the previously observed opposite signs of circular dichroism. Group-theoretical analysis for the nonsymmorphic space group $P2_12_12_1$ further accounts for band sticking,
symmetry-enforced degeneracies, and the disappearance of
spin polarization at specific Brillouin-zone-boundary points. These results provide a solid foundation for future studies of chirality-dependent electromagnetic responses, including circular dichroism, in
chiral hybrid organic-inorganic perovskites.
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All authors Tetsuya Furukawa, Kazushi Nakano, Youta Suzuki, Takumi Kaneko, Ayumi Ishii, Tetsuaki Itou
Chemical Physics
Dynamics of charge fluctuations in nanocapacitors: effects of salt concentration and electrode metallicity from Brownian dynamics
Paul Desmarchelier and Benjamin Rotenberg
Electric double-layer capacitors (EDLCs) rely on the dynamical response of confined electrolytes to store and release charge, yet the interplay between ion transport, electrostatic interactions, and electrode
metallicity remains poorly understood at the nanoscale. We develop a comprehensive Brownian dynamics framework to compute the frequency-dependent admittance of nanocapacitors, explicitly accounting for salt concentration and the finite screening length of electrodes (modeled via Thomas-
Fermi theory). We derive the fluctuation-dissipation relation connecting the dynamics of
equilibrium charge fluctuations to the linear response of the system quantified by the frequency-dependent admittance. Specifically, we obtain two
estimators for the admittance, based on ionic positions and forces, and combine them via a control variate method to reduce uncertainty across all frequencies. We show that the admittance exhibits a low-frequency regime dominated by capacitive effects, and a high-frequency one governed by the ideal Nernst-Einstein conductivity. The crossover between these regimes is characterized by a timescale that depends on both the electrode
metallicity and salt concentration, highlighting the role of ion-wall collisions and electrostatic interactions. Comparisons with analytical models show that while mean-field theories capture qualitative trends, they systematically overestimate low-frequency admittance and underestimate high-frequency behavior, underscoring the necessity of explicit ion-ion and ion-wall interactions. This work connects microscopic dynamics to macroscopic electrochemical observables, offering a tool to interpret impedance spectra in nanoscale systems. Beyond charge storage in EDLCs, our framework provides insights for sensing applications in nanofluidic devices, where charge/current fluctuations enable the detection of electrochemically active species.
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Instrumentation and Methods for Astrophysics
The "dark dips" phenomenon in the LSST Camera on-sky images
Claire Juramy, Pierre Antilogus, Pierre Astier et al. (+4 more)
When the commissioning camera (ComCam), and then the LSST Camera, started taking on-sky images at the Vera Rubin Observatory, some of the ITL STA3800 CCDs exhibited a previously undocumented effect. When a sufficiently bright
star is superimposed over the sky background, the sensor columns that contain the
star appear slightly darker than the background, both above and below the position of the
star. The visual appearance of these "dark dips" in the background is enhanced by a slight excess of flux within the neighboring columns, suggesting that they are caused by a lateral field distortion that shifts charges away from the central columns. This effect is not uniform across sensors, reaching an amplitude of up to seven percent of the background in the worst cases, but being undetectable in other sensors under the same conditions. For the affected sensors, the threshold required for the dips to become detectable also varies, from a few hundred to a few thousands saturated pixels within the
star footprint. We developed means to quantify the dips, and studied the effect statistically over hundreds of frames, in order to categorize each sensor. In particular, we found no significant dependence on the filter color. We then developed a strategy to dynamically mask the affected columns during the Instrument Signature Removal process, to avoid any potential effect on photometric and astrometric performance.
