Papers

We study the effect of pitch and yaw on the bifurcations of the laminar flow past an Ahmed body, a bluff body of width-to-height ratio $W/H=1.2$ and length-to-height ratio $L/H=3$. When perfectly aligned with incoming flow, its wake first undergoes pitchfork bifurcations leading to a static vertical or horizontal deflection, and becomes oscillatory via a secondary Hopf bifurcation at larger Reynolds number $Re$. As commonly observed for imperfect pitchfork bifurcations, any small misalignment preselects one of the steady states, referred to as the "primary" branch, at low $Re$. At larger $Re$, a disconnected "secondary" branch is born via a saddle-node bifurcation. Here, we investigate the effect of misalignment using three-dimensional computations. We first focus on pure pitch and pure yaw with linear stability analysis. In both cases, the secondary branch becomes unstable as soon as the incidence exceeds a small value. In the pure yaw case, the primary branch becomes unstable via a horizontal Hopf bifurcation, destabilised by yaw. In the pure pitch case, the primary branch sees the crossover of vertical Hopf and horizontal pitchfork bifurcations, destabilised and stabilised by pitch, respectively. This motivates use of DNS to study this nonlinear competition, already observed for aligned Ahmed bodies in ground proximity. We then study the effect of simultaneous yaw and pitch with a weakly nonlinear analysis. The competition between the two stationary modes gives rise to rich bifurcation diagrams, allowing us to predict the number of stable solutions and phase space trajectories between different states

Blended data acquired via simultaneous-source seismic exploration conventionally require post-acquisition deblending, which typically relies on the coherence differences introduced by firing time delays (time dithering). To reduce the dependency of the deblending process on these time dithers, a novel joint constraint based on the synchrosqueezed transform and the Radon transform is proposed, operating directly in the common-shot gather (CSG) domain. Specifically, by exploiting the differences in propagation directions of the blended signals within CSGs, the synchrosqueezed transform is first employed for an initial iterative separation to extract individual sources directly from the continuous records. Once the majority of the valid signals are separated, the Radon transform is subsequently applied in further iterations to suppress the residual blending interference, thereby preventing amplitude damage to the effective signals. Compared to conventional non-CSG deblending methods, this approach bypasses the reliance on time-delay coherence differences, thus enabling real-time quality monitoring of individual sources during field acquisition. Furthermore, compared to other existing CSG-based separation techniques, the proposed joint-constraint iterative framework demonstrates superior performance when handling complex data. Applications on both synthetic and field blended datasets demonstrate that high-fidelity data separation can be successfully achieved independently of the time-dithering constraints. Finally, because the proposed method operates completely independently across different CSG slices, it is highly amenable to parallel computing, facilitating the efficient processing of massive datasets within a short timeframe.

Non-equilibrium systems challenge the standard definitions of phases and phase transitions from equilibrium statistical physics. For example, in active fluids continuous energy injection at the microscale drives the system intrinsically out of equilibrium. This process gives rise to collective turbulent-like flows whose onset remains poorly defined. Here we show that the onset corresponds to an activity-driven phase transition, marked by the emergence of a system-spanning critical backbone of vorticity nodal lines. Combining two independent experiments, microtubule kinesin active nematics and dense suspensions of swimming bacteria, with large-scale simulations of active nematics and fluctuating nematohydrodynamics, we show that this transition occurs at a critical activity threshold. Below this threshold, vorticity structures are fragmented and vortex centres form only finite, mechanically floppy networks. Above this threshold, the nodal lines of the vorticity field percolate and the vortex centres form a rigid, system-spanning cluster. The geometric transition is characterised by the emergence of critical percolation statistics for the vorticity nodal lines, while the mechanical transition reflects the emergence of a vortex configuration that shows rigidity percolation statistics for vortex centres. We show that both transitions are absent in equilibrium systems that obey detailed balance, demonstrating that the transition is intrinsically non-equilibrium. These results establish an experimentally accessible definition of fully developed active turbulence, linking microscopic activity to macroscopic geometry, and mechanics of living systems.

