Strongly Correlated Electrons
Exact dimer ground states of long-range spin chains and ladders
Jędrzej Wardyn and Miłosz Panfil
Interacting
spin chains and ladders are known to support a plethora of
quantum phases with complex ground-state phase diagrams. In this work, we study a large family of such models and determine precise, explicit conditions under which an exact dimer state is guaranteed to be the ground state. These general conditions are validated for various generalizations of the Majumdar-Ghosh model using exact diagonalization. Our results provide exact reference points in the phase diagrams of a wide class of
spin chains and ladders, including those with anisotropic and arbitrary-range interactions.
Read the full abstract ▾
Nuclear Theory
Purifying one-neutron removal as a probe of single-particle strength
Erxi Xiao, Guangshuai Li, Yu Yang et al. (+4 more)
One-
neutron removal reactions exhibit a strong
proton-
neutron asymmetry dependence in the inclusive reduction factor $R_s$, a long-standing issue that has been discussed in terms of both possible intrinsic isospin dependence of single-particle strength and reaction-mechanism effects. We address this issue by reframing inclusive removal as a coupled fast-dynamics and deexcitation process, and by validating this transport-deexcitation chain against a global, mutually constraining data set. Confronting 73 one-
neutron removal cross sections and 28 residue parallel-momentum distributions with isospin-dependent
quantum molecular dynamics followed by GEMINI evaporation shows that the apparent $R_s$-$\Delta S$ trend is correlated with evaporation feeding and evaporation loss. By subtracting the feeding contribution and correcting for the loss component in the measured cross sections, we construct a purified reduction factor $R_{\rm dir}$, that more closely reflects single-particle strength than the inclusive $R_s$. The resulting $R_{\rm dir}$ exhibits a much weaker $\Delta S$ dependence within current uncertainties, consistent with the weak isospin-asymmetry dependence observed in nucleon-transfer and quasifree-knockout systematics.
Read the full abstract ▾
All authors Erxi Xiao, Guangshuai Li, Yu Yang, Long Zhu, Jianwei Zhao, Jun Su, Baohua Sun
Statistical Mechanics
Universal Short-Imaginary-Time Quantum Critical Dynamics Near Boundaries
Yu-Rong Shu, Yuan-Biao Li and Shuai Yin
While imaginary-time
evolution has long served as a standard paradigm for ground-state preparation in numerical simulations and
quantum devices, its intrinsic dynamical properties has been largely overlooked. Here, we investigate the short-imaginary-time critical dynamics in
quantum systems with boundaries. A universal scaling theory is developed and verified in the two-dimensional
quantum Ising model, uncovering rich dynamic critical behaviors dictated by boundary universality classes. For ordered initial states, the boundary order parameter $M_s$ decays with imaginary time $\tau$ as $M_s \propto \tau^{-\beta_1/\nu z}$, where $\beta_1$ denotes the boundary order parameter exponent, and $\nu$ and $z$ correspond to the correlation length exponent and the dynamic exponent, respectively. For disordered initial states, the autocorrelation of the boundary order parameter is governed by a novel critical exponent $\theta_1$, which is closely related to the critical initial slip behavior of $M_s$ characterized by the corresponding exponent $\theta_1'$. In contrast to its positive bulk counterpart, the boundary initial-slip exponent $\theta_1'$ is negative for the ordinary transition while remaining positive for the special transition. Although the static universality classes of $d$-dimensional
quantum phase transitions generally coincide with those of $(d+1)$-dimensional classical phase transitions, we show that $\theta_1$ does not follow this conventional
quantum-classical mapping. We further discuss the implications of our results for more exotic forms of boundary criticality. Our findings provide new physical insights into boundary critical dynamics and offer a novel route for probing exotic boundary critical behaviors in
quantum many-body systems.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Shedding light on the nature of $\phi(2170)$ with the parton and hadron cascade model PACIAE
Jian Cao, Wen-Chao Zhang, Bo Feng et al. (+8 more)
The nature of $\phi(2170)$ remains open. We simulate its production in $e^+e^-$ collisions at $\sqrt{s}=4.95$ GeV using PACIAE 4.0, which sequentially generates the final partonic state (FPS) and the final hadronic state (FHS). While previous studies have interpreted $\phi(2170)$ as an $ss\bar{s}\bar{s}$ or a $u\bar{u}s\bar{s}$ state, the $U(1)$ anomaly coupling allows non-strange
quarks to couple to a vector $s\bar{s}$ component via soft-
gluon interactions. This motivates us to also explore the $d\bar{d}s\bar{s}$ tetraquark configuration. In addition, we consider $\phi(2170)$ as an excited strangeonium state, an $s\bar{s}g$ hybrid state, a $\bar{\Lambda}\Lambda$ bound state, and a $\phi K^+K^-$ resonance state. The strangeonium, hybrid, and tetraquark candidates are formed by coalescing their constituent partons in the FPS using the dynamically constrained phase-space coalescence model. The $\bar{\Lambda}\Lambda$ and $\phi K^+K^-$ states are produced via recombination of their constituent
hadrons in the FHS. We calculate the orbital angular momentum
quantum number of each candidate in its rest frame and perform spectral classification. Given $J^{PC}=1^{--}$, $\phi(2170)$ can be interpreted as a $D$-wave $s\bar{s}$, a $P$-wave $s\bar{s}g$, a $P$-wave $u\bar{u}s\bar{s}/d\bar{d}s\bar{s}/ss\bar{s}\bar{s}$, an $S$-wave $\bar{\Lambda}\Lambda$, or an $S$-wave $\phi K^+K^-$ state. The yields of the $D$-wave $s\bar{s}$, $P$-wave $s\bar{s}g$, $u\bar{u}s\bar{s}$ and $d\bar{d}s\bar{s}$ states are of order $10^{-4}$; those for the $S$-wave $\bar{\Lambda}\Lambda$ and $\phi K^+K^-$ states are of order $10^{-5}$; while the $P$-wave $ss\bar{s}\bar{s}$ yield is of order $10^{-6}$. Moreover, significant discrepancies are observed in the rapidity distributions and the $p_T$ spectra among the various candidates. These discrepancies could serve as valuable criteria for unraveling the nature of $\phi(2170)$.
