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Physics

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Thursday 4 June

Soft Condensed Matter

Geometry-Driven Polarization Control in Ferroelectric Nematic Liquid Crystals

Kazuma Nakajima, Hirokazu Kamifuji, Hirotsugu Kikuchi et al. (+2 more)

Ferroelectric nematic liquid crystals (FNLCs) combine fluidity with spontaneous polarization, offering promising avenues for flexible electromechanical systems. Here, we demonstrate that mechano-electrical conversion in FNLCs can be enhanced by mechanically programming a robust macroscopic polarization alignment. Using hybrid liquid crystal cells composed of rigid glass and flexible substrates, we show that deformation in the ferroelectric nematic phase suppresses polarization domains and produces long-range ordered polarization alignment over millimeter-scale areas. This geometry-driven alignment originates from coupling between the FNLC's spontaneous splay deformation and the deformation-imposed cell geometry, and we further find that the selected polarization direction exhibits clear material dependence. Leveraging this deformation-enabled alignment, we develop an FNLC-based energy harvester that converts mechanical deformation into an output of approximately 1 V. These findings establish geometry-driven alignment as a practical design strategy for boosting FNLC mechano-electrical conversion while providing polarization control for soft electronic devices.
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All authors Kazuma Nakajima, Hirokazu Kamifuji, Hirotsugu Kikuchi, Kenjiro Fukuda, Masanori Ozaki

Fluid Dynamics

Multiple critical Froude numbers for the centrifugal effects on heat transport in rotating Rayleigh-Bénard convection

Zhi-Cong Kang, Guang-Yu Ding, Lu Zhang et al. (+1 more)

The influence of centrifugal effects in rotating Rayleigh-Benard convection is investigated using direct numerical simulations. We find that the Nusselt number decreases beyond a critical Froude number, Fr_c*. This critical value depends on both the Rayleigh number Ra and the aspect ratio Gamma, following power-law scalings with each parameter. We interpret Fr_c* as the onset of centrifugal effects within the thermal boundary layers. This interpretation is supported by the thickening of the boundary layers and a reduction in the planar heat flux. We compare Fr_c* with two previously proposed critical Froude numbers. The first, Fr_Hu, marks the onset of centrifugal effects in the bulk, as evidenced by changes in local heat flux and radial vortex motion. For Fr_Hu < Fr < Fr_c*, centrifugal effects primarily redistribute heat within the bulk and have little influence on the global heat transfer. The second, Fr_Horn, is based on a global force-balance argument. The similar dependence of Fr_c* and Fr_Horn on the aspect ratio suggests a close connection between the global force balance and the onset of centrifugal effects in the thermal boundary layers. These results demonstrate that centrifugal forcing influences the bulk flow and the thermal boundary layers differently in rotating Rayleigh-Benard convection. While relatively weak centrifugal forcing modifies the bulk dynamics, substantially stronger forcing is required to alter boundary-layer properties and global heat transport.
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All authors Zhi-Cong Kang, Guang-Yu Ding, Lu Zhang, Ke-Qing Xia

Strongly Correlated Electrons

A microscopic design rule for spin supersolids in triangular-lattice magnets

Ryota Ono, Jun'ichi Ieda, Michiyasu Mori et al. (+1 more)

Spin supersolids emerge as a central topic in frustrated magnetism, motivating the search for realization in quantum materials. To this end, we study the origin of exchange anisotropy, $\Delta$, in triangular-lattice cobaltate families $X_2$$Y$Co(PO$_4$)$_2$ and $X_2$Co(SeO$_3$)$_2$ ($X$ = Na, K, Rb, Cs; $Y$ = Mg, Ca, Sr, Ba) by tailoring realistic spin models. We show that $\Delta$ is determined by the ratio of trigonal crystal field to spin-orbit coupling strength. This framework explains contrasting anisotropies in these families, predicts systematic trends in $\Delta$ across $X/Y$-substitutions, and identifies candidate materials for spin supersolids. Our results establish trigonal field engineering as a microscopic route toward the design of spin supersolids.
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All authors Ryota Ono, Jun'ichi Ieda, Michiyasu Mori, Sadamichi Maekawa

Astrophysics of Galaxies

Grain-size evolution and rapid dust growth in high-redshift galaxies

Daisuke Toyouchi, Andrea Ferrara, Yurina Nakazato et al. (+3 more)

We present a galaxy evolution model that incorporates grain-size evolution in a multiphase interstellar medium (ISM) to investigate dust attenuation in galaxies at $z \geq 5$. Our fiducial setup assumes a low dust yield of $y_{\rm d} = 10^{-4}~\rm M_\odot$ and a small characteristic size of stellar dust of $a_0 = 0.01~\mu$m, motivated by efficient dust destruction by reverse shocks in dense ISM environments. Our model demonstrates that, even with such low dust yields, massive galaxies with $M_\ast > 10^9~\rm M_\odot$ reach high dust-to-stellar mass ratios of $M_{\rm d}/M_\ast \sim 10^{-2}$ by $z \sim 7$ because small grains supplied by SNe efficiently serve as seeds for metal accretion in the ISM. Because dust growth significantly lags behind star formation, the outer regions beyond the half-star-formation-rate radius remain relatively dust poor, allowing a non-negligible fraction of UV photons to escape without strong attenuation. We further find that dust growth becomes most efficient when the ISM is dominated by cold dense gas but still contains a modest warm component, as the former promotes metal accretion while the latter supplies additional small grains through shattering, thereby further enhancing subsequent grain growth. In particular, with a cold dense gas fraction of $\sim 90~\%$, our model predictions become broadly consistent with the dust-to-stellar mass ratios inferred for dust-rich galaxies at $z \sim 7$, as well as the upper limits for blue galaxies at $z \gtrsim 10$. Self-consistently, the model successfully reproduces the UV luminosity functions observed at both $z = 7$ and $z = 12$. Overall, this study demonstrates that a physically motivated treatment of grain growth in a multiphase ISM is essential for linking the dust content of high-redshift galaxies to their radiative properties during cosmic dawn.
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All authors Daisuke Toyouchi, Andrea Ferrara, Yurina Nakazato, Kosei Matsumoto, Raffaella Schneider, Koki Otaki