We construct the first known fault-tolerant scheme for injecting states into quantum error-correcting codes with constant space and time overhead. That is, we construct a family of constant-rate quantum error-correcting codes for which a set of bare physical qubits can be injected, i.e. fault-tolerantly encoded, into a code block. Similarly, a code state can be ejected, i.e. fault-tolerantly decoded, back into bare physical qubits. We show that these injection and ejection procedures succeed under circuit-level locally stochastic noise, while incurring just a small constant probability of corrupting each qubit, which is unavoidable for bare physical qubits. We also show how to perform fault-tolerant error correction and code-state preparation under locally stochastic noise. All of our gadgets can be implemented with constant quantum circuit depth (i.e. are single-shot), and with a number of physical qubits growing linearly with the number of logical qubits, assuming the ability to run polynomial-sized noiseless classical circuits on the side. We construct our quantum codes by taking a high-dimensional hypergraph product of classical LDPC codes, which in turn are a simplified version of Spielman's linear-time encodable codes (STOC'95). As our resulting product codes are only resilient to physical errors occurring with non-uniform probabilities across qubits, we then show how to concatenate with inner codes of various sizes to obtain fault-tolerance against uniform noise.

For the three-qubit Shifts unextendible product basis (UPB), the minimum product-state expectation value $\lambda_{\mathrm{Shifts}}=1-3\sqrt6/8$ of the UPB projector is known, and four attaining product states were exhibited previously. We determine the complete equality set over all complex product states and prove that it consists of exactly eight product rays: two rays invariant under cyclic permutation of the three qubits and two cyclic orbits of size three. The proof combines exact phase analysis, a Gröbner-basis classification of all 28 finite real stationary points, and a complete treatment of the projective boundaries. Crucially, the eight contact rays span the full three-qubit Hilbert space, whereas the four previously known rays do not. The complete equality classification therefore establishes that the associated projector witness satisfies the spanning criterion and is optimal in the sense that no nonzero positive semidefinite operator can be subtracted while preserving block positivity. As a corollary, for the white-noise family $\rho(p)=(1-p)\rho_{\mathrm{Shifts}}+p\mathbb I/8$, where $\rho_{\mathrm{Shifts}}$ is the complementary-projector Shifts state, the same witness detects entanglement for $p<2-3\sqrt6/4\approx16.29\%$.

Accurate oscillator strengths for doubly and triply ionised heavy elements are required for quantitative spectroscopy of hot subdwarfs, but available data remain sparse. We present new radiative data for As III, Se III, Hf IV and Tl IV, calculated with the pseudo-relativistic Hartree-Fock (HFR) method including core-polarization effects and semi-empirical adjustment of radial parameters to experimental energy levels. Independent multiconfiguration Dirac-Hartree-Fock (MCDHF) computations were also performed for As III, Hf IV and Tl IV, while published MCDHF data were adopted for Se III to assess the reliability of the HFR oscillator strengths. The largest discrepancies between the two approaches are mainly associated with weak transitions, strong cancellation effects, or significant gauge disagreement. For strong transitions satisfying the adopted reliability criteria, we found a good agreement between the oscillator strengths obtained by both methods. The new data have already been applied to the spectra of the heavy-metal hot subdwarfs LS IV-14$^\circ$116 and EC 22536-5304, enabling abundance determinations for As, Se, Hf, and Tl and providing additional lines for future spectroscopic studies.

Quantum information complexity (QIC), introduced by Touchette [Touchette, STOC 2015], has been shown to be one of the most powerful methods for proving quantum communication complexity and has also been shown to be equal to amortized quantum communication complexity. Unfortunately, QIC is generally hard to analyze because it is a sum of quantum conditional mutual information terms, which are difficult to estimate. In this work, we introduce a new variational approach, the information potential, for analyzing QIC and proving quantum communication lower bounds inspired by the resolvent representation for quantum relative entropy. This approach connects the QIC of individual messages to a quadratic form, making it more amenable and thus enables us to bound the cumulative positive increments of the potential throughout an interactive quantum protocol by its QIC. Lower bounds on the growth of the potential therefore translate into lower bounds on both QIC and quantum communication complexity. As an application, we give an optimal $\Omega(1/r)$ lower bound on the QIC of the two-bit $\mathsf{AND}$ function as well as an optimal $\Omega(n/r)$ lower bound on the quantum communication complexity of $r$-round Set-Disjointness, answering an open problem in~[Braverman, Garg, Ko, Mao, Touchette FOCS 2015]. Moreover, we further prove a direct-sum theorem for bounded-round quantum communication complexity of Set Disjointness. With the tight bound on the QIC of $\mathsf{AND}$ function, we further establish a nearly tight tradeoff for the asymmetric quantum communication complexity of $\mathsf{Set} \mathsf{Disjointness}$: $(q_A+1)(q_B+1)=\Omega(n)$, where $q_A$ and $q_B$ denote the total numbers of qubits sent by Alice and Bob, respectively.

