High Energy Physics (Phenomenology)
Testable neutrino mass and TeV-scale leptogenesis in a $D_4$ inverse seesaw model
Qiu Yan, Yakefu Reyimuaji and Xianshuo Zhang
An inverse seesaw model for
neutrino masses and mixing is proposed, based on the spontaneous breaking of a $D_4$
flavor symmetry. The model simultaneously accounts for the
neutrino oscillation parameters, the
baryon asymmetry of the Universe through TeV-scale leptogenesis, and makes predictions for charged-
lepton flavor violation (cLFV) that are consistent with present experimental limits. A phenomenological analysis shows that the model is consistent with the observed
neutrino oscillation data for both normal and inverted mass orderings. Successful leptogenesis is realized for the lightest pseudo-Dirac pair in the multi-TeV range. The predicted cLFV branching ratios lie well below experimental upper bounds, ensuring compatibility with existing constraints. These results establish the model as a viable framework that links low-energy
neutrino observables to TeV-scale leptogenesis and cLFV phenomenology.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Effects of super-Gaussian pulse shape and relative phase on dynamically assisted pair production in spatially inhomogeneous electric fields with frequency chirping
Abhinav Jangir and Anees Ahmed
We investigate the effects of super-Gaussian pulse shapes on dynamically assisted pair production in spatially inhomogeneous electric fields with frequency chirping within the framework of the (1+1)-dimensional Dirac-Heisenberg-Wigner formalism. The analysis is carried out for both single-color fields and dynamically assisted two-color combined fields by varying the chirp parameter, super-Gaussian pulse shape, and the spatial scale of the external field. Our results are presented in terms of the reduced momentum distribution and the total particle yield, revealing that the interplay between pulse shaping, spatial inhomogeneity, frequency chirping, and dynamical assistance can significantly modify the pair-production dynamics. In particular, chirping substantially enhances the absolute pair-production yield and reshapes the momentum spectrum, with chirping of the weak component being particularly effective, while simultaneous chirping of both components produces the largest yields. The super-Gaussian order has a relatively modest influence on strong-field production, while increasing the flat-top character of the pulse enhances spectral structures and momentum redistribution in the weak and dynamically assisted regimes, particularly under chirping. Finally, we show that the relative phase between the two field components provides an additional control parameter, with its influence becoming more pronounced for larger spatial scales leading to significant changes in the momentum-space structure. Overall, our results provide a useful reference for optimal control of dynamically assisted pair production in space- and time-dependent electric fields within a prescribed range of field parameters.
Read the full abstract ▾
Materials Science
Electrolyte Dependent Structure Transport Relationships in Electrodeposited Prussian Blue Analogue Thin Films
Larissa de O. Garcia, Michael Pohlitz, Mohammed F. Kalady et al. (+1 more)
Understanding how electrolyte composition influences charge storage in Prussian blue analogues (PBAs) requires clarifying the coupled effects of structural disorder and ion transport. Here, we investigate Fe-, Co-, and Ni-based hexacyanoferrate thin films electrodeposited from KCl, NaCl, NH4Cl, and LiCl electrolytes under identical electrochemical conditions. Although all films retain the cubic PBA structure, electrolyte identity produces pronounced differences in
lattice parameters, defect concentration, and local coordination environments. Na+ promotes
lattice expansion accompanied by increased vacancy formation, microstrain, and structural heterogeneity, whereas K+ and NH4+ yield more structurally coherent frameworks. Raman spectroscopy shows that increasing structural disorder broadens the distribution of local coordination environments and correlates with increasingly dispersed electrochemical behavior. Electrochemical impedance spectroscopy further reveals coupled ion-electron transport, with impedance increasing by more than one order of magnitude from FeHCF to NiHCF. Notably, the CPE exponent decreases systematically with Raman band broadening, establishing a direct correlation between structural disorder and transport dispersion. These results demonstrate that electrolyte identity controls not only
lattice dimensions but also the organization and connectivity of defect networks, highlighting structural coherence and accessible transport pathways as key factors governing electrochemical performance in PBA thin films.
Read the full abstract ▾
All authors Larissa de O. Garcia, Michael Pohlitz, Mohammed F. Kalady, Christian K. Muller
Superconductivity
Electromagnetic Proximity Effects and Spontaneous Currents in Clean Superconducting Heterostructures
Jian-Lin Li, Chien-Te Wu and Klaus Halterman
When ferromagnets are brought into contact with a
superconductor, superconducting proximity effects give rise to a variety of interesting phenomena, including oscillatory singlet Cooper-pair amplitudes and long-ranged odd-frequency triplet correlations induced by the exchange interactions in the ferromagnets. From an electrodynamic perspective, however, it is equally important to understand when and how spontaneous currents can emerge. To investigate the interplay between electromagnetic and conventional superconducting proximity effects, we study clean ferromagnet/ferromagnet/
superconductor spin-valve
heterostructures in which the relative angle between the two
ferromagnetic layers can be tuned. Our approach is based on a self-consistent numerical solution of the coupled Bogoliubov-de Gennes and Maxwell equations, providing a microscopic description capable of resolving physics on atomic length scales. Several notable features emerge. In both the weak- and strong-exchange-field regimes, the central
ferromagnetic layer plays a dominant role in generating sizable spontaneous currents when its exchange-field strength is varied. We further find that the resulting electromagnetic response extends across the entire superconducting layer, in sharp contrast to the short-ranged inverse proximity effect. In noncollinear configurations, the electromagnetic proximity effect also reconfigures the local
magnetic-field orientation and reduces the angular mismatch between the fields in the two
ferromagnetic layers. The long-ranged odd-frequency triplet amplitudes are consequently modified by the orbital response, which alters the underlying quasiparticle states by changing their momentum-space structure. Finally, our framework can be naturally generalized to other superconducting spintronic systems, possibly including Josephson junctions and altermagnet/
superconductor heterostructures.
