Quantum Physics
Squeezing enhanced homodyne weak force sensing in cavity optomechanics
Madan Mohan Mahana, Sanket Das and Tarak Nath Dey
Cavity optomechanical systems have emerged as a promising platform for
quantum sensing.
Quantum mechanics imposes a standard
quantum limit (SQL) on the force-sensitivity for the standard homodyne phase quadrature measurement of the cavity's output field. In this paper, we investigate ways to enhance weak force sensitivity beyond SQL by employing a variational homodyne quadrature readout and
quantum squeezing. Our study reveals a remarkable improvement in the force sensitivity of a cavity optomechanical sensor at a suitable homodyne angle, compared with standard phase quadrature detection of the cavity output field within a specific frequency band. We further demonstrate improved force sensitivity via intra-cavity squeezing (ICS) or injected external squeezing (IES) of the cavity mode. Both variational homodyne readout and
quantum squeezing induce
quantum correlations between the amplitude and phase quadratures of the cavity's output field, thereby improving force sensitivity. Our results suggest that IES is preferable to ICS for sub-SQL force sensing with system stability and lower probe power requirements. The squeezing-enhanced variational homodyne detection scheme can enable high-precision
quantum sensing across various hybrid
quantum platforms.
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Cosmology and Nongalactic Astrophysics
UV artefacts in ultra-slow-roll models of inflation
Gerald Barnert, Laura Iacconi, Hooshyar Assadullahi et al. (+2 more)
Within single-field inflation,
primordial black hole and scalar-induced gravitational wave production from enhanced
primordial perturbations typically requires a transient non-attractor phase, such as ultra-slow roll. We investigate the physical consistency of modeling such scenarios through analytical Hubble-flow parametrisation. By reconstructing the underlying scalar field potential, we show that even slow transitions in the slow-roll parameters can hide sharp, localised spikes in higher-order derivatives of the potential at the transition from ultra-slow-roll to slow-roll. These are typically not found in analytic potentials. To evaluate the impact of these structures, we implement a UV-filtering procedure based on discrete
Fourier transform to systematically suppress high frequency modes in field space in both classes of models. We find that the filter effectively removes sharp features in Hubble-flow-derived potentials. As a consequence, we show that UV-filtered models typically respect Wands duality invariance as the field evolves back from ultra-slow roll to slow roll. Beyond linear perturbation theory, the introduction of spurious UV effects might affect other observables, such as non-Gaussianity and loop contributions. Our results thereby question the robustness of simple analytical Hubble-flow parametrisation for modeling inflationary models with a transient non-attractor phase.
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All authors Gerald Barnert, Laura Iacconi, Hooshyar Assadullahi, Kazuya Koyama, David Wands
Quantum Physics
David Emmanuel-Costa and Michael Epping
The use of algebraic frameworks based on complex Clifford
algebras for the representation and simulation of
quantum circuits has been discussed in the literature. Recently, an alternative algebraic approach employing hard-core
bosons has been proposed. Hard-core
bosons provide a natural representation of multi-
qubit systems, in which the tensor-product structure is realized directly and no sign corrections are required, in contrast to realizations based on complex Clifford
algebras. Although both approaches are formally equivalent, the hard-core
boson formulation exhibits computational advantages. This work reviews and extends the hard-core
boson algebra for
circuit simulation and presents an efficient implementation. A performance comparison with IBM Qiskit shows substantially improved execution times for simulations. Moreover, a new application is introduced in which the hard-core
boson formalism is combined with genetic
algorithms for
quantum circuit synthesis.
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Soft Condensed Matter
Porosity Effects on Cyclic Gas Invasion and Trapping in Deformable Porous Media
Haiyi Zhong, Jieting Long, Xiangyu Ding et al. (+2 more)
Fluid transport in deformable porous media is central to many biophysical and geophysical processes. While extensive studies exist, how porosity governs fluid behaviour in deformable systems during cyclic injection remains elusive. Here, we investigate gas-
liquid multiphase flow in a quasi-2D Hele-Shaw
cell packed with soft hydrogel particles at different initial porosities. Alternative gas and water injection experiments, combined with high-resolution imaging and continuous pressure monitoring, are used to quantify gas dynamics and pressure
evolution. Results show that the gas entry pressure increases as porosity decreases, consistent with a Young-Laplace estimation based on effective pore-throat width. After entry, invasion shifts from cavity-dominated expansion in high porosity packings to localised pore invasion in low porosity packings, with a mixed cavity-fingering regime at intermediate porosity. Pressure fluctuations are linked to pore-scale gas escape and internal gas redistribution. Low porosity packings produce frequent small-amplitude pressure drops, whereas higher porosity packings produce more discrete pressure relaxations. Across cycles, the decreasing mean pressure suggests preferential-pathway reuse and reduced local capillary constraints. Residual gas saturation increases systematically with injection cycles and reaches higher terminal values as porosity decreases. Specific interfacial length increases as available pore space decreases and follows a power-law relationship with gas cluster size, with scaling exponent decreases as porosity decreases and cycling progresses. Together, these results demonstrate that gas trapping in deformable porous media depends on both initial packing structure and cyclically evolving gas-solid interactions. This study provides insights for interpreting porosity-dependent trapping and reinvasion during repeated gas injection.