This paper presents a systematic approach to plan and execute a time-efficient sailboat trajectory under the challenging stochastic wind conditions for automated sailboat. Unlike deterministic scenarios, stochastic wind disturbances introduce challenges such as gust unpredictability, directional shifts, and fluctuating apparent wind speeds. These characteristics render traditional planning methods, such as Line-of-Sight (LoS) and waypoint approaches, to be ineffective and not applicable, as they often rely on static or deterministic environmental models. This paper proposed a new path planner and controller based on nonlinear model predictive control method. It is compared with a baseline planner and controller. A Lie-algebraic analysis of the sailboat dynamics is carried out to identify the operating conditions under which the vessel loses first-order control authority in surge, and these conditions are embedded as constraints in the NMPC. Finally, simulation results are provided to validate the proposed framework.

A recent work studied quantum two-prover one-round proof systems $\mathsf{MIP}^{\psi}[\text{poly},O(1)]$. It showed that when $\psi$ is a noisy EPR state with quantum maximal correlation $\rho_{\max}(\psi)<1$, the resulting complexity class is equivalent to $\mathsf{NEXP}=\mathsf{MIP}$. In contrast, $\mathsf{MIP}^{\text{EPR}}[\text{poly},O(1)]=\mathsf{RE}$. Not all noise, however, decreases quantum maximal correlation. A basic example is dephasing noise: a dephased EPR pair retain quantum maximal correlation $1$. In this work, we remove the constant-answer restriction and establish a complete dichotomy for $\mathsf{MIP}^{\psi}[\text{poly},\text{poly}]$, where the provers share arbitrarily many copies of EPR pairs subject to unital noise. Equivalently, let $\psi$ be a fixed two-qubit state with maximally mixed marginals. We prove that \[\mathsf{MIP}^{\psi}[\text{poly},\text{poly}]=\mathsf{MIP} =\mathsf{NEXP},~\text{if $\psi$ is separable or $\rho_{\max}(\psi)<1$};\]\[\mathsf{MIP}^{\psi}[\text{poly},\text{poly}]=\mathsf{MIP}^{\psi}[\text{poly},O(1)]=\mathsf{RE},\text{if $\psi$ is entangled and $\rho_{\max}(\psi)=1$.}\] Beyond the complexity classification, our proof develops two techniques that may be useful more broadly in quantum information and quantum complexity. First, we introduce a positivity-preserving low-degree approximation framework for quantum measurements: instead of truncating positive operators directly in the Pauli basis, we approximate suitable square-root factorizations, simultaneously achieving low Pauli degree, positivity, and global control over an entire POVM. Second, we develop a new dimension-reduction method, called Pauli folding, for low-degree positive operators. Its key ingredient is an almost-multiplicativity theorem for randomized Pauli hashing, which allows noncommutative products, positivity, and normalization to survive compression with controlled error.

A long standing goal of magnetochemists is to be able to control ordering temperatures through compositional engineering. Here we report the synthesis of a perovskite oxide with twelve cations accommodated within a single phase solid solution, AM7O$_3$, A = La$_{\frac{1}{5}}$Sm$_{\frac{1}{5}}$Gd$_{\frac{1}{5}}$Nd$_{\frac{1}{5}}$Dy$_{\frac{1}{5}}$ (A5), and M7 = Ti$_{\frac{1}{7}}$Cr$_{\frac{1}{7}}$Mn$_{\frac{1}{7}}$Fe$_{\frac{1}{7}}$Co$_{\frac{1}{7}}$Ni$_{\frac{1}{7}}$Cu$_{\frac{1}{7}}$. Bulk magnetometry measurements for A5M7O$_3$, as well as for A = La, Gd and La$_{\frac{1}{2}}$Gd$_{\frac{1}{2}}$, show that all these compounds magnetically order as ferrimagnets between 89 and 115 K. We find that the magnetic properties are influenced by considering a combination of the size disorder parameter alongside the A-site cationic radii and valence electrons.

