Soft Condensed Matter
Position-dependent friction in protein folding from a GLE derived with a non-stationary localized projection distribution
Salma Salem, Lucas Tepper, Benjamin J. A. Héry et al. (+3 more)
The Generalized Langevin Equation (GLE) is an integro-differential equation of motion for a general observable of a many-body system and is rigorously derived using the projection operator formalism. In the standard derivation, a stationary canonical phase space distribution is used for the projection. Here, we derive a novel class of GLEs using a non-stationary projection distribution that constrains the initial ensemble to a hypersurface in phase space on which the observable has a fixed value $A_0$. As a result, all GLE parameters, and in particular the
memory friction kernel, depend on $A_0$ and can be extracted from short simulations that do not sample the entire phase space. Applying this non-stationary GLE to
protein folding trajectories, we find for villin and an $\alpha$-helical poly-alanine segment that the total friction is higher in the folded state. These results demonstrate that observable-dependent friction effects are non-negligible and can be accounted for using non-stationary GLEs derived by constrained projection schemes.
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All authors Salma Salem, Lucas Tepper, Benjamin J. A. Héry, Henrik Kiefer, David D. Girardier, Roland R. Netz
Quantum Physics
Quantum Topological Data Analysis Beyond Betti Numbers: Complexity Hardness $\&$ An Algorithm for Torsion Witness
Nhat A. Nghiem, Dominic W. Berry and Trung V. Phan
Recent advances have revealed an interplay between
quantum computing and topological data analysis (TDA). Most
quantum TDA has focused on Betti numbers, which characterize the connectivity and “holes” of a
dataset. Homology, however, contains additional information in the form of torsion: a nontrivial cycle can become trivial after being repeated finitely, revealing global constraints on how cycles combine and wrap around one another. Beyond applications in biomolecular studies, torsion appears in physical settings including homological
quantum rotor codes, discrete charges, and gauge sectors. We study torsion from both classical and
quantum perspectives. Given a graph $G$ and its clique complex $K = \mathrm{Cl}(G)$, we first prove that, for fixed $r$ and
prime $p$, deciding whether $H_r(K,\mathbb{Z})$ contains $p$-torsion is NP-hard. As a corollary, when a homological rotor code is specified by $G$, deciding whether the code has a finite-dimensional logical sector of a given order is NP-hard. We discuss related problems, including the Bockstein homomorphism, Smith normal form,
lattice saturation, and
cohomology. Second, for a finite set of
primes $P$, we develop a
quantum algorithm that serves as a one-sided torsion witness. For fixed $r$, it outputs WITNESS or INCONCLUSIVE, i.e. WITNESS certifies that either $H_r(K,\mathbb{Z})$ or $H_{r-1}(K,\mathbb{Z})$ contains $p$-torsion for some $p\in P$ while INCONCLUSIVE makes no claim about its presence or absence. We identify a regime in which the
algorithm achieves a near-quadratic
quantum speedup over the corresponding classical
algorithm under the same input model. Our NP-hardness result complements recent hardness results for estimating Betti numbers, adding a complexity-theoretic perspective to
quantum TDA. Together, these results demonstrate that integral homology, beyond its Betti numbers, can be computationally challenging.
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Instrumentation and Detectors
CBM T0 Detector Performance Study with Light Ions (4He, 12C) and the DOGMA Readout System
Yevhen Kozymka, Thomas Bergauer, Maximilian von Buelow et al. (+14 more)
This paper presents the realization and performance of the CBM T0 detector system. Built upon an approximately 70 {\mu}m thin polycrystalline CVD (pcCVD) diamond sensor with pad metallization, the detector is mounted on a flexible
vacuum manipulator and operates entirely under passive cooling. Interfaced with the DOGMA readout architecture, the system successfully meets all operational requirements for CBM. It demonstrates a high detection efficiency (near 100%) and a timing precision below 50 ps RMS across a broad range of beam species, from light ions (such as Carbon) to heavy ions (such as Gold). The DOGMA readout features two distinct data paths: a high-precision TDC path routing data directly to the global CBM DAQ, and a secondary path deliver in real-time rate measurements crucial for online beam quality monitoring and fast beam abort logic. Finally, detailed performance studies conducted with light-ion beams at EBG MedAustron are discussed.
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All authors Yevhen Kozymka, Thomas Bergauer, Maximilian von Buelow, Henrik Flörsheimer, Jochen Frühauf, Tetyana Galatyuk, Harald Handerkas, Henning Heggen, Mladen Kis, Sergey Linev, Jerzy Pietraszko, Christian Joachim Schmidt, Luca Schramm, Michael Traxler, Michael Träger, Felix Ulrich-Pur, Robert Visinka
Physics Education
Network lexical analysis of student integration of music and physics knowledge
W. Brian Lane and Emily E. Pipkin
Introductory physics students benefit from learning to integrate new physics knowledge with prior knowledge related to their interests. Writing assignments that offer high epistemic agency can foster this integration, and provide rich artifacts for qualitative analysis. Physics education researchers are increasingly interested in studying such artifacts using computer-based textual analysis. In this paper, we use lexical methods to look for evidence of knowledge integration in written assignments from a Physics of Music course. These assignments require students to communicate to an external audience a clear and cohesive narrative that synthesizes concepts from music and physics. To apply this methodology, we first establish a lexicon of music, physics, and integrated keywords that 10 students used across 6 writing assignments. Then, we visualize this word usage in a series of network diagrams based on which keywords were used in proximity to each other in each assignment. We find that students most strongly connected ideas from music and physics using keywords related to the physical structure of sound (sound, frequency, and wave). Applying these methods to each assignment
prompt and its resulting student submissions, we find that, in assignments with a lower degree of epistemic agency (assessed qualitatively by our experience teaching the course), students primarily followed the example of integration modeled by the assignment
prompt, but in assignments with a higher degree of epistemic agency, they explored music-physics integration to a greater degree. We use this analysis to offer a pedagogical contribution to introductory physics courses centered around students' interests, a theoretical contribution by illustrating a means of quantifying epistemic agency, and a methodological contribution that complements textual analysis and offers the scalability sought in such approaches.