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All authors Haiyi Zhong, Jieting Long, Xiangyu Ding, Zhongzheng Wang, Yixiang Gan
Accelerator Physics
Diagnosing Ghost Bunches with the Upstream Extinction Monitor in the Mu2e Experiment
R. Hensley, E. Prebys and A. Gaponenko
The Mu2e experiment has a stringent requirement for extinction of the pulsed
proton beam, referring to the elimination of particles between
proton bunches to a relative level of 10$^-10$, which means a single out-of-time particle in the inter-pulse gaps for every 250 complete
proton pulses. As the construction of the Mu2e experiment nears completion, it is crucially important to make an early measurement of the beam extinction in its current condition. Hence the upstream extinction monitor was constructed and operated to probe for problems in the
proton pulse structure or a higher than expected incidence rate of out-of-time particles. The analysis in this work comes from data taken in March 2026. The long data run showed a significant presence of out-of-time particles from ghost bunches in the Delivery Ring approximately 388 ns after the centers of the main
proton pulses. These are hypothesized to be the result of a combination of a RF frequency mismatch, particle space charge, and machine impedance during the rebunching sequence in the Recycler Ring, which can lead to particles leaking into adjacent buckets, but further studies and simulations are needed to confirm this
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Strongly Correlated Electrons
Ferrimagnetic and Haldane-type phases in a mixed-spin $1$-$\tfrac{1}{2}$-$\tfrac{1}{2}$ quantum trimer chain
A. Felinto and R. R. Montenegro-Filho
Bipartite Lieb-Mattis ferrimagnetism and the
symmetry-protected Haldane phase are paradigmatic mechanisms in quasi-one-dimensional
quantum magnets. Both emerge, in distinct regimes, in a mixed-
spin $1$-$\tfrac{1}{2}$-$\tfrac{1}{2}$ Heisenberg trimer chain with
antiferromagnetic backbone exchange $J$ and a side
spin-$\tfrac{1}{2}$ coupled to each backbone
spin by an exchange $J_t$ of either sign. Using the density
matrix renormalization group, we compute magnetization curves and the
entanglement spectrum and
entropy. For $J_t>0$ a robust ferrimagnetic plateau forms at magnetization per unit
cell $m=1$, whose multiplet
entropy reflects how the conserved magnetization splits between the halves. For $J_t<0$ an $m=0$ plateau opens and grows with $|J_t|$, while the $m=1$ plateau closes. As $J_t\to-\infty$ the chain maps onto a
spin-$1$ Heisenberg chain with coupling $J/2$: the $m=0$ width $\Delta h\simeq 0.196$ matches half the Haldane gap. Exponentially localized
spin-$\tfrac{1}{2}$ edge states and the even-fold degeneracy of the
entanglement spectrum confirm the Haldane character of the $m=0$ phase.
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Quantum Physics
Quantum Multi-Party Threshold Private Set Intersection with Explicit Cardinality Testing
Zixian Gong, Kun Tian, Yi Zhang et al. (+1 more)
Threshold private set intersection (TPSI) allows parties to reveal their intersection only when its cardinality reaches a prescribed threshold. Existing
quantum TPSI protocols typically rely on a third party (TP) to interpret the final results, which deviates from the cardinality-testing paradigm of TPSI. In this paper, we propose a
quantum multiparty TPSI protocol with explicit cardinality testing. Our protocol develops a rotation-based
quantum construction in which single-
photon sequences are sequentially processed through participant-side data rotations, TP–participant masking rotations, and correlated aggregate rotations. This design produces hidden-label measurement vectors: TP can complete the final measurement, but cannot interpret the semantic meaning of the outcomes. Based on these hidden measurements, we further realize the threshold decision through an oblivious linear evaluation (OLE)-based inner product procedure and a lightweight garbled
circuit, revealing only \(\mathbf 1[|\bigcap_i X_i|\ge \tau]\) before conditional intersection reconstruction. We prove the correctness and security of the proposed protocol, and further validate its feasibility through
quantum-
circuit simulations implemented on the IBM Qiskit platform.
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All authors Zixian Gong, Kun Tian, Yi Zhang, Fengxia Liu
General Relativity and Quantum Cosmology
Revisit Static Aether: Exact Vacuum Solution in Einstein-Aether Theory and Its Analytic Extension
Jie Zhu and Hao Li
We obtain an exact analytical
vacuum solution of Einstein-Aether theory with a strictly static aether configuration and investigate its maximal extension. The solution depends only on the coupling $c_{14}$ and reduces to the Schwarzschild geometry in the limit $c_{14}=0$. We show that Schwarzschild is an isolated member of this family: for any nonzero $c_{14}$ the spacetime ceases to be a black hole and instead becomes either a naked singularity ($c_{14}<0$) or a wormhole-like geometry ($0<c_{14}<2$). By constructing the complete analytic extension, we demonstrate that the internal infinity of the wormhole corresponds to an extremal Killing horizon. Crossing this horizon leads to a new spacetime region where the causal roles of time and radial coordinates are exchanged, and the spacetime ultimately terminates at a spacelike singularity. The resulting global structure, summarized by the corresponding Carter-Penrose diagrams, reveals a previously unexplored causal completion of the static-aether
vacuum spacetime.