Quantum algorithms and quantum hardware are advancing towards a promising paradigm for scientific applications. However, translating domain-specific problems into executable hybrid quantum-classical workflows remains a significant barrier for application researchers due to the required expertise in quantum algorithms, nuances in quantum programming, and hardware-aware system integration. At the same time, AI and primarily LLM based agents are increasingly capable of interpreting natural-language intent, reasoning over complex workflows, and translating high-level objectives into executable code and building computational pipelines. In this work, we introduce SQD Agent, an LLM-based agentic framework that translates natural-language user intent into executable workflows for Quantum Chemistry applications where algorithms from the Sample-Based Quantum Diagonalization (SQD) family are used. By automating this translation, SQD Agent reduces the level of human expertise and configuration overhead required, thereby simplifying experimentation in hybrid quantum-classical settings for application researchers new to quantum. SQD Agent adopts a modular and extensible architecture that supports seamless integration of heterogeneous quantum backends, classical solvers, and workflow components, ensuring adaptability to rapidly evolving quantum ecosystems. The framework further incorporates interactive capabilities for on-demand profiling, bottleneck analysis, resource optimization, intelligent result caching, and convergence visualization. Key features include quantum chemistry experiments, error mitigation on real quantum hardware, together with analysis of candidate mitigation schemes in terms of their potential error-recovery behavior and computational budget, helping users understand their practical trade-offs and decide which strategies to explore in subsequent experiments.

We develop a theory of phase separation in fluids conserving higher-order multipole moments of a scalar density, and investigate the resulting coarsening dynamics, nucleation, and interfacial fluctuations. We find that higher-order conservation laws slow the relaxation of all phenomena investigated, whereas nonequilibrium violations of the fluctuation–dissipation theorem suppress density and interfacial fluctuations while hindering nucleation. Simulations support these predictions.

Practical O-band quantum-dot (QD) mode-locked comb sources must combine wide flat-top bandwidth, low radio-frequency (RF) timing noise, error-correctable bare-line modulation, and feedback tolerance, yet these functions are usually optimized separately and their relation to comb-formation dynamics remains unclear. Here we map the gain-current/saturable-absorber-bias plane of a simple two-section InAs/GaAs QD mode-locked laser to resolve distinct application-specific regimes. A low-injection, high-reverse-bias regime produces 0.80 ps pulses, consistent with amplitude-modulated operation, whereas a high-injection, intermediate-bias regime yields a 16.16 nm (2.75 THz) flat-top comb with 110 lines and a 14.98 ps extended waveform, consistent with a stronger frequency-modulated contribution. To our knowledge, this is the broadest reported 3 dB bandwidth among QD mode-locked comb sources. At a separate low-noise bias, the beatnote exhibits a 0.58 kHz Lorentzian linewidth and a 41.6 fs integrated timing jitter over the 4 to 80 MHz range, to our knowledge the lowest reported for a high-channel-count O-band QD passive comb. In isolator-free 25 Gb/s NRZ transmission, all 94 carriers across a 13.73 nm 3 dB band remain below the 7 percent HD-FEC threshold. Using all 110 carriers at the maximum-bandwidth bias gives a projected aggregate rate of 2.75 Tb/s. At a separate feedback-test bias, broadband mode locking is preserved and, beyond approximately -28 dB feedback, the RF beatnote enters a feedback-stabilized regime whose linewidth is reduced 42-fold. Thus, short-pulse, broadband, low-noise, transmission-ready, and feedback-stabilized operation occupy distinct selectable regions rather than a single universal optimum. This regime-resolved map links QD comb-formation physics to isolator-free, terabit-scale O-band interconnects.