Read the full abstract ▾
Materials Science
C 1s core-level fingerprints of reconstructed titanium vacancies in titanium carbide
Jakub Koch and Pavel Ondračka
Recent first-principles searches predict that a titanium vacancy in rocksalt TiC is not an empty octahedral site but can reconstruct through the formation of carbon Frenkel pairs and short C-C bonds. We determine the C 1s signatures of these local structures and assess whether they remain specific in the presence of disordered carbon. Site-resolved binding energies were calculated with a self-consistent core-hole method for an unreconstructed vacancy and four representative C-C-bonded reconstructions. The unreconstructed vacancy shifts its nearest-neighbour C 1s level by only -0.36 eV. In contrast, the largest positive shift in each reconstructed model ranges from 2.34 eV to 2.80 eV. The large shifts occur at carbon atoms participating in the reconstructed C-C network and correlate with markedly less negative Mulliken charges, providing candidate local fingerprints of vacancy reconstruction. However, an exploratory TiC/amorphous-C model shows that disordered carbon environments can extend into the same high-binding-energy range. Overall, the calculated shifts provide reference energies for experimental searches for reconstructed Ti vacancies in TiC.
Read the full abstract ▾
Statistical Mechanics
Statistical mechanics of classical fractons on a line
Ylias Sadki, Abhishodh Prakash and S. L. Sondhi
We study the
equilibrium statistical mechanics of one-dimensional classical Machian fractons: particles whose dynamics conserves a global dipole moment and whose
Hamiltonian couples momentum differences through a position-dependent pair-inertia kernel. Compactly supported interaction kernels have a divergence in the Gibbs partition function, and have been shown to break ergodicity and
symmetry by forming non-
equilibrium steady states with particle clusters, evading the Hohenberg-Mermin-Wagner-Coleman
theorem. In this paper, we consider kernels with non-compact support and study their ergodic properties. For exponentially decaying kernels, graph-
Laplacian and
matrix-tree bounds provide an extensive free energy suggesting that a putative statistical mechanical description is valid. Similarly, uniform non-local kernels have a super-extensive free energy and require a Kac rescaling. A generalized Hohenberg–Mermin–Wagner–Coleman argument, supported by finite-size scaling, implies
symmetry-breaking density order parameter vanishes at all wave vectors melting the long-range translation-breaking density order of compact kernels. To study the resulting
equilibrium ensemble, we construct a nonreversible event-chain Monte Carlo (ECMC)
algorithm that samples the coupled position-momentum phase space while preserving the dipole moment and total momentum. The ECMC sampling is shown to quantitatively match long time-averaged quantites in
Hamiltonian dynamics. The
equilibrium liquid exhibits preferred short-range clustering and strongly non-Gaussian single-particle momentum tails associated with the correlated nature of positions and momenta. This paper provides a detailed investigation into the
equilibrium liquid properties of the non-compact regime, whilst the companion paper investigates the mechanisms that relax the
liquid.
Read the full abstract ▾
Materials Science
Interplay of Composition, Crystallinity, and Chemical Structure in CoHCF and NiHCF Thin Films Prepared at Different Temperatures
Larissa de O. Garcia, Michael Pohlitz, Mohammed F. Kalady et al. (+1 more)
Understanding how growth conditions govern structural order and ion transport in Prussian blue analogues (PBAs) thin films is essential for optimizing their electrochemical performance. Here, cobalt and nickel hexacyanoferrate (CoHCF and NiHCF) thin films were electrodeposited potentiostatically at temperatures between 20 and 60 degrees C. A combination of cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and Raman spectroscopy was employed to elucidate the interplay between composition, crystallinity, and chemical structure. Under identical conditions, CoHCF exhibits a maximum current density approximately 2.2 times higher than NiHCF, indicating significantly faster electrochemical kinetics. X-ray diffraction reveals temperature-dependent
lattice expansion without phase transitions, with a maximum near 40 degrees C, associated with structural relaxation and compositional variations. Raman spectroscopy further reveals temperature-dependent local structural
evolution, where cyanide band narrowing at intermediate temperatures indicates improved short-range order, while band broadening at higher temperatures reflects increased defect density. These findings demonstrate that temperature-controlled defect redistribution governs both short- and long-range structural order in PBA thin films, directly influencing ion transport and electrochemical response. This work provides new insights into structure-property relationships in PBAs and establishes deposition temperature as a key parameter for tuning electrochemical functionality in hexacyanoferrate-based electrodes.
Read the full abstract ▾
All authors Larissa de O. Garcia, Michael Pohlitz, Mohammed F. Kalady, Christian K. Muller
Nuclear Theory
Systematic study of macroscopic interaction models and short-range effects in $^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion
Azni Abdul Aziz and Norhasliza Yusof
The $^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion reaction is central to
stellar carbon burning, yet its cross section at astrophysical energies remains uncertain and theoretical extrapolations depend sensitively on the adopted
nucleus-
nucleus interaction. We systematically assess 24 macroscopic interactions within a common one-dimensional fusion framework and find that their relative agreement with experimental data depends strongly on both the statistical measure and energy interval considered, with no single interaction providing a uniformly superior description across all criteria. A common phenomenological short-range repulsive modification is then applied to all interactions without refitting their underlying parametrizations. Although the external fusion barrier remains essentially unchanged, the modification substantially reorganizes the inner-potential structure and produces strongly model-dependent changes in agreement with experiment. Detailed analysis of five representative interactions shows that the resulting low-energy suppression propagates into the thermonuclear reaction rates, but does not produce the conventional logarithmic-slope signature of fusion hindrance over the calculated energy range. These results demonstrate that additional short-range repulsion does not provide a universal improvement of macroscopic fusion potentials and that the reliability of extrapolations toward
stellar carbon-burning energies remains sensitive to both the choice of interaction and its short-range behavior.