Read the full abstract ▾
All authors Jian Cao, Wen-Chao Zhang, Bo Feng, Ya-Hui Hou, An-Ke Lei, Zhi-Lei She, Hua Zheng, Li-Lin Zhu, Dai-Mei Zhou, Yu-Liang Yan, Ben-Hao Sa
Quantum Physics
Optimizing Symmetry Informed Probabilistic Error Cancellation
Tom O'Leary, Daniel J. Egger and Dieter Jaksch
We show that combining
quantum error detection (QED) with probabilistic error cancellation (PEC) gives more accurate and lower-variance estimates than PEC alone, provided that the
symmetry measurements required for QED are carefully chosen. Because noisy
symmetry measurements can negate the benefits of the PEC+QED approach, we cast the selection of measurement configurations as a classical optimization problem that systematically suppresses the impact of noise. Applying optimized PEC+QED to GHZ-state output distributions and to simulating the time-dynamics of a generalized superfast encoded
Fermi-Hubbard model, we find consistent improvements over PEC. For GHZ states, the optimization over
symmetry measurement configurations is essential for achieving an advantage. For the
Fermi-Hubbard model, PEC+QED improves observable estimation on a $2 \times 2$
lattice and for larger systems the mitigation overheads can be reduced by measuring only subsets of stabilizers. Our results demonstrate the importance of
circuit-specific tailoring of QEM techniques and that fault-tolerant design principles may already provide value for near-term devices.
Read the full abstract ▾
Mathematical Physics
Scattering, Trapping and Cloaking-Type Effects of Plane Waves by Point Scatterers in Strain Gradient Elasticity
E. Alevras, Th. Zisis and P. A. Gourgiotis
Wave scattering by localized constraints in microstructured solids is strongly influenced by the interplay of material length scales, dispersion and geometry. This work investigates plane-strain scattering of time-harmonic P and SV waves by clusters of rigid point constraints embedded in an infinite strain gradient elastic medium. A closed-form dynamic Green's tensor is derived for the plane-strain problem. Unlike the classical elastodynamic Green's tensor, the strain gradient Green's tensor remains bounded at the source, enabling point constraints to be introduced directly through superposition of fundamental solutions. The multiple-scattering problem is reduced to a finite-dimensional algebraic system for the pin reaction amplitudes. A frequency-domain procedure is developed to identify resonance-like amplification and trapping. Candidate resonant frequencies are associated with local minima of the Green
matrix determinant, while higher-order
curvature criteria distinguish trapping-dominated resonances from non-localized scattering responses. The results show that the response is governed primarily by the ratio of the microinertial and energetic strain gradient lengths. In the anomalous dispersion regime, sharp resonances produce strong displacement localization, including perimeter-localized trapping modes in dense circular arrays. In the normal dispersion regime, these resonances are strongly attenuated and the pins behave as weak scatterers, producing a cloaking-type response in which the incident field is only weakly perturbed. The influence of Poisson's ratio, incidence angle and compound pin configurations is also examined, demonstrating how intrinsic material lengths and
geometric arrangement can be used to tune scattering, trapping and wave-screening mechanisms in microstructured elastic media.
Read the full abstract ▾
Strongly Correlated Electrons
Chiral enhancement of two-magnon bound states in an $S=1/2$ triangular-lattice magnet
László Rudner and Karlo Penc
We study one- and two-
magnon excitations above the fully polarized state of the
spin-$1/2$ triangular-
lattice $J_1$-$J_2$-$J_3$ Heisenberg model with a uniform scalar-chirality interaction. In the Heisenberg model, we identify two special
manifolds of one-
magnon minima by rewriting the dispersion in complete-square form. The chirality term cancels exactly in the one-
magnon sector, leaving the dispersion and instability field unchanged, but survives in the two-
magnon sector as an oriented interaction between neighboring
magnons. Using
symmetry-adapted
lattice harmonics, we show that scalar chirality splits two-
magnon states of opposite relative-motion chirality and selectively enhances the binding of one of them. It can strengthen an existing bound state, change the
symmetry of the lowest
magnon pair, or induce binding where none occurs without chirality. Exact diagonalization further shows that two-
magnon pairing can also occur at finite total momentum. Our results identify scalar chirality as a microscopic mechanism for enhancing two-
magnon pairing without modifying the one-
magnon spectrum.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Bandwidth-Limited Critical Currents in Electrically Tunable Moiré Bands
Riccardo Bertini, Xueqiao Wang, Sergey Slizovskiy et al. (+16 more)
Moiré superlattices host narrow minibands whose bandwidth governs correlated and topological phases. Here, we demonstrate that the bandwidth also sets the critical current for the onset of out-of-
equilibrium transport. In
bilayer graphene aligned to hexagonal boron nitride, we explore the high-current transport regime as we continuously flatten the valence miniband using an out-of-plane displacement field. We observe a significant reduction in the critical current, which is captured by a minimal analytical model and corresponds to the calculated narrowing of the miniband. Moreover, by comparing distinct moiré platforms, we show that the scaling between critical current and bandwidth is a universal feature of
graphene superlattices. Our results reveal a direct link between miniband dispersion and high-current transport, and establish this regime as a fast and accessible electrical probe of bandwidth
evolution.
