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Tuesday 4 August

Quantum Physics

When Complementary Measurements Count the Same Classical Bit Twice: Counterexamples to CQC, ECQC, and Complementarity-Based Certification

Jinbo Wang, Qihang Wang and Kun Chen

Mutually unbiased measurements are commonly expected to expose independent facets of a quantum state: a correlation that is classical in one basis should disappear in a complementary basis. In higher dimensions, however, this intuition becomes particularly subtle because correlations recovered in different settings need not represent different information. To expose this loophole, we propose a two-branch classical null test: before the setting is chosen, a shared bit selects one of two orthogonal product preparations, producing a rank-two classical–classical state, and the candidate protocol then runs unchanged. Different settings can read the same bit through different outcome patterns. This two-branch classical architecture disproves the complementary-quantum correlation (CQC) conjecture in every dimension $d\geq3$. A distinct rank-two classical–classical state disproves its complete-basis extension (ECQC) at $d=7$, with an overrun that grows without bound along prime dimensions. Its qutrit CQC instance also gives classical false positives for a proposed quantum-correlation measure and a proposed one-sided semi-device-independent steering criterion, and refutes a conditional-probability conjecture. The failures identify the missing requirement: information read in different settings must be nonredundant. In experiments and applications, the same low-overhead architecture can serve as a calibration test before a multibasis score is assigned quantum meaning.
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Quantum Physics

CNOT-Distance is NP-complete under all-to-all connectivity

Antonio Acuaviva, Arturo Acuaviva and Pablo Acuaviva

Given $A\in\operatorname{GL}(N,2)$ and an integer $K$, we ask whether $A$ can be implemented by at most $K$ CNOT gates on fixed labelled wires with all-to-all connectivity. We prove that this problem is NP-complete. From a finite simple graph $G=(V,E)$, we construct an upper-unitriangular matrix $A_G\in\operatorname{GL}(2|V|+|E|+1,2)$ satisfying $\ell_{\mathrm{CNOT}}(A_G)=2|V|+2|E|+\tau(G)$, where $\tau(G)$ is the minimum vertex-cover size. Each target matrix has $O(N)$ nonzero entries and row Hamming weight at most four. The lower bound unfolds an arbitrary CNOT circuit into an XOR directed acyclic graph and applies projection–contraction operations, allowing cancellation and unrestricted reuse of intermediate parities. For this family, the optimum is unchanged by any finite number of clean or borrowed ancillary wires that must be restored. A polynomial-time decoder further yields NP-hardness of approximation within every fixed additive constant and, through an L-reduction from Minimum Vertex Cover on cubic graphs, APX-hardness of the associated CNOT-circuit optimisation problem.
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Quantum Physics

Impossibility of Perfectly Complete Many-Round Key Agreement in the QROM

Longcheng Li, Qian Li, Xingjian Li et al. (+1 more)

This paper proves that it is impossible to construct perfectly complete quantum key agreement protocols (QKA) from quantumly secure one-way functions (OWFs) in a black-box manner. Specifically, consider any protocol in which Alice and Bob exchange only classical messages, make at most $q_{\mathsf{A}}$ and $q_{\mathsf{B}}$ quantum queries, respectively, to a Boolean-valued random oracle, and agree on a shared key with certainty. This paper shows that there exists an eavesdropper, given the classical messages, that can recover the shared key with certainty using $O((q_{\mathsf{A}}+q_{\mathsf{B}})^5)$ classical oracle queries. The bound is independent of the number of rounds, transcript length, key length, and oracle-domain size. Previous results only applies to two-round key agreement (Li et al. CRYPTO 26) or relies on unproven conjectures (Austrin et al. CRYPTO 22). GPT-5.6 Sol Ultra found this proof in a one-shot conversation and drafted a preliminary version of this paper. The authors are fully responsible for the correctness, writing and discussions of this paper.
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All authors Longcheng Li, Qian Li, Xingjian Li, Qipeng Liu

Superconductivity

Two-phonon pairing and superconductivity in $SrTiO_3$

Antonio Santacesaria, Cristiano Muzzi, Maria Eleonora Temperini et al. (+3 more)

We explore the possibility that the two-phonon pairing mechanism proposed by Ngai can explain superconductivity in doped strontium titanate (STO). The two-phonon deformation potential is evaluated using two distinct theoretical estimates based on first-principles calculations and two empirical estimates based on experimental data, yielding very large values of the same order of magnitude. We derive the effective electron-electron interaction mediated by two-phonon exchange. Crucial to our computations is the strong dispersion of the involved soft phonons. Because the scale of the two-phonon interaction is much larger than the Fermi energy, the Migdal theorem does not apply. We obtain a one-loop Eliashberg equation that can be solved in the weak-coupling limit. We find that despite the significant electron-phonon matrix element, phase space considerations considerably reduce the effective coupling. A two-phonon mechanism can not be excluded based on the $T_c$ magnitude, but its value is dominated by the high-energy-frequency physics and is weakly affected by the soft-phonon behavior. The theory predicts a $T_c$ that monotonously increases with doping, which is not in accordance with the experiment. We identify the conditions for a two-phonon mechanism to be effective in other materials and discuss possible candidates.
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All authors Antonio Santacesaria, Cristiano Muzzi, Maria Eleonora Temperini, Paolo Barone, Maria N. Gastiasoro, José Lorenzana

Optics

Self-Focusing Control for Depth-Precise Wafer Slicing of 4H-SiC in Femtosecond Laser Processing

Dong Hee Kang, Jaeseung Lim, Mishfaqur Rahman et al. (+4 more)