Read the full abstract ▾
Medical Physics
Towards real-time ion range verification via hybrid Compton-PET 3D imaging at isochronous cyclotrons
Javier Balibrea-Correa, V. Babiano-Suarez, J. Lerendegui-Marco et al. (+8 more)
Range uncertainties remain a major limitation to the full clinical exploitation of
proton therapy, motivating reliable in-vivo range-verification techniques. This work presents an experimental investigation of a hybrid
Prompt-Gamma Imaging (PGI)–Positron-Emission
Tomography (PET) concept at the isochronous cyclotron of the West German
Proton Therapy Centre under clinically representative pencil-beam-scanning conditions. Because this accelerator delivers a quasi-continuous beam, a pulsed shoot-and-step structure was imposed to mimic the interruptions associated with clinical energy-layer switching. This enabled PGI during irradiation and PET and delayed Compton imaging during beam-off intervals within the same sequence. Four two-plane Compton cameras were arranged in a co-planar cross-shaped geometry around the beam isocenter. Polyethylene phantoms were irradiated with 100~MeV
protons at known positions along the beam axis. Their positions were estimated from reconstructed one-dimensional profiles using supervised machine-learning models trained exclusively on Monte Carlo simulations. PET achieved the best performance, with a root-mean-square deviation of 0.8~mm, followed by PGI with 1.6~mm. Delayed Compton imaging based on e$^{+}$ annihilation
photons and $^{10}$C$^{*}$ decays yielded 2.4~mm and 3.8~mm, respectively. PET retained good performance down to 1% of the original event statistics, whereas PGI became increasingly statistics-limited. These results demonstrate the complementary strengths of hybrid PGI–PET and support its development towards millimetre-scale
proton-range verification under clinically relevant irradiation conditions.
Read the full abstract ▾
All authors Javier Balibrea-Correa, V. Babiano-Suarez, J. Lerendegui-Marco, P. Torres-Sánchez, I. Ladarescu, M. Pallàs, B. Brusasco, J. Wulff, C. Bäumer, A. Tarifeño-Saldivia, C. Domingo-Pardo
Quantum Physics
Maximum-Likelihood Amplitude Estimation for Quantum Monte Carlo Integration on Trapped-Ion Hardware: Convergence, Noise-Floor Saturation, Depth-Dependent Bias
Aditi Lal, Alex Khan, Rut Lineswala et al. (+1 more)
Quantum Amplitude Estimation promises to accelerate Monte Carlo integration by replacing the classical $\varepsilon \propto N^{-1/2}$ sampling law with the Heisenberg-limited $\varepsilon \propto N^{-1}$ scaling, but whether any part of that advantage survives on present-day hardware is an empirical question. We report a systematic experimental
benchmark of a Maximum-Likelihood Amplitude Estimation QMC pipeline on IonQ trapped-ion processors, comprising 60 hardware trials on IonQ Forte-1 across five settings(5 & 9
qubits, 100-200 shots per depth, linear & exponential amplification schedules, ~113 device-hours), together with 100 trials on IonQ Aria-1 & Forte-1 noise models at 5, 9 & 19
qubits. The pipeline combines controlled-$R_y$ rotational state preparation, Grover-based amplitude amplification and maximum-likelihood inference and is benchmarked against $b_{\max}^{-1}\!\int_0^{b_{\max}}\!\sin^2\!x\,\mathrm{d}x$ with $b_{\max}=\pi/5$ ,given results emerge. First, the noiseless limit it attains $\varepsilon \propto N^{-0.88}$, close to the Heisenberg-scaling reference, reducing the error 54-74x over a 133x increase in oracle calls. Second, scaling does not survive on hardware. Every noisy backend saturates at an error floor of (2-5)x 10^{-2}, with fitted exponents of 0.04-0.15 on Forte-1 linear schedules and $\alpha \le\!0$ on the vendor noise models: beyond the optimal shallow depth, however, deeper amplification provides no sustained accuracy gain and instead returns to the noise floor. Forte-1 hardware also outperformed IonQ's own Aria-1 noise model at every depth $m \ge 2$, indicating that vendor noise models are bad predictors of MLAE accuracy. The practical implication for UQ is that on current devices the useful operating point is a shallow, schedule-tuned amplification depth chosen so that the deepest
circuit lands near p~1/2 not the deepest schedule the coherence budget allows.
