Papers

We derive an exact coarse graining of generic Markov-jump processes into observable semi-Markov dynamics. Exact results for waiting-time distributions for jumps between observable states are derived and proved that these decompose into conditionally independent dwell and transition times. Dwell times are proved to be a local property of mesostates - they depend on the initial but not final state. Conversely, transition-path times depend on both states, trigger kinetic hysteresis, and, under suitable conditions on the hidden sub-network, are shown to obey a reflection symmetry. We characterize the stationary properties of the milestoned dynamics, prove its thermodynamic consistency, and demonstrate robustness to milestone positioning. Surprisingly, even in the limit of a time-scale separation rendering the observed dynamics approximately Markovian, the effect of kinetic hysteresis on the dissipation persists. A minimal example shows how the results lay the foundation for inferring affinities of hidden dissipative cycles from observations of transition-path times.

Structured baths can reshape transport fluctuations in mesoscopic quantum devices, yet a predictive criterion for when this enhances precision has been lacking. We propose a route towards such precision advantages by utilizing bath memory in coherent fermionic transport through a noninteracting quantum-dot chain. Using the Landauer-Büttiker formalism, we derive a dual impedance-matching condition that synchronizes the conductor mode splitting, boundary dissipation, and bath bandwidth, and sustains constructive multimode interference across the transmission window. The analytical predictions for the optimal bath bandwidths show excellent agreement with exact nonequilibrium Green's function calculations of the transport for Lorentzian, Gaussian, and Newns spectral densities. The prescription yields an optimal bath bandwidth at which the current Fano factor is minimized and the thermodynamic and kinetic precision coefficients are simultaneously enhanced beyond their Markovian limits. The alignment of the optimal precision regime with the experimentally accessible current Fano factor minimum thus provides a practical strategy for designing precision-enhanced transport in mesoscopic platforms such as semiconductor quantum-dot arrays and ultracold fermionic channels.

Distributed Acoustic Sensing (DAS) enables the repurposing of existing fiber-optic networks as ultra-dense, long-range seismic arrays for urban monitoring. However, constraints imposed by real-world fiber infrastructure topology and components limit its use for city-scale applications. Recent technological developments have paved the way for short-range, on-chip DAS. Assuming their availability, and based on a Graph Theory framework, we show that monitoring applications fall along a coverage spectrum with two critical thresholds that define three distinct regimes. Low coverage (<10%) can, with optimal design, resolve earthquake early warning, groundwater monitoring, geological mapping, and urban activity tracking. A percolation transition occurs at 51.6% coverage, beyond which the city effectively becomes fully covered and statistical traffic monitoring is possible. Only for effectively complete coverage, infrastructure monitoring, individual vehicle tracking, and pedestrian movement analysis become possible. Thus, privacy-related risks remain very low. We show and exemplify how, for metropolises around the world, an optimal sensing network can be designed for earthquake early warning, traffic monitoring, and urban activity tracking. This framework provides a near-future roadmap for deploying urban DAS networks as a backbone of smart city sensing.

Understanding the ionic transport and scaling behaviors in nanopore arrays is essential for bridging fundamental ion physics and blue energy applications. By fabricating sub-3 nm and sub-20 nm diameter nanopore arrays (NPAs) spanning from few pores to N ~ 10000, we systematically investigate ionic conductance, ion current rectification, and osmotic energy conversion. We report the ionic conductance scaling laws and nonlinearity with nanopore number, with stronger deviations from linearity at lower salt concentrations. Experimental evidence reveals that surface-charge-governed conductance and ion current rectification progressively weaken with increasing N and even vanish as the NPA scales up to N ~ 10000, resulting in an underestimation of surface charge density. In a sub-3 nm densely packed array (separation ~ 25 nm), the conductance exhibits an anomalous power-law dependence on concentration, deviating markedly from the single nanopore characteristics, attributed to the strong pore interactions. Furthermore, osmotic power harvesting measurements reveal a substantial reduction in power density upon scaling, with decreases of up to three orders of magnitude over the same range. To elucidate the underlying mechanism, we developed rigorous 3D modeling showing that the nonlinear behavior originates from concentration polarization at pore entrances and suppressed electric field across NPAs, collectively hindering ion transport. Our work provides insight into nonlinear ion-transport scaling and reveals fundamental differences between transport phenomena in single nanopores and nanopore arrays.

We describe version 5.0 of the Bottom-up Open-source Coarse-graining Software (BOCS) package. BOCS employs the force-matching variational principle to parameterize potentials for coarse-grained (CG) models directly from atomically detailed simulations. BOCS version 5.0 significantly extends previous versions by treating potentials that depend upon the local density (LD) around each particle, as well as potentials that depend upon the square gradient (SG) of this local density. We also describe a new package, PKG-BOCS, for simulating these potentials in LAMMPS. This software treats complex molecular topologies and provides considerable flexibility for defining the local density, as well as the LD and SG potentials. We present numerical calculations that provide physical insight into these potentials and demonstrate the accuracy of our implementation. Finally, we demonstrate that LD potentials can significantly improve the structural fidelity, thermodynamic properties, and transferability of CG models for water.

