Papers

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Physics

Wednesday 19 August

Astrophysics of Galaxies

A model for the enhanced production rate of early-type hypervelocity stars in the Galactic halo

Chunyang Cao, F.K. Liu, Xian Chen et al. (+1 more)

About twenty late B-type hypervelocity stars (HVSs) traveling faster than the Galactic escape velocity have been discovered in the Galactic halo, many of which were ejected from the Galactic center (GC). Recently, we have advocated that these HVSs most likely formed in the nuclear star cluster (NSC) $150$–$500\, \rm{Myr}$ ago and were predominantly ejected via the gravitational slingshot of a past intermediate-mass black hole (IMBH) orbiting the supermassive black hole (SMBH) Sgr~A$^{*}$. Here we explore the constraints of the production rate of young HVSs on the star formation region of the NSC. We propose that the young HVS progenitors are born in a lopsided eccentric disk that is comparable in radius to the NSC. By numerically tracking the orbital evolution of disk stars, we find that they undergo rapid angular momentum relaxation at formation due to eccentric disk instability, and that their slingshot interactions with the SMBH-IMBH binary at distances $\simeq 100\, \rm{au}$ produce HVSs at a rate of $10^{-5}$–$10^{-4}\, \rm{yr}^{-1}$. The rate is expected to trace the disk formation history, increasing with the accumulation of disk stars and dropping rapidly after the star formation stopped at $150\, \rm{Myr}$ ago. The rate is consistent with the observation and orders of magnitude higher than that expected for an old relaxed population in the literature, enhanced due to the gravitational torque from the non-spherical GC potential and radial velocity anisotropies of the disk stars. Our results imply that young HVSs should have a distinct radial and angular distribution from old ones.

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All authors Chunyang Cao, F.K. Liu, Xian Chen, Shuo Li

Quantum Physics

Unified Strong-Field Dynamics Simulations from Atoms to Heterostructures

Zakaria Dahbi and Amelle Zaïr

We present TDSE-Z, a high-performance open-source framework for strong-field quantum dynamics in atomic, molecular, and semiconductor effective-mass systems. The core engine implements a weak-form Galerkin discretisation of the Hermitian BenDaniel-Duke operator, $\hat{T}_{\mathrm{BDD}} = -\frac{1}{2}\nabla\cdot(m^{-1}(\mathbf{r})\nabla)$, on geometry-adapted B-spline meshes, supporting arbitrary potentials and customisable laser configurations in one to three dimensions. We validate the static position-dependent-mass (PDM) eigensolver through two stringent benchmarks: a comparison to the analytical Quesne PDM model and a $\text{GaAs/Al}_{0.3}\text{Ga}_{0.7}\text{As}$ double quantum well, where the exponential decay of computed tunnel splittings follows Wentzel-Kramers-Brillouin (WKB) theory at the sub-percent level. We further demonstrate the time-propagation engine on constant-mass systems, accurately reproducing high-harmonic generation (HHG) spectra in atomic benchmarks and confirming the importance of dimensionality in fully capturing the strong light-matter interaction. Our implementation demonstrates robust strong-scaling efficiency, maintaining performance across hundreds of CPU cores. While the static eigensolver currently supports optional GPU offloading, the time-propagation engine is CPU-optimised, providing a modular architecture for future expansion toward exascale quantum dynamics.

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Quantum Physics

Multicast quantum network coding as optimal symmetric universal cloning over a quantum network

Go Kato, Mio Murao and Masaki Owari

We study the problem of perfectly multicasting symmetric universal clones of unknown quantum states over quantum networks with free classical communication. We construct a protocol that multicasts symmetric universal clones of input states from multiple source nodes by extending the quantum network coding protocol proposed by Kobayashi et al. We further establish a sufficient condition for perfect multicast in the single-source setting. Specifically, we show that when a single copy of a $q^r$-dimensional input state is available at the source node, where $q$ is a sufficiently large prime power, perfect multicast of the corresponding symmetric universal clone is achievable using a small amount of entanglement shared among the target nodes. This result holds for quantum networks represented by an undirected graph $G$, where each edge corresponds to a noiseless $q$-dimensional quantum channel, provided that there exists an acyclic directed graph $G'$ obtained by assigning directions to the edges of $G$ such that the minimum cut of $G'$ is at least $r$.

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Materials Science

Room-temperature ferroelectrically switchable quantum geometry in few-layer WTe2 for complementary in-memory computing

Ruihan Wang, Pengfei Wang, Haoyun Chen et al. (+10 more)

Quantum geometry, describing the inherent geometric structure of electron wavefunctions in momentum space, transcends the traditional charge degree of freedom and provides a novel physical basis for information encoding and processing. The key to such new computing paradigms is the non-volatile electrical programming of quantum geometric states at room temperature, which, however, has not been established. Here, we demonstrate ferroelectrically switchable quantum geometry in few-layer WTe2, which uniquely enables complementary convolutional processing. By employing the intrinsic coupling between ferroelectric polarization and quantum geometry in few-layer WTe2, we show that the second- and third-order nonlinear anomalous Hall effects (NLAHE) can be deterministically and electrically switched in a nonvolatile and correlated manner. The switching is robust at room temperature for ~104 cycles and retention of ~105 s. Furthermore, leveraging the opposite switching behaviors of second- and third-order NLAHE at room temperature, we demonstrate complementary in-memory computing and implement a hardware-level complementary convolution kernel. This kernel overcomes the inherent directional specificity of conventional convolutional networks and achieves a texture recognition accuracy of 98%, thereby illustrating a viable pathway towards physics-native computing through exploiting exotic physics in quantum materials.