Nonlinear transformations are important in quantum machine learning and other quantum numerical applications, which can be reduced to the implementation of element-wise polynomials through polynomial approximation. Existing works establish the feasibility of transformations and improve query or auxiliary-space efficiency, but circuit depth remains linear in scale with degree. In this work, we develop a resource-tunable quantum framework that decomposes a $(2^d-1)$-degree polynomial into $m$ lower-degree factors, with $m$ controlling the degree of parallelism. By varying $m$ from $1$ to $2^d-1$, the framework provides a trade-off among query complexity, additional gate complexity, ancilla count, and normalization, ranging from a binary-tree implementation to a $\mathcal{O}(n+d)$-depth construction with highly parallel oracle queries that match the query lower bound. The effects of polynomial approximation and implementation errors are further analyzed. We demonstrate the framework for nonlinear activation functions such as sigmoid and tanh, as well as pixel-wise image transformations.

Physics-informed computational methods usually optimize parameters within a functional representation whose structure is fixed in advance. This work proposes a Physics-Informed Method of Group Data Handling (PI-GMDH), in which representations of coupled physical fields are progressively constructed during solution. Candidate functional directions are evaluated through the first variation of the complete physical and observational objective, introduced in packages, and followed by block-coordinate damped Gauss-Newton coefficient optimization. The framework is demonstrated with tensor-product Chebyshev functions on the incompressible Navier-Stokes equations using a two-dimensional time-dependent Taylor-Green benchmark. Under the tested configuration, adaptive PI-GMDH reached validation and held-out test losses of 5.299e-19 and 5.296e-19 with 204, 201, and 175 active functions for u, v, and p. Complete degree-by-degree and all-terms PI-GMDH variants, together with selected PINN and KAN reference configurations, are used to examine the effect of structural construction policy. The results show that, for this controlled synthetic benchmark, selective progressive construction can provide a favorable combination of accuracy, representation size, and wall-clock time. The comparison is illustrative rather than a claim of universal superiority over alternative physics-informed approaches.

We develop a unified formulation of leading soft photon theorems for nondegenerate static spherical horizons. By fixing the photon mode normalization from the horizon symplectic form, we obtain a common angular soft factor whose sign follows from the boundary orientation. We determine the geometric coefficients in the local angular and momentum representations for a chosen radial normalization. The charge balance includes horizon endpoint data and contributions from other boundaries. This formulation brings black hole and cosmological horizons into a common description. Applying the same construction to Yang-Mills fields yields the corresponding tree-level soft gluon theorem. These results identify the common soft structure underlying different horizon geometries.

We present the conceptual framework of the Astronomical Hub (AstroHub), a unified platform combining various optical instruments at a single observatory. Its major approach lies in arranging conditions for research groups to install telescopes and equipment and participate in joint projects. AstroHub is planned to integrate Virtual Observatory (VO) tools, FAIR data principles, and a telescope network to create a powerful and attractive ecosystem for both robust near-Earth object (NEO) monitoring and diverse deep space research. We provide an overview of the AstroHub development directions in the case study of the Assy-Turgen Observatory.

In an adiabatic evolution, the wave function follows the path of ground states $|\Phi_0(s)\rangle$ of a Hamiltonian $H(s)$ as $s$ is tuned from $0$ to $1$. The geometry of this adiabatic path is described by quantities such as its length $L=\int_0^1 \|\partial_s |\Phi_0(s)\rangle\|\,ds$ and its total curvature $K$. This geometry affects the evolution time $T$. For instance, $T$ is at least of order $L/\Delta_*$, where $\Delta_*$ is the minimum energy gap over $s\in[0,1]$. The traditional approach gives $L=O(\Delta_*^{-1/2})$ and $K=O(\Delta_*^{-1})$, which are loose in many cases. We improve these bounds by using $\mu_<(\gamma)$, the width of the region in $s$ on which the gap is below $\gamma$. The gap profile is in width class $p$ when $\mu_<(\gamma)$ falls at least as fast as $\gamma^{1/p}$. A typical avoided crossing is in width class $p=1$, which gives $L=O(\sqrt{\log \Delta_*^{-1}})$ and $K=O(\log \Delta_*^{-1})$. A profile in width class $p>1$ gives power laws with exponents $(p-1)/(2p)$ for $L$ and $(p-1)/p$ for $K$. The width class also bounds the evolution time. At $p=1$ we have $T=O(\Delta_*^{-2})$ with a schedule that advances $s$ at a constant rate, and $T=O(\Delta_*^{-1})$ up to a polylogarithmic correction with a schedule that traverses the path at a constant geometric speed. The bounds on $L$ hold for any twice continuously differentiable $H(s)$, and the bounds on $K$ for affine $H(s)$. We also prove the tightness of scaling of $L$ in $\Delta_*$ for every integer $p\ge1$, and the scaling of $K$ at $p=1$. We demonstrate the bounds on the adiabatic Grover search, the XXZ spin chain, and molecular electronic Hamiltonians.