4H-SiC has emerged as a third-generation chip material because its superior thermal conductivity and high breakdown field enable the material to achieve high power density and higher switching frequencies in power-electronics applications. As chip architectures evolve toward 3D and heterogeneous integration, the mechanical and thermal design space tightens while yield risks grow. In particular, advanced packages require mid-process wafer thinning to < 100 $\mu$m to shorten interconnects and control thermo-mechanical stress. Femtosecond laser slicing for 4H-SiC wafers offers a non-contact processing approach to produce thin layers with low defects, while strong optical nonlinearities obscure the relationship between the laser parameters and the resulting slicing quality. Here, we systematically investigate Kerr-induced self-focusing using a femtosecond laser in 4H-SiC slicing by combining experiments, a semi-empirical analytical model, and numerical ray optics simulations. We demonstrate that the interplay between pulse energy and processing depth governs the self-focusing behavior, which directly correlates with post-separation surface texture parameters and separation stress, thereby linking nonlinear beam propagation to slicing quality. Based on this relationship, we define a processability map in the pulse energy with self-focusing depth space over a normalized irradiance background. Analytically, the model extends the Marburger formula to focused beams by replacing the power ratio with a normalized irradiance. Ray optics simulations capture the geometric features at the self-focusing point and are validated against experimental observations. Within physically defined thresholds, the processability map directly connects laser parameters to separation stress and surface texture metrics, providing practical guidance for depth control beyond trial-and-error.
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All authors Dong Hee Kang, Jaeseung Lim, Mishfaqur Rahman, Seongheum Han, Jae-Hak Lee, Seungman Kim, Jihoon Jeong

Mesoscale and Nanoscale Physics

Controllable interaction between photons and distant spins via vacuum Rabi oscillations

Xiao Xue, Jurgen Dijkema, Tobias Bonsen et al. (+7 more)

Vacuum Rabi oscillations between a single photon and a single spin demonstrate the capability of harnessing light-matter interaction at the level of a single quantum of energy. Since the observation of strong spin-photon coupling in gate-defined quantum dots, probing this interaction in the time-domain has been a major objective. Here, we carefully engineer a device composed of two spatially separated double quantum dots hosting single electron spin qubits and a superconducting cavity to accommodate microwave photons. We observe multiple vacuum Rabi oscillations between each spin qubit and the cavity. By concatenating vacuum Rabi oscillations involving the two spins, an energy excitation in one qubit can be emitted as a photon and then transferred to the other qubit. When a single photon is emitted, the cavity is prepared in a Fock state, leading to an accelerated vacuum Rabi frequency. These results serve as building blocks not only in exploring light-matter interactions, but also in interfacing semiconductor spin qubits to photonic links.
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All authors Xiao Xue, Jurgen Dijkema, Tobias Bonsen, Patrick Harvey-Collard, Maximilian Rimbach-Russ, Sander L. de Snoo, Guoji Zheng, Amir Sammak, Giordano Scappucci, Lieven M. K. Vandersypen

Materials Science

Generalized Space Groups from Internal Configuration Spaces

Zeying Zhang, Zhenye Li, Zhi-Ming Yu et al. (+2 more)

We develop a unified construction of generalized space groups for crystals with unconventional internal degrees of freedom. Starting from the full group $G_P$ of allowed internal transformations and the stabilizer $P$ of a reference object, we determine the pointwise and setwise symmetries, $J$ and $K$, of the allowed configuration set. Goursat's lemma then couples the internal quotient $K/J$ to a spatial quotient. The framework includes ordinary, magnetic, spin, and color space groups as special cases. As an example, we consider a dodecahedral object with $P=I\simeq A_5$, for which we obtain the nontrivial pair $T\triangleleft O$ with $O/T\simeq\mathbb Z_2$. The resulting generalized space group hosts a point node with topological charge $|C|=12$.
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All authors Zeying Zhang, Zhenye Li, Zhi-Ming Yu, Gui-Bin Liu, Yugui Yao

Solar and Stellar Astrophysics

Expanding magnetic canopy structure and parasitic polarities in a quiet-Sun network element observed by Sunrise III/SCIP

Ryan J. Campbell, Carlos Quintero Noda, Mihalis Mathioudakis et al. (+35 more)

We present high-resolution multi-line spectropolarimetric observations of a quiet-Sun network element obtained with the Sunrise~iii Chromospheric Infrared SpectroPolarimeter. The observations combine photospheric, upper-photospheric, and chromospheric diagnostics at a spatial resolution and polarimetric sensitivity that allow the transverse magnetic structure of the network boundary to be examined directly. We find that the strongest linear polarisation is concentrated in a narrow ridge around the edge of the magnetic element, co-spatial with enhanced transverse magnetic field inferred from multiline inversions. The magnetic azimuth exhibits a coherent, predominantly radial organisation around a more vertical core, consistent with an expanding magnetic canopy. An azimuth proxy derived directly from the observed Fe~i and K~i linear polarisation reproduces the same large-scale organisation, showing that this structure is encoded in the Stokes profiles rather than imposed by the inversion. Response functions and a MURaM-based forward-synthesis test indicate that the Fe~i~8468~Å\ linear polarisation is sensitive to magnetic azimuth in the upper photosphere, with the closest proxy agreement occurring near $\log\tau\approx-3$. We find no evidence for strong azimuthal shear between the Fe- and K-sensitive diagnostics. At the network boundary, we also identify localised parasitic-polarity patches associated with complex, multi-lobed Stokes $V$ profiles, and one case in which the Stokes $V$ polarity reverses between photospheric Fe~i and chromospheric Ca~ii lines. These results demonstrate that quiet-Sun network boundaries contain organised upper-photospheric canopy fields together with small-scale mixed-polarity structure, providing new constraints on the three-dimensional magnetic structure of network elements.
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All authors Ryan J. Campbell, Carlos Quintero Noda, Mihalis Mathioudakis, Manuel Collados, Jack McFall, David B. Jess, Sami K. Solanki, Andreas Lagg, Achim Gandorfer, Jose Carlos del Toro Iniesta, Yukio Katsukawa, Pietro Bernasconi, Thomas Berkefeld, Alex Feller, Tino L. Riethmüller, Alberto Álvarez-Herrero, Masahito Kubo, H. N. Smitha, David Orozco Suárez, Bianca Grauf, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Francisco Javier Bailén, Julian Blanco Rodríguez, Juan Sebastián Castellanos Durán, Edvarda Harnes, Johannes Hölken, Francisco A. Iglesias, Ryohtaroh T. Ishikawa, Yusuke Kawabata, Takuma Matsumoto, Takayoshi Oba, Azaymi L. Siu-Tapia, Hanna Strecker, Dušan Vukadinović, Hirohisa Hara, Toshifumi Shimizu