Topological semimetals have been proposed as electrocatalytic platforms because their surface states can connect adsorbate bonding with interfacial charge and spin responses. Here we investigate hydrogen chemisorption on NbP(001) using density functional theory and Wannier-based analyses of surface spectra, chemical bonding, and current-induced spin polarization. Comparing calculations with and without spin–orbit coupling allows us to examine nodal-line-derived surface states and Weyl Fermi arcs on the same surface. Spin–orbit coupling leaves the adsorption thermodynamics essentially unchanged but reorganizes how hydrogen bonds with the Nb- and P-derived surface orbitals. The characteristic Fermi-arc branches persist after adsorption, with H-derived spectral weight appearing within the same near-Fermi-level surface manifold. Together, these results show that chemisorbed hydrogen participates in the spin-textured surface electronic response. The accompanying adsorbate-local current-induced spin polarization points toward opportunities to connect surface chemistry with electrically controlled spin phenomena in topological semimetals.

Higher-order correlations are essential for understanding exotic phases and uncovering universal aspects of quantum dynamics. While inelastic neutron scattering provides well-established access to two-particle correlations, measuring correlations in solids involving more than two particles remains a major challenge. Focusing on magnetic excitations in the Heisenberg spin-$\frac{1}{2}$ chain, we demonstrate that resonant inelastic X-ray scattering (RIXS) can selectively probe multi-spin dynamical correlations by exciting distinct intermediate states through energy detuning. Through theoretical modeling, we isolate the two- and multi- spin responses, and establish that: (i) The resonant energies of the two- and multi- spin dynamical correlations are separated by $\approx \frac{3}{4}J$; implying that the multi-spin part of the cross-section comes from intermediate states that contain spin flips; (ii) The spectral weight of the two-spin channel exhibits a Lorentzian resonant energy profile consistent with a single dominant electronic configuration, whereas the multi-spin channel response shows a Gaussian-like profile, implying contributions from multiple intermediate spin configurations. These characteristics are reproduced by exact diagonalization of the $t-J$ Hamiltonian, which further reveals that the widths of Lorentzian and Gaussian resonant energy profiles depend primarily on core-hole lifetime ($\Gamma/2$) and $\frac{2J}{\Gamma}$, respectively. Controlled access to multi-spin dynamics, using RIXS energy detuning as a knob, can open new pathways to explore many-body dynamics in quantum materials.

Electron-beam irradiation is an established route to create site-controlled, room-temperature single-photon emitters (SPEs) in hexagonal boron nitride (hBN), but two aspects remain underexplored: how the electron dose governs the properties of the resulting single emitters, and how the emission behaves when the host is heated above room temperature. Here, we create emitters deterministically with a focused electron beam and confirm single-photon emission across three independent flakes, with $g^{(2)}(0)=0.09$, $0.12$, and $0.16$. We map the single-emitter response (yield, spectrum, lifetime, and photon purity) as a function of electron dose, identifying an optimal window for high-purity single emitters. Consistent with recent cryogenic studies, we assign the bright room-temperature feature near 575 n to the phonon sideband (PSB) of a green–yellow emitter whose zero-phonon line (ZPL) lies near 548 nm. Temperature-dependent photoluminescence measured in situ under real-time from room temperature to 300 degrees C reveals a thermal quenching that is fully reversible upon cooling, in contrast to the irreversible annealing-induced degradation reported elsewhere, indicating that transient heating does not permanently damage the centers. These results add quantitative dose control and above-room-temperature operation to the toolbox for deterministic hBN quantum-light sources.

Superconducting domes in strongly correlated electronic systems are often accompanied by charge density waves and peculiar features in the electronic structure. The appearance of a pseudogap, in particular, and its relation to charge density waves remains insufficiently understood. Here, we investigate the electronic Green's function of the underdoped $t$-$t'$-$J$ model of the cuprate superconductors using tensor network algorithms for finite temperature dynamics on cylinders of width $4$. We find the prominent momentum differentiation, the hallmark of the pseudogap, to be strongly dependent on $t'$, which develops into a momentum-dependent opening of a gap upon decreasing temperature, consistent with the formation of a Fermi arc at intermediate temperatures. The nodal gap around ${\bf k}=(\pi/2,\pi/2)$ closes and fills with increasing temperature as coherent stripe order melts into a regime of fluctuating charge clusters.

Topology has emerged as a central concept for classifying phases of matter. The situation is especially rich in periodically driven systems, where anomalous Floquet topological phases break the usual bulk-boundary correspondence between Chern number and edges modes of two-dimensional systems. These phases were so far realized by periodic modulation of the tunneling elements at frequencies near-resonant with respect to the system's bandwidth, a regime where Floquet heating plays a significant role in interacting systems. Here we show that such anomalous Floquet topological phases can also be realized by means of an adiabatic protocol, where the system is always in the instantaneous ground state of the cyclic path in parameter space, like in a Thouless charge pump. We experimentally realize such a state using ultracold atoms in a hexagonal lattice where we adiabatically modulate the lattice geometry, including the sublattice offset. To infer the topology, we use the micromotion area in real-space, which was recently identified as a proxy for the winding number. This way of realizing anomalous phases avoids resonant Floquet heating and imperfect loading into the target state. We demonstrate the robustness of the adiabatic construction by observing the anomalous phase even in the presence of mean-field interactions of magnitude comparable to all other energy scales. These findings are promising for engineering novel topological states in a more robust way.