In this paper, we investigate a viscous regularization for the BGK model of the Boltzmann equation and its hydrodynamic limit. First, we establish rigorous convergence toward the viscous Euler equations, by exploiting bounds derived from spatial Fisher information. We then analyze the formal derivation of the Euler equations with an entropy inequality for both single-and multi-species case, comparing our results against symmetric hyperbolic thermodynamically compatible theory.

We investigate inflationary dynamics and isotropization in a phantom-field model with five families of potentials on Bianchi I, Bianchi III, and Kantowski-Sachs backgrounds. First, the general properties of the model are established, and Heusler's proposition is extended. To address the limitations of this proposition, a powerful dynamical-systems approach is then adopted to provide a comprehensive analysis of the cosmological evolution. In total, 87 critical points are identified and their properties are analyzed. Throughout the analysis, we emphasize the physical interpretation of the mathematical results and aim to provide a thorough explanation of the rationale behind the choice of each mathematical tool and variable. Within this framework, the conclusions of Collins and Hawking and of Burd and Barrow are revisited, and several challenging questions with deep conceptual implications are posed and discussed.

We give collective tomography protocols for quantum states and channels with known symmetries, using random purification and dilation to reduce learning to pure-state estimation. For states commuting with a compact-group representation with multiplicities $m_\lambda$, the optimal copy complexity is $\Theta((\sum_\lambda m_\lambda^2+\log\eta^{-1})/\varepsilon^2)$ for sufficiently small trace-distance error $\varepsilon$ and failure probability $\eta$ for the nontrivial case $\sum_\lambda m_\lambda^2>1$. For $G$-covariant channels with finite-dimensional unitary representations of a compact group $G$, parallel $\widetilde{O}(D_G/\varepsilon^2)$ queries achieve a diamond-distance error $\varepsilon $ at fixed success probability $2/3$, where $D_G$ counts the real parameters of covariant Choi operators before imposing trace preservation. For permutation-covariant channels on $k$ qudits of fixed local dimension $d$, at sufficiently small fixed error and fixed success probability $2/3$, we obtain the optimal query scalings $\Theta_d(k^{d^4-1})$ for diamond distance and $\Theta_d(k^{d^4-d^2})$ for Choi trace distance. Furthermore, we resolve an open problem in quantum tomography of constructing efficient quantum circuits that approximate the Hayashi measurement for optimal pure-state estimation. We encode states in the symmetric subspace into bosonic occupation modes, realize the measurement by heterodyne detection and normalization, and approximate this procedure on qubits using the quantum Hermite transform. Combined with our symmetry-compatible purification and dilation circuits, this yields query-optimal and gate-efficient learners of permutation-covariant states and channels with gate complexity $O_d(\mathrm{poly}(k,\varepsilon^{-1},\log\eta^{-1}))$.

Atomically precise graphene nanoribbons (GNRs) have electronic properties tunable through their width and edge structure, making them promising building blocks for nanoscale electronics and optoelectronics. Their integration into devices also requires understanding how the supporting surface and neighbouring ribbons affect their vibrations. Here, we use temperature-dependent Raman spectroscopy to compare five configurations of 9-armchair GNR arrays differing in substrate, alignment and coverage. Transferring the same unaligned film from Au to a Raman-optimised Al$_2$O$_3$-coated support reduces the measured $D$- and $G$-mode redshift rates by about 80%. This reduction is consistent with a substantial thermoelastic contribution. The fitted strain and anharmonic contributions depend on the assumed thermal expansion and strain transfer. Compared with the low-coverage array, the dense aligned Au array has higher extrapolated reference frequencies ($\omega_0$). On first heating, its $G$-mode linewidth decreases and then increases, forming an unusual intermediate-temperature minimum. The $D$-mode linewidth shows a similar, less pronounced variation. These findings establish substrate choice and array arrangement as routes to engineer nanoribbon vibrations, extending control beyond the atomic structure defined during synthesis.