Read the full abstract ▾
All authors Aditi Lal, Alex Khan, Rut Lineswala, Abhishek Chopra
High Energy Astrophysical Phenomena
Einstein Probe discovery of the magnetar EP J223759.5+531421
N. Rea, F. Coti Zelati, A. Borghese et al. (+44 more)
We report the discovery and early outburst
evolution of the new
Galactic magnetar EP J223759.5+531421, detected by the Einstein Probe Wide-field X-ray
Telescope on 2026 June 28. Follow-up observations with Einstein Probe, XMM–Newton, NuSTAR, SVOM, and IXPE revealed coherent X-ray pulsations at P ~ 6s and an average period derivative of Pdot ~ 2.8x10^{-12} s/s. These values imply a nominal polar dipolar
magnetic field of B_dip ~ 2.6x10^{14} Gauss and a characteristic age of tau_c ~ 34 kyr, although the structured timing residuals suggest possible torque variability. The rms pulsed fraction is approximately 20-25% below ~7 keV and decreases at higher energies. The broadband spectra require multiple thermal components and a hard power-law tail. Adopting a distance of 3.3 kpc, the 0.5-30 keV luminosity declined from 1.2x10^{35} to 5.7x10^{34} erg/s during the first month, accompanied by a decrease in the inferred thermal-emitting areas. At this distance, the
Galactic latitude b=-4.56 deg corresponds to a height of approximately 0.26 kpc below the
Galactic plane, which is difficult to reconcile with the nominal characteristic age under a simple midplane-birth scenario even for an extreme proper motion velocity. Short X-ray bursts independently confirm the magnetar nature of the source. No near-infrared or
radio counterpart were detected by GTC, Medicina or FAST, respectively, down to K_s>21 mag and S_{1.25 GHz} <2.3 microJy. These observations demonstrate the potential of the Einstein Probe WXT monitoring to uncover previously quiescent
Galactic magnetars and follow their outbursts from their earliest observed stages.
Read the full abstract ▾
All authors N. Rea, F. Coti Zelati, A. Borghese, Y.L. Wang, H. Yang, X. Mao, C.-Y. Dai, E. Arrigoni, J. Bai, G. Bernardi, M. Burgay, S. Cao, A. Coleiro, D. De Grandis, P. Esposito, H. Feng, Y.-C. Fu, A. Geminardi, D. Götz, S. Guillot, Y. Huang, M. Imbrogno, G. L. Israel, C. Jin, A. Kong, Y. Li, L. Lin, C.-S. Liu, C. Maitra, A. Marino, S. Mereghetti, J.-U. Ness, S. Ng, M. Pilia, A. Possenti, H. Sun, L. Tao, R. Taverna, A. Tiengo, R. Turolla, W. Yuan, S. Zane, B. Zhang, L.-X. Zhang, Z. Zhang, W.-W. Zhu, Y.-C. Zou
Fluid Dynamics
Intrinsic dynamical shadowing of point vortices and finite time singularities
Xavier Leoncini, Perla El Kettani and Edgardo Ugalde
The trajectories of point
vortices after a division using reverse collapse route are studied. In this setting, an unexpected peculiar phenomenon appears, corresponding to the shadowing of the
vortex breakup. This occurs at least for a finite time, when the system evolves from three to five
vortices after a breakup. An analytical study reveals that this observed numerical phenomenon is related to the condition of scale invariance, a condition necessary for the finite time singularity. Further simulations agree with our analytical findings and indicate that shadowing can occur with more than five
vortices, and as well with higher order singularities. This phenomenon leads to question what a
vortex is actually measuring, triggering speculations if this shadowing property could be generalized to other
Hamiltonian systems with finite-time singularities.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Options for Compression of radio interferometry data: lossy compression of visibilities and lossless compression of uv-visibility grids for the MHONGOOSE survey
Richard Dodson, Jonghwan Rhee, W.J.G. de Blok et al. (+6 more)
Next generation
radio astronomy
telescopes are challenging existing data reduction paradigms. With ever more
antennas, larger bandwidths, and sometimes multiple primary beams, they often generate more observed data products than can readily be stored long-term. Thus, data storage becomes a major cost driver and processing constraint. In this paper, we test two methods of addressing this problem: grid-stacking, a two-stage lossless compression solution; and the lossy compression of the raw visibilities before traditional processing. To demonstrate these solutions we utilised a deep imaging pipeline based on software for the ASKAP
telescope, ASKAPSoft, but applied to a strong source (NGC1566) from the deep MeerKAT HI spectral line project, MHONGOOSE. The grid-stacking solution reproduces the spectrum from traditional processing to within better than 0.7%, and also allows for the reconstruction of other weighting scales without significant computing costs. In comparison, image-stacking also reproduces the spectrum from the traditional processing, to within better than 3% but with worse image residuals in the cube. The lossy compression, even at a near ten-fold reduction in file size, reproduces the spectra almost perfectly (to better than ~0.01% in all cases). Thus both compression methods are promising solutions, and we discuss considerations for their application.