Read the full abstract ▾
All authors Riccardo Bertini, Xueqiao Wang, Sergey Slizovskiy, Zhiren Zheng, Julien Barrier, Chiara Pizzo, Robin Smeyers, Krystian Nowakowski, Hitesh Agarwal, Alvaro Moreno, Bert Jorissen, Kenji Watanabe, Takashi Taniguchi, Milorad V. Milošević, Lucian Covaci, Vladimir Fal'ko, Pablo Jarillo-Herrero, Roshan Krishna Kumar, Frank H. L. Koppens
High Energy Astrophysical Phenomena
Bridging the gap between SLSNe and SE-SNe. Multi-wavelength analysis of the SLSN-Ib SN 2024jlc
A. Simongini, F. Acero, M. Imbrogno et al. (+15 more)
The Type I super-luminous
supernova SN~2024jlc (ZTF24aapadbb) exploded on the 25th of May 2024 at $z = 0.039$. Being the closest
supernova of this class discovered in recent years and one of the closest ever, represented a rare opportunity to study in detail this type of objects. We performed a multi-wavelength analysis, spanning ten orders of magnitude in frequency, including optical/UV photometry and spectroscopy, soft and hard X-rays, and high-energy $\gamma$-rays. We characterized the event as a slow-evolving and He-rich
supernova, with one of the lowest peak luminosities reported for a super-luminous event $M_g\sim-19.37$ mag, and a light curve
evolution compatible with both circumstellar interaction and magnetar
spin-down models, with noticeable contribution from $^{56}$Ni decay. No significant excess was found in the soft and hard X-ray bands, for which we provide upper-limits on the flux. Additionally, we analyzed two years of
Fermi-LAT data, from which we report an intriguing hint of a $\gamma$-ray signal at the $\sim 3.6 \sigma$ level, although no firm detection can be claimed. The gamma to optical efficiency ratio, $\eta = 0.38$, is suggestive of the presence of a central-engine scenario, similar to SN~2017egm. Our analysis suggests that SN~2024jlc could bridge the gap between SLSNe and classical stripped-envelope
supernovae. While still poorly populated, this bridge could consist of all SLSN-Ib
supernovae, with the key difference residing in the powering mechanism.
Read the full abstract ▾
All authors A. Simongini, F. Acero, M. Imbrogno, J. L. Wise, J. Sollerman, S. Schulze, N. Paul M. Kuin, T. X. Chen, C. Fremling, A. Gangopadhyay, M. M. Kasliwal, R. R. Laher, Z. McGrath, D. A. Perley, J. N. Purdum, N. Rehemtulla, R. M. Rich, R. Riddle
Superconductivity
Breathing mode inducing dynamical pairing in Kagome materials
Debmalya Chakraborty, Anushree Datta and Jorge Cayao
The breathing mode in Kagome materials is a structural modulation that breaks inversion
symmetry and has been shown to be a crucial source for intriguing phases in the normal state. In this work, we carry out a full classification of superconducting
symmetries in kagome
superconductors and demonstrate the emergence of odd-frequency dynamical Cooper pairs entirely driven by the breathing mode. We then show that odd-frequency
spin-singlet Cooper pairs can be realized by controlling the breathing mode in kagome
lattices with conventional
spin-singlet $s$-wave superconductivity. Since odd-frequency pairing is intrinsically nonlocal in time, our results put forward the breathing mode for designing dynamical Cooper pairs in kagome materials.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Foreground Characterization and Mitigation in the Observations of the CD/EoR with the SKA
Philip Bull, Jacob Burba, Emilio Ceccotti et al. (+20 more)
The Square Kilometre Array (SKA), with its unprecedented sensitivity, frequency coverage, and large collecting area, is poised to revolutionize our understanding of the
Cosmic Dawn (CD) and Epoch of Reionization (EoR) epochs marking the formation of the first luminous sources and the subsequent reionization of the intergalactic medium (IGM). However, detecting the faint redshifted 21-cm signal from neutral hydrogen remains one of the foremost challenges in observational cosmology, as it is buried beneath bright foregrounds from
Galactic synchrotron radiation, free-free emission, and extragalactic point sources that are 4-5 orders of magnitude stronger than the cosmological signal. In this chapter, we highlight the key components and characteristics of these foregrounds and review ongoing efforts to model, characterize, and mitigate them. We emphasize how the SKA-Low AA* configuration, through its optimized array design, wide field of view, and improved calibration accuracy, enhances our capacity to suppress foreground contamination and recover the cosmological signal. The SKA Observatory Foreground Challenge plays a pivotal role in this effort by bringing together the global EoR/CD community to develop, compare, and validate foreground removal pipelines using realistic simulated
datasets. Building on the experience of existing pathfinders such as LOFAR, MWA, and HERA, these collaborative initiatives are helping refine statistical and machine learning-based approaches for signal recovery. Together, these advancements are laying the groundwork for the SKA to probe the thermal and ionization history of the early Universe with unprecedented precision.