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Quantum Physics
Verifiable and Collusion-Resistant Multi-Party Quantum Private Set Operations
Zixian Gong, Kun Tian, Yi Zhang et al. (+1 more)
Threshold private set intersection (TPSI) allows parties to reveal their intersection only when its cardinality reaches a prescribed threshold. Existing
quantum TPSI protocols typically rely on a third party (TP) to interpret the final results, which deviates from the cardinality-testing paradigm of TPSI. In this paper, we propose a
quantum multiparty TPSI protocol with explicit cardinality testing. Our protocol develops a rotation-based
quantum construction in which single-
photon sequences are sequentially processed through participant-side data rotations, TP–participant masking rotations, and correlated aggregate rotations. This design produces hidden-label measurement vectors: TP can complete the final measurement, but cannot interpret the semantic meaning of the outcomes. Based on these hidden measurements, we further realize the threshold decision through an oblivious linear evaluation (OLE)-based inner product procedure and a lightweight garbled
circuit, revealing only \(\mathbf 1[|\bigcap_i X_i|\ge \tau]\) before conditional intersection reconstruction. We prove the correctness and security of the proposed protocol, and further validate its feasibility through
quantum-
circuit simulations implemented on the IBM Qiskit platform.
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All authors Zixian Gong, Kun Tian, Yi Zhang, Fengxia Liu
General Relativity and Quantum Cosmology
Probing Two Dark Dimensions through Primordial Black Holes, Gravitational Waves, and Colliders
Waqas Ahmed and George K. Leontaris
We study
primordial-black-hole (PBH) dark matter in the two-dark-dimensions (2DD) framework, a six-dimensional brane-world scenario with two compact extra dimensions and a fundamental
gravity scale of order $10\,\mathrm{TeV}$. We calculate the
evolution of higher-dimensional PBHs including the recently proposed
quantum-gravitational
memory-burden effect. For a
memory exponent $p=2$, the evaporation rate is strongly suppressed, allowing PBHs with initial masses as small as $\sim10^{-3}\,\mathrm{g}$ to survive until the present epoch. Consequently, PBHs can account for the observed dark matter over a mass range extending from $10^{-3}\,\mathrm{g}$ to $10^{21}\,\mathrm{g}$. We further compute the
stochastic gravitational-wave background generated at second order by the
primordial curvature perturbations responsible for PBH formation. We show that the conventional four-dimensional formalism for scalar-induced gravitational waves remains applicable throughout the mass range accessible to current and future gravitational wave experiments. The resulting signals can be probed by LISA, DECIGO, and
pulsar timing arrays. Using Fisher forecasts, we find that these observations can constrain the PBH mass, dark-matter fraction, and width of the
primordial curvature spectrum with high precision. The low fundamental
gravity scale of the 2DD framework also permits the production of microscopic black holes at future high-energy
colliders. Their decay signatures, together with gravitational-wave measurements, provide complementary tests of higher-dimensional
gravity, the
memory-burden mechanism, and
primordial-black-hole dark matter.
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Strongly Correlated Electrons
Competing spin-1 and spin-2 regimes in a frustrated four-leg spin-1/2 ladder
D. S. Almeida and R. R. Montenegro-Filho
We investigate a frustrated four-leg
spin-$1/2$ ladder using density
matrix renormalization group calculations. The uniform system displays three regimes: short-range
antiferromagnetic legs, short-range
ferromagnetic legs, and an effective
spin-2 Heisenberg chain, separated by a crossover and a first-order transition. The
spin-2 regime is confirmed through its finite string order parameter, edge-localized excitations, and excellent agreement with a projected $S_r=2$ effective
Hamiltonian. Recasting the model as two frustrated two-leg ladders coupled by rung and diagonal interactions, we track how the trivial and Haldane phases of an isolated ladder evolve as interladder couplings are introduced. The resulting phase diagrams reveal crossover and first-order lines whose locations are captured by the
spin-2 projection and show how singlet- and triplet-dominated regimes reorganize when two ladders merge into a four-leg structure, clarifying the emergence of effective
spin-1 versus
spin-2 behavior.