Read the full abstract ▾
All authors Richard Dodson, Jonghwan Rhee, W.J.G. de Blok, Martin Meyer, Alexander Williamson, Daniel Mitchell, Kristóf Rozgonyi, María J. Rioja, Pascal J. Elahi
Nuclear Experiment
Photoneutron reactions on $^{165}$Ho and $^{169}$Tm in the giant dipole resonance region
I. Gheorghe, S. Goriely, K. Stopani et al. (+19 more)
Photoneutron reactions were investigated for the deformed $^{165}$Ho and $^{169}$Tm
nuclei from the vicinity of the
neutron emission threshold up to $\sim$40~MeV, well above the
giant dipole resonance (GDR) region, using quasimonochromatic
laser Compton scattering $\gamma$-ray beams provided at the NewSUBARU facility, Japan. A high-and-flat efficiency moderated array of $^3$He counters was used for the
neutron detection and an associated
neutron multiplicity sorting method for extracting the $(\gamma,\,1nX)$, $(\gamma,\,2nX)$, $(\gamma,\,3nX)$ and $(\gamma,\,4nX)$ reaction cross sections and average
neutron emission energies. The present $^{165}$Ho cross sections were compared to existing data, revealing discrepancies with the Saclay multiplicity sorting results and an overall 10$\%$ strength difference with the Livermore ones. There are no other data for $^{169}$Tm. GDR parameters based on phenomenological Lorentzian models were extracted by fitting the present $\sigma(\gamma,\,Sn)$ data with adjustments for the missing contribution of charged-particle-only reactions not observed experimentally. For both
nuclei we observed high energy structures at 20-25~MeV, matching
giant quadrupole resonance KMFR predictions. Based on the present centroid energies of the first and second GDR peaks, hydrodynamic model predictions gave intrinsic electric quadrupole moments of +7.00(34)~b and +7.38(28)~b for the ground states of $^{165}$Ho and $^{169}$Tm, respectively. The present experimental excitation functions and photoneutron energies were compared to statistical model calculations. Using the EMPIRE code, we performed a sensitivity test to phenomenological models of
photon strength functions and
nuclear level densities. The TALYS code was used to reproduce the present experimental $(\gamma,\,inX)$ cross sections and average
neutron energies using microscopic
nuclear level density models.
Read the full abstract ▾
All authors I. Gheorghe, S. Goriely, K. Stopani, S. Belyshev, M. Krzysiek, D. Filipescu, H. Wang, G. Fan, L. Liu, H. Scheit, D. Symochko, T. Aumann, T. Renstrøm, G.M. Tveten, F. Furmyr, A. Görgen, A.C. Larsen, S. Siem, V. Orlin, T. Ari-izumi, S. Miyamoto, H. Utsunomiya
Nuclear Experiment
Observation of a magnetic shift in neutron whispering-gallery states
K. Schreiner, J. A. Pioquinto, S. Baeßler et al. (+19 more)
We developed experimental and theoretical methods to create and describe high-resolution whispering-gallery interference patterns and show the feasibility of measuring their small shifts by external interactions. Such experiments can be used to search for extra fundamental interactions, time parity violations, nonzero electric charges, precisely measuring the gravitational properties of (anti)matter, parity violations,
neutron polarizability,
quantum reflection, surface state effects, etc. Here, we measure a
magnetic shift of such a
neutron pattern $\delta g/g\sim (6.5 \pm 0.8_{st} \pm 1.2_{sys}) \cdot 10^{-4}$, and our sensitivity to
spin-dependent differences between the scattering lengths was $\delta b_n/b_n \sim 10^{-4}$.
Read the full abstract ▾
All authors K. Schreiner, J. A. Pioquinto, S. Baeßler, V. V. Nesvizhevsky, P. Clade, P. Crivelli, R. Cubitt, J. Guyomard, C. Killian, U. Miniotaite, F. Nez, E. Perry, S. Reynaud, T. Saerbeck, L. Shen, K. Stinson, J. Vivier, A. Vorobiev, J. Walsh, E. Widmann, P. Yzombard, A. Zhao
Quantum Physics
Dynamical, thermal, and ground-state multiparameter quantum metrology: Fundamental limits and their attainability in magnetometry
Riccardo Pedroni, Víctor Izquierdo, Advay Burte et al. (+3 more)
We consider the simultaneous estimation of multiple parameters in
Hamiltonians of the form $H_{\vec{\theta}}= H_{\vec{\theta}}^P + H^C$, where $H_{\vec{\theta}}^P$ encodes the unknown parameters and $H^C$ is a control term. We consider three basic paradigmatic frameworks for metrology: (i) dynamical, where the parameters are encoded unitarily, (ii) thermal, and (iii) ground state. We generalize previous bounds for single-parameter estimation to simultaneous multiparameter estimation for all three metrological settings and establish the conditions required for their saturability. We then focus on vector magnetometry, deriving tight bounds for the simultaneous estimation of
magnetic-field components and identifying optimal many-body control
Hamiltonians $H^C$ that saturate them. These results establish the fundamental limits of vector magnetometry for
unitary dynamics, thermal
equilibrium states, and ground states.
Read the full abstract ▾
All authors Riccardo Pedroni, Víctor Izquierdo, Advay Burte, Paolo Abiuso, John Calsamiglia, Martí Perarnau-Llobet
Physics and Society
Emotions as intrinsic colored noise in biological systems
V.I. Yukalov and E.P. Yukalova
The idea that
emotions in biological systems are analogous to intrinsic colored noise is advanced and justified. A model describing the dynamics of operation of biological networks under the influence of colored noise is suggested. The
agents of a biological network can be represented either by biological species, such as humans and animals, or by
neurons of the
brain, or by the nodes of a neural network. Operational actions, or decisions, in a biological noisy network are based not only on the evaluation of utility of alternatives, but also on the
agents emotions. The model is probabilistic, with the choice of alternatives characterized by the related probabilities. At the initial step, the
agents make decisions individually and then start exchanging information with each other and imitating the actions of other
agents, thus forming a biological network of interacting
agents. Numerical simulations are accomplished for a heterogeneous society consisting of three groups of
agents, one group possessing long-range
memory, the other group, short-range
memory, and the third group of super-rational
agents acting strictly on the basis of utility, being deprived of
emotions. Dynamics of opinions in different groups can be smooth, oscillatory, or chaotic. Altogether, eight types of operation are found, depending on the dynamics of group decisions. Under strong imitation effect, there appears chaotic motion in the
evolution of decision choice. It is shown how the Ellsberg paradox can be resolved and how the exchange of information influences the dynamics of this paradox.