Read the full abstract ▾
All authors Philip Bull, Jacob Burba, Emilio Ceccotti, Arnab Chakraborty, Samir Choudhuri, Abhirup Datta, Khandakar Md Asif Elahi, Sambit K. Giri, Takumi Ito, Vibor Jelic, Yi Mao, Florent Mertens, Satyapan Munshi, Ridhima Nunhokee, Andre R. Offringa, Samit Kumar Pal, Rashmi Sagar, Huanyuan Shan, Peter H. Sims, Emma Tolley, Anshuman Tripathi, Le Zhang, Zhenghao Zhu
Instrumentation and Methods for Astrophysics
Studying Ionosphere Using SKA-Low and SKA-Mid
Abhirup Datta, Samit Kumar Pal, Sarvesh Mangla et al. (+4 more)
The Earth's ionosphere introduces systematic effects that limit the performance of
radio interferometers operating at low frequencies ($\lesssim 1$\,GHz). These ionospheric effects intensify during periods of heightened geomagnetic activity or for observations with extended baseline configurations. As each Pathfinder
telescope operates at a different
magnetic latitude, they experience distinct ionospheric regimes, offering complementary insights into ionospheric behaviour. In this work, we present a comparative study of ionospheric disturbances using observations from the uGMRT, VLA, MWA, and LOFAR, spanning a wide range of geographic and geomagnetic conditions. We present both
antenna-based and field-based analyses to quantify phase fluctuations, positional offsets, and scintillation effects across these arrays. The measured total electron content (TEC) gradients reveal variations in spatial and temporal ionospheric structures with sensitivities that exceed those achievable with Global
Navigation Satellite System (GNSS) measurements. By combining multi-
telescope results, we assess the impact of ionospheric
turbulence on calibration and imaging fidelity, and use these findings to forecast the expected ionospheric effects on observations with SKA-Low and SKA-Mid.
Read the full abstract ▾
All authors Abhirup Datta, Samit Kumar Pal, Sarvesh Mangla, Bhuvnesh Brawar, Sumanjit Chakraborty, Sudipta Sasmal, Anshuman Tripathi
Strongly Correlated Electrons
Exact interlayer triplet-pairing eigenstates in the extended Hubbard model
F. X. Liu and Z. Song
$\eta$-pairing
symmetry generalizes the pairing mechanisms in superconductivity but is broken in the presence of interlayer interactions. In this work, we extend this approach to triplet pairs. We propose interlayer triplet-pairing operators for the multi-layer extended Hubbard model. We find that a set of exact condensate-pair eigenstates can be constructed, which exhibit off-diagonal long-range order. In contrast to the $\eta$-pairing mechanism, this originates from restricted spectrum generating
algebra and is only available for
bilayer and trilayer systems in the presence of interlayer Hubbard interactions. Nevertheless, the system also retains the original on-site $\eta$-pairing
symmetry in the absence of interlayer interactions. Consequently, both singlet and triplet pairs coexist in the eigenstates of the multi-layer Hubbard model. We employ quench dynamics to demonstrate the results through numerical simulations. Our findings open avenues for the study of exact condensate-pair states in strongly correlated systems.
Read the full abstract ▾
Quantum Physics
Quantum-Informed Portfolio Selection: An End-to-End Pipeline Validated on Trapped-Ion Hardware with Real Market Data
Romina Yalovetzky, Martin J. A. Schuetz, Zichang He et al. (+11 more)
Portfolio diversification - a cornerstone of modern investment management - can be formulated as a Maximum Independent Set (MIS) problem on asset correlation graphs. Solving this problem at scale is computationally challenging, motivating the exploration of
quantum algorithms for practical financial optimization. We propose an end-to-end pipeline leveraging qReduMIS, a recursive hybrid
quantum-classical
algorithm. Rather than using
quantum optimization to directly produce a final solution, qReduMIS leverages independent set measurements from the
Quantum Approximate Optimization
Algorithm (QAOA) to identify frozen nodes - vertices likely to belong to optimal solutions - thereby guiding and unblocking subsequent (provably optimal) classical reductions on the remaining graph. We
benchmark qReduMIS on real financial data from four major
market indices with up to 225 assets, executing experiments on Quantinuum's 98-
qubit trapped-ion Helios system, with QAOA
circuits acting on kernels of up to 78
qubits and 1016 two-
qubit gates. While standalone QAOA fails to find the optimal solution for two of the largest indices (S&P 100 and Nikkei 225), qReduMIS achieves success probabilities of $0.40$ and $0.95$, respectively, with average approximation ratios $\geq 0.96$ across all four indices. We perform a systematic
benchmark on the Quantinuum H2-1 noisy emulator over 73 asset correlation graphs of varying size showing that, for $p=2$ QAOA layers, the optimal time-to-solution scaling exponent of qReduMIS is $3.2$ times smaller than that of standalone QAOA.
Read the full abstract ▾
All authors Romina Yalovetzky, Martin J. A. Schuetz, Zichang He, Jiayu Shen, Yue Sun, Rudy Raymond, Shauna Sahay, Kishore Perla, Ruben S. Andrist, Grant Salton, Helmut G. Katzgraber, Roger Bongiovanni, Niraj Kumar, Rob Otter
Quantum Physics
Susceptibility-kinetic uncertainty relations for quantum systems
Didrik Palmqvist, Ludovico Tesser and Janine Splettstoesser
Kinetic uncertainty relations bound current precision of
stochastic processes by dynamical activity. The extension of these bounds to
quantum systems has been impeded by coherence, strong system-reservoir coupling, and the subtlety of defining dynamical activity in the
quantum regime. Here, we introduce a partial dynamical activity through the
quantum Fisher information associated with the rescaling of the system-reservoir coupling and show that it bounds current precision via a universal susceptibility-kinetic uncertainty relation. The general validity of this relation for any open
quantum system is guaranteed by the natural contribution of a susceptibility term, which is experimentally accessible by tuning the system-reservoir coupling strength. We show how the partial dynamical activity encompasses previous definitions of activity in the weak-coupling Markovian limit and that it provides an information-
geometric interpretation of correlator-based activities. We illustrate the tight constraint on precision that our bound provides with the example of steady-state transport through a double
quantum dot, where
quantum effects invalidate previously developed kinetic uncertainty relations. We expect our bound to provide a powerful tool for optimizing precision in arbitrary
quantum systems.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Point spread function wavefront recovery from in-focus stellar observations
Ezequiel Centofanti, Samuel Farrens, Jean-Luc Starck et al. (+1 more)