Quantum Physics

Deployed trusted-node quantum key distribution over 300 km with a multi-core fiber access link

Martin Clason, Joakim Argillander, Didrik Bergström et al. (+8 more)

Quantum key distribution (QKD) is increasingly considered for deployment in realistic communication networks, where long distances, heterogeneous fiber infrastructure, and coexistence with classical traffic present substantial challenges. Here, we demonstrate trusted-node QKD between Linköping University and the Stockholm hub of the Swedish national quantum communication infrastructure over 270 km of deployed single-mode fiber, extended by a 33 km multi-core fiber (MCF) segment emulating a metropolitan access link, for a total distance of 303 km. The two sub-links use commercial QKD systems whose receivers are interfaced with external superconducting nanowire single-photon detectors, enabling operation at losses beyond those supported by standard internal gated-mode detectors. We operate the link while actively switching the QKD channel between two MCF cores, with co-propagating Ethernet traffic and injected broadband optical noise in the other cores. The results demonstrate the integration of commercial QKD into demanding, dynamically reconfigurable fiber infrastructure relevant to future hybrid quantum-classical networks. Finally, using the generated secret keys, we illustrate how limited and time-varying QKD throughput affects one-time-pad-protected image transmission: image fidelity depends strongly on the available QKD-generated key budget and the choice of compression algorithm, highlighting application-level challenges for QKD-based encryption in realistic scenarios.
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All authors Martin Clason, Joakim Argillander, Didrik Bergström, Daniel Spegel-Lexne, Giulio Foletto, Ashraf El Hassan, Mohamed Bourennane, Onur Günlü, Katia Gallo, Rui Lin, Guilherme B. Xavier

High Energy Physics (Phenomenology)

Bulk viscosity of a binary mixture: the role of the intra-species interaction

Gabriele Parisi, Vincenzo Nugara, Shams Ul Arfeen et al. (+2 more)

The bulk viscosity $\zeta$ is a transport coefficient which is of central importance for various areas of modern physics. In particular, its determination for a mixture of more than one fluid is challenging, since it involves a complex interplay of multiple microscopic processes that operate on different time scales. Within the Chapman-Enskog framework, based on a series expansion of the Boltzmann distribution function, many previous works have derived the 1$^{\text{st}}$ order result for the $\zeta$ of a mixture. However, such a result fails to reproduce relevant physical features of the system, especially when the masses of the two components are similar. In this work we improve the 1$^{\text{st}}$ order Chapman-Enskog result by deriving the $\zeta$ at the 2$^{\text{nd}}$ order in the expansion. We show that this improved formula encodes many physical properties that the 1$^{\text{st}}$ order result misses: under specific conditions, the 2$^{\text{nd}}$ order result can be qualitatively and quantitatively very different from the 1$^{\text{st}}$ order one. Moreover, this result is compared against the $\zeta$ evaluated within the Green-Kubo formalism, by means of a numerical solution of the Relativistic Boltzmann equation. The agreement with respect to this benchmark is significantly improved when moving from the 1$^{\text{st}}$ to the 2$^{\text{nd}}$ order CE result.
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All authors Gabriele Parisi, Vincenzo Nugara, Shams Ul Arfeen, Salvatore Plumari, Vincenzo Greco

Quantum Physics

Quantum-limited estimation of atmospheric turbulence via spatial mode decomposition

A. Hrebeniuk, M. Klen, I. Karuseichyk et al. (+2 more)

We establish the ultimate precision limit for estimating the optical spatial coherence radius (Fried parameter) within a quantum metrological framework. In the weak field regime, we show that spatial-mode decomposition – originally introduced for superresolution imaging – enables substantially more precise estimation than conventional direct imaging when the receiver aperture is smaller than the coherence radius.
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All authors A. Hrebeniuk, M. Klen, I. Karuseichyk, N. Treps, A. A. Semenov

Medical Physics · Cross-listed from cs.AI

Integrating Mechanistic and Data-Driven Models for Neurological Disorders through Differentiable Programming