Read the full abstract ▾
Statistical Mechanics
Intersection Exponents of Simple Random Walks in Two and Three Dimensions
Qiyuan Shi, Runsheng Liu, Xinyi Li et al. (+2 more)
The probability that several independent random walks avoid one another decays algebraically with the number of steps $N\to\infty$ in two and three dimensions, $P_N\sim N^{-\xi/2}$, where the intersection exponent $\xi$ depends on the number of random walks. More generally, one may consider several groups of independent random walks, with intersections allowed within each group and forbidden between different groups. We first study intersection exponents in two dimensions, where our results agree with the known exact formulas and test the numerical approach. In three dimensions, where no general exact expression is known, we determine $\xi$ for a range of cases. For two groups containing $k$ and $m$ random walks, respectively, we obtain the exponents $\xi(k,m)$ for $k=1,2$ and $m=1,2,\ldots,7$. We further extend $m$ to a continuous parameter $\lambda$, allowing us to obtain numerical values for $\xi(k,\lambda)$ for $k=1,2,3$ and $0.25\leq\lambda\leq3$. Away from the smallest moment orders, these functions increase with $\lambda$ with decreasing slopes, as expected from the strict concavity of Brownian intersection exponents. We also investigate three-group configurations for several representative cases. The resulting integer and continuous exponents supply numerical values for analytical studies of non-intersecting random paths.
Read the full abstract ▾
All authors Qiyuan Shi, Runsheng Liu, Xinyi Li, Ming Li, Youjin Deng
High Energy Astrophysical Phenomena
IXPE observation of the new magnetar source EP J223759.5+531421
Roberto Taverna, Lorenzo Marra, Roberto Turolla et al. (+9 more)
We report on the detection of polarized X-ray emission from the new
Galactic magnetar EP J223759.5+531421, discovered by the Einstein Probe Wide-field X-ray
Telescope on 2026 June 28. The Imaging X-ray Polarimetry Explorer (IXPE) follow-up observation started on 2026 July 6 and detected the source at a (absorbed) flux of $\approx 4.5\times 10^{-11} \, \mathrm{ erg\,cm^2\,s}^{-1}$ ($2$–$7.5\, \mathrm{keV}$ range), confirming the presence of two thermally emitting regions on the
star surface, with temperatures $\approx 0.5$ and $\approx 1\, \mathrm{keV}$. A significant (at $> 4\sigma$ confidence level) phase- and energy-integrated polarization degree of $\approx 7\%$ was detected with the polarization angle $\approx -2^\circ$ East of the celestial North. The two thermal components exhibit quite different polarization properties, with the hotter one being more polarized. The difference is larger in the phase-folded data, with the polarization degree reaching $\sim 63\%$ in the range $4$–$7.5\,\mathrm{keV}$, in correspondence with the secondary peak of the pulse profile, and never exceeding $\sim 30\%$ at lower energies. The polarization angle continuously oscillates from $-90^\circ$ to $+90^\circ$ over one rotational cycle and is well fit by the rotating vector model, with an inclination of the line of sight and of the
magnetic dipole axis relative to the
star spin axis of $\approx 28^\circ$ and $\approx 109^\circ$, respectively. The data point to an emission geometry in which the cold thermal component likely originates from two antipodal caps, possibly in a magnetically condensed state, while the hotter one comes from a smaller region covered by an atmosphere.
Read the full abstract ▾
All authors Roberto Taverna, Lorenzo Marra, Roberto Turolla, Ruth M. E. Kelly, Silvia Zane, Alice Borghese, Francesco Coti Zelati, Paolo Esposito, Gian Luca Israel, Nanda Rea, Haonan Yang, Yilong Wang
Materials Science
Ab initio study of magnetic Cu$_2$Sb compounds related to antiferromagnetic CuMnAs
Vojtěch Pařízek and Jakub Železný
The
antiferromagnetic metal CuMnAs has become a workhorse of
antiferromagnetic spintronics. A broad range of phenomena has been demonstrated in this material, most notably current-induced switching and heat-driven quench switching, both first realized in CuMnAs. CuMnAs belongs to a much larger family of intermetallic compounds sharing the tetragonal Cu$_2$Sb-type structure, yet the
magnetic properties of most of its members, and their potential for spintronics, have not been studied. Here we report a systematic density functional theory (DFT) study of the
magnetic and electronic structure of more than 50 compounds of this family, intended to guide future theoretical and experimental work toward spintronic applications. We find a wide range of
magnetic ground states, among them over 20 new
antiferromagnetic candidates.
Read the full abstract ▾
Atmospheric and Oceanic Physics · Cross-listed from cs.CE
Analysis of trade-offs in urban heat mitigation using a Bayesian Optimization framework for an urban canopy layer model
Rebekka Walter, Johanna Gelhaus, David Anton et al. (+2 more)
To mitigate the challenges of
climate change and intensifying heat stress in urban areas, local adaptation strategies are discussed and introduced in cities worldwide. To understand processes and potential trade-offs of these strategies a
Bayesian optimization and surrogate modeling framework was employed to investigate urban parameter ranges of heat mitigation strategies with focus on three thermal metrics: daytime air temperature, Universal Thermal
Climate Index (UTCI), and nighttime air temperature. Based on an urban street canyon configuration, it was shown that heat mitigation measures that reduce daytime air temperature and UTCI are often associated with higher nighttime temperatures. This results in a curved Pareto front that reflects the trade-off between daytime and nighttime thermal comfort. Under identical forcing conditions, different urban configurations, varying in geometry, vegetation, and surface characteristics, are shown to alter peak canyon air temperature by up to 5.2~$^\circ$C during the day and 2.6~$^\circ$C at night, while UTCI varies by up to 7.9~$^\circ$C, demonstrating that favorable urban configurations can substantially mitigate microclimatic heat stress. These findings suggest that combining multi-objective
Bayesian optimization and surrogate modeling can help bridge the gap between computationally intensive
climate simulations and practical decision-making in urban planning. An interactive visualization tool was developed to explore these trade-offs, making the often opposing relationships between urban parameters and the three thermal metrics directly accessible to planners.