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Materials Science
Achieving 5-angstrom-resolution diffraction contrast with an uncorrected electron probe and nanosized defect characterizations
Yao Li, Austin C. Houston, Ziang Yu et al. (+8 more)
Atomic-resolution micrographs remain limited in application due to small field of view and low numbers of recorded defects. Defect imaging with reliable statistics in transmission electron microscopy (TEM) relies heavily on diffraction contrast. However, with 200-300 kV electrons, low-
curvature Ewald sphere limits diffraction resolution at ~5 nm. Here, we imaged defects with a forbidden condition in TEM and improved the resolution in diffraction contrast from 5 to 0.5 nm. The superiority of our equal-s method is demonstrated by the discovery of a novel phase and dislocation loop structure in steels, which have not been previously reported experimentally or theoretically. Our equal-s can largely replace the classical two-beam condition for defect study.
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All authors Yao Li, Austin C. Houston, Ziang Yu, Zehui Qi, Siwei Chen, Yajie Zhao, Sung Joo Kim, Steven J. Zinkle, Gerd Duscher, Blas P. Uberuaga, Benjamin K. Derby
High Energy Physics (Theory) · Cross-listed from math.QA
The Kazhdan-Lusztig category of $\mathfrak{osp}_{1|2n}$ at irrational levels
Thomas Creutzig, Robert McRae and Jinwei Yang
We prove the Kazhdan-Lusztig correspondence for the Lie superalgebra $\mathfrak{osp}_{1|2n}$ at irrational levels, that is, we show the category $\mathrm{KL}_k^{\rm ev}(\mathfrak{osp}_{1|2n})$ of finite-length even ordinary modules for the affine vertex operator superalgebra of $\mathfrak{osp}_{1|2n}$ at level $k \in \mathbb{C} \setminus \mathbb{Q}$ is braided tensor equivalent to the category of finite-dimensional even weight modules for the
quantum group of $\mathfrak{osp}_{1|2n}$ at parameter $q = e^{\pi i/(2k+2n+1)}$. We also prove that ${\rm KL}_k^{\rm ev}(\mathfrak{osp}_{1|2n})$ is braided tensor equivalent to the category ${\rm KL}_\ell^{\rm ns}(\mathfrak{so}_{2n+1})$ of finite-length ordinary modules with non-spinorial top level for the affine vertex operator
algebra of $\mathfrak{so}_{2n+1}$ at level $\ell$ such that $ \frac{1}{\ell+ 2n-1} = \frac{1}{2k+2n+1} + 1 \ \ ({\rm mod}\ 2\mathbb Z).$ Consequently, by gluing vertex operator (super)
algebras via tensor categories, we construct a few new families of simple conformal vertex (super)
algebras, including the mixed kernel VOAs that were the missing ingredient for proving certain Feigin-Frenkel type dualities in previous work of the first-named author with Linshaw, Nakatsuka, and Sato.
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High Energy Astrophysical Phenomena
Shock-free super-Eddington accretion onto magnetized neutron star
Galina Lipunova and Pavel Abolmasov
Strong
magnetic fields allow accreting
neutron stars to form magnetically controlled funnel flows. At sufficiently high
accretion rates, such flows become radiation-pressure-supported. In the conventional picture, the magnetospheric flow contains a nearly free-falling transonic outer region, a radiation-mediated shock, and a subsonic
accretion column. We investigate the regime in which the height of the column is expected to exceed the magnetospheric radius. In this case a self-consistent transonic solution with a standing shock is no longer possible, and the entire magnetospheric flow remains subsonic. We construct a semi-analytical hydrodynamical solution for a fully subsonic, radiation-supported magnetospheric flow in the low-Mach-number limit. The
magnetic field is treated in the force-free approximation, while the flow structure is determined by mass conservation, energy conservation, and the momentum equation along the field lines. We test the solution using one-dimensional time-dependent simulations with the code HACol. The shock-free solution is highly advective. Its enthalpy profile is close to the adiabatic limit, while the energy density is regulated by leakage of mass and heat through the sides of the
accretion channel. Most of the observable power is expected to be released by
plasma leaving the magnetospheric flow above the
neutron-
star surface. Such systems should be associated with super-Eddington
accretion discs and low pulse fractions due to visibility selection and scattering in the disc wind. We suggest that many non-pulsating ultraluminous X-ray sources containing
neutron stars may accrete in this shock-free regime.
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High Energy Astrophysical Phenomena
First X-ray detection of symbiotic nova CN Cha with eROSITA/SRG
Sara Saeedi, Jaroslav Merc, Manami Sasaki et al. (+2 more)
Aims. We report on the first X-ray detection of the symbiotic
star CN Cha with eROSITA (extended Roentgen Survey with an Imaging
Telescope Array) onboard Spektrum-Roentgen Gamma (Spektr-RG). Methods. We analyse the eROSITA observations from eRASS2 to eRASS5 individually, as well as the combined eRASS:5 data of all five surveys in order to investigate the X-ray spectral and timing properties of CN Cha throughout the eRASS. Results. Although CN Cha was not detected during the first eROSITA All-Sky Survey (eRASS1), it was detected for the first time in the second eRASS2. Our analysis shows that the X-ray emission of CN Cha gradually increased from eRASS2 to eRASS5. The X-ray spectrum of the source, with the main emission at <2.4 keV, allows us to classify it as a e̱ta}-type symbiotic
star. However, a more detailed analysis suggests that there is very soft component, which may originate either from thermonuclear burning on the white
dwarf, or from the wind collisions. Additional X-ray observations are required to better understand the origin and emission mechanisms of the source.