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All authors Ruihan Wang, Pengfei Wang, Haoyun Chen, Yunze Peng, Bingyan Liu, Junlin Xiong, Xueyuan Zhang, Chen Pan, Xin Chen, Shengyuan A. Yang, Shi-Jun Liang, Feng Miao, Peng Song

Other Condensed Matter

Efficient calculation of real-space lattice propagators in the presence of a Fermi sea

Oliver Tong and Mona Berciu

We present an efficient method for computing the real-space propagators (lattice Green's functions) of any tight-binding Hamiltonian in the presence of a Fermi sea with carrier concentration $x$. The method is valid for any lattice, dispersion, and dimension, provided the corresponding $x=0$ propagators are known. We show that suitable combinations of the finite-$x$ particle-addition propagators have a real or imaginary part trivially related to their $x=0$ counterpart, while the remaining part follows from a Kramers-Kronig relation that can be evaluated for all energies at once using the fast Fourier transforms. The computational cost is therefore independent of the dimensionality, unlike that of direct Brillouin-zone integration. The particle-removal propagators follow from general identities. We validate the method against direct integration for hypercubic lattices in one, two, and three dimensions, and use the 2D square lattice to illustrate how the shape of the Fermi surface is imprinted on the spatial structure of the propagators. In particular, at energies far outside the band, the propagator maps converge to the Fraunhofer diffraction pattern whose aperture is the unoccupied part of the Brillouin zone.

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Astrophysics of Galaxies

The MAGPI Survey: Emission Line Products Data Release and the Role of Spectroscopic Aperture Covering Fraction on the Balmer Decrement-Stellar Mass Relation

A. J. Battisti, E. G. M. Muller, E. Wisnioski et al. (+27 more)

The Middle Ages Galaxy Properties with Integral field spectroscopy (MAGPI) survey is a Large Program on the European Southern Observatory Very Large Telescope using the MUSE instrument. This paper presents the data release for the MAGPI emission line products and includes emission line maps for 836 galaxies at $0.05\leq z_\mathrm{spec}\leq 0.424$ ($\mathrm{H}\alpha$-window) and aperture-based emission line measurements for 2,607 galaxies at $0.05\leq z_\mathrm{spec}\leq 1.50$ (upper bound is [OII] cut-off), both based on the GIST software, for all 56 MAGPI fields. We use these data to examine dust attenuation, which represents a major source of uncertainty in the derived properties of galaxies that are critical to constrain models of galaxy evolution. We examine the role that the spectroscopic aperture covering fraction ($f_c$) has on the relationship between the Balmer decrement ($\mathrm{BD}=F(\mathrm{H}\alpha)/F(\mathrm{H}\beta)$; a common proxy for dust attenuation) and the total stellar mass ($M_\star$). Several studies have suggested that the BD-$M_\star$ relation may be redshift invariant; however, the compared surveys often have different $f_c$ due to their differing fibre or slit sizes that can cause systematic offsets. Our results indicate that $f_c$ has a significant impact on this relationship, due to galaxies having negative BD radial gradients, which are more negative for more massive galaxies at $z\lesssim0.4$. Comparing spectroscopic surveys with $\left<f_c\right> \gtrsim 0.5$, we find that the BD-$M_\star$ relation shows a preference for redshift evolution and is roughly consistent with the behaviour of UV stellar continuum attenuation redshift evolution ($A_\mathrm{FUV}$-$z$), with the average dust attenuation in galaxies peaking at $z\sim1.2$ and decreasing at lower and higher redshifts.

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All authors A. J. Battisti, E. G. M. Muller, E. Wisnioski, J. T. Mendel, C. Foster, C. D. P. Lagos, K. E. Harborne, I. U. Aalia, S. Barsanti, I. Breda, D. Calzetti, S. M. Croom, P. K. Das, A. Ferré-Mateu, T. Gao, E. Gjergo, K. Grasha, Y. Mai, A. Mailvaganam, T. Mukherjee, M. Mun, R.-S. Remus, G. Sharma, S. M. Sweet, S. Thater, L. M. Valenzuela, J. van de Sande, G. van de Ven, T. Zafar, B. Ziegler

Nuclear Theory

Comparison of several model averaging methods in nuclear charge radius predictions

Huan-Yu Zhang, Rui Jing, Zhen-Hua Zhang et al. (+2 more)

The performance of five model averaging methods, including the arithmetic mean (AM), weighted mean (WM), naive Bayesian model averaging (NBMA), principal component analysis (PCA), and power-moderated mean (PMM) methods, in nuclear charge radius predictions is investigated. Five commonly used nuclear charge radius models are adopted as inputs for the averaging procedures. The charge radius differences between the experimental data and the original nuclear models are analyzed and the results after considering the model averaging methods are also discussed. The calculations show that the NBMA method can provide the best root-mean-square (rms) deviation among these five model averaging methods. The PCA method can extract useful physical information and not only helps to interpret the model differences but also offers a feasible way to construct improved empirical models by recombining the principal components. In contrast to the other methods, whose results worsen upon including a new model with a larger rms deviation, the rms deviation of the PCA method remains almost unaffected. The PMM method is capable of integrating the strengths of various nuclear models and delivering reasonable uncertainty estimates not only in known regions but also in unknown ones. This method can automatically adjust data uncertainties to achieve consistency, and it can provide a tool for a smooth transition of the nuclear charge radius prediction from the WM to the AM. The extrapolation ability of these model averaging methods is checked by 66 newly observed data after year 2021. The calculations show that model averaging offers a reliable strategy for nuclear charge radius predictions, combining high accuracy on known data with robust extrapolation to new measurements. The charge radii and the odd-even staggering in calcium isotopes are also discussed.