Read the full abstract ▾
All authors Rebekka Walter, Johanna Gelhaus, David Anton, Henning Wessles, Stephan Weber
High Energy Physics (Phenomenology)
Big Bang Nucleosynthesis Confronts Domain Walls and First-Order Phase Transitions as the Pulsar Timing Array Explanations
Fatemeh Elahi, Diego Fortini, Yann Gouttenoire et al. (+2 more)
Pulsar timing arrays (PTAs) have detected a nanohertz gravitational-wave background, often attributed to annihilating domain walls (DWs) or first-order phase transitions (FOPTs). Their reheating imprints fluctuations in the
baryon-to-
photon ratio. These so-called
baryon isocurvature fluctuations $S_B$ survive until Big Bang Nucleosynthesis, whose yields depend nonlinearly on it. Modest $S_B$ fluctuations can therefore alleviate the current deuterium tension in parts of the PTA preferred regions and therefore strengthen their interpretation. Overabundant DWs and too strong FOPTs overproduce $D/H$ and are ruled out.
Read the full abstract ▾
All authors Fatemeh Elahi, Diego Fortini, Yann Gouttenoire, Nicholas Leister, Pedro Schwaller
Quantum Physics
Bridge of $\Psi$'s: Quantum Circuit Optimization with Schrödinger Bridges
Lino S. Hofstetter, Lia Yeh and Prakash Murali
Quantum circuit optimization replaces a
circuit with an equivalent one of fewer gates and lower depth, reducing execution cost and error rate. We ask whether a generative model can learn this transformation directly from examples, rather than selecting from a fixed rewrite library or rigid algebraic routines. We present Bridge of $\Psi$'s (BOPS), a generative model based on Schrödinger bridges, using a custom denoiser architecture, that learns a transformation from a source
circuit into an equivalent optimized
circuit. We train it on data constructed to be hard for existing optimizers, by applying rewrite rules backwards so that each input has a known lower-cost target. On held-out 8
qubits $\times$ 64 depth Clifford+$T$
circuits, BOPS reduces gate count by $2.46\times$ and depth by $2.45\times$ in
geometric mean, outperforming all nine baseline optimizers. This constitutes the first generative model bridging
quantum circuits and frontier machine learning methods, opening up the
quantum compilation stack to learned optimization along multiple axes.
Read the full abstract ▾
Optics
Haichun Liu and Jerker Widengren
Finite-
memory optical tracers can encode transport properties through their previously experienced excitation. Using such
memory features, harboured in the population of excitable long-lived electronic states within the emitters, instantaneous localization assessments are not needed to determine their transport properties. Here we formulate this principle for monitoring of
stochastic transport extracted from transport-history integral over conditional transport histories. Under structured illumination, this history yields a measurable transfer-function response from which scalar and tensor
diffusion are reconstructed without time-resolved acquisition. Fisher-information analysis identifies the optimal operating regime and yields first-principles, parameter-free predictions of scalar and tensor reconstruction precision, in quantitative agreement with independent Monte Carlo simulations. These results establish finite optical
memory as a general principle for
stochastic transport imaging.
Read the full abstract ▾
High Energy Physics (Experiment)
Future Muon Physics Experiments: Muon Beams and Experimental Apparatus
Yi Yuan, Leyun Gao, Jian Tang et al. (+1 more)
Muons are powerful probes of fundamental physics at the precision and intensity frontiers. We review the status and planned upgrades of
muon-beam facilities worldwide, together with the experimental apparatus required across three experimental categories. Charged-
lepton flavor violation (CLFV) searches test charged-
lepton flavor conservation through rare
muon decays,
muon-to-electron conversion in
nuclei, and muonium–antimuonium conversion. Precision measurements of the
muon magnetic and electric dipole moments, muonium spectroscopy, and muonic-atom spectroscopy test the Standard Model and bound-state QED and determine fundamental constants and
nuclear charge and magnetization distributions.
Muon-scattering programs include the MUonE determination of hadronic
vacuum polarization, NA64$\mu$ missing-momentum searches for invisible dark sectors, and the phased PKMu program, which investigates muonphilic dark matter, light mediators, LFV
muon–electron processes, and atomic effects in resonant annihilation. We emphasize the beam intensity, timing, purity, and phase-space control, as well as beamline and detector design, background suppression, and experimental techniques needed to achieve next-generation sensitivity and precision.