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Lattice Field Theory
Diagonal Kenney-Laub Rational Approximation to the Overlap Operator using Wilson and Brillouin Kernel
Stephan Durr, Stylianos Gregoriou and Giannis Koutsou
We propose a formulation of the overlap Dirac operator in
lattice QCD that employs diagonal Kenney-Laub (KL) iterates to approximate the
matrix sign function. KL iterates require no prior spectral information about the kernel operator and, when expressed via their partial fraction decomposition, offer a practical and efficient approximation scheme. We evaluate this approach in a proof-of-concept implementation using quenched
lattices at $\beta=6.2$ and two Dirac operator discretizations as a kernel, namely the Wilson and the Brillouin operators. By examining the approximate overlap operator's violation of the Ginsparg-Wilson relation and the critical bare
quark mass for increasing approximation order, we find that KL iterates deliver enhanced
chiral symmetry preservation and computational efficiency compared to the Chebyshev
polynomial approach.
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Fluid Dynamics
Flow dynamics in a wavy channel filled with anisotropic porous material under the effect of wall slip
Shyamal Kumar Mondal, Sougata Mandal and Sukhendu Ghosh
In this study, a theoretical and graphical analysis is conducted to examine the effects of wall-velocity slip, anisotropic ratio, and porosity parameter on a two-dimensional, viscous, laminar, and incompressible flow through a wavy channel filled with anisotropic porous media. The flow is assumed to be steady and symmetric, with a constant volumetric flow rate imposed along the channel walls. The governing equations are described using the Darcy-Brinman model coupled with the continuity equation, while the tangential velocity at the wavy boundaries is represented through Navier slip conditions. An analytical solution is obtained using a perturbation approach under physically consistent boundary conditions. The effects of key parameters, including anisotropic ratio, Darcy number, and slip parameter, on flow characteristics such as axial velocity, pressure gradient, shear stress, and streamline patterns are examined in detail and presented graphically. The results indicate that wall velocity slip significantly reduces flow reversal, enhances near-wall velocity, and decreases the center-line velocity. For a fixed non-zero slip, a decrease in the Darcy number leads to a pronounced modification in the velocity profile, while increased slip further strengthens near-wall flow and weakens the core flow. Additionally, the streamline analysis reveals that velocity slip plays an important role in controlling flow separation near the crest of the wavy wall. In the case of isotropic porous media with a large amplitude wavy channel, flow separation can also be effectively regulated. Overall, the study demonstrates that velocity slip provides a powerful mechanism for controlling flow behavior by altering the shear distribution within the perturbed flow, with potential applications in technological, geophysical, and biophysical transport systems.
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Statistical Mechanics
Nonextensive Statistical Signatures of the Bilaterian Transition in Proteome Length Distributions
Sertac Eroglu
Protein length distributions across the tree of life carry a quantitative signature of organismal complexity. Nonextensive statistical mechanics, through the Tsallis generalized
entropy formalism, provides a natural framework for describing complex systems characterized by long-range correlations, scale invariance, and hierarchical organization – features that classical Boltzmann-Gibbs statistics cannot accommodate. In this work, the complementary cumulative distribution function (CCDF) of
protein lengths is analyzed within this framework for the reference proteomes of 22 fully sequenced organisms spanning the domains Archaea, Bacteria, and Eukarya, with deliberate sampling across the animal transition zone from sponges and cnidarians to higher bilaterians. Maximum likelihood (MLE) fitting of truncated discrete q-exponential distributions, with bootstrap 95% confidence intervals (CIs) reveals that the entropic index q resolves into three statistically distinct regimes: superextensive (q < 1) for prokaryotes, unicellular and non-animal multicellular eukaryotes, and basal animals; a boundary regime (CI on spanning unity) for the two cnidarians studied and the basal bilaterian C. teleta; and subextensive (q > 1) for all higher bilaterians, with q increasing monotonically across the four deuterostomes sampled from S. purpuratus (1.033) to H. sapiens (1.147). The q-exponential outperforms the ordinary exponential distribution across all 22 proteomes and becomes progressively more competitive against alternative two-parameter distributions as proteome complexity increases. These results identify the Tsallis entropic index as a continuous, physically interpretable indicator of proteome organizational complexity and extend the applicability of nonextensive statistical mechanics to proteomic systems.
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Biological Physics · Cross-listed from q-bio.PE
Reconstructability of evolutionary intermediates in generative epistatic landscapes
Roberto Netti and Martin Weigt
Evolutionary intermediates connect observed
proteins, but the sequence of steps that produced them is rarely recoverable from extant data alone. Here we ask what can, and cannot, be inferred about such intermediates from the endpoints. Using generative sequence landscapes as controlled models of
protein-family
evolution, we
benchmark data-driven reconstruction against ground-truth simulated trajectories. We find that the best point prediction is not necessarily the most faithful evolutionary reconstruction: maximum-likelihood intermediates can be residue-wise accurate yet statistically atypical, whereas conditional sampling better captures the ensemble of plausible histories. Predictability is limited by the
topology of the landscape. Constrained, low-mutability regions preserve information about the path, while permissive high-mutability regions open many alternative routes and erase path-specific
memory. We also show that sequence divergence alone is an insufficient measure of elapsed evolutionary time; incorporating endpoint mutability provides a more reliable way to place intermediates in the landscape. These results recast intermediate reconstruction as a calibrated probabilistic problem. Rather than seeking a single "true" sequence, data-driven models should identify when endpoints contain evolutionary information, and return realistic ensembles.