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All authors Claire Juramy, Pierre Antilogus, Pierre Astier, John Banovetz, Sean Patrick MacBride, Andrew P. Rasmussen, Yousuke Utsumi
Materials Science · Cross-listed from cs.AI
Graph-Native Reinforcement Learning Enables Traceable Scientific Hypothesis Generation through Conceptual Recombination
Subhadeep Pal, Shashwat Sourav, Tirthankar Ghosal et al. (+1 more)
Accelerating materials discovery requires AI systems that can generate scientifically valid hypotheses through multi-step, domain-grounded
reasoning. Standard large
language models often produce fluent but weakly traceable responses to open-ended materials design problems, making it difficult to determine whether final answers are supported by coherent intermediate
reasoning. We develop Graph-PRefLexOR, a family of graph-native
reasoning models fine-tuned with Group Relative Policy Optimization (GRPO) to organize
reasoning into explicit phases for mechanism exploration, graph construction, pattern extraction, and hypothesis synthesis. This design links neural
language generation with symbolic relational structure, enabling causal connections to be constructed, inspected, and reused. On 100 open-ended questions from materials science and mechanics literature, Graph-PRefLexOR achieves 40-65% improvements over corresponding base models, with the largest gains in
reasoning traceability.
Embedding analyses show broader semantic exploration and approximately 2-3 times greater semantic diversity than baselines. Semantic backtracking and layer-wise hidden-state analyses further show stronger
alignment between structured
reasoning and final answers. Finally, test-time graph expansion reveals that additional compute primarily increases long-range conceptual recombination within a bounded semantic space, rather than simply expanding semantic coverage. These results establish graph-native reinforcement learning as a pathway toward interpretable AI systems for scientific hypothesis generation in materials design and other scientific applications.
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All authors Subhadeep Pal, Shashwat Sourav, Tirthankar Ghosal, Markus J. Buehler
Biological Physics
Identity and Self as Physical Signatures of Life in Dictyostelium and Multicellular Systems
Yehuda Roth
In previous work we sought to address the fundamental question “What is life?”. Building on that conceptual foundation, we here integrate traditional criteria for living systems with our recent proposals on physical identity and self, and apply them to concrete biological cases. We suggest that life can be characterized as the preservation of a well-defined identity “at all costs” together with the presence of a physically grounded self, and we show how this perspective illuminates the organization and social behavior of Dictyostelium and other multicellular systems.
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Astrophysics of Galaxies
Spatially resolved optical and mid-infrared spectroscopy of SDSS1335+0728: implications for the origin of the Ansky event
P. Sánchez-Sáez, M. Masterson, L. Hernández-García et al. (+25 more)
The
galaxy SDSS1335+0728 brightened abruptly in December 2019 (the Ansky event) and has since been confirmed as the host of extreme X-ray quasi-periodic eruptions (QPEs) of debated origin. We constrain the origin of its transient activity using spatially resolved VLT/MUSE and JWST MIRI/MRS spectroscopy to characterise the host
galaxy and its
nuclear accretion history. The
stellar kinematics reveal two counter-rotating
stellar components and kinematically cold gas ($\sigma_{\rm gas} \lesssim 60$~km~s$^{-1}$), consistent with a past minor merger. The host is dominated by old
stars, with ongoing
star formation confined to a ring at intermediate radii. Ionisation diagnostics reveal a three-zone structure: a central
accretion-powered region, where high-ionisation coronal lines ([\ion{Ne}{VI}], [\ion{Ne}{V}], [\ion{O}{IV}]) are predominantly concentrated, a
star-forming ring, and a LINER-like outer region. A Balmer-line light-echo analysis yields a minimum ionising luminosity $\log L_{\rm ion,min} \approx 40.5$~erg~s$^{-1}$ at projected distances beyond the reach of radiation from the Ansky event, suggesting
nuclear activity prior to 2019. Strong silicate emission at 9.7 and 18\,$\mu$m indicates directly illuminated
dust viewed through a low effective mid-infrared (MIR) optical depth; its 9.7\,$\mu$m strength lies at the upper end of the active
galactic nuclei (AGN) distribution, closer to that of MIR-selected
tidal disruption events (TDEs). The data are consistent with pre-2019
accretion from either a low-luminosity AGN (LLAGN) or a long-lived TDE remnant disc. In both cases, Ansky is a slow, faint transient in a $\sim\!10^6\,M_{\odot}$ black hole with ongoing
accretion prior to December 2019, offering an alternative to the “faded AGN” interpretation proposed for some QPE hosts.