Read the full abstract ▾
All authors Yi Yuan, Leyun Gao, Jian Tang, Qiang Li
Quantum Physics
Spin-Orbit-Mediated Magnetization Transfer in the Fermi-Hubbard Model
Jialiang Tang, Ruoqian Xu, Gloria Platero et al. (+2 more)
We demonstrate
spin–orbit-coupling (SOC) catalysis of magnetization-sector transfer in the half-filled
Fermi–Hubbard model. Without SOC, conservation of total magnetization confines the dynamics to the initial sector, preventing an antiferromagnetically correlated state from reaching the polarized
ferromagnetic sector under a Zeeman ramp. A transient SOC control lifts this obstruction by coupling otherwise disconnected magnetization sectors and converting
symmetry-protected crossings into avoided crossings, thereby opening a finite-gap pathway for
magnetic-state conversion. We further accelerate the SOC-enabled dynamics beyond the adiabatic timescale using gradient-ascent pulse engineering (GRAPE) and a variational
quantum circuit. Both approaches achieve rapid magnetization transfer in one- and two-dimensional
Fermi–Hubbard
lattices. Our results establish transient SOC as a controllable catalyst for overcoming
symmetry-imposed dynamical constraints, while optimal control sets the timescale for the resulting magnetization-sector transfer.
Read the full abstract ▾
All authors Jialiang Tang, Ruoqian Xu, Gloria Platero, Yue Ban, Xi Chen
Statistical Mechanics
Thermodynamic efficiency of communication channels
Nahuel Freitas, Pedro E. Harunari and Massimiliano Esposito
We identify a broad class of communication channels that captures common physical constraints in both artificial and natural systems and derive bounds on their thermodynamic cost. We find that the
entropy production per channel use is bounded from below by the input-output mutual information, and their ratio -mutual information divided by
entropy production- defines the thermodynamic efficiency. Unlike previous studies of energy-constrained communication channels, our analysis shows that thermodynamic costs must be assigned not only to the input symbols themselves, but also to transitions between successive symbols. As a result, maximizing thermodynamic efficiency favors a biased input that switches only rarely, rather than the capacity-achieving input. For the binary symmetric channel, this preference emerges through a pitchfork bifurcation that spontaneously breaks the
symmetry of the channel. A minimal model of cellular sensing exhibits the same phenomenon.
Read the full abstract ▾
Quantum Physics
On the Computational Complexity of Guided Berry Phase Estimation
Gabriel Waite
We prove that deciding the Berry phase for parameterised 2-local
qubit Hamiltonians is BQP-complete when presented with a classical description of a guiding state, promised to overlap with the ground state of the system. Our results extend to systems with weighted Heisenberg interactions and when restricted to a 2D square or triangular
lattice geometry. The techniques we develop leverage the Schrieffer–Wolff transformation, typically used in the construction of perturbative gadget reductions for local
Hamiltonian problems, extending it to parameterised families of
Hamiltonians. We demonstrate that there exists a choice of parameterised simulator
Hamiltonians whose Berry phase well-approximates that of a parameterised target family. Using the perturbative gadget reduction framework of Oliveira and Terhal and of Schuch and Verstraete, we adapt the arguments to parameterised interactions and demonstrate the error bounds in the resulting simulation can be controlled. Additionally, we provide an explicit proof that families of 1-local
Hamiltonians have a Berry phase that can be efficiently computed to inverse-
polynomial precision. This establishes a complexity transition between 1-local and 2-local
Hamiltonian families.
Read the full abstract ▾
Quantum Physics · Cross-listed from cs.NI
Modulating Retroreflector-Aided UAV-Based FSO/QKD Systems
Duy N. Luong, Duy-Tuan Dao, Cuong T. Nguyen et al. (+2 more)
Unmanned aerial vehicles (
UAVs)-based free-space optics (FSO)/
quantum key distribution (QKD) systems require high-precision pointing mechanisms. This increases system complexity and limits rapid deployment for lightweight and energy-constrained
UAVs. This paper proposes a modulating retroreflector (MRR)-equipped
UAV architecture for BB84-QKD systems that enables simplified yet accurate tracking while relaxing pointing requirements. A realistic
quantum channel model is developed, for which we newly derive the channel probability distribution of transmittance (PDT). Capitalizing on the derived channel PDT, several QKD performance metrics are analytically obtained. Numerical results verify the feasibility of the proposed MRR-aided
UAV for practical QKD deployment, highlight its effectiveness over conventional
UAV-ground systems, and validate the accuracy of the developed analytical framework.
Read the full abstract ▾
All authors Duy N. Luong, Duy-Tuan Dao, Cuong T. Nguyen, Hoang D. Le, Anh T. Pham
Strongly Correlated Electrons
Fractional Quantum Geometry in Topological Mott Regime
Junyu Tang, Hongquan Lv and Gang v. Chen
Inspired by recent interests in
quantum geometry in electronic bands, we consider a two-dimensional topological Mott
insulator, i.e.
chiral spin liquid, whose spinon bands develop nontrivial band topological and
quantum geometry. The virtual polarization of the gapped charge sector transfers the electromagnetic drive to the charge-neutral spinons through the emergent U(1) gauge field, producing a tensor Ioffe-Larkin response and enabling two complementary optical protocols for measurements. In the off-shell (low-frequency) regime, a self-calibrated ratio of the physical longitudinal and
Hall conductivities yields the spinon Chern number without the microscopic knowledge of the charge response. In the on-shell (resonant) regime, combining the inverse Ioffe-Larkin response with the Kramers-Kronig relation enables reconstruction of the
quantum-metric and Berry-
curvature spectral densities. Our approach directly applies to the triangular
lattice Hofstadter-Hubbard model in Moiré systems, can be well adapted to other triangular
lattice antiferromagnets such as Nb$_3$Br$_8$ with appropriate modifications. We establish a unified framework for quantitatively probing the
quantum geometry of fractionalized quasiparticles in topological Mott regime.
Read the full abstract ▾