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Strongly Correlated Electrons
Comment on "Altermagnetic and Dipolar Spitting of Magnons in FeF_2" arXiv:2601.04303
S. W. Lovesey
Conclusions by Sears et al. (arXiv: 2601.04303) about dispersions of
magnons in rutile FeF_2 are unsound because compulsory
lattice vibrations are omitted in the analysis of their
neutron scattering spectra. Hybridized
magnon-
phonon modes in magnetically ordered FeF_2 were observed and successfully analysed half a century ago.
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Statistical Mechanics
A Finite Element Method for Fluctuating Navier–Stokes Equations
Dimitrios Gourzoulidis, Mirko Gallo, Soumaya Elkantassi et al. (+2 more)
We introduce a finite-element framework for simulating thermal fluctuations in compressible fluids governed by the fluctuating Navier-Stokes equations. The method is designed to preserve the fundamental fluctuation-dissipation balance at the discrete level. This is achieved by defining the
stochastic forcing term in the weak formulation, ensuring its covariance is proportional to the discrete viscous dissipation operator. A nodal quadrature rule is employed to eliminate unphysical mesh-scale correlations. The time integration is performed using the Crank-Nicolson scheme to maintain numerical stability and accuracy. The proposed approach is numerically validated in one, two, and three spatial dimensions, demonstrating its capability to correctly capture
equilibrium fluctuation statistics across various discretisation parameters.
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All authors Dimitrios Gourzoulidis, Mirko Gallo, Soumaya Elkantassi, Toby Kay, Serafim Kalliadasis
Astrophysics of Galaxies
Formation of Isotopically Heterogeneous Molecular Cloud Cores in Filamentary Molecular Clouds
Yoshiaki Misugi, Shu-ichiro Inutsuka, Taishi Nakamoto et al. (+1 more)
Meteorite analysis shows that the older solids of the
solar system, such as the calcium-aluminum-rich inclusions (CAIs), have isotopic inhomogeneity. This indicates that the isotopic inhomogeneity could originate from parental molecular clouds. We investigate the
evolution of the isotopically heterogeneous molecular cloud cores formed from filament fragmentation using the smoothed particle hydrodynamics method. We show that the effect of the variation of isotopic ratio along the minor axes of the filament is smaller than that along the longitudinal axis of the filament due to the filament geometry. Our results also suggest that isotopic inhomogeneities remain in the resulting cores, although the amounts of initial inhomogeneities are reduced by a factor of 100 from those over the initial filament length of 1 pc. This fraction corresponds to 1-10% of the maximum isotopic ratio that the core can acquire from the filament in each model. The origin of the isotopic inhomogeneity of the shells could be attributed to the initial difference in the center-of-mass of shells caused by the turbulent velocity field. Our model indicates that the isotopic inhomogeneity could survive even in the circumstellar disk.
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All authors Yoshiaki Misugi, Shu-ichiro Inutsuka, Taishi Nakamoto, Tetsuya Yokoyama
Physics and Society
SimPol: Simulating polarisation in political belief networks in European countries
Isabela Burattini Freire, Hongryol Cha, Irina Epure et al. (+7 more)
Here we combine empirical network analysis with
agent-based modelling to understand how different ways of structuring belief systems may affect the polarisation drive, and how the diversity of belief systems in Europe may result in different polarisation trajectories. Using the 2016 European Social Survey, we infer belief networks across 23 European countries via a
Bayesian algorithm, revealing that belief systems are predominantly organised around immigration, LGBT rights, and economic interventionism, reflecting the influence of populist discourse across the continent. We further verify a Western-Eastern divide across the national belief networks: in Western European countries, left-right self-identification is a more reliable predictor of broader belief
alignment, whereas in Eastern Europe this relationship breaks down. By applying these empirical belief networks into a sociologically grounded
agent-based model, we further show that polarisation is amplified by high individual belief
rigidity and low susceptibility to social influence, and that cross-country differences in polarisation levels mirror the same geographic divide observed in belief network
topology. These findings establish belief networks
topologies as a structural driver of political polarisation, with implications for understanding and anticipating polarisation dynamics across diverse European contexts. We find that populations are not polarised when little
attention is placed on maintaining internal coherence and polarisation levels are moderate when high
attention is placed in both keeping internal coherence and agreement in beliefs with others.