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All authors Sara Saeedi, Jaroslav Merc, Manami Sasaki, Lorenzo Ducci, Michael Freyberg
Mathematical Physics · Cross-listed from math.SP
Spectral Asymptotics of a Singular Harmonic Oscillator with Aharonov–Bohm Flux
Bernard Helffer, Ayman Kachmar and François Nicoleau
Motivated by a recent article of R. Vanlaere (2026), we investigate the spectral asymptotics of a singular harmonic oscillator arising from the radial reduction of the
magnetic Schrödinger operator on the unit disk in the presence of a constant
magnetic field and an Aharonov-Bohm flux. The corresponding
eigenvalue problem is equivalent to the study of the zeros of the Kummer confluent hypergeometric function with respect to its first parameter. Combining now standard semiclassical methods with the uniform asymptotic theory of Whittaker and confluent hypergeometric functions developed by Dunster (1989), Gabutti-Gatteschi (2001) and improved quite recently by Dunster (2026), we obtain a comprehensive description of the different spectral regimes. When the boundary lies in the classically forbidden region, we derive the exponentially small asymptotic correction to the
eigenvalue caused by the tunneling effect. For energy levels above the tunneling regime, we derive a shifted Bohr-Sommerfeld asymptotics for highly excited states at a fixed
magnetic field. Finally, for the transition regime where the energy level touches the boundary, we derive a three-term asymptotic expansion of the
eigenvalue. In an appendix, we translate these spectral results into explicit asymptotic formulas for the zeros of the Kummer function.
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Nuclear Experiment
Mean-$p_T$ fluctuations in Au+Au collisions at $\sqrt{s_{\rm NN}}=3.0$–$19.6$ GeV within JAM2
Yaqi Liu, Liuyao Zhang, Chunjian Zhang et al. (+2 more)
Event-by-event mean-$p_T$ fluctuations probe initial-state fluctuations and their
evolution through the dynamics of heavy-ion collisions. We study second-order mean-$p_T$ fluctuations in Au+Au collisions at $\sqrt{s_{\rm NN}}=3.0$–$19.6$ GeV using JAM2 in the RQMDv mean-field mode with the MH2 parameterization. The model qualitatively reproduces the measured identified-particle $p_T$ spectra, providing a single-particle baseline for the fluctuation analysis. The scaled fluctuation $k_2$ decreases with increasing $\langle N_{\rm part}\rangle$ and shows broad agreement with the available measurements at 7.7–19.6 GeV, whereas its calculated centrality dependence is stronger than that in the data at 3.0–4.5 GeV. For the combined
proton-plus-antiproton sample, the unnormalized correlator $\langle c_2\rangle$ is positive and larger than that for charged pions. The charged-pion correlator $\langle c_2\rangle$ is negative or consistent with zero over most centrality intervals at 3.0 and 3.5 GeV, becomes weakly positive at 4.5 GeV, and remains positive at higher energies. Its energy
evolution resembles the change in the reaction-plane
elliptic flow, but this comparison does not establish a common microscopic origin. These calculations provide species-dependent predictions within a transport model without an explicit partonic stage. Isolating the contributions of mean fields, rescattering, and spectator interactions requires controlled variations of the transport dynamics.
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All authors Yaqi Liu, Liuyao Zhang, Chunjian Zhang, Jinhui Chen, Chunwang Ma
Solar and Stellar Astrophysics
Nature of small-scale Ca II H brightenings associated with weak fields in a quiet Sun region
Xiang Li, H. N. Smitha, S. K. Solanki et al. (+3 more)
Context. Chromospheric emission observed in the Ca II H and K resonance lines is generally positively correlated with photospheric
magnetic fields. However, a fraction of strong Ca II H&K brightenings are found to occur over regions of low photospheric
magnetic flux density. Aims. We aim to understand the origin of these chromospheric brightenings associated with weak fields in quiet Sun regions. Methods. We use Ca II H observations taken by the SuFI along with the photospheric magnetograms recorded by the IMaX, instruments onboard the first flight of the balloon-borne observatory Sunrise. We also use the atmospheric physical parameters inverted from IMaX data by the SPINOR code. Results. 217 Ca II H brightenings associated with weak fields are identified. 111 of these are located at the peripheries of strong field regions, in the
magnetic canopies formed by the expansion of the kG flux tube. The other brightenings are associated with either weak unipolar
magnetic patches, with interactions between weak mixed-polarity
magnetic fields, or at locations with no clear
magnetic features. For the latter two situations, the Ca II H intensity varies with a period of 3-5 mins, accompanied by variations in the line-of-sight velocity, the temperature, and the
magnetic flux with a similar period. Conclusions. About half of the strong Ca II H brightenings associated with weak fields are located in
magnetic canopies overlying very weak photospheric fields. About 10-12% are associated with
magnetic bright points where the
magnetic field is probably not spatially resolved. The remainder appears to be Ca II H grains, which are overwhelmingly associated with
magnetic emergence or cancellation events. We conclude that although Ca II grains are mainly driven by (magneto-)acoustic shock waves, interactions between opposite-polarity
magnetic fields also contribute to the formation of the brightest peaks.