Recovering the wavefront error (WFE) field of an optical system from intensity in-focus observations is a challenging inverse problem with broad implications for
telescope point spread function (PSF) modelling. Accurate WFE recovery enables both precise PSF modelling and direct insight into the state of the
telescope optics, facilitating the detection of potential malfunctions. Recently, non-parametric PSF models have shown promising performance in modelling complex optical systems in space-based
telescopes. WaveDiff is a semi-parametric PSF model that represents the PSF in wavefront space by combining parametric and learnable features with a differentiable forward optical model. This parameterisation enables phase
retrieval from in-focus observations by exploiting the spatial variation of the PSF across the field of view (FOV). The original version of WaveDiff achieves outstanding PSF recovery results in pixel space; however, the recovered WFE is far from the ground truth, with a relative error of around $30 \%$. In this paper, we present a new optimisation scenario that bridges WaveDiff's parametric and non-parametric components through wavefront feature projection, yielding a substantial improvement in WFE recovery and making WaveDiff the first demonstrated method to combine wide-field WFE recovery, in-focus-only polychromatic observations, and non-parametric wavefront features in a single framework. We show that incorporating wavefront projections and increasing the number of optimisation cycles enables WaveDiff to recover the WFE with an error of approximately $3 \%$ using only noisy, undersampled, in-focus observations. This represents a tenfold improvement over the original model while further reducing the pixel-space error. The code to reproduce the results of this article is publicly available at https://github.com/tobias-liaudat/wf-psf/tree/v1.4.0
Read the full abstract ▾
All authors Ezequiel Centofanti, Samuel Farrens, Jean-Luc Starck, Tobias Liaudat
Soft Condensed Matter
Diffusiophoretic transport of colloids and emulsions in complex environments
Amir A. Pahlavan
Chemical gradients are ubiquitous in porous and crowded environments, including soils, filters, fabrics, tissues, hydrogels, biofilms and living
cells. They arise from displacement fronts, dissolution and precipitation, ion exchange, metabolism, root exudation, evaporation, gas dissolution, freeze–thaw cycles and externally imposed chemical treatments. These gradients can drive colloids, macromolecules and emulsion droplets by diffusiophoresis, while simultaneously driving diffusioosmotic flows along confining surfaces. Classical models of colloid transport in porous media emphasize hydrodynamic dispersion, surface interactions, straining, deposition, detachment and filtration. This chapter places diffusiophoresis within that broader transport framework and reviews how porous media generate, stretch, disperse and sustain the solute gradients that drive phoretic motion. We first discuss sources of chemical gradients and the distinction between spreading and mixing, then summarize classical colloid transport, the minimal physicochemical model for diffusiophoresis and diffusioosmosis, and the experimental platforms used to study these effects. Particular emphasis is placed on recent results showing that diffuse solute fronts can enhance phoretic removal from dead-end pores by prolonging the duration of forcing, and that cross-streamline migration within flowing pathways can change macroscopic breakthrough and dispersion by orders of magnitude. We close by discussing emulsion droplets, multiphase flows, confined and living media, and open problems, including the transition from algebraic mixing in two-dimensional micromodels to chaotic mixing in three-dimensional porous media.
Read the full abstract ▾
Quantum Physics
Analytical connection between exact and approximate solutions of the periodically-driven two-level system starting from the Heun equation
Pietro Follia and Bassano Vacchini
We investigate and establish an analytic connection between the exact solutions describing the dynamics of a two-level system driven by periodic external fields, focusing on the cases of linear driving and the so-called rotating-wave approximation, or circular driving. In both cases, the exact solutions can be obtained by mapping the Schrodinger equation onto Heun equations: the confluent Heun equation for linear driving and the Heun equation for the rotating-wave case. In particular, we demonstrate a direct analytic connection between the exact solutions for linear driving and those for the rotating-wave case. This result is obtained by analyzing local solutions expressed in terms of hypergeometric functions, which, in the case of the confluent Heun equation, can be derived by considering path-multiplicative Floquet solutions involving a bilateral series. This series leads to two continued-fraction expansions that can be perturbatively solved by imposing a suitable consistency condition. The connection between the linear-driving and rotating-wave solutions is established through a perturbative procedure that allows us to recover not only the rotating-wave approximation itself, but also the correct Stark and Bloch-Siegert shifts, as well as the so-called high-frequency approximation.
Read the full abstract ▾
Earth and Planetary Astrophysics
Understanding eccentric temperate giants: an in-depth study of the architecture and stellar obliquity of the TOI-2134 system
Federica Rescigno, Manu Stalport, Ancy Anna John et al. (+28 more)
We revisit the TOI-2134 planetary system with three new high-cadence TESS sectors and 98 more spectra. This new analysis confirms the two orbiting
planets by simultaneously modelling a total of eight sectors of corrected TESS photometry and 280 HARPS-N and SOPHIE radial velocities: an inner mini-Neptune in a near-circular $9.229198\pm0.000003$ days orbit, and an outer temperate sub-Saturn orbiting with a $95.852840\pm0.000042$ days period and eccentricity of $0.31\pm0.01$. The masses and radii of the
planets were computed to be $9.37\pm0.54$ Me and $2.735\pm0.068$ Re for
planet b, and $58.3\pm1.9$ Me and $7.35\pm0.18$ Re for
planet c. The new data not only improves the detection significance and precisions on the planetary orbits, but also breaks the original multimodality in the eccentricity solution for the outer
planet. We also detect a long-term trend in the radial velocity data, which we attribute to a
stellar magnetic cycle. We investigate the
spin-orbit
alignment of the system via observations of the Rossiter-McLaughlin effect for TOI-2134~b with EXPRES and TOI-2134~c with PARAS-2. No RM effect was detected for
planet b, but we find a 4.7$\sigma$ detection of a $59\pm31^{\circ}$ obliquity for
planet c. Finally, we examine the architecture of the system, assess its completeness, investigate the planetary interior, and their suitability for follow-up atmospheric analysis.