Shah Pallav Dhanendrakumar, Saikat Pal and Sitikantha Roy

Advances in computational modeling, neuroimaging, and artificial intelligence are revolutionizing the modeling of neurological disorders for improved diagnostics, prognosis, and treatment planning. Mechanistic models provide valuable scientific insight into the disorders, but in practice they are often simplified with assumptions or computationally expensive and slow to solve. However, while purely data driven approaches provide speed and scalability, they require large, high quality data to train and generally suffer from interpretability and generalization issues. This perspective paper presents a structured overview of hybrid modeling strategies, which combine deep learning models with physics based solvers, and are categorized into parallel, series, and parallel-series architectures. Three main approaches that have been emphasized are residual modeling for missing or incomplete physics, Neural Ordinary Differential Equations (NODEs) for continuous time dynamics approximation, and solver in the loop that accelerates traditional solvers with neural approximations. These hybrid models integrate the governing differential equation based formulations and deep learning to characterize the evolution of neurological disorders, and promise advanced personalized neurological modeling. In addition, the study explores and proposes different hybrid configurations to improve diagnosis accuracy, predict disease progression, and inform treatment strategies across a range of neurological disorders. These capabilities outperform standalone mechanistic or purely data driven approaches, making hybrid modeling a powerful tool, especially in applications involving modeling the progression and treatment responses in neurological conditions such as brain tumors, Alzheimer's disease, and stroke.
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Computational Physics · Cross-listed from math.NA

A tensor-train multidimensional inverse Laplace transform

Martin Mikkelsen and Michael Kastoryano

Laplace transforms and their numerical inverses arise throughout applied mathematics, physics, finance, and probability theory. Numerical inversion, however, quickly becomes intractable in high dimensions because the number of quadrature evaluations grows exponentially with dimension. We develop a tensor train (TT) formulation of the multidimensional inverse Laplace transform. The method constructs a TT approximation of the transformed function on the complex quadrature grid and then performs the inversion through a sequence of tensor contractions. Under suitable low-rank assumptions, this reduces the computational cost from exponential to polynomial in the dimension, provided that the relevant bond dimensions remain bounded. The method has only a small number of tunable parameters and admits error estimations. We demonstrate its performance in numerical experiments, benchmarked against Monte Carlo estimates and exact references, for multivariate normal-inverse Gaussian, Wishart, and correlated Gamma-type distributions.
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Optics

Tunable Mid-Infrared Chiral Selective Absorber Based on Asymmetric V-Shaped Metasurfaces Driven by Chiral quasi-Bound State in the Continum

Yuqing Liu, Yi Wang, Ruihan Ma et al. (+3 more)

Efficient discrimination of circularly polarized light (CPL) is of great significance in photonics. In this study, we propose a nanophotonic device based on asymmetric V-shaped metasurfaces that exhibits strong discrimination between left- and right-circularly polarized (LCP and RCP) light at the resonant wavelengths of the absorption spectra. The chiral-selective response originates from a quasi-bound state in the continuum (qBIC) mode enabled by controlled symmetry breaking in the V-shaped structure, which exhibits high absorption under LCP illumination while the resonance is strongly suppressed under RCP incidence, leading to a large absorption contrast between the two circular polarizations. This significant absorption difference enables highly efficient chiral discrimination. Furthermore, the resonant wavelength can be broadly tuned from 5200 to 6200 nm by scaling the structural dimensions without compromising the high absorption contrast between LCP and RCP. This work not only enables high-performance chiral detection and separation, but also offers valuable guidance for reconfigurable chiral nanodevices, with promising applications in areas such as enantiomer sensing, chiral imaging, and CPL spectroscopy.
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All authors Yuqing Liu, Yi Wang, Ruihan Ma, Nianzhao Wang, Mengtao Sun, Yuqing Cheng

Solar and Stellar Astrophysics

Interaction of Fast Magnetoacoustic Wave with the Localized Coronal Null and Generation of the Energetic Alfvén Wave Packet

Akash Bairagi, Abhishekh K. Srivastava, Sripan Mondal et al. (+5 more)

In the present paper, we have performed 2.5D resistive magnetohydrodynamic simulations of the interaction of a fast magnetoacoustic wave with a localized coronal magnetic null point. As a result, an Alfvén wave packet is generated by the mode conversion when a fast magnetoacoustic perturbation interacts with the null point. The field-aligned plasma flows are also generated due to the non-linear effects. When the fast mode wavefront interacts with the null, some parts of this wavefront get refracted around it, while some other part is trapped at the null region. Subsequently, the velocity fluctuation out of the plane and in-phase magnetic field fluctuations have evolved and propagated with the local Alfvén speed along the separatrixes at one side of the coronal null region. The resulting disturbance behaves as an incompressible and energetic Alfvén wave packet. A secondary fast magnetoacoustic wave is also produced and propagates. In the synthetic SDO/AIA observations, no intensity fluctuations are evident in the region where the Alfvén wave packet propagates, while the fast magnetoacoustic wave fronts are clearly evident. Our results suggest that given the appropriate physical conditions at the null, when the fast mode wave is incident, Alfvén packets can be excited due to the mode conversion, further carrying substantial momentum and energy flux in the solar corona.
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All authors Akash Bairagi, Abhishekh K. Srivastava, Sripan Mondal, T.V. Zaqarashvili, Astrid Veronig, P. Bourdin, Ding Yuan, Ryun-Young Kwon

Quantum Physics

Efficient Quantum Circuit Construction of Controlled Time-Evolution for Arbitrary Pauli-Sum Hamiltonians