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All authors Xiang Li, H. N. Smitha, S. K. Solanki, T. L. Riethmüller, L. P. Chitta, S. Jafarzadeh
Astrophysics of Galaxies
Detection of metal absorption lines in quasar spectra: a neural network approach using U-Net
Elena Sofia Mangola, Francesco Pistis, Michele Fumagalli et al. (+7 more)
Current and future large spectroscopic surveys are significantly enhancing the volume and resolution of
quasar spectra that are observed, which requires the creation of efficient and precise automated techniques to detect absorption features. This study focuses on the detection of metal absorption features using a novel U-Net model on WEAVE-like mock spectra in the
quasar rest-frame wavelength interval $1230\,\mathring{\mathrm{A}} \leq \lambda_{\rm RF} \leq 3095\,\mathring{\mathrm{A}}$. We test the network performance for absorption detection both on ideal data and after simulating the continuum fitting step as applied on real data. The performance of these architectures is evaluated by the completeness, purity, and F1 score reached in bins of signal-to-noise ($\mathrm{S}/ \mathrm{N}_\mathrm{line} $) for the absorption lines and with the absolute fractional flux error for the continuum. The ability to recover the correct line centers is also studied. The U-Net reaches scores of $\approx 90\%$ for all metrics (completeness, purity, and F1 score) at $\mathrm{S}/ \mathrm{N}_\mathrm{line} \approx 4$. All false positive detections with $\mathrm{S}/ \mathrm{N}_\mathrm{line} \geq 5$ fall in the tails of the broad Ly$\alpha$ absorbers distribution of damped Ly$\alpha$ systems. The combination of continuum fitting and line detections has negligible effects on the detection performance at $\mathrm{S}/ \mathrm{N}_\mathrm{line} \geq 4$. Our proposed U-Net architecture offers a competitive tool for the analysis of absorption lines in current and upcoming large spectroscopic surveys and is well-suited to the identification of any absorption line feature.
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All authors Elena Sofia Mangola, Francesco Pistis, Michele Fumagalli, Matteo Fossati, Ting-Yun Cheng, Ryan J. Cooke, Rajeshwari Dutta, Ignasi Pérez-Ràfols, Matthew Pieri, Emanuel Gafton
Quantum Physics
Non-Hermitian Purcell Physics in Dissipatively Coupled Planar Photon-Magnon Systems
Shubham Singh, Sachin Verma, Animesh Chakraworty et al. (+3 more)
The Purcell effect has emerged as a powerful mechanism for controlling spontaneous emission and dissipation in cavity and nanophotonic systems; however, its realization in dissipative non-Hermitian hybrid platforms remains largely unexplored. In this work, we investigate the Purcell effect in a dissipatively coupled
photon-
magnon hybrid
quantum system consisting of a yttrium iron garnet (YIG) thin film integrated with an inverted octa-ring resonator (IORR) in a planar geometry. To describe the underlying dissipative hybrid dynamics, we develop a
quantum theoretical framework based on non-Hermitian coupled-mode theory combined with the input-output formalism. We also analyze the temporal decay dynamics of the
photon-
magnon system. Full-wave electromagnetic simulations demonstrate that the system can be engineered to operate in the level-attraction regime through dissipative
photon-
magnon coupling. By systematically tuning the
magnon damping, we uncover the emergence of a Purcell regime in which cavity-
photon dissipation is selectively enhanced through
magnon-mediated loss channels. We further show that the saturation magnetization (Ms) provides an additional degree of control over the onset, tunability, and robustness of the Purcell enhancement. The combined modulation of
magnon damping and Ms strongly influences the effective
photon-
magnon coupling, hybrid-mode
evolution, and dissipation landscape, enabling precise control of hybrid
quantum states. These findings establish a versatile strategy for engineering magnetization- and dissipation-controlled
photon-
magnon interactions in planar, chip-compatible architectures, opening new avenues for non-Hermitian cavity magnonics, tunable microwave dissipation engineering, and hybrid
quantum information technologies.
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All authors Shubham Singh, Sachin Verma, Animesh Chakraworty, Abhishek Maurya, Biswanath Bhoi, Rajeev Singh
Nuclear Theory
Strangeness Production in Heavy-Ion Collisions: Color Ropes or Hydrodynamic Evolution?
Carl B. Rosenkvist and Hannah Elfner
We investigate strangeness production and transverse dynamics in heavy-ion collisions at $\sqrt{s_{\mathrm{NN}}}\approx 2.5-20~\mathrm{GeV}$ using the transport approach SMASH (Simulating Many Accelerated Strongly-interacting
Hadrons), its extension with rope hadronization, and the SMASH+vHLLE hybrid approach. Results from the Pythia-based heavy-ion model Angantyr, with and without rope hadronization, are included for comparison. We study midrapidity particle yields and average transverse masses as functions of the number of wounded nucleons, as well as their energy dependence. For the $K^+/\pi^+$ ratio, SMASH+vHLLE overpredicts strangeness production at low energies but describes the higher-energy behavior reasonably well. SMASH+Ropes reproduces the ratio up to $\sqrt{s_{\mathrm{NN}}}\sim 10~\mathrm{GeV}$ but does not capture the turnover at higher energies. In contrast, the transverse-mass observables favor the hybrid approach, while the non-thermal models considered here do not generate sufficient collective transverse expansion. These results show that strangeness enhancement alone does not uniquely distinguish microscopic string interactions from a locally equilibrated medium. Simultaneously constraining strangeness production and transverse dynamics is therefore essential for disentangling thermal and non-thermal mechanisms in heavy-ion collisions.