Materials Science

Physics-Informed Machine Learning for Refractory Alloy Design

Blaise Awola Ayirizia, Bimal K C and Jorge A. Munoz San Martin

Refractory complex concentrated alloys (CCAs) exhibit exceptional mechanical properties at elevated temperatures, but their vast compositional space (approximately 10^15 possible combinations) poses significant challenges for experimental exploration. We develop a physics-informed machine learning framework combining quantile gradient boosting with Born stability constraints to predict eight mechanical properties (bulk modulus B, shear modulus G, Vickers hardness Hv, elastic constants C11, C12, C44, Young's modulus E, and Poisson's ratio nu) of refractory CCAs. Using 393 density functional theory (DFT)-computed alloys from a 10-element design space (Cr, Hf, Mo, Nb, Re, Ta, Ti, V, W, Zr), we achieve coefficient of determination (R^2) values of 0.89 to 0.97 with mean absolute errors of 0.85 to 14.74 GPa across six properties on a held-out test set (n = 59). Remarkably, all test predictions satisfy the Born stability criteria (100% compliance), demonstrating the efficacy of physics-informed constraints. Compositional screening in valence electron concentration (VEC)-atomic size mismatch (delta) space identifies high-performance candidates, with MoReW exhibiting the highest predicted shear rigidity (C44 = 139 GPa). Elemental analysis reveals that rhenium appears in 100% of the top-performing alloys, molybdenum in 90%, and chromium in 80%, establishing quantitative design rules: VEC = 6.0 to 6.4, delta < 10%, and Re-Mo-Cr ternary systems maximize shear resistance. This physics-informed screening framework enables accelerated discovery of mechanically stable, high-performance refractory alloys from the trillion-scale compositional space.
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Atmospheric and Oceanic Physics

Unexpected limitation of tropical cyclone genesis by subsurface tropical central-north Pacific during El Niño

Cong Gao, Lei Zhou, Chunzai Wang et al. (+2 more)

The vast tropical Pacific is home to the majority of tropical cyclones (TCs) which threaten the rim countries every year. The TC genesis is nourished by warm sea surface temperatures (SSTs). During El Niño, the western Pacific warm pool extends eastward. However, the number of TCs does not increase significantly with the expanding warm pool and it remains comparable between El Niño and La Niña. Here, we show that the subsurface heat content change counteracts the favorable SSTs in the tropical central-north Pacific. Due to the anomalous positive wind stress curl, the 26 {\deg}C isotherm shoals during El Niño over this region and the heat content diminishes in the tropical central-north Pacific, even though warm SST anomalies prevail. This negative correlation between SST and 26 {\deg}C isotherm depth anomalies is opposite to the positive correlation in the tropical eastern and western Pacific. This is critical because quantifying the dynamics of the subsurface ocean provides insight into TC genesis. The trend in TC genesis continues to be debated. Future projections must account for the net effect of the surface-subsurface dynamics on TCs, especially given the expected El Niño-like pattern over the tropical Pacific under global warming.
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All authors Cong Gao, Lei Zhou, Chunzai Wang, I.-I. Lin, Raghu Murtugudde

Materials Science

From phase transformation to amorphization: damage accumulation in Yb-implanted $\beta-Ga_2O_3$

Joanna Matulewicz, Renata Ratajczak, Ewa Grzanka et al. (+11 more)

This study provides a comprehensive analysis of the radiation response and structural evolution of differently oriented$\beta-Ga_2O_3$ single crystals subjected to Yb ion implantation over a wide fluence range from $5 \times 10^{12}$ to $1 \times 10^{16}$~cm$^{-2}$ ($0.04$–$74$~dpa). A multi-technique approach (RBS/c, PAS, HRTEM, and HRXRD) was employed to investigate the mechanisms of damage accumulation. The results reveal a multi-stage process of defect evolution. At a critical threshold of around $0.4$~dpa, the accumulation of lattice strain triggers a phase transformation from monoclinic $\beta$-Ga$_{2}$O$_{3}$ to a defective spinel structure of $\gamma$-Ga$_{2}$O$_{3}$. Notably, the formation of this new phase is accompanied by strain relaxation. With further irradiation, defects develop within the crystal structure of $\gamma$-Ga$_{2}$O$_{3}$. The associated atomic reorganization at this stage is reflected by a distinct dip in the damage accumulation curve and the appearance of stacking faults in the subsurface region of the implanted layer. In contrast to previous reports suggesting high radiation stability of this phase, the present study clearly demonstrates that continuous defect accumulation results in a significant increase in both displaced atoms and vacancy-type defects, with a strong depth dependence in their type and density. Ultimately, at an irradiation level of approximately $7$~dpa, the surface layer amorphizes. With further irradiation, the amorphous layer expands, gradually replacing the transient $\gamma$-Ga$_{2}$O$_{3}$ phase. These findings reveal that the radiation tolerance of gallium oxide is highly sensitive to ion-specific interactions and strain-induced instabilities, thereby challenging the previously assumed robustness of this material under high-fluence ion irradiation.
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All authors Joanna Matulewicz, Renata Ratajczak, Ewa Grzanka, Maciej Oskar Liedke, Damian Kalita, Eric Hirschmann, Andreas Wagner, Mikolaj Grabowski, Michal A. Strozyk, Cyprian Mieszczynski, Przemyslaw Jozwik, Ulrich Kentsch, Rene Heller, Frederico Garrido