Shintaro Fujiwara, Naoki Yamamoto and Naoki Ishikawa

Controlled time-evolution circuits select forward or backward Hamiltonian time evolution according to the state of an ancilla qubit. They are fundamental building blocks in quantum eigenvalue transformation of unitaries, Hamiltonian filtering, and related quantum algorithms. A direct realization adds ancilla control to the elementary gates of the time-evolution circuit and therefore increases the two-qubit gate count, compiled T depth and CX depth. We develop an efficient recursive algorithm that, for an arbitrary Pauli-sum Hamiltonian, partitions the input Pauli terms into groups and assigns to each group a sign-flip Pauli string that anti-commutes with the in-group terms, thereby removing ancilla control from the grouped time-evolution blocks. Numerical benchmarks on random Hamiltonians and structured spin Hamiltonians show reductions in compiled T depth and compiled CX depth. For a Kagome Hamiltonian with 24 spins under full connectivity, the proposed construction reduces the compiled T depth by 85.2% and the compiled CX depth by 68.9%, compared with a conventional implementation that decomposes the Hamiltonian into individual Pauli terms and implements the controlled time evolution of each term by directly adding the ancilla qubit to the corresponding Pauli-rotation circuit.
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Quantum Physics

Forbidden transitions in superconducting artificial atoms

Alberto Del Ángel, Théo Sépulcre, Ricardo Gutiérrez-Jáuregui et al. (+1 more)

Artificial atoms built from Josephson junctions have become a powerful tool to explore the limits of quantum optics due to their strong coupling to electromagnetic fields and their sensitivity to changes at the single-photon level. This sensitivity to quantum fluctuations complements their metrological and computational use, which are based on the precise oscillating frequency of the underlying supercurrents. We present here a theory for Josephson junctions immersed in electromagnetic fields where focus is shifted from temporal correlations and towards spatial ones. Unlike the commonly used circuit and black-box descriptions, our work is based on a microscopic model that enables systematically accounting for the effect of the spatial and vectorial profile of an electromagnetic field over a junction. As an example of the interactions that emerge in such a setup, we investigate the possibility of driving a junction via a quadrupole transition, using typical experimental parameters in existing devices. With the transition being dependent on the gradient of the electric field – rather than its intensity – the junction can be excited in a region where the electric field vanishes.
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All authors Alberto Del Ángel, Théo Sépulcre, Ricardo Gutiérrez-Jáuregui, Anton Frisk Kockum

Quantum Physics

Barbell Codes: qLDPC Codes for Superconducting Quantum Hardware

Shin Ho Choe, Vincent Steffan, Florian Vigneau et al. (+5 more)

The major challenge on the way to fault-tolerant quantum computing comes from the insufficient quality of hardware components and the difficulty of scaling their number without further compromising fidelity. Quantum Low-Density Parity-Check (qLDPC) codes offer a promising solution by encoding logical qubits with low overhead and at a comparatively high code distance. However, it remains an open question how to scalably implement efficient qLDPC codes on fixed-connectivity quantum chips without increasing hardware complexity to enable the non-local interactions in their underlying QEC cycles. We resolve this challenge for the first time by introducing a family of qLDPC "barbell" codes accompanied by a realistic chip layout that natively supports all required two-qubit interactions. Crucially, the hardware complexity required to implement barbell codes remains constant as code distance increases. We provide a detailed investigation into the feasibility of all required hardware components and simulate a specific family of barbell codes against circuit-level noise. We find that, with a modest overhead of $<30$ data qubits per logical qubit, barbell codes can preserve information at a physical noise strength of $10^{-4}$ for several trillion QEC cycles. Simulations of logical multi-Pauli measurements, performed with circuits tailored to the chip, yield similar logical performance per QEC round, indicating that entangling gates between logical qubits in barbell codes can be realized fault-tolerantly.
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All authors Shin Ho Choe, Vincent Steffan, Florian Vigneau, Pedro Parrado-Rodríguez, Hsiang-Sheng Ku, Martin Leib, Francisco Revson Fernandes Pereira, Fedor Šimkovic IV

Applied Physics

Unravelling Challenges in Heating Power Measurements for Magnetic Hyperthermia – the RADIOMAG Round Robin Study Revisited

Lise G. Hanson, Daniel Ortega and Cathrine Frandsen

Non-adiabatic AC calorimetry is the most widely used technique for estimating the heating power of magnetic nanoparticles in magnetic hyperthermia. However, it is prone to systematic errors which lead to a standard deviation in the intrinsic loss power (ILP) of approximately 30-40%, as revealed by the RADIOMAG EU COST Action TD1402 round-robin study involving 21 European laboratories. In this study, we re-examine the RADIOMAG dataset to both uncover previously unreported instrumentation issues, and to explore more deeply some of the reported instrumentation issues. We identify four common sources of error: i) Insufficient temperature resolution, ii) AC-field sensitive thermometers, iii) Non-physical temperature oscillations, and iv) Apparent non-linear heat loss. Based on these findings, we propose criteria for sufficient measurement quality and apply them to re-estimate the ILP values. These results have a standard deviation of 18-30%., demonstrating that addressing instrumentation and analysis issues can improve measurement reliability and decrease the inter-laboratory deviation by up to 38%. When re-estimating ILP, we used the initial slope method, arguing that the corrected slope method, which was previously used to investigate the RADIOMAG data, could introduce misleading interpretations of systematic ILP deviations due to sub-optimal measurement conditions and the unnoticed influence of non-linear heat losses. However, we emphasise that the corrected slope method is preferred, given a linear heat loss. Based on our analysis, we introduce a diagnostic protocol by using slope curves - a simple yet effective plot type - for identifying and solving common instrumentation challenges proactively before the data acquisition phase.
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High Energy Physics (Experiment)

Mountain Muography for China Jinping Underground Laboratory

Xinshun Zhang, Shaomin Chen, Wei Dou et al. (+31 more)