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All authors Huan-Yu Zhang, Rui Jing, Zhen-Hua Zhang, Xin-Hui Wu, Zhong-Ming Niu

Materials Science

Room-Temperature Polarity Control of the Anomalous Nernst Effect in a High-Magnetic-Anisotropy Topological Nodal-Line MnAlGe

Nanhe Kumar Gupta, Keisuke Masudaa, Masaaki Kakoki et al. (+7 more)

Controlling the polarity of anomalous Nernst thermopower is a promising strategy for enhancing the performances of thermoelectric applications. However, realizing such control at room temperature (RT) in topological ferromagnets with high magnetic anisotropy (Ku) remains challenging. Here, we report RT polarity control of the anomalous Nernst effect (ANE) in quasi-two-dimensional nodal-line MnAlGe epitaxial thin films through Al/Ge compositional tuning while preserving robust high Ku. This polarity reversal originates from intrinsic Berry curvature contributions modulated by sublattice-selective carrier doping, as supported by spin-resolved electronic band structure analysis and hard X-ray photoemission spectroscopy. To demonstrate the practical feasibility, we also fabricated a meander-structured device combining MnAlGe with positive and negative polarity enhanced the thermoelectric output. Our results demonstrate that tuning the Fermi level relative to the nodal-line electronic structure while preserving high Ku enables controllable ANE polarity reversal within a single material, providing a route toward RT transverse thermoelectric devices.

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All authors Nanhe Kumar Gupta, Keisuke Masudaa, Masaaki Kakoki, Benugopal Bairagya, Satoki Tazawaa, Weinan Zhoua, Hirofumi Sutoa, Ryo Toyama, Akio Kimura, Yuya Sakuraba

General Relativity and Quantum Cosmology

Covariant Energy Momentum Tensor in General Relativity by Generalized Canonical Method

Masakatsu Kenmoku

Defining a complete and covariant energy-momentum tensor in general relativity is a longstanding issue of concern. A widely attempted approach is to define it as a pseudo-tensor in an asymptotic Lorentz system. In this paper, we present a complete covariant definition of the gravitational energy-momentum tensor in the generalized canonical form. The key is incorporate higher-order differential terms of the metric tensor into the gravitational action in order to derive the energy-momentum tensor consistently. This completely covariant form ensures that the gravitational energy is correctly obtained in any coordinate system, including polar coordinates and asymptotic Lorentz systems.

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Earth and Planetary Astrophysics

Stellar Abundances as Probes of Rocky Exoplanet Interiors: The Mantle Composition and Mineralogy of GJ 486b

Harshit Krishna, Asmit Gupta, Sneha Bhowmik et al. (+3 more)

Over the past three decades, hundreds of rocky exoplanets have been discovered. Some of these show atmospheric signatures indicative of diverse chemical compositions. Interpreting these atmospheres requires a physically grounded understanding of planetary interiors, as interior composition and mineralogy govern the formation and evolution of secondary atmospheres. Rocky terrestrial exoplanets are expected to inherit the refractory composition of their host stars, providing a direct pathway to constrain their bulk composition and mineralogy. However, a large fraction of these planets orbit M-type stars, whose compositions remain poorly constrained because of limited and uncertain stellar abundance measurements. Here, we present a physically consistent framework that connects stellar abundances to the interior structure and mineralogy of rocky exoplanets by combining stellar abundance inference, devolatilization modeling to estimate bulk and mantle elemental abundances, interior structure calculations to derive pressure-temperature profiles, and thermodynamic equilibrium modeling of mantle mineralogy. We first benchmark the framework against Earth and then apply it to the super-Earth GJ 486b using chemically consistent abundances derived from ensembles of similar M-dwarf hosts. We find that GJ 486b likely hosts an iron-rich and silica-poor mantle relative to Earth while preserving the major mantle phase transitions. Sensitivity analyses show that the overall mineralogical structure is robust to variations in bulk composition and pressure-temperature profiles, with temperature primarily modulating phase proportions near key transitions. Finally, our results show that stellar-abundance inference combined with devolatilization models constrains the interior composition of rocky exoplanets and provides a foundation for linking planetary interiors to atmospheric characterization.

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All authors Harshit Krishna, Asmit Gupta, Sneha Bhowmik, Chandan K. Sahu, Sudipta Mridha, Liton Majumdar

High Energy Astrophysical Phenomena

An invariant energy release hierarchy in a repeating fast radio burst

X. Yang, S. B. Zhang, Y. Li et al. (+9 more)

Fast radio bursts (FRBs) are luminous millisecond radio transients whose physical origin remains unsettled. A key diagnostic is whether their burst-energy distributions retain characteristic physical scales that are intrinsic and temporally stable within an individual engine. Here we report a 3.2-year monitoring campaign of the hyperactive repeater FRB~20220529 with FAST and Parkes, yielding more than 1,300 bursts spanning nearly five orders of magnitude in spectral energy density. The cumulative burst-rate distribution is described by an exponential-plus-power-law (EXP+PL) form, linking a low-energy exponential component with characteristic scale (E_0) to a scale-free bright-end tail. This scale remains invariant despite the burst rate declining by more than an order of magnitude, revealing a stable dissipation scale decoupled from the source's macroscopic trigger activity. Within a magnetar interpretation, this phenomenology is consistent with localized sub-critical reconnection episodes coexisting with plasmoid-mediated magnetic avalanches in a twisted magnetosphere. The invariant (E_0) constrains the dissipation region to the inner-to-middle magnetosphere and reveals a robust energy-release hierarchy beneath the variable activity of repeating FRBs, providing an observational benchmark for relativistic reconnection in an ultra-magnetized neutron-star environment.