High Energy Astrophysical Phenomena

Iron K$\alpha$ signatures from accretion disks around fermionic dark matter cores

V. Crespi, F. L. Vieyro, C. R. Argüelles et al. (+1 more)

The fluorescent iron line and its broadening due to relativistic effects are excellent probes to study the inner part of an accretion disk and the space-time geometry near the compact object. We investigate the iron K$\alpha$ line profile within the extended RAR model, which describes a fermionic dark matter distribution on galaxy scales. The most general solutions are characterized by a compact and highly degenerate core able to mimic the central black hole, transitioning into an extended halo composed of the same particles. We aim to contrast the resulting line morphologies in this scenario with those predicted by the standard Kerr black hole paradigm. Special attention will be given to MCG-06-30-15 galaxy. We compute the line profile using the numerical ray-tracing code, Skylight. We consider two distinct configurations for the emissivity of the cold accretion disk: an irradiation profile based on the lamp-post corona prescription, and a phenomenological power-law profile. The resulting profiles exhibit a diverse phenomenology. In particular, the most compact fermion cores produce a line broadening comparable to that observed in rapidly rotating black holes. The presence of emitting matter at radii smaller than a gravitational radius yields distinctive spectral features that are entirely absent in the black hole scenario. For MCG-06-30-15 galaxy, we find a good agreement with the observed broad features of the iron line profile, provided the compactness of the fermion core is close to critical. These results reinforce the need for independent black hole spin measurements. Combined with such constraints, iron-line spectroscopy may provide a powerful observational tool to distinguish black holes from alternative compact solutions, in particular compact fermionic dark-matter cores.
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All authors V. Crespi, F. L. Vieyro, C. R. Argüelles, J. A. Rueda

High Energy Physics (Phenomenology)

Deser formula for the shift of energy levels of hadronic atoms in terms of the effective radius of the strong interaction with the Coulomb wave function of hadronic atoms at the origin

O. Voskresenskaya

It is shown that the relations between probabilities of A_2{\pi}-atoms creation in ns-states, derived with neglecting of strong interaction between pions, remain practically unchanged if the strong interaction is taken into account in the first order of perturbation theory. The formulation of Deser equation for the energy shift of energy levels of hadronic atoms is given in terms of the effective range of strong interaction and the relative correction to the Coulomb wave function of hadronic atoms at the origin, caused by the strong interaction.
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Soft Condensed Matter

Geometry-Controlled Motility of Microswimmers in elementary microfluidic confinements

Marvin Brun-Cosme-Bruny, Philippe Peyla and Salima Rafai

The motility of microswimmers in confined environments is a fundamental problem in active matter physics, with direct implications for microfluidic applications and the understanding of microorganism behavior in complex natural habitats. Although the run-and-tumble dynamics of flagellated microalgae such as Chlamydomonas Reinhardtii (CR) are well characterized in bulk suspension, the extent to which elementary geometric confinements alter their swimming remains insufficiently understood, particularly regarding the relative contributions of steric contact versus hydrodynamic interactions. Here, we experimentally investigate the trajectories of individual CR cells in a diversity of PDMS microfluidic geometries of growing complexity using single-particle tracking and statistical analysis. We show that cells in straight channels accumulate near walls and align along the channel axis, a behavior qualitatively reproduced by steric Active Brownian Particle simulations, yet showing a confinement-dependent velocity enhancement consistent with hydrodynamic wall coupling. In circular cavities with diameter below the persistence length L_0 ~350 microns, cells transition from bulk active Brownian exploration to quasi-circular wall-following trajectories. In dumbbell geometries, inter-compartment dwell length reflect purely geometric predictions, evidencing no measurable hydrodynamic contributions even for strong confinements. Together, these results demonstrate that environmental geometry can selectively amplify or suppress motility modes in active biological suspensions, opening avenues for the passive control of microswimmer transport in engineered microfluidic networks.
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Instrumentation and Methods for Astrophysics