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Solar and Stellar Astrophysics
High-Resolution Modelling of Coronae and Winds in Solar-type Stars with Varying Rotation Rates II. Stellar Winds
Yue-Hong Chen, Julián D. Alvarado-Gómez, Xin Cheng et al. (+6 more)
Observations suggest a connection between steady-wind mass loss and coronal X-ray activity in low-mass main-sequence
stars. Interpreting this connection is challenging because the wind is controlled mainly by the large-scale open field, whereas X-ray emission traces heating in small-scale closed fields often unresolved in global wind models. Here we use Space Weather Modelling Framework-Alfvén-Wave
Solar Model with global convective dynamo-generated
magnetic maps and
solar magnetograms. We model Alfvén-wave-heated winds for four
solar-type
stars plus the Sun, spanning rotation rates of $1.0$–$23.3$ times the
solar rate, and
magnetic field strengths of $6.0$–$1200$ G. Our models show that faster rotation yields a more tightly wound spiral, a larger Alfvén surface, higher terminal wind speeds, and a harsher wind-pressure environment for orbiting
exoplanets, different from that of the present-day Sun. We estimate the mass- and angular-momentum-loss rates and find systematic differences from Zeeman-Doppler Imaging-based predictions. Building on the successful reproduction of X-ray coronae in our Paper~I, we obtain the first self-consistent activity–wind relation in a unified modelling framework: the mass-loss rate scales with the surface X-ray flux following a power law with an index of ${\sim}0.67$. We also re-examine
magnetic braking via open-flux magnetisation, finding that the effective Alfvénic lever arm depends on the magnetisation parameter with a power-law index of ${\sim}0.35$. Finally, we quantify the
stellar wind pressure at the orbits of several super-Earths. Together with our Paper~I, the series of results shows the distinct roles of multi-scale
magnetic fields and provides physically grounded inputs for assessing habitable-zone space weather.
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All authors Yue-Hong Chen, Julián D. Alvarado-Gómez, Xin Cheng, Victor See, Yu Dai, Maarit J. Korpi-Lagg, Jörn Warnecke, Chen Xing, Mingde Ding
Quantum Physics
Quantum Metrology for Signals with an Unknown Causal Structure
Gwon Ryul Han, Hyukgun Kwon and Seok Hyung Lie
Quantum sensing protocols usually presuppose where and when each signal acts, yet this information is unavailable beforehand in experiments such as scattering and radar. We show that causal agnosticity forces a measurement scheme to be interferometric even when only discrete interactions are allowed. Describing the sensing events in the recently developed
quantum state over spacetime formalism, we then prove that the Fisher information of an interferometer is bounded by the squared sum of the local generator norms, independently of how the events are ordered. Nonunitary and spatiotemporally correlated signals can be explained as well when their physical dilation has a spacetime state on the enlarged events. Notably, the bound holds without presupposing a background spacetime that orders the events whenever the full collection of target and auxiliary events has a spacetime state. We show that this bound yields the spacetime Heisenberg limit and characterize its saturation through marginals of the spacetime state `dressed' by the signal. The $N^2$ scaling of the Fisher information with $N$ sensing events arises from the coherence of a single reference system shared across spacetime, whereas independently repeated interferometry obeys the standard
quantum limit.
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Quantum Physics
Quantum Advantage in Topological Data Analysis via Mayer Homology
Nhat A. Nghiem, Ryan Babbush, Adam Zalcman et al. (+4 more)
Prior work has explored
quantum algorithms for topological data analysis (TDA), revealing the possibility of exponential
quantum speedups in estimating the ratios of Betti numbers to the dimension of the combinatorial
Laplacian. However, this quantity is only non-vanishing and efficient-to-quantumly-estimate when Betti numbers are exponentially large, a case for which concrete examples are rarely known. Furthermore, certain randomized classical
algorithms are sometimes efficient in this regime. Thus, the prospect of achieving
quantum advantage in conventional TDA appears fairly narrow. Here, we address these challenges to the
quantum advantage in TDA by developing
quantum algorithms for Mayer homology, which generalize simplicial homology to $N$-nilpotent boundary operators ($\partial^N =0$) and have recently been successfully applied to real-world TDA contexts. We introduce an efficient
quantum algorithm for estimating Mayer Betti numbers and their persistent counterparts. We then prove that for high-order simplices, Mayer Betti numbers are often exponentially large in the dense regime, which ameliorates the normalization bottleneck of conventional
quantum TDA. In the same regime, we argue that existing dequantization
algorithms developed for conventional TDA, when applied to Mayer homology, generally lose theoretical guaranties, facing certain structural barriers that prevent their practical utilities. We also provide logical resource estimates revealing that a
quantum computer with roughly a few hundred
qubits and sixty million Toffoli gates could solve Mayer homology problems beyond the capabilities of known classical approaches. Finally, we discuss real-world applications of Mayer homology in genomics, supersymmetry, drug discovery, and neuroscience, revealing the potential of our
quantum algorithm to deliver real-world impacts via Mayer homology.
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All authors Nhat A. Nghiem, Ryan Babbush, Adam Zalcman, Dominic W. Berry, Trung V. Phan, Guo-Wei Wei, Ryu Hayakawa
High Energy Astrophysical Phenomena
Akihiro Inoue, Yudai Suwa, Ryuichiro Akaho et al. (+3 more)
Young isolated
neutron stars exhibit a wide range of
magnetic field strengths. To understand the origin of this diversity, it is important to observationally constrain
magnetic fields during the proto-
neutron star (PNS) phase. We propose a novel diagnostic of PNS
magnetic fields using
neutrinos associated with
supernova fallback. By performing one-dimensional general-relativistic magnetohydrodynamic simulations of the
supernova fallback onto a magnetized PNS, we investigate how the energy spectra of the fallback
neutrinos depend on the PNS
magnetic field strength and the fallback
accretion rate. We find that stronger
magnetic fields and lower
accretion rates produce softer spectra because the fallback
neutrinos are emitted mainly near the magnetospheric radius, which becomes larger under these conditions. To quantify this spectral softening, we define a hardness ratio based on event rates above and below 30 MeV and introduce a hardness-event-rate diagram. Using this diagram, we identify the parameter region in which our diagnostic is applicable. Its applicability depends on the PNS
magnetic field strength, fallback
accretion rate, onset time of the fallback phase, and
neutrino mass ordering. We also investigate the dependence on the PNS radius and find that a larger radius produces softer spectra, indicating a degeneracy between the
magnetic field and PNS compactness. An independent constraint on the PNS compactness would therefore enable us to better constrain the
magnetic field. These results suggest that future multimessenger observations of
galactic supernovae can provide a new window into the NS diversity.