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All authors X. Yang, S. B. Zhang, Y. Li, D. Xiao, W. L. Zhang, J.-J. Wei, J.-J. Geng, J.-S. Wang, Y. P. Yang, F. Y. Wang, X. F. Wu, Z. G. Dai

Plasma Physics

Beam-Tracing-Based Quantitative Reconstruction of Density Fluctuations in QUEST Using Doppler Backscattering

T. Kinoshita, T. Tokuzawa, V. H. Hall-Chen et al. (+8 more)

A three-channel X-/Ku-band Doppler backscattering (DBS) system has been developed and installed on QUEST for turbulence and electric-field measurements. In spherical tokamaks, the large magnetic-field pitch angle increases the geometric mismatch between the probing beam wave vector and the local magnetic-field vector, reducing the effective perpendicular projection and resulting in a systematic underestimation of the measured scattering intensity. In addition, in QUEST, where low plasma density requires a low-frequency probe beam, beam propagation effects become increasingly significant, further complicating the interpretation of the measured DBS power in terms of local density fluctuation amplitude. To address these issues, a quantitative correction methodology based on the synthetic DBS code SCOTTY was established. All relevant diagnostic response effects were evaluated using SCOTTY along ray trajectories, yielding a correction factor for reconstructing the local turbulence amplitude from the measured scattering signal. The correction factor exhibits strong spatial and frequency dependence, varying by up to an order of magnitude between the plasma core and edge regions, highlighting the necessity of frequency-dependent corrections. By applying the derived correction factor to experimental measurements, quantitative density fluctuation amplitudes were reconstructed from the detected scattering signals. Evaluation of the fluctuation amplitude indicates enhanced turbulence activity in the plasma edge region, where a finite negative radial electric field is inferred. This work demonstrates the first quantitative turbulence evaluation using low-frequency X-/Ku-band DBS measurements in QUEST and establishes a framework for quantitative DBS analysis in spherical tokamaks.

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All authors T. Kinoshita, T. Tokuzawa, V. H. Hall-Chen, Y. T. Tan, T. Ido, H. Idei, R. Ikezoe, K. Hanada, M. Hasegawa, T. Onchi, Y. Peng

Quantum Physics

Asymptotic Entanglement Hiding under Stabilizer Restrictions

Jicun Li, Wei Xie, Jun Wu et al. (+2 more)

Entanglement is central to quantum information processing, while stabilizer operations underpin fault-tolerant quantum computation. We ask how much entanglement remains visible or distillable under stabilizer restrictions. We quantify stabilizer-visible entanglement by restricting the measured relative entropy of entanglement to stabilizer measurements, thereby obtaining converse bounds on entanglement distillation under stabilizer operations. We demonstrate magic-free asymptotic entanglement hiding: we construct explicit convex mixtures of pure stabilizer states on $N$ qutrits per party whose unrestricted visible entanglement and LOCC-distillable entanglement both grow as $\Omega(N/\log N)$, while their stabilizer-visible and stabilizer-distillable entanglement vanish as $N\to\infty$. Thus, an unbounded amount of LOCC-distillable entanglement carried by stabilizer states can become asymptotically invisible and undistillable under stabilizer restrictions. We further prove that stabilizer-visible entanglement is $O(1)$ with high probability for Haar-random pure states despite extensive unrestricted visibility, and vanishes uniformly over entangled Werner states as the local dimension grows through odd primes. These results reveal a fundamental separation between entanglement and magic as resources, exposing intrinsic limits on entanglement extraction using stabilizer operations.

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All authors Jicun Li, Wei Xie, Jun Wu, Honglin Chen, Xiang-Yang Li

General Relativity and Quantum Cosmology

Bounds on the Lyapunov Exponent of Circular Null Orbits in $n$-Dimensional Black-Hole Spacetimes

Anagha V., C. Fairoos and T. K. Safir

Unstable circular null orbits provide a geometric bridge between black-hole optics, photon rings, strong gravitational lensing, and the eikonal sector of quasinormal ringing. In four-dimensional Einstein gravity, the instability rate of such orbits, measured by the Lyapunov exponent $\lambda$, obeys model-independent upper bounds when the matter sector satisfies standard energy conditions. We extend this analysis to static, spherically symmetric, asymptotically flat black holes in arbitrary dimensional Einstein gravity, allowing for an anisotropic matter distribution. We show that, under the tangential null energy condition, the Lyapunov exponent admits a dimension-dependent upper bound in terms of the generalized surface gravity $\kappa (r)$ and the metric function $\mu(r)$, both evaluated at the photon sphere $r =r_\gamma$. For $n$- dimensional black hole spacetime, the bound is $\lambda\leq\sqrt{n-3}\, {\kappa_\gamma}/{\sqrt{\mu_\gamma}}$. Related bounds are derived in terms of the critical impact parameter (shadow radius), the orbital frequency, a local acceleration scale, and eikonal quasinormal-mode damping. All principal inequalities reduce to the known four-dimensional results for $n=4$. Also, the bounds involving the critical impact parameter and orbital frequency are saturated by the Schwarzschild-Tangherlini vacuum solution. The results provide a compact set of consistency conditions linking the dimensionality of spacetime to the instability of photon trapping in Einstein gravity.