Read the full abstract ▾
All authors Federica Rescigno, Manu Stalport, Ancy Anna John, Tiger Lu, Daisy A. Turner, Lorena Acuña-Aguirre, Anand Bhongade, Anjali A.A. Piette, Vedad Kunovac, Michael Cretignier, Andrew Vanderburg, Ken Rice, Annelies Mortier, Rishikesh Sharma, Guillaume Hébrard, Abhijit Chakraborty, Alessandro Sozzetti, Andrew Collier Cameron, Pía Cortés-Zuleta, Rosario Cosentino, Florian Destriez, Mercedes López-Morales, Luca Malavolta, Jesús Maldonado, Giacomo Mantovan, Francesco Pepe, Matteo Pinamonti, André M. Silva, Stephane Udry, Shreyas Vissapragada, Thomas G. Wilson
Applied Physics
How Much Do RF Drone Benchmarks Overstate? A Controlled Study and Theory of Data Leakage in UAV Signal Identification
David Shulman
Radio-frequency (RF) sensing is a central modality for counter-unmanned-aerial-system (counter-UAS) defence because it exploits the control, telemetry, and
video links between a drone and its operator. Reported accuracies for RF-based drone detection and identification are often very high, but many are obtained using cross-validation that splits a small number of continuous recordings into short segments. This can place near-duplicate slices of the same recording in both training and test partitions, creating data leakage. We study this leakage problem through theory and measurement. We formalise the optimism of segment-level cross-validation and show, using Cover's function-counting
theorem, that a classifier can exactly memorise the recording-to-label map when the number of independent recordings, R, is small relative to the feature dimension, d. In particular, this can occur when 2R is less than or approximately equal to d. Under these conditions, naive accuracy approaches 1, and the inflation gap approaches 1 - ACC*, where ACC* is the Bayes accuracy. The inflation eases only once R grows beyond this separability threshold. A controlled synthetic experiment with 10 seeds confirms the predicted curves: naive balanced accuracy rises from the Bayes level toward 1.0 as recording-specific nuisance variation grows, while honest recording-grouped evaluation declines to chance, with a gap reaching about 0.5. On the public DroneRF
dataset, pooled leave-one-recording-out cross-validation shows drone type identification, AR versus Bebop, collapsing from a naive macro-F1 of 0.74 to 0.46, the two-class chance level. A leakage-pathway ablation attributes essentially all of the inflation to segment-level leakage.
Read the full abstract ▾
Mathematical Physics · Cross-listed from math.DG
Madelung hydrodynamics and Poisson geometry of wave functions
Boris Khesin and Klas Modin
We describe the Poisson geometry of the Madelung transform between
quantum mechanics and hydrodynamics for generic wave functions. We prove that for arbitrary oriented
manifolds this transform, being regarded as a momentum map, naturally defines prequantum bundles for coadjoint orbits of semidirect extensions of diffeomorphism groups. Furthermore, we show that the Madelung framework provides a natural infinite-dimensional version of the convexity results for
Hamiltonian torus actions, thus giving a partial answer to Atiyah's question. In particular, for wave functions without zeros our results provide a Kähler map between the infinite-dimensional Fubini–Study and Fisher–Rao geometries, thus extending previous results to non-simply-connected
manifolds. Furthermore, for wave functions with noncritical zeros, the Madelung transform is shown to be a symplectomorphism to the coadjoint orbits with Morse–Bott densities. The latter, in turn, furnishes a novel momentum map point of view on the Wallstrom quantization condition for the hydrodynamical form of
quantum mechanics. We also comment on the relation between the Madelung setting and the Marsden–Weinstein
symplectic structures on
knots and membranes.
Read the full abstract ▾
Fluid Dynamics
The PICNN-Assisted Physics-Preserving Scheme for Thermodynamically Consistent Two-Phase Flow in Porous Media
Yuanshuo Kong, Xue Wang and Yujing Yan
In this paper, we develop a physics-informed convolutional neural network (PICNN) assisted physics-preserving method for a thermodynamically consistent model of incompressible and immiscible two-phase flow in porous media. Following the physics-preserving prediction-correction scheme of Li et al. \cite{li2025class}, the prediction step is performed by a PICNN trained with finite-volume residuals, where the interfacial fluxes are evaluated by the two-point flux approximation (TPFA) using two-point difference quotients of neighboring
cell-centered unknowns to approximate interfacial normal gradients. The PICNN output is further corrected by a post-processing procedure to obtain energy-stable, mass-conservative, and bounds-preserving solutions. Numerical results show that the finite-volume residuals trained PICNN can replace the traditional prediction solver within the physics-preserving framework. Compared with conventional physics-informed neural networks (PINNs), the PICNN better captures local spatial interactions between each control volume and its neighboring
cells, while the finite-volume residuals accommodate discontinuous permeability fields and interfacial flux continuity.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Horizon-scale intensity and polarization images of rotating Konoplya-Zhidenko black holes with thick accretion flows
Bing-Bing Chen, Chen-Yu Yang, Guo-Ping Li et al. (+1 more)
We investigate the shadow and polarization images of a Konoplya–Zhidenko rotating non-Kerr black hole surrounded by a geometrically thick and optically thin
accretion flow. The
accretion flow is described by an analytical ballistic approximation
accretion flow model. The numerical results show that the shadow image exhibits two main features, an outer bright ring and an inner dark region. The former corresponds to higher-order images, while the latter is associated with
photon capture by the black hole. Increasing the deformation parameter $\eta$ does not significantly change the overall shape of the higher-order images, but it enlarges their size. Increasing either the
spin parameter $a$ or the observer inclination angle $\theta_o$ enhances the asymmetry of the higher-order images and makes the intensity on the left side much larger than that on the right side. This behavior is associated with frame dragging and the relativistic Doppler effect. In the polarization images, the degree of linear polarization is much smaller in the higher-order image region than in other regions, and the polarization vectors extend over the whole image plane. Within the framework used in this work, these results illustrate how the spacetime geometry and near-horizon
accretion dynamics jointly influence the intensity and polarization images.