The China Jinping Underground Laboratory (CJPL), located $\sim 2,400$~m beneath Jinping Mountain, is one of the world's deepest and largest ($\sim 300{,}000~\mathrm{m}^3$) underground facilities, hosting dark matter, nuclear astrophysics, and neutrino experiments. We report the first muon radiography (muography) conducted at this extraordinary depth. Cosmic muons detected by a one-ton prototype developed for the Jinping Neutrino Experiment were used to perform non-invasive subsurface density mapping over a 3~km lateral range. The 1.3~m diameter detector provides nearly isotropic acceptance and an angular resolution of $\sim 4.5^\circ$. By correlating the predicted surface muon flux distributions with the underground measurements, we reconstruct a directional opacity map that constrains the density structure of the overburden and shows excellent agreement with satellite-derived terrain models. This work demonstrates the feasibility of muography at extreme depths with kilometer-scale overburden and establishes a robust methodology for future geophysical applications and large-scale facilities, such as the full Jinping Neutrino Experiment. Based on this validated overburden model, we further predict the total muon fluxes for the eight experimental halls in CJPL-II, providing essential input for their physics programs.
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All authors Xinshun Zhang, Shaomin Chen, Wei Dou, Haoyang Fu, Lei Guo, Ziyi Guo, XiangPan Ji, Jianmin Li, Jinjing Li, Bo Liang, Ye Liang, Qian Liu, Wentai Luo, Ming Qi, Wenhui Shao, Haozhe Sun, Jian Tang, Yuyi Wang, Zhe Wang, Changxu Wei, Jun Weng, Yiyang Wu, Benda Xu, Chuang Xu, Tong Xu, Tao Xue, Haoyan Yang, Yuzi Yang, Aiqiang Zhang, Bin Zhang, Yang Zhang, Zhicai Zhang, Lin Zhao, Yangheng Zheng

Statistical Mechanics

Hidden periodicities allow the prediction of locked particle motions on quasicrystalline surfaces

Seemant Mishra, Artem Ryabov and Philipp Maass

Motion of particles across quasicrystalline surfaces exhibits peculiar features due to the presence of long-range order without translational periodicity. Under time-periodic forcing, this motion can become locked in directions thatn deviate strongly from the mean driving direction. We show that for surface potentials with a quasicrystalline pattern of minima generated by a superposition of plane waves, particle trajectories are nonperiodic, yet their mean direction and speed are determined by hidden periodic potentials. The lattice vectors of these underlying potentials define characteristic velocities that dictate both directional and speed locking. The particle motion does not synchronize with the driving, and it is possible for the mean speed to remain nonlocked even in directionally locked states. These findings are demonstrated using a model directly amenable to experimental realization.
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Earth and Planetary Astrophysics

Morphological and mineralogical characterization of the Freundlich-Sharonov Basin: Implications for the lunar farside magmatism

Tvisha Kapadia, Neha Panwar, Neeraj Srivastava et al. (+3 more)

Volcanism on the Moon is highly asymmetric, with the nearside having extensive mare emplacements and the farside exhibiting only sparse, localized volcanism. The Freundlich-Sharonov Basin (FS Basin), a preNectarian/Nectarian impact basin located on the central farside of the Moon (18.35N, 175.2E), hosts a limited volume of spatially restricted and isolated volcanic patches, which provide an ideal geological setting to investigate controls on the lunar magmatism in a thick, KREEP poor farside crust. In this study, detailed geological characterization of the FS Basin is provided for the first time, incorporating insights from morphological, chronological, and compositional analyses using high resolution datasets from missions such as Chandrayaan1 (Moon Mineralogy Mapper), Kaguya, and Lunar Reconnaissance Orbiter. The results of this study reveal a previously undetected ~192 km diameter inner depression ring, along with spatially aligned subsurface magmatic intrusions, and exposures of PAN and orthopyroxenes along the basin rings. Compositional analyses indicate that the FS Basin experienced at least two volcanic eruptions dominated by exceptionally high-alumina basalts (~16 to 24 wt% Al2O3) around ~3.4 Ga and ~2.1 Ga. This is the highest reported alumina content in the lunar maria, also expanding the period of known high alumina volcanism on the Moon to the late phase. We propose that the limited extent of volcanic eruptions in the FS Basin is a result of the combined effects of composition-dependent magma buoyancy, reduced magma production, and impact modified crustal structures determining the magma extrusion sites.
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All authors Tvisha Kapadia, Neha Panwar, Neeraj Srivastava, Rishitosh Sinha, Megha Bhatt, Anil Bhardwaj

Quantum Physics

Polymer quantum mechanics on compact configuration spaces

Maxwell R. Siebersma, Basie Seibert, Samuel Shuman et al. (+1 more)

"Polymer quantum mechanics" is the name given to a quantization scheme inspired by loop quantum gravity in which the configuration space of the theory is chosen to have a discrete topology. Polymer quantization yields a representation of the canonical commutation relations that is genuinely distinct from the conventional "Schrödinger" representation. In this paper, we summarize the main features of polymer quantum mechanics and investigate in detail the polymer quantization of systems with configuration spaces that are classically compact. We show explicitly how using the standard construction of polymer states leads to a Hilbert space of states defined on a finite graph of points. By way of example, we find the exact energy eigenvalues and eigenfunctions for a particle on a ring and a particle in a box defined on such lattices, and discuss similarities and differences from standard Schrödinger quantum mechanics. We also explore the continuum limit of states in these systems, and demonstrate in detail how the exact eigenfunctions in the position representation approach their continuum counterparts.
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All authors Maxwell R. Siebersma, Basie Seibert, Samuel Shuman, David A. Craig