Data reduction pipeline for the SuMAC millimeter-wave spectrometer at the LMT

A. M. Lapuente, P. S. Barry, M. Becerril-Tapia et al. (+22 more)

We present the data reduction and analysis pipeline for the SuperSpec-MUSCAT Collaboration (SuMAC) along with several key science data products. In Summer 2025, SuperSpec on-chip spectrometers operating from $190-300$ GHz at $R\sim200$ were deployed in the MUSCAT cryostat at the Large Millimeter Telescope, obtaining several days of on-sky data. Analysis of these data has been used to characterize noise performance and study spectra of various astrophysical sources, establishing the viability of deploying SuperSpec detectors in future instruments. These proceedings discuss the modular data reduction pipeline which uses timestreams of the kinetic inductance detectors (KIDs) and auxiliary instrument data to generate a variety of data products. We present an on-sky calibration method for converting the KID fractional frequency shift to on-sky brightness temperature. The mapmaking module generates 3D data cubes of extended sources, while the spectrum module produces a millimeter-wave spectrum of an object. The observations all incorporate measurements of the atmosphere to model and correct for absorption. We also discuss data processing choices including detector weighting, despiking, and notch filtering. Finally, we present preliminary data products including detection of carbon monoxide in NGC 253 and spectral maps of the central region of the Orion KL nebula.
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All authors A. M. Lapuente, P. S. Barry, M. Becerril-Tapia, C. Benson, C. M. Bradford, T. Brien, S. C. Chapman, S. Doyle, V. Gómez-Rivera, S. Hailey-Dunsheath, J. Hernández-Aguilar, J. L. Hernández-Rebollar, D. Hughes, E. Kane, K. S. Karkare, R. McGeehan, R. Naranjo-Romero, A. Papageorgiou, J. G. Redford, I. Rodríguez-Montoya, S. Rowe, D. O. Sánchez-Argüelles, S. Savorgnano, A. Tan, J. Vega-Méndez

Instrumentation and Methods for Astrophysics

SuMAC: On-sky demonstration of multi-pixel on-chip millimeter-wave spectroscopy at the Large Millimeter Telescope

Marcial Becerril-Tapia, Peter S. Barry, Christopher S. Benson et al. (+22 more)

The SuperSpec-MUSCAT Collaboration (SuMAC) is an effort to operate SuperSpec spectrometers in the MUSCAT instrument at the Large Millimeter Telescope (LMT). SuperSpec is an on-chip filterbank spectrometer using kinetic inductance detectors (KIDs), with moderate $R\sim 200$ spectral resolution for observing in the 1 mm atmospheric window (190-300 GHz). While nominally a continuum camera operating a 1.1 mm, MUSCAT was also designed to operate as a testbed for pioneering detection technologies. In July 2025, three SuperSpec devices were installed and commissioned in the MUSCAT cryostat with minimal modifications to the system. This work presents an overview of SuperSpec's deployment and performance in MUSCAT along with the main results from the Summer 2025 observation campaign. Highlights include the detection of CO emission line in the galaxy NGC253, mapping the Orion KL region, and preliminary line intensity mapping scans.
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All authors Marcial Becerril-Tapia, Peter S. Barry, Christopher S. Benson, Charles M. Bradford, Thomas L. R. Brien, Scott C. Chapman, Simon Doyle, Víctor Gómez-Rivera, Steven Hailey-Dunsheath, Jesús Hernández-Aguilar, José Luis Hernández-Rebollar, David H. Hughes, Elijah Kane, Kirit S. Karkare, Alex M. Lapuente, Ryan McGeehan, Raúl Naranjo-Romero, Andreas Papageorgiou, Joseph Redford, Iván Rodríguez-Montoya, Sam Rowe, David O. Sánchez-Argüelles, Sofia Savorgnano, Annie Tan, Jair Vega-Méndez

Strongly Correlated Electrons

Antisymmetric Dynamical Spin Correlations: Spin-Space-Group Constraints and Frequency-Moment Sum Rules

Tsutomu Momoi

Polarized inelastic neutron scattering probes the handedness of magnetic excitations through the spin-component-antisymmetric part of the dynamical spin-structure-factor tensor. We derive its symmetry constraints under unitary and antiunitary residual operations of magnetic space groups and spin-space groups. These constraints determine the allowed tensor components, their parity under momentum reversal, and symmetry-enforced nodes. We then introduce the corresponding antisymmetric commutator spectral function and derive exact zero-temperature sum rules for its frequency moments. The zeroth moment is fixed by the uniform magnetization. For Heisenberg or XXZ exchange Hamiltonians, the first moment of the $xy$ component is fixed by a momentum-weighted static vector chirality. For compensated collinear antiferromagnets, the antisymmetric dynamical structure factor is forbidden when inversion or a translation relates the opposite-spin sublattices. In rotation-related altermagnets, however, an $xy$ component that is even under momentum reversal is allowed at generic wave vectors. Finite antisymmetric spectral weight can therefore coexist with vanishing zeroth and first moments of the commutator spectral function. In a planar helix, by contrast, a residual antiunitary spin-space-group symmetry makes the allowed $xy$ component odd under momentum reversal. Its first moment is generally nonzero and is fixed by a momentum-weighted static vector chirality through the first-moment sum rule. Linear spin-wave calculations for representative altermagnetic and helical models explicitly realize these symmetry and sum-rule constraints.
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Mathematical Physics · Cross-listed from math.NA

Collimated Sunlight and Air Temperature

Olivier Pironneau

Atmospheric temperature on Earth results from complex phenomena that climate models must account for. One important module is radiation, which has three sources: infrared radiation emitted by the Earth and the air, and visible light from the Sun. The latter arrives from an almost point-like source in the sky, producing a Dirac singularity in the boundary conditions known as collimated light. Following Siewert and Maiorino (1980), we propose a very fast numerical implementation to handle the singularity.
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Space Physics

Simultaneous Mars-orbit observations reveal Kelvin-Helmholtz instability-driven bulk atmospheric ion escape

Chi Zhang, Chuanfei Dong, Gangkai Poh et al. (+11 more)