Read the full abstract ▾
All authors Bing-Bing Chen, Chen-Yu Yang, Guo-Ping Li, Xin-Yun Hu
Materials Science
Effect of radially heterogeneous band gap collapse on formation of swift heavy ion tracks in Al2O3
Roman Voronkov, Danil Zainutdinov, Nikita Medvedev et al. (+1 more)
We estimate the effects of radial heterogeneity in the collapse of the electronic band gap on the damage in Al2O3 after impact of a swift heavy ion decelerated in the electronic stopping regime. The Monte Carlo code TREKIS describes the initial excitation of the electronic and ionic systems following the ion passage, while the density functional theory based molecular dynamics traces changes in the band structure in the ion track. This combination of methods enables us to compute the profile of energy transferred to the
lattice by the time of relaxation of the electronic excitation, accounting for the induced spatial inhomogeneity of the band structure around the ion trajectory. We demonstrate that impact of a 700 MeV Bi ion induces a transient metal-
semiconductor heterojunction in Al2O3: the metallization (the band gap collapse) occurs within a radius of about 2 nm from the ion trajectory. The band gap shrinks at distances of about 3-5 nm, while it remains almost unaffected at radii larger than 5 nm. Using this data, we estimate the atomic heating depending on the degree of band gap reduction at different radii from the ion trajectory. This approach refines the damage modeling, producing more pronounced discontinuous damage patterns along the ion path for all crystallographic directions compared to the model that assumes all the energy accumulated in the electron-hole ensemble is delivered to the atoms.
Read the full abstract ▾
All authors Roman Voronkov, Danil Zainutdinov, Nikita Medvedev, Alexander E. Volkov
Astrophysics of Galaxies
Exploring the Milky Way stellar disk. Carbon, nitrogen, oxygen, sulphur, potassium, and copper abundances for 714 F- and G-type dwarf stars in the solar neighbourhood
Thomas Bensby
[ABRIDGED] We aim to determine abundances of carbon, nitrogen, sulphur, potassium, and copper for 714 nearby F and G
dwarf and subgiant
stars, and to re-derive oxygen abundances using updated corrections for departures from the assumption of local thermodynamic
equilibrium. These elements extend the chemical inventory of our previous studies and provide new constraints on the relative enrichment histories of the
Galactic thin and thick disks. The alpha-element behaviour of oxygen is confirmed, with old
stars defining an enhanced sequence relative to young
stars. Sulphur closely follows oxygen, while potassium shows broadly alpha-like behaviour in [K/Fe] but residual trends relative to oxygen. Carbon and nitrogen show only modest separation in [X/Fe], but much clearer population differences in [X/O]. Copper displays a strong
metallicity dependence and clear separation between old and young populations when compared to oxygen. We also find that [O/Mg] is not constant, demonstrating that oxygen and magnesium provide complementary rather than interchangeable reference scales. Quantitative comparisons of all elements analysed in our studies show that carbon, oxygen, sulphur, and potassium rank among the most age-sensitive abundance ratios in the sample and provide strong discrimination between old and young disk populations. The new abundance measurements substantially expand the diagnostic power of this local
stellar sample. The results show that abundance ratios relative to oxygen, together with precise
stellar ages, reveal population differences that are partly hidden in traditional [X/Fe] trends. The expanded abundance inventory provides a homogeneous reference
dataset for studies of
Galactic chemical
evolution,
Galactic archaeology, and large spectroscopic surveys.
Read the full abstract ▾
Statistical Mechanics
Phase diagram of a double-occupancy cell model of a fluid with Curie-Weiss interaction
R. V. Romanik, O. A. Dobush, M. P. Kozlovskii et al. (+2 more)
A double-occupancy
cell model of a fluid with Curie-Weiss interaction is studied. First, we show that the model is isomorphic to the Blume-Capel model on a complete graph through a simple transformation from
spin to occupancy variables. We then investigate its phase behavior within the grand-canonical ensemble using a combination of analytical and numerical methods. Despite its simplicity, the model exhibits a remarkably rich thermodynamic behavior depending on the ratio between the local repulsive and global attractive interactions. We identify the regimes characterized by a single critical point, two distinct critical points, tricritical behavior, and triple-point formation. For sufficiently strong repulsion, the system possesses three fluid phases of different densities, leading to both gas-
liquid and
liquid-
liquid coexistence. The locations of the critical, tricritical, and triple points are determined, and the corresponding phase diagrams are constructed. These results demonstrate that the competition between double-occupancy repulsion and long-range attraction is sufficient to generate a complex phase behavior in a minimal multiple-occupancy
lattice-gas-like model.