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All authors Akihiro Inoue, Yudai Suwa, Ryuichiro Akaho, Shinsuke Takasao, Kazumi Kashiyama, Hiroyuki R. Takahashi
Optics
Channel closing in strong-field photoemission from tip arrays
Leon Brückner, Jonas Heimerl, Constantin Nauk et al. (+1 more)
Ultrafast photoemission is a promising avenue for the development of petahertz electronics. For such devices, identifying the precise emission mechanism and quantifying the local field strength at the emission site are of utmost interest. While this information can be extracted from electron energy spectra or the scaling of the emission rate with peak intensity, such measurements are not always technically feasible and a clear interpretation of the results can be challenging. Here, we demonstrate channel closing as a precision gauge for the local enhanced optical nearfield strength. Channel closings originate from a field-induced upshift of the
vacuum level, which leads to a small decrease of the emission yield with increasing intensity. We report the first experimental observation of such channel closings in the photoemission rate from an array of nanometer-sharp gold tips. Our data are well matched by simulated yields, enabling us to precisely measure the local, field-enhanced optical nearfield at the tip array in situ. We expect this method to be a versatile diagnostic tool for the characterization of lightwave optoelectronic devices, as it suffices to measure currents only.
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All authors Leon Brückner, Jonas Heimerl, Constantin Nauk, Peter Hommelhoff
Optics
Theory of Airy-Beam Wavefront Sensing
Surya Kamal
A new wavefront sensing framework based on the interference of counter-accelerating Airy beams is presented. An engineered cubic phase function transforms a single Gaussian beam into two coherent Airy beams with opposite transverse accelerations, which self-recombine during free-space propagation to form an interference pattern encoding the aberrated incident wavefront. Numerical simulations demonstrate accurate recovery of the aberrated exit-pupil phase across the aberration sets considered, with a root-mean-square phase reconstruction error below $10^{-6} \mathrm{\;rad}$ for the aberration set shown and consistently low errors for the other sets, while maintaining accurate recovery in the presence of measurement noise. The approach eliminates collection optics and enables a compact wavefront-sensing architecture for applications where conventional interferometric systems are difficult to implement, including electron-optical systems, augmented and virtual reality systems.
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Optics
Photonics-GCCE: group collaborative-competitive evolution multi-agent framework for universal and autonomous optical design
Weijie Xu, Ming Wang, Ruicheng Ma et al. (+20 more)
Large
language model (LLM)-empowered photonic
agents connect natural-
language intents to executable solvers, showing significant advantages over conventional optical design approaches. However, current multi-
agent frameworks operate within a collaborative paradigm without extrinsic selective pressure, which could inherit shared blind spots, converge prematurely, and fail to accumulate transferable experience for intricate tasks. Here, we introduce a group photonics collaboration-compete
evolution (GCCE) framework and its LLM instantiation, termed Photonics-GCCE. Two independent
agent groups pursue the same design target and undergo structured competitive evaluation across refractive-index fidelity, fabrication sensitivity, algorithmic adequacy, and physical consistency. Each group comprises a leader and three specialist
agents dedicated to materials, optimization, and code validation.
Agents refine their skills through competitive evaluation across design rounds. Benchmarking across six device categories against single-
agent and multi-
agent baselines shows that Photonics-GCCE elevates composite scores into the high 90s, improves fabrication robustness by 15 to 17 points, and reduces solver iterations to roughly 40 rounds. A representative quasi?BIC demonstration achieves a practically fabricable design with a quality factor of 13120. Our results demonstrate Photonics-GCCE as a general-purpose and closed-loop framework for autonomous optical design, capable of producing high-performance, fabrication-ready devices across diverse nanophotonic tasks.
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All authors Weijie Xu, Ming Wang, Ruicheng Ma, Zeyong Wei, Di Zhang, Jian Chen, Zining Wang, Sijun Hu, Linyuan Dou, Haoyu Li, Haigang Liang, Yijie Luo, Shuqiao Li, Qinghua Song, Huihui Zhu, Hongfei Jiao, Chao Liu, Ali Momeni, Zhanshan Wang, Yuzhi Shi, Romain Fleury, Cheng-Wei Qiu, Xinbin Cheng
High Energy Physics (Experiment)
Enhanced track reconstruction at the HL-LHC
Brunella D'Anzi
The High-Luminosity Large
Hadron Collider (HL-LHC) will substantially increase the charged-particle multiplicity and detector occupancy in the ATLAS and CMS experiments, posing new challenges for the reconstruction of charged-particle tracks. Both experiments are upgrading their tracking detectors, with fully silicon-based systems providing a finer granularity, extended acceptance and updated geometry with respect to the current ones, with the goal to reduce the combinatorial complexity of pattern recognition tasks. At the same time, the more demanding reconstruction environment at the HL-LHC requires
algorithms capable of retaining high tracking efficiency while reducing the associated computational cost. To this purpose, both the ATLAS and CMS Collaborations are developing tracking
algorithms for offline and online reconstruction, exploiting parallelized, vectorized and heterogeneous architectures. The ATLAS experiment is moving toward an ACTS reconstruction chain, based on the Combinatorial Kalman Filter
algorithm. In the CMS experiment, the new High-Level Trigger tracking baseline combines the Patatrack and the Line Segment Tracking
algorithms for seed reconstruction, using the mkFit
algorithm for track building. These developments yield tracking efficiencies above 85% across the full phase space at high pileup, extending the acceptance to forward and displaced tracks with transverse displacements of up to tens of centimetres, while significantly reducing the reconstruction time. Machine-learning techniques are also being explored at several stages of the reconstruction, including track building. The state-of-the-art performances of the tracking strategies developed by the ATLAS and CMS Collaborations for the HL-LHC are presented, together with prospects of further improvements.