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All authors Isabela Burattini Freire, Hongryol Cha, Irina Epure, Sara Filippini, Karan K.H. Manjunatha, Chethan Kavaraganahalli Prasanna, Ivan Samoylenko, Niels Van Santen, Adarsh Prabhakaran, Guillermo Romero Moreno
Mesoscale and Nanoscale Physics
Hidden valley dynamics behind vanishing circular polarization in moiré excitons
Yuto Urano, Lata Chouhan, Nurul Fariha Ahmad et al. (+4 more)
Optically addressable valley degrees of freedom in transition-metal dichalcogenide
heterostructures provide a powerful platform for valleytronic and
quantum-optical functionalities. In moiré superlattices, interlayer
excitons inherit valley-contrasting optical selection rules while acquiring long lifetimes, electric dipoles, and site-dependent optical responses. However, because conventional measurements typically probe time-integrated valley polarization, the dynamical origin of vanishing polarization has remained elusive. Here, we show that a nearly zero steady-state valley polarization in electrically tunable moiré
excitons does not necessarily indicate fast valley relaxation. Helicity-resolved time-resolved photoluminescence reveals a temporal crossing between co- and cross-circularly polarized emission, indicating that helicity-opposite dynamical components coexist and compensate after time integration. A minimal two-channel model, representing A-like and B-like moiré emission channels with opposite optical selection rules and distinct effective decay/depolarization rates, reproduces the observed helicity crossing without invoking a single rapid valley relaxation process. Furthermore, two-dimensional gate-field maps show that the crossing time evolves systematically with electrostatic tuning, demonstrating that the hidden valley dynamics are electrically controllable. These results show that time-integrated circular polarization can give a false-negative indication of valley polarization in multichannel valley emitters.
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All authors Yuto Urano, Lata Chouhan, Nurul Fariha Ahmad, Kenji Watanabe, Takashi Taniguchi, Daichi Kozawa, Ryo Kitaura
General Relativity and Quantum Cosmology
Horizon-Evanescent Scalar Clouds from Coupled Rotation and Magnetic Fields around Black Holes
Hengyu Xu, Haowei Chen and Shao-Jun Zhang
We show that black-hole rotation and an external
magnetic field can jointly generate a distinct class of scalar clouds. Using the Kerr-Bertotti-Robinson geometry as a separable laboratory for magnetized rotating black holes, we study a charged massive scalar field and map the radial Klein-Gordon equation into a one-dimensional Schrödinger-like form. The
magnetic coupling shifts the near-horizon dispersion relation and realizes a positive horizon gap: a sufficient near-horizon criterion under which the horizon wavenumber becomes purely imaginary in a finite frequency band below the usual kinematic synchronization frequency. In this band the physical horizon boundary condition is no longer a propagating ingoing wave, but a regular exponentially decaying state. This rotation-
magnetic-field mechanism quenches the superradiant flux and supports horizon-decaying scalar clouds (Type-II), distinct from the usual synchronized propagating clouds (Type-I). Matched asymptotic expansions and numerical shooting solutions are used to exhibit both branches and their spatial profiles. Thus the Kerr-Bertotti-Robinson solution is not an isolated curiosity, but an explicit realization of a broader positive-gap criterion for horizon-evanescent stationary configurations that are absent in isolated Kerr systems.
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Physics and Society
From streaks to synergies: A multi-scale analysis of performance and scoring in the NBA
Malvina Bozhidarova, Yanpei Cai, Ricardo M.S. Carvalho et al. (+7 more)
Modern play-by-play data make it possible to test long-standing intuitions about basketball with the same statistical rigour now routinely applied to other professional sports. Using play-by-play data from 7,054 regular-season and 504 playoff NBA games spanning the 2020-2025 seasons, we provide quantitative insights into scoring patterns and the performance of individual players and teams through methods from statistics, network science, and complexity science. Our findings offer an evidence-based perspective on in-season and in-game performance that can inform coaching strategies, player evaluation, and tactical decision-making.
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All authors Malvina Bozhidarova, Yanpei Cai, Ricardo M.S. Carvalho, Daniele Cirulli, Quentin Dehaene, Martin Diaz, Alexandra Krasnokutskaya, Bernardo Pereira, Onkar Sadekar, Federico Battiston
Physics and Society
Linking the "inner" and "outer" self to mental health and brain networks
Cosimo Agostinelli, Ivan Casanovas, Lochan Chaudhari et al. (+8 more)
How are psychosocial profiles, mental health, and
brain functional connectivity related? Studies have been dedicated to unraveling the associations of social support perception and neural functional connectivity. Additionally, personality traits have been explored by examining
brain networks. Research on mental health has been developed using a broad range of methods and different approaches. However, little
attention has been devoted to understanding how personality traits and social variables are related, and to what extent these components are reflected in
brain functional connectivity and mental health outcomes. In this work, we aim to address these complex relations by using data from the Human Connectome Project, both from surveys and resting-state fMRI. The survey data includes personality traits measures and self-reported social support-related variables, which we will refer to as inner- and outer-self, respectively. It also includes data on mental health outcomes. Using z-score standardized measures, we analyze correlation
matrices to evaluate the association between the inner- and outer-self domains. Our results show that the social indicators are more evidently grouped by impact on social experience than by the duality of inner-outer selves. Using a $k$-means clustering
algorithm, we separate individuals into two groups according to social profiles. When confronting these results with the mental health outcomes, we show that the more socially desirable cluster exhibited a higher score on positive aspects such as life satisfaction and purpose in life. In the functional
brain connectivity, we observe that the cluster with a more socially beneficial profile exhibits lower interconnectivity, especially in the default mode network. The pipeline we present uses a combined analysis of both fMRI and psychosocial variables, which could open the path for more extensive analysis.