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Materials Science

Optical poling of a quantum ferroelectric metal across the order-disorder phase transition

Mohamed Kandil, Yasuhide Tomioka, Yafei Ren et al. (+3 more)

Electron-doped strontium titanate has emerged as a prototypical quantum ferroelectric metal. It provides a fertile ground to explore how ferroelectric instability intertwined with itinerant electrons creates quantum phenomena, including unconventional superconductivity. Despite extensive studies, the microscopic origin of the ferroelectric transition remains unsettled, with distinct interpretations based on displacive mechanism driven by soft mode and order-disorder alignment of local dipoles. In particular, the local dipoles form nanoscale, spatially heterogeneous clusters, termed polar nanoregions, posing a significant challenge for probing or manipulating them. Here, using rotational anisotropy second harmonic generation, a symmetry-resolved probe, we quantify the orientational statistics of polar nanoregions in dilute electron-doped Sr$_{0.95}$Ba$_{0.05}$Ti$_{1-x}$Nb$_x$O$_3$. By tracking the alignment and meltdown of polar nanoregions in thermal cycles, we unambiguously demonstrate the order-disorder nature of the ferroelectric transition. We further show that, above transition temperature, femtosecond optical fields enable deterministic control of otherwise disordered polar nanoregions, realizing reversible write and readout of polar textures on ultrafast timescales. Our findings provide new insight into ferroelectric instability and establish an all-optical route of controlling polar metal systems where conventional electrical approaches are not feasible.

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All authors Mohamed Kandil, Yasuhide Tomioka, Yafei Ren, Ryan Comes, Isao H. Inoue, Wencan Jin

Soft Condensed Matter

Vesicle-surface-templated catalytic polymers drive differential growth in synthetic minimal cell variants

Minoru Kurisu, Taro Suzuki, Ryosuke Katayama et al. (+6 more)

Understanding how life-like behaviors can emerge from simple molecular assemblies and primitive compartments remains a central challenge in origins-of-life research. Synthetic minimal cells provide a bottom-up platform for investigating, from scratch, the minimal physicochemical principles underlying compartment growth, reproduction, and evolution. Previously, we developed a vesicle/polymer-based compartment system in which the vesicle membranes template the formation of a catalytic polymer. This polymer promotes selective incorporation of amphiphiles into the vesicle membrane, driving vesicle growth while maintaining the compositional identity and enabling spontaneous deformation and division over several generations. Here, we report about experiments in which we advanced this system beyond reproduction by systematically constructing eight synthetic minimal cell variants from combinations of two template vesicles, two catalytic polymers, and two supplied amphiphiles. The variants exhibited distinct, composition-dependent vesicle growth responses, ranging from pronounced growth to suppressed growth or vesicle shrinkage. These growth responses were described by the Hill kinetics and characterized by three parameters, revealing a multi-dimensional fitness landscape shaped by environmental conditions, in which the relative advantage of each variant depends on both composition and amphiphile availability. This framework links molecular recognition, compositional inheritance, and differential growth, providing a physicochemical route toward evolvable synthetic minimal cells.

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All authors Minoru Kurisu, Taro Suzuki, Ryosuke Katayama, Kazuki Maruyama, Daisuke Unabara, Tasuku Hamaguchi, Koji Yonekura, Peter Walde, Masayuki Imai

Mathematical Physics

A hypercomplex partition function for dissipative quantum field theory

O. Cruz-Limón, C. Ramírez-Romero and R. Cartas-Fuentevilla

We develop a finite-temperature formulation for a hypercomplex dissipative quantum field theory [1], using the imaginary-time path-integral approach and the idempotent structure of the hypercomplex algebra. The resulting partition function naturally separates into two conjugate complex sectors whose recombination preserves the hypercomplex Hermitian structure while generating a nontrivial thermal phase. From this construction, the standard thermodynamic observables are obtained consistently, and the conventional relativistic charged Bose gas is recovered in the vanishing-dissipation limit. Beyond this equilibrium correspondence, the hypercomplex formulation reveals a distinctive perturbative hierarchy: dissipative effects first appear in the complementary phase sector, while corrections to ordinary real thermodynamic quantities arise only at higher order. These results show that dissipation can be encoded through an enlarged algebraic thermal structure without abandoning the familiar framework of relativistic finite-temperature field theory, opening a path toward broader applications of hypercomplex methods in dissipative, open, and effectively non-Hermitian quantum systems.

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Quantum Physics

Multiqubit orthogonal product bases

Yvkai Zhao and Lin Chen

We use edge-colored complete multigraphs to study complete orthogonal product bases (OPBs) in $n$-qubit systems. We prove that two OPBs are equivalent if and only if their associated multigraphs are isomorphic, thereby reducing OPB classification to graph isomorphism. Within this framework, we establish the upper bound $v\le 2^n-1$ on the number of variables of an $n$-qubit OPB. We also derive $\binom{a_{n-1}+1}{2}\le a_n\le B_{2^{n-1}}^n$ for the number $a_n$ of equivalence classes of $n$-qubit OPBs, where $B_m$ denotes the number of partitions of an $m$-element set. These bounds imply the asymptotic behavior $a_n=2^{2^{n+o(n)}}$. For every OPB, the connectivity pattern of its color layers characterizes local irreducibility, which in turn implies indistinguishability by finite-round local operations and classical communication (LOCC); the existence of a complete color-splitting tree characterizes perfect distinguishability by finite-round LOCC. Finally, we give an algorithm for testing OPB equivalence and a recursive graph algorithm that constructs a finite-round LOCC protocol whenever such perfect discrimination is possible.