Atmospheric ion escape driven by the solar wind is a key process controlling the long-term loss of the Martian atmosphere. Localized plasma clouds can carry substantial fluxes of planetary ions away from Mars, representing episodes of bulk escape. However, their origin has remained unclear due to the absence of simultaneous upstream measurements. Using joint observations from the MAVEN and Tianwen-1 missions, which provide real-time upstream monitoring, we present direct evidence that these plasma clouds are nonlinear wave packets generated by the Kelvin-Helmholtz instability (KHI). The spatial scale of KH waves is constrained for the first time via two-point measurements. Ion fluxes within plasma clouds are one to two orders of magnitude higher than those in typical steady-state escape channels. Our results indicate that KHI is an important process for solar wind coupling to planetary upper atmospheres and plays a crucial role in shaping atmospheric ion escape for unmagnetized planets.
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All authors Chi Zhang, Chuanfei Dong, Gangkai Poh, Jasper Halekas, Xuanye Ma, Ruhunusiri Suranga, Kathleen G. Hanley, Han-Wen Shen, Hongyang Zhou, Xinmin Li, Liang Wang, Jiawei Gao, Shannon Curry, Christian Mazelle

Quantum Physics

Optimal and Deterministic Quantum Search on the Simplex of Complete Graphs

Kiyoji Huang Fujiwara, Yujia Shi and Thomas G. Wong

The simplex of complete graphs, also known as the first-order truncated simplex lattice, is a network of $M+1$ identical complete graphs, each with $M$ vertices, such that each clique contains an edge or bridge to every other clique. It contains $N = M(M+1)$ vertices, and previous asymptotic results using a continuous-time quantum walk to search this graph for a single marked vertex have either numerically demonstrated an optimal runtime of $O(\sqrt{N})$, or analytically proved a deterministic success probability of 1, but not both, even when the bridges are weighted. In this paper, we give the first analytical proof of optimal quantum search on this graph, proving that it occurs when the weight of the bridges equals $M$. In addition, we numerically show that the optimal runtime is achieved more broadly whenever the weight is at least $\sqrt{M}$. Furthermore, the algorithm is also deterministic when the weight scales between $\sqrt{M}$ and $M$, and this is the first example of quantum search on the simplex of complete graphs that is both asymptotically optimal and deterministic. In addition, for weights where the algorithm is nondeterministic, we give a way to find the marked vertex by inspecting neighboring vertices. Finally, while it is known that connectivity is not a reliable indicator of fast quantum search when comparing different graph families, we show that it is also unreliable within the graph family of weighted simplex of complete graphs.
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Solar and Stellar Astrophysics

Horizontal Magnetic Fields Dominate the Weak Field Quiet Sun in Sunrise III Observations. Evidence from Traditional and Transformer-Based Inversions

Ryan J. Campbell, Carlos Quintero Noda, Manuel Collados et al. (+32 more)

The relative prevalence of horizontal and vertical magnetic fields in the quiet-Sun remains debated, owing to the weak linear polarisation signals that make the inferred magnetic inclination distributions sensitive to observational quality and inversion methodology. We analyse observations obtained with the Sunrise Chromospheric Infrared spectroPolarimeter (SCIP). Transformer-based inversions (SINN), trained exclusively on synthetic Stokes profiles generated from a large radiative magnetohydrodynamic simulation, are compared with independent inversions performed using the DeSIRe code. We separate the selected pixels into weak- and strong-field populations according to their circular-polarisation amplitudes. Linear polarisation exceeding $4\sigma$ is detected in $34.6\%$ of the field of view, enabling the magnetic topology to be constrained over a substantially larger detected population than in typical short-integration Hinode observations. Both inversion methods recover a quiet-Sun magnetic topology in which the weak fields are strongly dominated by the horizontal component, whereas strong fields exhibit a substantially more balanced topology. At $\log\tau=-1$, the median horizontal and unsigned line-of-sight field components in the weak-field population are 63 and 7~G with DeSIRe, and 60 and 6.5~G with SINN, respectively, corresponding to a horizontal-to-line-of-sight ratio of approximately nine for both methods. The agreement between the two fundamentally different optimisation methodologies indicates that the weak-field quiet-Sun in this dataset is characterised by a substantially stronger horizontal than vertical magnetic field component.
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All authors Ryan J. Campbell, Carlos Quintero Noda, Manuel Collados, Mihalis Mathioudakis, Andreas Lagg, Achim Gandorfer, Jose Carlos del Toro Iniesta, Yukio Katsukawa, Pietro Bernasconi, Thomas Berkefeld, Alex Feller, Tino L. Riethmüller, Alberto Álvarez-Herrero, Masahito Kubo, H. N. Smitha, David Orozco Suárez, Bianca Grauf, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Francisco Javier Bailén, Julian Blanco Rodríguez, Juan Sebastián Castellanos Durán, Edvarda Harnes, Johannes Hölken, Francisco A. Iglesias, Ryohtaroh T. Ishikawa, Yusuke Kawabata, Takuma Matsumoto, Takayoshi Oba, Azaymi L. Siu-Tapia, Hanna Strecker, Dušan Vukadinović, Hirohisa Hara, Toshifumi Shimizu

High Energy Physics (Phenomenology)

Formation of Quark-Gluon Plasma droplets under Ultra-Relativistic Heavy Ion Collisions in the presence of magnetic fields with a modified hadronic medium

Ananya Sharma, Divya Rathee and Agam K. Jha

We build upon the previous studies conducted in this domain using the density of states of various components of the quark-gluon plasma(QGP) modelled after the Thomas-Fermi and Bethe models. This study provides an analysis of the stability of the quark-gluon plasma droplet by the inclusion and variation of chemical potential and magnetic field. An effective mass term is included to account for both the rest mass and thermodynamic mass terms of the quarks and gluon. We also expand on the inclusion of a different meson, kaon, into the medium of the droplet. The analysis on these quantities is done by calculating the free energy of the system and examining it as a function of droplet radius, chemical potential and magnetic field to find conditions for stable droplet formation. We discover that a kaonic medium, along with a pre-existing pionic medium, provides greater stability to the system. At the same time, it is realised that the parameters of chemical potential and magnetic field, due to their opposing effect, help in containing the droplet. Further calculations on entropy and heat capacity yield information about the nature of the phase transition of the system. Our analysis and results are in accordance with lattice QCD simulations.
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High Energy Physics (Theory) · Cross-listed from math.PR