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All authors Cosimo Agostinelli, Ivan Casanovas, Lochan Chaudhari, Arda Ergin, Pablo Estévez-Gutiérrez, Akanksha Gupta, Juliane T. Moraes, Mario Edoardo Pandolfo, Carlos Gershenson, Haily Merritt, Andreia Sofia Teixeira
High Energy Physics (Theory)
Seok Kim, Seongmin Kim, Siyul Lee et al. (+1 more)
Microstates of BPS AdS black holes have been studied from the classical
cohomologies of the maximal super-Yang-Mills theories, but their
quantum natures have been conjectural. It was recently found that a classical black hole (fortuitous)
cohomology in the $SO(7)$ theory is lifted by 1-loop corrections. We show that such lifts also happen in the $SU(2)$ theory, presenting both lifted/unlifted examples. In particular, the lightest fortuitous
cohomology and its `hairy' versions are unlifted, while many heavier `core' fortuitous ones are lifted. We argue that the
entropy of classical
cohomologies in the Cardy limit is larger than the indicial
entropy of strictly protected states by at least $\approx 1.2 \%$.
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All authors Seok Kim, Seongmin Kim, Siyul Lee, Jiyoo Park
Physics and Society · Cross-listed from cs.CY
AI Persuasive Framing in Collective Dilemmas
Anders Giovanni Møller, Alessia Galdeman, Arianna Pera et al. (+1 more)
AI
agents are promising tools that can act as flexible behavioral nudges to enhance human cooperation in addressing large-scale societal problems. However, evidence on whether AI
agents can effectively boost cooperation remains mixed. We recruited 1,283 participants to play iterated Collective Risk Games in small groups, testing whether AI assistants could nudge participants toward cooperation. By using persuasive framing personalized to each player's Social Value Orientation profile, the AI interventions significantly increased contributions and group success rates. These cooperative effects were short-lived, however, fading after the first few rounds. Strikingly, when the AI treatments were reconfigured to promote selfish behavior through exculpatory framing, the negative effects on contributions and group success were larger and substantially more persistent, particularly for personalized interventions. This asymmetry between prosocial and antisocial persuasion highlights the dual-use risks of AI systems designed to influence group behavior in collective action settings.
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All authors Anders Giovanni Møller, Alessia Galdeman, Arianna Pera, Luca Maria Aiello
Disordered Systems and Neural Networks · Cross-listed from q-bio.NC
Cell-type-specific synaptic motifs generate coupled mean-variability dynamics in recurrent neural networks
Meiyi Zhang, Jinjian Yu, Louis Tao et al. (+1 more)
Synaptic-resolution network connectomics has revealed that
brain circuits feature fine-scale structural connectivity, such as pairs of correlated synaptic couplings known as second-order motifs. Large-scale recordings of neuronal activity in networks containing nonlinear
neurons reveal macroscopic heterogeneous population dynamics throughout the
brain. These findings rekindle the inquiry into this intriguing question: Can microscale synaptic structures contribute to macroscopic heterogeneous dynamics and computations in ways that canonical
brain circuit models cannot? To answer this question, we construct random RNNs with various
cell types, nonlinear non-negative neural responses, and arbitrary marginal and second-order correlated synaptic statistics. We derive low-rank mean-field equations for \(P\)-population networks in which the pre- and postsynaptic neuronal population identities determine the synaptic and motif strengths. Our framework requires \(2P\) latent dynamic variables with \(P\) variables describing mean population activity and \(P\) variables capturing within-population variability. Theoretical and numerical results demonstrate that chain motifs induce correlations in synaptic variability, coupling within-population variability to population mean dynamics through nonlinear gain. We use this framework to construct network models constrained by experimentally observed motif statistics that reproduce key population activity patterns in the mouse primary visual cortex. By explicitly linking synaptic organization to coupled mean-variability dynamics, our results provide a testable framework for studying the relationship between fine-scale connectivity, heterogeneous dynamics, and task-related responses.
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All authors Meiyi Zhang, Jinjian Yu, Louis Tao, Yuxiu Shao
Mesoscale and Nanoscale Physics
Open Nanoacoustic Resonators Based on SrTiO$_3$/YBa$_2$Cu$_3$O$_{7-x}$ Superlattices
S. Sandeep, O. Colmegna, S. Carreira et al. (+4 more)
We report the design and experimental demonstration of an open nanophononic cavity based on a hybrid
oxide superlattice composed of SrTiO$_3$ (STO) and YBa$_2$Cu$_3$O$_{7-x}$ (YBCO), combined with a metallic Ni transducer for coherent
phonon generation. The STO/YBCO periodic stack acts as an acoustic distributed Bragg reflector supporting confined longitudinal acoustic
phonons in the sub-THz regime, while the Ni layer enables efficient ultrafast optical excitation and detection by time-domain Brillouin scattering. Transient reflectivity measurements reveal confined acoustic dynamics and a well-defined cavity resonance, in agreement with transfer-
matrix calculations of acoustic reflectivity and mode profiles. These results demonstrate
phonon confinement in multifunctional
oxide heterostructures and establish complex
oxide superlattices as a platform for hybrid nano-acoustic resonators and ultrafast
phonon control of correlated electronic phases.