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Quantum Physics

Entropic Rigidity in Quantum Memories: How Geometry and Algebra Control the Onset of Degeneracy Corrections

Yixin Zhao and Fei Yan

Maximum-probability (MP) decoding selects the most probable microscopic error, whereas degenerate maximum-likelihood (MLD) decoding includes the configurational entropy of an entire logical sector. Using code-capacity Pauli noise to isolate rigidity intrinsic to the code, we determine the first physical error weight $m$ at which their logical winner sets become disjoint, even under optimal MP tie resolution. Code distance imposes the universal bound $m\geq h=\lceil d/2\rceil$. We define the entropic rigidity depth $r$ through $m=h+r$ and certify a three-level hierarchy: $r=0$ for planar surface codes and two concatenated families, $r=1$ for odd-distance square toric codes and the Gross $[[144,12,12]]$ quantum low-density-parity-check code, and $r=2$ for a separable family with hypergraph product and bivariate bicycle descriptions. The onset fixes the leading operational failure gap, proportional to the $m$th power of the physical noise strength. Geometry and algebra therefore provide quantifiable controls of configurational entropy and an exact benchmark for low-noise decoder selection.

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Materials Science

Solidification-cell confinement of domain-wall pinning in additively manufactured ferromagnets

Dennis Boakye, Eric K.K. Abavare and Chuang Deng

As-built printed ferromagnets typically exhibit higher coercivity than optimized wrought materials, yet existing explanations rely on empirical fits or costly simulations. Herein, we provide a missing analytical theory that links print parameters directly to cooling rates, cellular spacing, dislocation density, and domain-wall pinning coercivity. Informed by metallographic grain data and using a single fitted constant, our model predicts six experimental datasets for pure Fe, Fe-6.9Si, and a multicomponent alloy within a factor of 1.9. We demonstrate that configurational lattice distortion is negligible, implying that single-phase printed alloys follow dilute-pinning laws. Critically, we introduce a confinement factor, $E=\sqrt{\lambda_{c}/2\delta_{w}}$, proving that solidification-induced dislocation packing makes cellular microstructures harder than conventionally cold-worked metals. The framework enables an alloy-sensitivity map to screen and rank compositions before manufacturing.

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Atmospheric and Oceanic Physics

Impacts of Nuclear War on Human Health from Changed Surface Ultraviolet Radiation

Shu Xu, Lili Xia, Alan Robock et al. (+4 more)

Climate model simulations indicate that surface ultraviolet (UV) radiation would change after soot injection into the stratosphere during a nuclear war, due to the competing effects of ozone depletion and aerosol attenuation. Using climate model simulations, we evaluate UV impacts under two scenarios: a regional India-Pakistan conflict producing 5 Tg of soot and a global U.S.-Russia war producing 150 Tg. UV enhancements due to ozone depletion substantially shorten safe outdoor exposure time, particularly for individuals with lighter skin types. Applying UV dose-response relationships to the year 2000 population data, without accounting for direct conflict mortality or famine-related population loss, the 5 Tg scenarios result in approximately 5,300-9,800 additional skin cancer deaths within 10-15 years and up to 75,000 cumulative excess deaths over the following century. In contrast, strong aerosol attenuation under the 150 Tg scenario initially suppresses surface UV, resulting in about 8,500 fewer skin cancer deaths within 15 years and a maximum cumulative reduction of approximately 17,000 deaths over the following century. These findings demonstrate that nuclear war-induced changes in surface UV radiation represent a persistent but previously understudied health impact of nuclear war. While skin cancer would not dominate overall mortality following a nuclear war, enhanced cumulative surface UV radiation represents an additional, long-lasting threat to human health that compounds other global impacts such as climate disruption and food insecurity. The excess UV may also pose negative impacts on animals and plants, including those used for agriculture, which remain to be quantified.

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All authors Shu Xu, Lili Xia, Alan Robock, Charles Bardeen, Simchan Yook, Sasha Madronich, Soko Setoguchi

Tuesday 18 August

Quantum Physics

Decoder-Prior Poisoning in Quantum Error Correction: Attacks and PriorGuard Defense

Xinyi Li, Yifeng Peng, Juntao Chen et al. (+1 more)

Quantum error correction (QEC) protects quantum computations by repeatedly measuring stabilizer syndromes and using a classical decoder to infer corrections. Modern surface-code decoders are increasingly calibration-aware: they use recent device behavior to set priors such as matching-graph edge probabilities, and these priors directly shape the selected correction. We identify the prior-update path as an overlooked integrity-critical attack surface: a poisoned prior can change decoding decisions even when the syndrome stream, logical labels, and decoder implementation are unchanged. This makes prior poisoning different from ordinary syndrome anomalies and difficult for raw syndrome-anomaly tests to detect. We introduce PriorGuard, a lightweight semantic guard that checks proposed prior changes on high-influence detector-graph entries against private syndrome-derived evidence, accepts updates only when their log-odds movement is evidence-supported, and otherwise falls back to the last evidence-supported prior. We evaluate on Stim-generated rotated surface-code memory circuits decoded with PyMatching. Prior influence is highly concentrated, with the top 10 percent of entries carrying over 60 percent of positive logical-error influence; poisoning only 6.4 percent of decoder-prior entries can raise logical error rate (LER) by 3.35x. PriorGuard recovers most attack-induced loss with a low false-positive rate and modest update-boundary overhead of about 1.7–1.8 ms and less than 0.31 MB auxiliary memory per update.