Local law and delocalization for the Sachdev-Ye-Kitaev model

Lucas Benigni and Giorgio Cipolloni

We establish a mesoscopic local law and quantitative eigenvector-delocalization estimates for the Sachdev–Ye–Kitaev model (SYK) Hamiltonian of $N$ interacting Majorana fermions subject to a $q$-body interaction. For even $q\ll N^{\frac{1}{2}}$, we prove that the normalized Stieltjes transform is approximated, uniformly on bounded energy intervals, by an explicit deterministic profile which we construct as an asymptotic expansion in the proportion $\alpha_{N,q}$ of anticommuting $q$-body interaction terms. The result holds both on the full Hilbert space and in each fermion-parity sector. We derive mesoscopic eigenvalue counting and spectral form factor estimates. For fixed $q$, we further obtain high-probability $\ell^\infty$-delocalization bounds in any deterministic orthonormal basis for individual bulk eigenvectors. These are the first mesoscopic laws and eigenvector delocalization estimates for the SYK Hamiltonian, which we obtain using the resolvent method.
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Disordered Systems and Neural Networks

Analytical results of Typical Medium Theory for the Bethe lattice with Cauchy disorder

A. Östlin, I. Titvinidze, M. Kollar et al. (+2 more)

We present a combined numerical and analytically tractable realization of the typical medium theory (TMT) for Anderson localization on the infinite-connectivity Bethe lattice with Cauchy-distributed on-site disorder. Exploiting the special properties of the Cauchy distribution and the Bethe lattice, we derive an analytical expression for the typical density of states (TDOS) and obtain a simplified TMT self-consistency scheme. We show that the TDOS at the band center decreases linearly with disorder strength and vanishes at the critical disorder $W_c=D/2$. The resulting $\omega$–$W$ phase diagram reveals the continuous collapse of the mobility edge and the disappearance of extended states.
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All authors A. Östlin, I. Titvinidze, M. Kollar, D. Jones, L. Chioncel

Applied Physics

Circuit-Level Design, Modeling, and On-Wafer Characterization of a Coplanar THz Optoelectronic Mixer

S. Islam, V. Merupo, C. Chamek et al. (+13 more)

We report the design, modeling, and on-wafer characterization of a photoconductive heterodyne mixer implemented as a true terahertz monolithic integrated circuit (TMIC). Unlike previous photoconductive heterodyne demonstrations, the proposed circuit is characterized using RF integrated circuit metrics including input return loss, RF/IF isolation, broadband impedance matching, and conversion loss. The mixer combines a microcavity photoconductor with a broadband coplanar matching network incorporating a Ti shunt resistor, an RF DC-blocking MIM capacitor, and an RF/IF decoupling capacitor. A circuit-level model including both the photoconductor and the distributed CPW accesses is developed and validated. The passive circuit is experimentally characterized up to 500 GHz using on-wafer VNA measurements and accurately reproduced by simulation. Under illumination, the model predicts an input reflection coefficient below -10 dB up to 215 GHz and better than -6.5 dB up to 500 GHz. Measured and simulated conversion losses agree within +/-1 dB over the entire 1-500 GHz range. Conversion loss varies from 22.5-25.5 dB below 320 GHz and 26-34 dB up to 500 GHz. The proposed TMIC demonstrates broadband operation and provides a validated circuit design methodology for future integrated THz photonic mixers.
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All authors S. Islam, V. Merupo, C. Chamek, M. Sassi, C. Coinon, Y. Deblock, E. Okada, S. Lepilliet, F. Braud, Q. Fornasiero, G. Di Gioia, M. Faucher, G. Ducournau, G. Loas, S. Arscott, E. Peytavit

High Energy Physics (Theory)

The Hitchin and Sutcliffe metrics for hyperbolic 2-monopoles

Thomas Galvin

We compare two currently known examples of hyperbolic SU(2) two-monopole metrics and their candidacy as models of hyperbolic monopole dynamics. The first is Sutcliffe's boundary metric and the other is a well-known self-dual Einstein metric found by Hitchin. We show that these metrics are conformally inequivalent and make significantly different predictions for monopole dynamics. We compare each metric to the Franchetti-Ross point particle approximation of hyperbolic monopole dynamics. We show Sutcliffe's metric does not converge to the point particle approximation in the large separation limit. We also check Sen's conjecture for each metric by computing their $L^2$ harmonic two-forms. By a symmetry argument we are able to show that Hitchin's metric has a single $L^2$ harmonic two-form consistent with the conjecture.
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Materials Science

Guided Synthesis of EMT Zeolites by Machine Learning

Emmanuel A. Olanrewaju, Santosh Adhikari, Zhiyin Niu et al. (+4 more)