Read the full abstract ▾
All authors R. V. Romanik, O. A. Dobush, M. P. Kozlovskii, I. V. Pylyuk, M. A. Shpot
Cosmology and Nongalactic Astrophysics
Strong Lensing Tomography: Double and pseudo multi-source plane strong gravitational lensing to constrain dark energy
Paras Sharma, Simon Birrer, Narayan Khadka et al. (+12 more)
Tomographic measurements of gravitational
lensing with different lens and source
redshift distributions contain crucial information about the universe's relative expansion rate, and hence dark energy. While this technique is well-established in weak
lensing, its application to strong
lensing has traditionally focused on Double Source Plane Lenses (DSPLs). However, DSPLs are exceedingly rare and fundamentally limited by the Mass-Sheet Degeneracy (MSD), a systematic uncertainty underexplored in previous literature. To overcome these challenges, we introduce Pseudo Double-Source Plane Lenses (PDSPLs): pairs of independent single-source plane lenses with self-similar deflectors. This generalizes the DSPL formalism to the $\sim 10^5$
galaxy-
galaxy lenses expected from LSST, Euclid, and Roman. Unlike true DSPLs, PDSPLs are free from the intermediate source mass problem by construction, eliminating the associated secondary MSD and the need for multi-plane ray tracing. We incorporate the deflector MSD into a hierarchical population model to forecast dark energy constraints in Flat $w_0w_a$CDM, showing that MSD severely degrades constraints from small DSPL samples and motivates our PDSPL statistical approach. Assuming unbiased Gaussian photo-z errors of $\sigma_z/(1+z)=0.03$, the mock LSST Y10 photometric sample yields $\sigma(w_0)\sim0.45$, constraining the population-mean MSD parameter and deflector power-law slope to $\sim2\%$. A prior $\Omega_m\sim\mathcal{N}(0.3,0.05)$, representing combination with external cosmological probes such as CMB, BAO, or SNe Ia, improves this to $\sigma(w_0)\sim0.29$, comparable to Stage III weak
lensing. The statistical advantage over smaller spectroscopic subsets (e.g., 4MOST) assumes unbiased photo-zs. Real-data use requires spectroscopic photo-z calibration and validation of how paired deflectors' mass-profile differences affect Einstein-radius ratios.
Read the full abstract ▾
All authors Paras Sharma, Simon Birrer, Narayan Khadka, Timo Anguita, Adam Bolton, Sydney Erickson, Phil Holloway, Tian Li, Phil Marshall, Dieu D. Nguyen, Graham P. Smith, Crescenzo Tortora, Bryce Wedig, the Strong Lensing Science Collaboration, the LSST Dark Energy Science Collaboration
Materials Science
Complex crystal structure prediction using ML-enhanced multi-minima iterative genetic algorithm
Ling Tang, Weiyi Xia, Tyler J. Slade et al. (+2 more)
Current machine learning (ML) approaches for materials discovery rely heavily on known structural databases, limiting their ability to identify entirely novel structure types. In this work, we develop a multi-minima iterative genetic
algorithm (MMIGA) that integrates an artificial-neural-network machine learning (ANN-ML) interatomic potential with an iterative, metadynamics-inspired penalty scheme. We demonstrate the robustness of this method on a complex ternary La-Co-Pb system, characterized by Co-Pb immiscibility and an intricate energy landscape. The ML-enhanced MMIGA successfully predicts the ground-state Pbam structure of the recently synthesized La4Co4Pb antagonistic-pair-phase, a novel structure missed by previous database-reliant ML predictions, while also identifying multiple metastable competing phases. Additionally, we challenged the MMIGA method to predict the structure of La5CoPb2 antagonistic-pair-phase, a new compound discovered during earlier attempts to synthesize the predicted phase La3CoPb. With only knowledge of the composition, our MMIGA approach successfully predicts the orthorhombic structure of La5CoPb2, producing an exact match with the structure independently determined by x-ray diffraction. By efficiently mapping both global minimum and relevant competing metastable states, this approach provides critical theoretical insights into phase selection for novel
quantum and
magnetic materials.
Read the full abstract ▾
All authors Ling Tang, Weiyi Xia, Tyler J. Slade, Paul C. Canfield, Cai-Zhuang Wang
Quantum Physics
Limitations of Error Model Approximations in Quantum Network Simulation
Julia Freund, Jorge Miguel-Ramiro, Julius Wallnöfer et al. (+1 more)
Efficient classical simulation of large-scale
quantum networks frequently relies on noise approximations, which consider a restricted set of operators to describe noisy channels and operations. In this work, we demonstrate how such simplified error models, such as Pauli twirling or reset channels, can lead to severe quantitative and qualitative discrepancies in protocol performance predictions. We analyze, in particular, how small differences can accumulate in iterative and sequential protocols such as
entanglement purification,
entanglement swapping, and repeater chains. Our results reveal that neglected error contributions can lead to important performance under- and over-estimations, measurement-outcome dependency, and oscillations in the fidelity, which are entirely overlooked by the simplified error model approximations. These results show that rigorous validation of complete noise architectures is indispensable for accurately predicting operational thresholds in future
quantum technologies.
Read the full abstract ▾
All authors Julia Freund, Jorge Miguel-Ramiro, Julius Wallnöfer, Wolfgang Dür
Materials Science
Geometry-Driven Magnetoelectric Coupling in Two-Dimensional Compensated Ferrimagnets
Peibo Xu, Yixuan Che, Haifeng Lv et al. (+2 more)
The magnetoelectric coupling in compensated magnets enables stray-field-free manipulation of
spin-splitting, holding great promise for spintronics, but inherently hindered by the
symmetry mismatch between spatial-inversion-broken ferroelectricity and time-reversal-broken
spin states. Here, based on a
symmetry-decoupled analysis of magnetoelectric coupling in compensated magnets, we establish a geometry-driven
spin-ferroelectric coupling mechanism in
bilayer breathing kagome
lattices. Within this
geometric framework interlocking the out-of-plane electric polarization with cooperative intralayer structural distortions, we demonstrate that polarization switching drives a deterministic reversal of the global
spin splitting. First-principles calculations on a prototype
bilayer Nb3Cl8 successfully validate this mechanism, demonstrating the switching of
spin-splitting states through an energetically feasible, asynchronous layer-by-layer transition pathway. Our proposed coupling originates from
lattice geometry and structural
symmetry, establishing a unique route toward switchable
spin splitting in compensated ferrimagnets.
Read the full abstract ▾
All authors Peibo Xu, Yixuan Che, Haifeng Lv, Xiaojun Wu, Jinlong Yang