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All authors Xinyi Li, Yifeng Peng, Juntao Chen, Ying Wang

Materials Science

Self-assembly and Electronic Properties of Graphyne and Graphdiyne Molecular Wires on Metallic Surfaces

Victor M. S. da Conceição, Dominike Pacine, Juliana M. Morbec et al. (+1 more)

Molecular self-assembly on solid surfaces has been the subject of extensive research, motivated by both fundamental and technological interests. On the fundamental side, these studies seek to elucidate the mechanisms governing molecular self-assembly and the resulting surface structures. From an applied perspective, they provide a route toward controlling surface reactions and engineering molecular electronic devices. Here, based on first-principles density functional theory calculations, we present a comprehensive study of self-assembled molecular wires (MWs), composed of graphyne (GY(1D)) and graphdiyne (GYD(1D))-like structures, adsorbed on Au(111), Ag(111), and Al(111) surfaces. Our total-energy calculations reveal that non-aligned MW arrays are energetically preferred on all three metal substrates. The GY(1D) and GYD(1D) molecular wires interact with the metal surfaces through van der Waals (vdW) forces, while their molecular orbitals do not contribute to the formation of metallic interface states. Simulated X-ray photoelectron spectroscopy (XPS) spectra reveal that the C 1s spectral features of the molecular wires are largely preserved upon adsorption, while the absolute binding energies undergo a substantial downshift that is nearly independent of the metal substrate, indicating that metallic screening effects dominate the adsorption-induced core-level shifts. Electronic band-structure calculations further show that the semiconducting character of the molecular wires is retained, resulting in vdW metal-semiconductor heterostructures in which the semiconducting component consists of one-dimensional semiconducting channels. These findings demonstrate that self-assembled graphyne- and graphdiyne-based molecular wires on metal surfaces provide a promising platform for the realization of low-dimensional molecular electronic devices.

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All authors Victor M. S. da Conceição, Dominike Pacine, Juliana M. Morbec, Roberto H. Miwa

Chemical Physics

Polyaniline as a conductive polymer and its role in improving the efficiency and conductivity of perovskite solar cells

Mehran Hosseinzadeh Dizaj

This article investigates the role of polyaniline as a conductive polymer in the active layer of perovskite solar cells. Samples were created by incorporating polyaniline into the transport layers to assess its impact on enhancing efficiency and conductivity. The application of this polymer across various layers of the cell structure led to improved stability and performance. Given its high doping capability, polyaniline was examined in detail, particularly focusing on two types of oxidation doping and its integration into the hole transport layer. Graphene oxide and reduced graphene oxide were chosen as comparative models, and their performance was evaluated against the standard polyaniline configuration. Laboratory results revealed that power conversion efficiency increased by 17.5% with graphene oxide and by 36.8% with reduced graphene oxide. Furthermore, short-circuit current density improved by 9.8% and 23.1%, respectively. These findings are consistent with existing studies in the field and support the validity of the approach.

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Quantum Physics

Comment on 'Supervised quantum machine learning models are kernel methods'

Rajiv Krishnakumar

We identify a few small errors in the proof of Theorem 1 in M. Schuld, 'Supervised quantum machine learning models are kernel methods' (arXiv:2101.11020v2), Appendix A. These do not affect the validity of the theorem, but do matter if one wants to use the appendix to explicitly compute the Fourier coefficients of a quantum kernel. We give the corrected derivation, and additionally show that the paper's worked cosine-kernel example contains a second, unrelated error that happens to cancel the first, thereby coincidentally yielding the correct result.

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Chemical Physics

Multi-Species Multi-Reaction Model Parametrization of a Commercial NCA Positive Electrode from Half-Cell Open-Circuit Potential Data

Michele Galasso, Petr Čech, Ivo Horstkötter et al. (+3 more)

Physics-based models of lithium-ion batteries require the open-circuit potential (OCP) of each electrode as a function of its lithiation. The multi-species multi-reaction (MSMR) model provides a compact, thermodynamically grounded description of this relationship, representing each insertion reaction by a standard potential, a site fraction and a disorder parameter. Here, we parametrize the MSMR model for nickel-cobalt-aluminum oxide (NCA), a cathode chemistry widespread in automotive cells, using the positive electrode of a commercial silicon-graphite/NCA cell. Cathode material was harvested from a pristine cell and from cells cycle-aged to the end of life under two state-of-charge windows, and its half-cell OCP was measured by slow galvanostatic cycling. Smooth differential-capacity curves were obtained by histogram counting, and the charge and discharge branches were fitted with a constrained, scale-invariant optimization that keeps every reaction anchored to a visible peak. We report the first MSMR parameter set for an NCA cathode and show, through a differential-capacity peak analysis across aging states, that its thermodynamic signature is essentially unchanged by aging. This finding supports the common modeling practice of holding the electrode's intrinsic parameters fixed and ascribing aging to electrode-level capacity and alignment changes.