We investigate the phase diagram and critical properties of the two-dimensional classical XY model with interactions decaying as $1/r^{2+\sigma}$. At the marginal case $\sigma=2$, we show that the low-temperature phase is characterized by logarithmic quasi-long-range order (log-QLRO), where spin correlations decay as a power of the logarithm of distance, $C(r)\sim(\ln r)^{-\eta_\ell}$ with $\eta_\ell\propto T$, and that the transition into this phase is a continuous transition beyond both the Ginzburg-Landau-Wilson paradigm and the Berezinskii-Kosterlitz-Thouless mechanism. Our analysis combines a near-exact Gaussian spin-wave theory, an adiabatic renormalization-group analysis, and large-scale Monte Carlo simulations. We find that the $1/r^4$ interaction logarithmically modifies the spin-wave stiffness kernel as $\gamma(k)\simeq\kappa k^2\ln(1/k)$, which suppresses vortex proliferation and gives rise to a nonuniversal correlation-length exponent $\nu\propto1/\sqrt{2\pi\kappa}$. Crucially, our simulations reveal that the short-range algebraic QLRO phase is unstable against a weak long-range perturbation for $\sigma\le2$. These results establish $\sigma=2$ as the crossover boundary between the long-range and short-range universality classes and provide a critical evaluation of recent theoretical proposals.

Qiu, Guan, and Yu conjectured that in the even-order Kaleidoscope Yang–Baxter equation every word $\Lambda T^{k_1}\Lambda\cdots T^{k_M}\Lambda$, built from a square-zero matrix $\Lambda$ and integer powers of a shift $T$ of order $N$, vanishes once $M\geq N/2$. We prove this for every even $N\geq4$ and every complex parameter $u$ with $u\neq0$ and $u^N\neq1$, and show that the bound is sharp. For $M=N/2-1$ we determine exactly which words are nonzero; each of them has rank two. After block reduction, the factors associated with the intervening powers of $T$ lower a common flag of length $N/2$ by at least one step. The spectral idempotents of $T$ then give a presentation of the algebra generated by $T$ and $\Lambda$ by paths between levels, in which two paths compose only when the level changes monotonically. This algebra is independent of $u$, has dimension $N^2-N+2$, and is a pullback of two incidence algebras. Its radical is generated by $\Lambda$ and has nilpotency index $N/2+1$, and the algebra has infinite global dimension and infinite representation type. Replacing powers of $T$ by arbitrary functions of $T$ gives exact rank formulas and, for $N\geq6$, rank-one elements in the top radical power. Finally, four conditions on a filtered pair of operators over an arbitrary field recover the threshold and the radical; none of them can be omitted.

Characterizing entanglement in quantum materials through experimentally accessible observables remains a central challenge. Quantum Fisher information associated with sums of one-site spin operators provides one route by linking entanglement to measurable magnetic response functions. Extending this approach to local composite observables requires new entanglement bounds. Here we establish a rigorous bound for the total nearest-neighbour vector chirality of periodic spin-$1/2$ chains with an even number of sites. The quantum Fisher information per spin cannot exceed $k+1$ for any $k$-producible state, so exceeding this bound certifies entanglement depth of at least $k+1$. Combining infinite density-matrix renormalization group and thermal pure quantum-state calculations, we demonstrate multipartite entanglement encoded in vector-chiral correlations at zero and finite temperatures in an extended $J_1$-$J_2$ XXZ chain. The spin-current coupling between vector chirality and electric polarization offers, in principle, access to this witness through dielectric loss spectroscopy in multiferroic magnets, extending entanglement diagnostics beyond dipolar spin correlations.

We show that periodically modulating the self-propulsion of active particles in an asymmetric potential can both enhance rectified transport and reverse its direction, even when the propulsion speed itself never changes sign. Current enhancement results from the nonlinear response of active transport to propulsion strength, whereas current reversal emerges from the interplay between activity-induced spreading and passive relaxation. Our theoretical analysis identifies the regimes governed by these distinct rectification mechanisms and predicts the finite range of driving periods over which current reversal occurs. These results establish cyclic activity as a means of dynamically controlling rectified active transport, with potential applications to the selective sorting of active particles.