Zeolites are microporous crystalline materials with diverse frameworks, widely used in industrial applications such as petroleum refining and molecular separation. Unlike most zeolites, EMT can be synthesized under mild conditions (at low temperatures and without the use of organic structure-directing agents), making it attractive for cost-effective and environmentally sustainable production. However, the specific synthesis conditions that selectively produce EMT rather than similar frameworks like FAU are not yet well established. In this work, we develop machine learning (ML) models to guide the discovery of synthesis conditions for EMT zeolites. Our dataset comprises 174 experimental synthesis attempts, recording reaction time, temperature, silica and alumina sources, Si/Al stoichiometric ratio, and other synthesis parameters. We apply both classical ML methods and pretrained foundation models to predict zeolite framework outcomes from these synthesis parameters. Feature importance analysis identifies critical parameters for EMT formation, validating known synthesis principles. Leveraging the ML models, we explore the synthesis space and identify six promising new conditions for EMT formation. Experimental validation confirms EMT crystallization in five cases, including two with Si/Al stoichiometric ratios outside the training dataset's range. Evaluation on independent literature-reported synthesis conditions further demonstrates the generalizability of the model. This work demonstrates a data-driven approach to accelerating zeolite synthesis, closing the loop between ML prediction and experimental validation.
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All authors Emmanuel A. Olanrewaju, Santosh Adhikari, Zhiyin Niu, Michael Nikolaou, Jeremy C. Palmer, Jeffrey D. Rimer, Mingjian Wen

Optics

AFLOW-EMERALD: ElectroMagnetic modes EngineeRing in Advanced LayereD materials

Stefano Campanaro, Luca Bursi, Nicholas H. Anderson et al. (+2 more)

Layered and periodically patterned heterostructures underpin advanced optical, photonic, and plasmonic (meta)materials, whose rational design demands electromagnetic solvers that are both numerically robust and tightly linked to the underlying material properties. Here, we present AFLOW-EMERALD (ElectroMagnetic modes EngineeRing in Advanced LayereD materials), an open-source, modular, Python-based computational framework for simulating electromagnetic wave propagation in finite and periodic layered (meta)materials. Built around a unified object-oriented architecture, AFLOW-EMERALD combines a numerically stable scattering-matrix method with plane-wave expansion and extends to rigorous coupled-wave analysis for laterally patterned structures such as gratings. The software computes optical spectra, spatial field distributions, and photonic band structures, including complex-k dispersion in lossy, dispersive media. A streamlined YAML workflow allows users to seamlessly import dielectric function datasets from experimental, literature, or first-principles sources. Owing to its modular design, AFLOW-EMERALD is readily extensible and suitable for integration into computational materials-design pipelines, providing a practical platform for the coupled material-geometry engineering of dielectric photonic crystals, plasmonic multilayers, hyperbolic metamaterials, and more complex architectures supporting, e.g., surface and volume plasmon-polariton modes.
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All authors Stefano Campanaro, Luca Bursi, Nicholas H. Anderson, Stefano Curtarolo, Arrigo Calzolari

Quantum Physics

Uncovering Non-Gaussianity through Multi-Copy Symmetries

Hao Dai and Yue Zhang

Gaussian states are fundamental in continuous-variable quantum information, yet characterizing non-Gaussianity remains challenging due to the non-convexity of the Gaussian set. Existing witnesses typically rely on Wigner negativity or other information-theoretic quantities. In this work, we develop a group-theoretic, multi-copy approach to detect non-Gaussianity in bosonic systems. We study passive linear optical transformations that mix copies of a quantum state and analyze their commutation with identical Gaussian unitaries applied to each copy. Orthogonal copy-mixing transformations commute with the symplectic part of the Gaussian action, while the displacement part restricts the symmetry to the stabilizer of the collective mode. This structure yields a family of witnesses satisfied by all single-mode Gaussian states. Fixing the thermal reference parameter via the purity, violation of these identities certifies non-Gaussianity. We illustrate the method with several single-mode examples and present an experimental protocol based on passive interferometry and photon-number-resolved detection, showing that the relevant multi-copy expectation values can be estimated from bounded phase observables. Finally, we extend the construction to multi-mode systems and discuss how the same symmetry framework may lead to quantitative measures of non-Gaussianity.
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Chaotic Dynamics

Chaos suppression via adaptive feedback control of intermittency: From exactly solvable ergodic maps to interacting microbubble clusters

Mohammad Yahyavi, Sina Gholizadeh, Sohrab Behnia et al. (+1 more)

Intermittency represents a fundamental route to chaos in nonlinear dynamical systems. In this work we introduce an adaptive control strategy in which the control parameter of an intermittent system is promoted to a dynamical variable that evolves autonomously under an auxiliary nonlinear map drawn from the same functional hierarchy as the system itself. The construction eliminates the need for orbit identification, local linearization, and trajectory-triggered perturbations, which are central ingredients of conventional feedback schemes. The theoretical framework is developed within a class of one-dimensional nonlinear ergodic maps with exactly known invariant (Sinai–Ruelle–Bowen) measures, for which we derive in closed form (i) the dynamics and invariant measure of the evolving control parameter, (ii) the invariant measure of the coupled system, and (iii) the $q$-generalized Lyapunov exponents before and after control. The generalized Lyapunov spectrum serves as an analytical order parameter for the control process: the collapse of its positive regions provides a quantitative and initial-condition-independent signature of chaos suppression, and yields the sensitivity to initial conditions in explicit form. To establish the physical relevance of the approach beyond low-dimensional maps, we apply the same construction to a cluster of three interacting ultrasound-driven microbubbles described by the Keller–Herring model, promoting the experimentally accessible acoustic driving frequency to a dynamical variable. Systematic bifurcation and Lyapunov analyses, performed over wide ranges of driving pressure, frequency, and equilibrium radii, demonstrate that intermittent chaotic radial oscillations are progressively suppressed and replaced by stable periodic motion.
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All authors Mohammad Yahyavi, Sina Gholizadeh, Sohrab Behnia, Bilal Tanatar