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All authors Michele Galasso, Petr Čech, Ivo Horstkötter, Simon Schwunk, Zuzana Vlčková Živcová, Václav Knap

General Physics

Striving to find a bridge between noncommutative and generalized entropy parameters in the harmonic oscillator dynamics

J.Sadeghi, Mohammad Ali S. Afshar, H.Z.Kalbasti et al. (+1 more)

In this study, we use the harmonic oscillator s energy spectrum to connect its dynamical behavior to the formalism of statistical mechanics through entropy. We perform a thermal analysis of the entropy generated by this spectrum in both commutative and noncommutative two-dimensional configuration spaces, employing the Tsallis and Renyi entropy measures. The primary objective is to examine the possibility of an intrinsic link and mutual influence between the noncommutative parameter({\theta}) and the parameters arising from generalized entropies. By analyzing both Tsallis and Renyi frameworks, we investigate whether a fundamental relationship exists between {\theta} and the entropy index q. Establishing such a connection could provide new insights into the interplay between spacetime geometry and generalized statistical mechanics.

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All authors J.Sadeghi, Mohammad Ali S. Afshar, H.Z.Kalbasti, H.Razazchian

General Physics

A No-Go Theorem for Curvature Neutrality in f(Q) Cosmology?

Gamal G.L. Nashed and Amare Abebe

In the framework of $f(Q)$ gravity, we investigate whether spatial curvature can be made dynamically invisible in the cosmological background equations. We consider open spatial sections, $k<0$, on an explicitly specified homogeneous and isotropic symmetric-teleparallel connection branch. For $k\neq0$, the coincident gauge cannot be imposed simultaneously with the standard curved-FLRW coordinate form. Re-deriving the background equations from the minisuperspace action, we show that curvature enters through $x=H+\delta\sqrt{-k}/a$ and appears with inequivalent weights in the energy and pressure equations. For $f\in C^3((0,\infty))$, we prove a branch-specific no-go theorem: strict curvature independence for every scale factor and every $k<0$ requires $f=\mathrm{const}$, which contains no metric kinetic term. STEGR is not curvature-neutral, since its Friedmann equation retains the usual $3k/a^2$ contribution. A weaker cancellation, imposed only on backgrounds satisfying $\delta\sqrt{-k}/a=cH$, necessarily produces a coasting expansion and yields $f(Q)=A Q^{(c+2)/2}+B$, or $f(Q)=A\ln Q+B$ when $c=-2$. For the illustrative choice $c=-3$, the solution becomes $f=\alpha_1/\sqrt Q+\beta_1$. Under the conventional positive-coupling assumption $f_Q>0$, the required source violates the null energy condition. Moreover, adding positive radiation or pressureless matter forces a compensating negative-energy component at sufficiently early times. The weak branch is therefore neither curvature-neutral in an invariant sense nor a viable cosmological model. The principal result is the background-level obstruction itself. Perturbative stability and gravitational-wave propagation require a separate analysis including perturbations of the nontrivial affine connection and are not established in this work.

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Atomic Physics

Artifact side peaks in saturated absorption spectroscopy caused by inappropriate lock-in amplification

Leo Matsuoka

Saturated absorption spectroscopy is a powerful technique that provides valuable information about gas-phase atomic targets, including not only the precise positions of transitions but also the effects of velocity-changing collisions, which manifest as changes in the shape of the peaks. However, using a lock-in amplifier inappropriately can generate artifact side peaks, potentially leading to a misinterpretation of results. To investigate the emergence of these artifacts, we conducted numerical calculations based on the basic Lambert-Beer's law. Our model reproduced the artifact side peaks and revealed that these artifacts become more significant as the transmittance of the probe laser decreases.

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Quantum Physics

Collective photon echoes in the Tavis-Cummings model: distribution independence, two detuning regimes, and the Dicke ladder

Michael Tavis

An ensemble of $N$ two-level molecules prepared in its ground state and sharing a lossless cavity with a weak field does not simply absorb: the intensity collapses and then recurs, in a train of collective photon echoes. Working from the exact solution of the Tavis-Cummings model in the few-photon regime $\bar n<N$, we confirm the echo time $\tau_E=4\pi\sqrt{N+\Delta}/g$ numerically at resonance from $N=5$ to $400$, the small-$N$ end discriminating this form from the alternative $4\pi\sqrt{N-\bar n+\Delta}/g$ in its favor. The initial state requires no preparation, being the ground state. The echo time is independent of the initial photon distribution: coherent, thermal, squeezed and oscillatory-squeezed distributions spanning variances from 2 to 34 all recur together, as does a controlled pair with identical mean and variance differing only in the shape of $\rho_{nn}$. The echo amplitude is not: it varies at the tens-of-percent level at fixed mean, including a factor of 1.8 with the squeezing phase at fixed squeezing strength. Detuning organizes the dynamics into two clean regimes separated by a fragmented crossover, the dispersive-branch echo time approaching one-half the resonant one, and sufficient detuning removes the dependence on the initial Dicke state. For arbitrary initial Dicke state, emission replaces absorption at $m\simeq-N/2+\bar n$, and the echo envelope acquires one component per step up the ladder: a single-component echo occurs only at the ground state. A feasibility analysis against a five-qubit superconducting device, with Lindblad simulations of cavity decay and dephasing and full-Hilbert-space disorder simulations, shows the first echoes observable at $N\sim5$-$20$ on existing hardware: the echo survives the dominant loss channel with contrast $\sim e^{-\kappa\tau_E/2}$, photons being shielded from cavity decay while resident in the emitters.

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