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All authors S. Sandeep, O. Colmegna, S. Carreira, L. M. Vicente-Arche, L. B. Steren, J. Briatico, N. D. Lanzillotti-Kimura
Biological Physics · Cross-listed from q-bio.BM
Towards coevolution-aware ancestral sequence reconstruction
Alya Zeinaty, Leonardo di Bari, Saverio Rossi et al. (+3 more)
Ancestral sequence reconstruction (ASR) is a powerful approach for studying molecular
evolution and the emergence of
protein function. Yet most ASR methods assume that sites evolve independently, neglecting the epistatic constraints that shape
protein structure, stability, and function. This simplification affects both ancestral inference and its evaluation: maximum-a-posteriori reconstructions may over-concentrate probability into a single over-idealized sequence, whereas independent posterior sampling can generate implausible or poorly functional ancestors. Here, we introduce a coevolution-aware ASR framework that combines standard phylogenetic inference with Direct Coupling Analysis (DCA), thereby preserving site-wise ancestral uncertainty while enforcing residue-residue constraints learned from extant
protein families. To
benchmark the method, we develop a controlled forward-
evolution framework based on a DCA evolutionary sampler, allowing reconstructed ancestors to be compared with known ground-truth sequences generated under realistic epistatic constraints. Applied to beta-lactamases and DNA-binding domains, the approach improves reconstruction when ancestral states are epistatically constrained, and yields ensembles of candidate ancestors that are both phylogenetically consistent and statistically compatible with natural
protein families. This framework bridges the gap between single-sequence MAP reconstruction and unconstrained posterior sampling, providing a practical route toward ancestral reconstructions that better reflect the coupled nature of
protein evolution.
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All authors Alya Zeinaty, Leonardo di Bari, Saverio Rossi, Pierre Barrat-Charlaix, Francesco Zamponi, Martin Weigt
Physics and Society
Students using GenAI lag behind in problem-solving competence: an agent-based study of classroom networks
Lorenzo Betti, Iacopo Caporossi, Carsten Källner et al. (+8 more)
The development of problem-solving competence (PSC) among high school students is foundational for preparing resilient and adaptive citizens. Generative artificial intelligence (GenAI) can support this process, but it may also encourage students to offload part of the cognitive work that is necessary for deep learning. While the individual effects of GenAI use are increasingly studied, its collective consequences for competence development within classroom environments remain underexplored. In this study, we use an
agent-based model to simulate the
evolution of PSC in a high school physics classroom, where students complete tasks individually, in collaboration with peers, or with the support of GenAI. By comparing classrooms with and without access to GenAI across different peer-network structures, we show that GenAI use can diminish competence development and increase the share of students remaining in lower competence tiers. These results suggest that the educational impact of GenAI should be assessed not only through individual learning outcomes but also through its effects on collective competence dynamics.
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All authors Lorenzo Betti, Iacopo Caporossi, Carsten Källner, Karolina Levanaitė, Chenyu Li, Xuan-Chen Liu, Giulia Lorenzini, Vittoria Socci, Michele Re Fiorentin, Ilaria Stanzani, Marta Baratto
Physics and Society
Preferentiality and bandwidth drive tie activity in online and offline ego networks
Gamal Adel, Shrichand Bhuria, Alessandro Catalano et al. (+7 more)
Ego networks capture the variety of structural patterns in the social interactions of individuals. Recently it has been shown that ego networks in online settings display universal patterns of tie strength distributions, but it is unclear how constraints such as spatial proximity and bounded social bandwidth affect such generic behaviour in offline settings. Here, we analyse the time
evolution of interaction activity in ego networks constructed from offline face-to-face and colocation data, compare them to online communication networks, and explore simple cumulative advantage models that capture the varying preferentiality of individuals for specific social ties. We find that patterns of preferentiality at the population level are similar for online and face-to-face networks, but not for colocation data, suggesting that the latter is a poor proxy of social network structure. We also provide evidence that empirical ego networks exhibit a bandwidth in the way communication events are allocated across connections. A model implementing this notion uncovers evidence of universal scaling between the tie preferentiality and bandwidth of individuals, common to all online and offline systems explored. Our findings strengthen our understanding of the fundamental mechanisms governing human communication and help disentangle the internal and external factors shaping tie
evolution across social contexts.
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All authors Gamal Adel, Shrichand Bhuria, Alessandro Catalano, Liber Dorizzi, Leonardo Federici, Theodora Moldovan, Berné Nortier, Chara Deanna Punzal, Giulia de Meijere, Gerardo Iñiguez