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Mesoscale and Nanoscale Physics
Theory of optical alignment and orientation of excitons in an ensemble of semiconductor nanoplatelets
O. O. Druzhinina and A. V. Rodina
We present the theory of
exciton optical
alignment and optical orientation effects in a single
semiconductor nanoplatelet (NPL) and in an ensemble of NPLs. The theoretical model is developed to take into account the emission from both bright and dark
exciton states in the case of strong electron-hole exchange interaction and an isotropic distribution of in-plane orientations of the NPLs' edges with respect to the linear polarization axis. The conditions for the linear optical response regime on the polarized resonant excitation of the bright
exciton are considered, and the steady-state and time-dependent expressions for polarized photoluminescence are presented for the low temperature case in the Faraday
magnetic field at normal incidence. The
symmetry of the obtained optical response corresponds to the $C_{2}$ point group for the single NPL and the $C_{\infty}$ point group for the NPL ensemble. The bright-to-dark
exciton coupling mechanism allowing one to observe the optical
alignment of the dark
exciton is considered. The example calculations of the effects are presented for the parameters close to those of CdSe/CdS core/shell NPLs. The effect of the fluctuations in the
exciton parameters in the ensemble on the polarization dephasing in the transverse effective
magnetic field is demonstrated.
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Pattern Formation and Solitons
Computation of Turing bifurcation normal form for n-component reaction-diffusion systems
Edgardo Villar-Sepúlveda and Alan R. Champneys
General expressions are derived for the amplitude equation valid at a Turing bifurcation of a system of reaction-
diffusion equations in one spatial dimension, with an arbitrary number of components. The normal form is computed up to fifth order, which enables the detection and analysis of codimension-two points where the criticality of the bifurcation changes. The expressions are implemented within a Python package, in which the user needs to specify only expressions for the reaction kinetics and the values of
diffusion constants. The code is augmented with a Mathematica routine to compute curves of Turing bifurcations in a parameter plane and automatically detect codimension-two points. The software is illustrated with examples that show the versatility of the method including a case with cross-
diffusion, a higher-order scalar equation, and a four-component system.
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Pattern Formation and Solitons
Amplitude equations for wave bifurcations in reaction-diffusion systems
Edgardo Villar-Sepúlveda and Alan R. Champneys
A wave bifurcation is the counterpart to a Turing instability in reaction-
diffusion systems, but where the critical wavenumber corresponds to a pure imaginary pair rather than a zero temporal
eigenvalue. Such bifurcations require at least three components and give rise to patterns that are periodic in both space and time. Depending on boundary conditions, these patterns can comprise either rotating or standing waves. Restricting to systems in one spatial dimension, complete formulae are derived for the evaluation of the coefficients of the weakly nonlinear normal form of the bifurcation up to order five, including those that determine the criticality of both rotating and standing waves. The formulae apply to arbitrary $n$-component systems ($n\geq 3$) and their evaluation is implemented in software which is made available as supplementary material. The theory is illustrated on two different versions of three-component reaction-
diffusion models of excitable media that were previously shown to feature super- and subcritical wave instabilities and on a five-component model of two-layer chemical reaction. In each case, two-parameter bifurcation diagrams are produced to illustrate the connection between complex dispersion relations and different types of
Hopf, Turing, and wave bifurcations, including the existence of several codimension-two bifurcations.
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Pattern Formation and Solitons
General conditions for Turing and wave instabilities in reaction-diffusion systems
Edgardo Villar-Sepúlveda and Alan R. Champneys
Necessary and sufficient conditions are provided for a
diffusion-driven instability of a stable
equilibrium of a reaction-
diffusion system with $n$ components and a diagonal
diffusion matrix. These can be either Turing or wave instabilities. Known necessary and sufficient conditions are reproduced for there to exist
diffusion rates that cause a Turing bifurcation of a stable homogeneous state in the absence of
diffusion. The method of proof here though, which is based on a study of dispersion relations in the contrasting limits in which the wavenumber tends to zero and to $\infty$, gives a constructive method for choosing
diffusion constants. The results are illustrated on a model for the dispersion of malaria, a 3-component FitzHugh-Nagumo-like model proposed to study excitable wavetrains, and for two different coupled Brusselator systems with 4 components
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High Energy Physics (Theory)
Relational background field formulation of discrete quantum gravity models: The case of $O(N)$ vector models in zero dimensions
Vincent Lahoche, Dine Ousmane Samary and Parham Radpay
In a recent paper arxiv.org/abs/2609.21031, we have introduced the concept of a relational background field as a new approach to the renormalization group (RG) for discrete
quantum gravity models, focusing on random
matrix models. The proposed method offers the dual advantage of preserving the model's gauge
symmetry (typically $U(N)$ or $O(N)$), whose breaking in conventional approaches has remained an open problem, and providing a more satisfactory treatment of the continuum or infrared (IR) limit. In this limit, the theory is described by a non-local field theory in dimension $D = 2k + 3$, where $k$ denotes the number of cuts in the effective spectrum as dictated by random
matrix theory. This pedagogical paper reviews this construction for real random vector models in zero dimensions, with $O(N)$ as the
symmetry group. Following the general strategy of background-field-type formulations, we show, using the BBP (Baik-Ben Arrous-P'ech'e) phase transition, that a partial Hubbard–Stratonovich decomposition of the quartic interaction, involving a
matrix-valued intermediate field, allows a preferred notion of scale to emerge. This scale, in turn, defines an RG flow, whose perturbative structure is analyzed. Our calculation demonstrates the existence of an asymptotic Wilson–Fisher-type fixed point, whose sole relevant critical exponent is in qualitative agreement with the double-scaling critical exponent of these models.