Superconductivity

Superconductivity beyond band geometry: emergence of pair quantum geometry

Mehmet Akif Keskiner and M. Iskin

The quantum geometry of Bloch states is known to shape the effective mass of single particles in multiband systems. We show that this connection extends to paired states. For a multiband Hubbard model with on-site attraction, we derive an exact effective-mass theorem for two-body bound states in vacuum and its counterpart for Cooper pairs near the critical temperature within Gaussian fluctuation theory. In both cases, the inverse mass contains, besides a “conventional” term from band dispersion and band geometry, a distinct term governed by a quantum metric on the manifold of paired states. This pair-geometric term requires a sublattice pairing texture that varies with the pair momentum and, like the band quantum metric, depends on the orbital embedding, whereas the total mass does not. The one-body, two-body, and Cooper-pair theorems follow from a single construction, with the band mass recovered as a special case. When a collective mode lies inside the two-particle continuum, its continuation to the second Riemann sheet renders the fluctuation kernel non-Hermitian, leading to a biorthogonal quantum geometry and a complex Cooper-pair mass whose real and imaginary parts describe propagation and damping. Exact calculations for the sawtooth, Su-Schrieffer-Heeger, Hofstadter, and fluorite-like lattices show that pair geometry contributes significantly to the mass of bound pairs, and the fluorite-like lattice exhibits both an undamped Cooper pair with a real mass and a damped one with a complex mass. Pair quantum geometry thus emerges as an essential ingredient of multiband superconductivity beyond band geometry.
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Atmospheric and Oceanic Physics

Leveraging MTG-FCI fire observations for event-based fire behavior monitoring from near-real-time operation to seasonal analysis

Ronan Paugam, Jean-Baptiste Filippi, Akli Benali et al. (+10 more)

Wildfire monitoring and suppression require timely information on fire behavior, including fire energy release and rate of spread, to support operational decision-making and resource allocation. Active fire products from the Flexible Combined Imager (FCI) aboard the geostationary Meteosat Third Generation (MTG) satellites provide 10-min observations over Europe and Africa. Deriving fire behavior information from these observations requires associating individual hotspot detections into coherent fire events. We present a Fire Event Tracker (FET) algorithm that performs spatio-temporal clustering of hotspot detections from the LSA-SAF FCI active fire product. The algorithm assigns persistent identifiers to fire events and updates their geometry, fire radiative power, and rate of spread at each 10-min interval. The same parameterization is used for both near-real-time and retrospective processing. FET was applied retrospectively to the Mediterranean FCI hotspot archive of 2025 and operationally in two near-real-time contexts: wildfire monitoring in Portugal and support of the 2025 SILEX airborne campaign within the EUBURN project, where besides fire monitoring, FET products were also used to initialize coupled FOREFIRE-MesoNH simulations for plume forecasting. Results show that event-based clustering of FCI active fire detections provides a consistent description of fire evolution, enabling both tactical wildfire management and high-frequency seasonal fire analyses.
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All authors Ronan Paugam, Jean-Baptiste Filippi, Akli Benali, Jorge Gomes, Weidong Xu, Emanuel Dutra, Francois Andre, Damien Boulanger, Vianney Retornard, Andrea Meraner, Julia Harvie, Victor Penot, Cyrielle Denjean

Chemical Physics

Quantum computing for accurate large-scale electronic-structure calculations: DFT-embedded, post-processed quantum-selected configuration interaction

Tuan Minh Do, Yuichiro Yoshida, Tomoya Shiota et al. (+1 more)

We present a multilevel embedding framework for quantum chemistry calculations on a quantum computer. In our framework, a quantum algorithm treats the strongly correlated active space, while a high-level wave-function method such as coupled cluster theory or multireference perturbation theory recovers the remaining correlation in the surrounding region. A sampling-based quantum algorithm, quantum-selected configuration interaction, bridges the quantum and classical treatments. The entire calculation is embedded in a low-cost density functional theory description of the surrounding environment using Manby's projection technique. We apply the framework to organic, metal-organic, and metallic systems, computing bond dissociation energies, adsorption energies, and reaction barriers using only the subset of qubits of a 144-qubit superconducting quantum computer at the University of Osaka and achieving $\sim$1 kcal/mol agreement with classical references for a Menshutkin $\mathrm{S_N2}$ reaction inside a carbon nanotube. Our results may open the way to quantitatively reliable quantum-classical hybrid calculations for large-scale chemical systems.
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All authors Tuan Minh Do, Yuichiro Yoshida, Tomoya Shiota, Wataru Mizukami

Atomic and Molecular Clusters

Influence of DFT Functionals on Low-Energy Electron Scattering Cross Sections of Nitric Oxide

Ashutosh Yadav, Felipe Fantuzzi, Nigel J. Mason et al. (+1 more)