We derive the classical logarithmic soft graviton theorem for the scattering of massive particles in four-dimensional asymptotically flat spacetime using a position-space analysis of the Weyl tensor. Starting from the Iyer-Damour multipole solution in harmonic gauge, we obtain an infinite tower of antipodal matching relations across spatial infinity for all five Newman-Penrose Weyl scalars, at linear order in $G$ and for the leading matter-induced logarithms at order $G^2$. We connect the relation relevant to the logarithmic soft theorem to the radiative-gauge formulation of Boschetti-Campiglia and Compère-Robert. We then compute the required asymptotic fields directly from scattering data, including matter contributions and nonlinear effects responsible for graviton drag. Combining these results with the Newman-Penrose evolution equations yields position-space proofs of the classical leading and logarithmic soft graviton theorems, independently confirming the frequency-space derivation of the latter originally performed by Laddha and Sen.

In atmospheric neutrino analyses, the usable zenith-angle range is generally restricted to upward-going events to suppress the cosmic-ray muon background. Motivated by the exceptionally low underground muon background at the China Jinping Underground Laboratory (CJPL), we investigate whether extending the zenith-angle acceptance can improve the sensitivity of atmospheric neutrino oscillation measurements. An existing 1725 m$^{3}$ liquid-nitrogen volume is adopted as the basis of a simplified detector model, in which the accepted zenith-angle range is extended from $\cos\theta_{\mu}\in[-1,0]$ to $\cos\theta_{\mu}\in[-1,0.3]$, and the projected oscillation sensitivity is evaluated for a 10-year exposure. The atmospheric neutrino flux is estimated by interpolating standard flux predictions as a function of geomagnetic latitude. Neutrino interactions in the surrounding rock and the liquid-nitrogen volume are simulated for neutrino energies of $E\ge0.1$ GeV, followed by secondary-particle transport and geometry-based event selection. For the benchmark oscillation parameters $\Delta$m$^{2}_{32}$ = $2.4\times10^{-3}\ \mathrm{eV}^{2}$ and $\sin^{2}\theta_{23}=0.5$, the neutrino-induced muon flux from the surrounding rock is estimated to be $(3.65 \pm 1.00)\times10^{-13}$ cm$^{-2}$ s$^{-1}$ sr$^{-1}$, corresponding to a muon yield of $(0.13 \pm 0.034)$ day$^{-1}$ in the 1725 m$^{3}$ liquid-nitrogen volume. Three-flavor neutrino oscillations are incorporated into a Poisson-likelihood $\chi^{2}$ analysis to evaluate the sensitivity to the oscillation parameters. Extending the usable zenith-angle range leads to a clear improvement in the projected oscillation sensitivity at the 90% confidence level over a 10-year exposure.

Miniaturizing magnonic circuits and increasing their processing speed require spin waves with progressively shorter wavelengths. However, conventional directional couplers rely on the dynamic dipolar interaction between spatially separated waveguides, which rapidly weakens in the exchange-dominated regime. As a result, their coupling length increases as the spin-wave wavelength decreases, limiting further device miniaturization. Here, we introduce an exchange-mediated directional coupler by replacing the nonmagnetic gap between two waveguides with a magnetically modified YIG spacer. The spacer provides a continuous exchange pathway and preserves the splitting between the symmetric and antisymmetric modes at large wavenumbers. We develop an analytical model to describe this mechanism and verify it using micromagnetic simulations. Based on this concept, we design a straight coupler without curved access waveguides, with a footprint of only 400 nm * 30 nm. For a spin-wave wavelength of approximately 100 nm, the device transfers approximately 98% of the normalized output power to the target waveguide. Its performance remains nearly unchanged even when the damping of the spacer is strongly increased. These results overcome the short-wavelength limitation of dipolar couplers and provide a route toward highly integrated magnonic circuits for information processing.

In this paper, we study nonlinear Schrödinger equations arising in the study of Markovian open quantum systems. These equations are derived from the normalization of linear stochastic Schrödinger equations. First, we prove the global well-posedness of the linear equation in the energy space, which is less regular than the usual space for this equation. Then, we show the indistinguishability of solutions to the nonlinear SPDE under a relaxation of the usual monotonicity assumption. Finally, by proving the pathwise uniqueness and normalizing the solutions to the linear equation, we are able to prove the well-posedness of solutions to the required class of nonlinear stochastic equations.