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All authors P. Sánchez-Sáez, M. Masterson, L. Hernández-García, R. Arcodia, P. Arévalo, F. Ávila-Vera, F. E. Bauer, J. Chakraborty, J. Cuadra, P. Lira, T. Wevers, R. J. Assef, A. Bayo, S. Bernal, R. Cartier, Y. Diaz, M. Giustini, H. Guo, D. Ilić, E. Kara, A. B. Kovačević, M.L. Martínez-Aldama, A. Merloni, G. Miniutti, C. Ricci, M. Sniegowska, G. Calistro Rivera, M. J. Graham
Mesoscale and Nanoscale Physics
Symmetry Classification of Non-Reciprocal Responses in Multiterminal Ring Devices
Chen-How Huang and Tero T. Heikkilä
We present a
symmetry-based framework to classify the non-reciprocal responses of multiterminal ring
quantum devices. The device is modeled as a ring of $n$ vertices, where a binary variable $e_k\in\{+1,-1\}$ on each bond encodes the preferred direction of signal flow between terminals. Non-reciprocity corresponds to a preferred current configuration on the ring, and the
symmetry group of the device partitions all $2^n$ configurations into equivalence classes(orbits) characterized by a topological winding number $W$. Using the minimal non-trivial case $n=3$, we establish two results independent of microscopic details. First, lifting the degeneracy within an orbit generates non-reciprocal responses. For $n=3$ this requires simultaneous breaking of both time-reversal $T$ and spatial inversion $I$. Breaking either alone is insufficient. Second, the residual geometry
symmetry after $T$ and $I$ are broken determines which responses are observable. For an isosceles triangular geometry, only two types of response are allowed: uniform circulation (all bonds carrying current in the same direction) and semi-circulation with the reversed bond on the geometrically distinct base. Semi-circulation with the reversed bond on either equal leg is
symmetry-forbidden. Both predictions are validated using a minimal toy model of three
quantum dots coupled to superconducting baths, which demonstrates a reactive
quantum circulator response.
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Superconductivity
Imaging superconducting weak spots through vortex-assisted THz near-field photovoltage
Sergio J. Salvía-Fernández, Ekaterina Khestanova, Zoe Velluire-Pellat et al. (+9 more)
Nanoscale inhomogeneities are a defining feature of many superconducting materials, yet their local electromagnetic response has remained difficult to access experimentally. This is because their relevant energy scale lies in the terahertz range, where wavelengths – on the order of hundreds of microns – are too large to spatially resolve nanoscopic variations. Here, we demonstrate the first application of THz near-field photovoltage nanoscopy in a
superconductor, achieving 300 nm spatial resolution at 2.52 THz. Scanning a current-biased NbN strip, we reveal photovoltage peaks within the bulk associated with nanoscopic defects of reduced superfluid density. The observed photovoltage follows the
evolution of the
vortex-dissipative state and is attributed to enhanced
vortex-antivortex pair nucleation at defect sites. Together, these results open a direct route to probing how material inhomogeneities influence light-matter interactions in
superconductors, with implications for superconducting devices and strongly inhomogeneous systems such as high-Tc and moiré materials.
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All authors Sergio J. Salvía-Fernández, Ekaterina Khestanova, Zoe Velluire-Pellat, Leonardo R. Cadorim, Sergi Batlle-Porro, David A. Czaplewski, Johann Osmond, Sebastian Castilla, Adrian Bachtold, Milorad V. Milošević, Aharon Kapitulnik, Frank H.L. Koppens