Nitric oxide (NO) is important in biological, atmospheric, plasma, industrial, and astrophysical environments, where reliable electron-collision data support modelling charged-particle interactions with matter. Its well-known experimental properties make it suitable for assessing how the target electronic-structure description affects low-energy electron scattering calculations. In this work, NO properties were evaluated using B3LYP, M06-2X, PBE0, and $\omega$B97X-D3, with basis sets ranging from minimal to quadruple-zeta quality. Bond length, dipole moment, ionisation potential, and polarisability were compared with experiment to assess the sensitivity of the target description to the functional and basis set. The aug-cc-pVQZ basis set was then used to generate target models for ab initio R-matrix calculations over 0.1–20 eV. The total cross sections show low-energy resonance features, with the strongest functional dependence around the broad peak near 0.8–1.0 eV. A sharper, higher-energy structure is also observed below 2 eV, shifting from 1.74 to 1.82 eV depending on the functional. Differential cross sections show modest functional sensitivity, with more noticeable angular differences at 7.5 and 10 eV. These results show that the DFT functional and basis set affect the target properties, with the resulting target description influencing low-energy electron-scattering observables of NO. The comparison supports $\omega$B97X-D3/aug-cc-pVTZ geometry optimisation followed by aug-cc-pVQZ target-property calculations as a practical protocol for R-matrix modelling of NO.
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All authors Ashutosh Yadav, Felipe Fantuzzi, Nigel J. Mason, Bobby Antony

Astrophysics of Galaxies

The Multi-phase Biconical Outflow in the local IR-Luminous Merger IRASF01364-1042

Y. Song, V. U, J. Kader et al. (+36 more)

We investigate the spatially-resolved ISM properties of the local ($z = 0.048$), IR-luminous ($L_{\rm IR} = 10^{11.87}$\,L$_\odot$), late-stage galaxy merger IRAS F01364-1042, combining multi-wavelength IFU observations from JWST/MIRI-MRS, ALMA and Keck/KCWI. Using these datasets, we construct emission line maps of several key tracers of the ionized (e.g., [Ne\,II]\,12.8$\mu$m, [O\,III]$\lambda5007$), warm molecular (e.g., \ce{H2}\,0-0\,S(3)), and cold molecular gas (e.g., CO (J$=2-1$)), and perform detailed decomposition of spectra extracted in resolved regions across the areas of emission. We confirm the presence of a multi-phase galactic biconical outflow along the minor axis of a highly inclined rotating disk. The inferred outflow velocities are $\sim\,$500 - 600\,km\,s$^{-1}$ $\sim\,$350\,km\,s$^{-1}$, and $\sim\,$200 - 300\,km\,s$^{-1}$, in the ionized, warm and cold molecular phase, respectively, with corresponding mass outflow rates of $\sim 0.3 - 2.3$, $\sim 31$, and $\sim 38 - 240$\,M$_\odot\,$yr$^{-1}$. The cold molecular phase dominates both the total mass outflow rate and the associated kinetic energy ($\sim\,2 - 8 \times 10^{42}$\,erg\,s$^{-1}$). We confirm, for the first time, a dust-obscured AGN in IRAS\,F01364-1042, via detection of the [Ne\,V]\,14.3$\mu$m line. The low inferred AGN bolometric luminosity ($1.2 - 1.8 \times 10^{43}$\,erg\,s$^{-1}$) suggests that the nuclear starburst alone, with a star formation rate of $\sim 40 - 60$\,M$_\odot$\,yr$^{-1}$, can account for the energy required to drive the outflow, though a more active AGN phase in the recent past may have also played a role. Our work showcases the necessity of multi-wavelength observations for interpreting the gas dynamics in merger-driven dusty starbursts, and the capability of JWST/MIRI-MRS to uncover obscured, low-luminosity AGN that may be common in these systems.
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All authors Y. Song, V. U, J. Kader, M. Bianchin J. Agostino, L. Barcos-Muñoz, N. Torres-Albà, A.Medling, C. Ricci, L. Armus, T. Lai, L. Ghodsi, A. Evans, H. Inami, S. Stierwalt, T. Bohn, K. L. Emig, V. Buiten, G. Donnelly, E. Treister, A. Jimenez-Gallardo, T. Böker, D. Kakkad, S. Linden, P. van der Werf, V. Charmandaris, R. Remigio, L. Lenkic, C. Finlez, M. Sanchez-García, C. Lofaro, A. Saravia, I. Yoon, G. C. Privon, T. Gao, H. Aziz, R. McGurk, T. Díaz-Santos, D. Kunneriath, David B. Sanders

Materials Science

Resolving room temperature microscale fracture and plasticity of iron oxides along the cascade of iron ore reduction via nanoindentation and microcantilever bending

Shreehard Sahu, James P. Best, Gerhard Dehm et al. (+1 more)

Understanding the fundamental mechanical behaviour of iron oxide phases is essential for controlling attrition and fracture during iron ore reduction process, particularly in hydrogen-based direct reduction systems. This study investigates the room temperature plasticity and fracture behaviour of single-crystal hematite, magnetite, and Wustite using nanoindentation and micro-cantilever fracture testing. Hematite exhibited the highest hardness, H and elastic modulus, E (H=18.5 GPa, E=281 GPa), followed by magnetite (H=8.7 GPa, E=165 GPa) and Wustite (H=7.5 GPa, E=145 GPa), reflecting differences in slip activity along the iron oxide reduction sequence. Furthermore, fracture toughness was measured using notched microcantilevers for all three iron oxide phases, aligned along low index and high index crystallographic planes, respectively. For the low index-oriented case hematite showed increased fracture toughness owing to crack deviation and faceting while magnetite and Wustite exhibited single plane cleavage fracture. Distinct changes in the deformation behavior in terms of plasticity and cracking of the three iron oxides were evident from both methods. Further investigation of a magnetite-gangue interface, particularly relevant to low-concentration ores, revealed significantly reduced fracture toughness compared to the magnetite phase. Overall, these results provide a comprehensive set of mechanical properties of iron oxides with potential application in material models for predicting fracture and attrition during hydrogen-based direct reduction.
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All authors Shreehard Sahu, James P. Best, Gerhard Dehm, Anwesha Kanjilal