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General Relativity and Quantum Cosmology
Neural Network Guided Parameter Space Constraints for Gravitational Wave Searches from Binary Black Holes
Chetan Verma, Amit Reza, Gurudatt Gaur et al. (+2 more)
The detection of gravitational waves (GWs) from compact binary coalescences (CBCs) using matched filtering is computationally demanding because detector data must be correlated with many template waveforms spanning a high-dimensional intrinsic parameter space. In our previous work, we showed that a convolutional neural network (CNN) can classify noisy signals against pure noise and constrain the intrinsic parameter space of a true non-spinning binary black hole (BBH) signal, enabling a narrower matched-filter search region and reducing computational cost. Here, we extend this framework to aligned-
spin BBH systems and investigate how different parameter-space representations affect CNN-based patch identification. Using IMRPhenomD waveforms over the aligned-
spin BBH parameter space and Advanced LIGO design sensitivity, we show that a CNN trained solely on the aligned-
spin template bank achieves more than 99.8% signal-noise classification accuracy on independently generated uniformly sampled BBH signals, indicating that additional uniformly sampled training data are unnecessary. We partition the template bank into four approximately balanced patches using a Principal Component Analysis (PCA)-based
quantile scheme and evaluate five parameter-space representations for patch identification. The chirp mass-duration representation achieves the highest average accuracy (93.2%), followed by chirp mass (91.6%) and component masses (90.5%). The post-Newtonian coordinates tau_0-tau_3 and theta_0-theta_3-theta_3s yield substantially lower accuracies. These results show that the existing template bank is sufficient for training and high-accuracy signal detection, while the choice of parameter-space representation is critical for constraining the parameters of the true signal.
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All authors Chetan Verma, Amit Reza, Gurudatt Gaur, Dilip Krishnaswamy, Sarah Caudill
Astrophysics of Galaxies
The Neutral Hydrogen Gas Content of Star-forming and Quiescent S0 Galaxies
D. A. A. Lee, Karen L. Masters, David V. Stark et al. (+1 more)
Lenticular (S0)
galaxies that remain actively
star-forming (SFS0s) are a unique transition population among
galaxies. We investigated the HI (21cm) neutral hydrogen content of a sample of lenticular
galaxies identified from within the Mapping Nearby
Galaxies at Apache Point Observatory (MaNGA) survey and which have been classified as
star-forming or quiescent (qS0s). We compared these populations to each other and to a sample of
star-forming spiral (SFSp)
galaxies in MaNGA. We found that the HI mass fraction and HI deficiency of the SFS0s were intermediate between the qS0s and the SFSps, but more similar to the spirals. The HI depletion time of the qS0s is very much longer than that of the SFS0s and spirals, which have roughly similar times. We also compared the molecular gas fractions of the three groups which shows that the lowest fraction of the three populations is found in the qS0s, followed by the SFS0s and then the SFSps. A comparison of total baryonic mass indicates that the SFS0s have significantly lower masses than the qS0s in the sample. This suggests that the SFS0s must form from lower mass progenitors (unobserved by MaNGA) which either accrete external gas or lose spiral arms. The more massive qS0s are a completely separate population, most likely to be formed either from fading SFSps or from medium- to high-mass spirals undergoing mergers. The SFS0s in this sample cannot form from the qS0s in this sample that receive in-falling gas, nor can they fade to create these qS0s.
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All authors D. A. A. Lee, Karen L. Masters, David V. Stark, Z. Z. Abidin
Quantum Physics · Cross-listed from cs.IT
Cubical Sheaf Complexes with Constant Expansion with Applications to Asymptotically Good qLTCs
Yeyuan Chen, Miryam Mi-Ying Huang, Yinchen Liu et al. (+1 more)
For every fixed integers $r \ge 4$ and $2 \le k \le r-2$, we construct $r$-dimensional cubical sheaf complexes whose degree-$k$ CSS codes have positive constant rate, linear distance, and constant soundness, with bounded row and column weights. Taking $r=4$ and $k=2$ gives a family of asymptotically good binary qLTCs. At the core of our construction is a uniform product-expansion
theorem for explicit Reed-Solomon codes on norm-one evaluation sets. The key point is that the expansion constant stays bounded away from zero as the local code lengths grow. We place these codes on arithmetic cubical complexes, obtaining constant local expansion for both the resulting sheaf and its dual. Together with the local-to-global framework of Dinur, Lin, and Vidick (FOCS 2024) and sheaf duality, this gives linear distance and constant soundness, while an asymmetric choice of local code dimensions gives positive rate. The resulting codes are explicit and
polynomial-time computable.
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All authors Yeyuan Chen, Miryam Mi-Ying Huang, Yinchen Liu, Er-Cheng Tang