Quantum Physics

Rapid Gaussian Boson Sampling Circuit Screening for GKP States Creation via a Two-Stage Machine Learning Surrogate

Mohammad Amin Khanpour and Hossein Davoodi Yeganeh

Gottesman-Kitaev-Preskill (GKP) states are essential non-Gaussian resources for fault-tolerant photonic quantum computing, enabling logical qubit encoding with intrinsic robustness against errors. Several approaches to GKP state preparation have been explored, including measurement-based protocols in circuit QED and trapped-ion systems, cat-state breeding, and photon-subtraction schemes. However, these methods are either restricted to specific platforms or require deep non-Gaussian resource chains with exponentially low success probabilities. Gaussian Boson Sampling (GBS) offers a compelling all-photonic alternative by generating non-Gaussian states through measurement-induced nonlinearity, without the need for matter-based ancilla or active feedforward. Nevertheless, its practical implementation is limited by the exponential computational cost of evaluating matrix hafnians-#P-complete functions that govern photon-number probabilities. To address this challenge, we introduce a two-stage Histogram Gradient Boosting surrogate pipeline that predicts, without any hafnian computation, the optimal heralding pattern, circuit fidelity, and post-selection probability for candidate GBS circuits, while reserving exact quantum simulation exclusively for surrogate-selected candidates. Trained on circuit configurations across 3-5 optical modes, the surrogate achieves 90.0% GKP-detection accuracy on a held-out set, representing a 23.7 percentage-point improvement over the baseline, with a fidelity mean absolute error of 0.032 and a log-scale post-selection probability $R^2 = 0.837$, reducing the total simulation burden by approximately 90%.
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Chemical Physics

A Comparative Study of Exponential Sum-Connectivity and Product-Connectivity Gourava Indices for Benzenoid Hydrocarbons

H. M. Nagesh, B. Azghar Pasha, U. Vijaya Chandra Kumar et al. (+1 more)

In this work, the exponential sum-connectivity Gourava index ($e^{SGO(G)}$) and the exponential product-connectivity Gourava index ($e^{PGO(G)}$) are computed and comparatively analyzed for benzenoid hydrocarbons. Our results demonstrate that these descriptors exhibit a strong mutual correlation and provide enhanced sensitivity in modeling the structural characteristics of molecular graphs. Regression analysis reveals that both indices are exceptionally reliable predictors of $\pi$-electronic energies, achieving correlation coefficients exceeding $0.999$. Notably, a comparative assessment indicates that the exponential product-connectivity variant offers a slightly superior fit, as its coefficients align more precisely with optimal least-squares results. These findings confirm that both exponential Gourava-based indices provide a robust framework for characterizing electronic properties, with the product-connectivity version showing particular promise for high-precision QSPR studies in benzenoid systems.
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All authors H. M. Nagesh, B. Azghar Pasha, U. Vijaya Chandra Kumar, Narahari N

Optics

Laser fractional frequency instability at $\mathbf{4\times 10^{-17}}$ with a room temperature optical reference cavity

Adam L. Parke, Eve Clulow, Wei Huang et al. (+8 more)

Ultrastable lasers play a key role in optical frequency metrology, setting measurement speed and ultimately impacting both stability and accuracy of optical frequency standards. Here we demonstrate laser fractional frequency instability at ${4}\times10^{-17}$ and laser frequency linewidth of $12\,$mHz full width at half maximum, employing a 68 cm long optical reference cavity operating at room temperature. To the best of our knowledge, both frequency instability and linewidth are the lowest ever reported for a room temperature system. This work highlights that state-of-the-art frequency stability and spectral purity are achievable at room temperature, making them accessible to a broader range of users.
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All authors Adam L. Parke, Eve Clulow, Wei Huang, Namneet Kaur, Reinhard Karembera, Jacques-Olivier Gaudron, Xi Zhang, Matias Risaro, Jacob Tunesi, Henry Bourne, Marco Schioppo

2606.05987 · 4 Jun · Copyright 2026 Optica Publishing Group. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved

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Biological Physics

Emergent swimming strategies of a smart three-bead swimmer

Ruma Maity, Maximilian Huebl, Julian Lemmel et al. (+2 more)

Low-Reynolds-number microswimmers have recently attracted much interest for their ubiquity in biology and their applications in biotechnology and medicine. However, a key obstacle for the design and deployment of artificial microswimmers lies in their autonomy: to successfully perform tasks in any real-world scenario, these swimmers need to be able to interact with and adapt to their environment without external control. Here, we train a simple two-dimensional model microswimmer (consisting of three-bead) to learn autonomous swimming strategies via Reinforcement Learning, focusing on neuroevolution techniques to derive controller architectures with minimal complexity. We identify five different, characteristic swimming gaits: three of these gaits lead to directed locomotion with varying grades of efficiency and two gaits result in a rotational, inefficient movement. Remarkably, all of these gaits can be achieved by very simple neural networks (with less than ten nodes and weights), showing that low-Reynolds-number swimming can be achieved efficiently and robustly while requiring only minimal computational power. These results are of particular interest to the experimental design of artificial microswimmers and may have implications for modeling biological microorganisms such as Chlamydomonas reinhardtii.
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All authors Ruma Maity, Maximilian Huebl, Julian Lemmel, Benedikt Hartl, Gerhard Kahl