We build and commission a time-of-flight photon spectrometer (TOFS) for scanning tunneling microscopy luminescence (STML). We obtain the spectrum by exploiting the wavelength dependent refractive index of a long dispersive optical fiber that converts photon arrival times into wavelength information; blue photons are delayed more than red photons. The setup uses a pulsed excitation source, either laser flashes or voltage pulses, to launch the photons from the junction into a single photon detector. The TOFS calibration can be performed and transferred to the STML setup from a separate benchtop experiment using pulsed light sources with known wavelength. We verify the TOFS during STML operation by simultaneously recording luminescence from the Ag-Ag(111) plasmon using a conventional grating spectrometer. Our experiments show that the TOFS is a straightforward and cost-effective addition to existing STML setups with good performance in the near-infrared range. The TOFS is compatible with a drop-in replacement of the single photon detector such as a superconducting nanowire single photon detector or even bolometers that may expand the useful spectral range beyond the abilities of current STML setups.

Dynamical manipulation of Majorana zero modes and their unambiguous distinction from topologically trivial states remain paramount challenges in topological quantum computation. Here, we propose a phase-biased altermagnetic Josephson junction as a versatile platform for generating and controlling Majorana corner configurations. Moving beyond conventional global parameter tuning that merely toggles the topological phase in situ, our platform utilizes the macroscopic superconducting phase difference and the Néel-vector orientation as independent control knobs to dynamically reshape the boundary mass. This synergistically enables the deterministic spatial relocation of Majorana corner modes (MCMs) among selected corners of a fixed device geometry. Crucially, this spatial reconfiguration yields a definitive experimental fingerprint: a control-correlated conductance switching. As the MCMs are relocated, the quantized zero-bias peak perfectly emerges at the target corner while simultaneously vanishing at the initial one. This macroscopically phase-locked spatial correlation effectively eliminates false positives from trivial Andreev bound states, establishing a control-correlated diagnostic and a promising route toward future Majorana braiding architectures.

Recent ultracold-atom experiments have observed ferromagnetic correlations in a geometrically tunable Fermi–Hubbard lattice at intermediate densities. Motivated by subsequent theoretical work that connected the low-density limit of the same model to the Mueller–Hartmann mechanism for itinerant ferromagnetism, we investigate the stability of ferromagnetism across a broad density range using the T-matrix approximation, a controlled approach in the dilute limit. We reproduce the ferromagnetic regime observed experimentally at intermediate densities and systematically compare finite-size and thermodynamic-limit calculations in the dilute regime. We find that the low-density ferromagnetic phase reported for the one-diagonal hopping lattice is strongly suppressed with increasing system size and disappears in the thermodynamic limit, indicating that it originates from finite-size effects. By contrast, low-density ferromagnetism remains robust in the square-lattice Hubbard model with hopping along both diagonal directions. We show that this qualitative difference cannot be explained by the degeneracy of the band minima alone, which occurs in both models. Instead, it is controlled by the singular behavior of the density of states at the band bottom: a weak divergence is insufficient to stabilize ferromagnetism, whereas a much stronger quasi-one-dimensional singularity supports a fully polarized ground state even in the dilute limit. Our results demonstrate that band-minimum degeneracy alone is not sufficient for low-density ferromagnetism and that the nature of the band-bottom density-of-states singularity ultimately controls its stability.

Parametric driving is a powerful route to amplification and nonlinear control in nanomechanical resonators, but its signatures can be ambiguous because standard dc electrical readout does not directly reveal the frequency of motion. Here we resolve this ambiguity by measuring the motional frequency of a vibrating carbon nanotube independently of the drive frequency. We operate the nanotube as an electromechanical mixer and detect microwave sidebands using a low-noise superconducting amplifier. This frequency-resolved readout distinguishes direct motion of the first overtone from parametric motion of the fundamental, even when the corresponding drive frequencies nearly coincide. The two mechanisms are further separated by their drive-power dependence. Beyond conventional parametric resonance at $2f_0$, we observe responses to driving at $3f_0$ and $4f_0$, consistent with high-order parametric excitation associated with nonlinear stiffness terms.

Bond disorder in frustrated pyrochlore antiferromagnets can give rise to fundamentally different quantum ground states depending on the nature of the local magnetic moments. Here, we show that the bond-disordered $J_{\rm eff}=\frac{1}{2}$ pyrochlore antiferromagnet NaCdCo$_2$F$_7$ realizes an unconventional spin-glass-like state with continued dynamics, in stark contrast to its isostructural $S=\frac{1}{2}$ NaCdCu$_2$F$_7$ counterpart. High-field magnetization and Co $L_{2,3}$-edge XAS/XMCD establish spin-orbit-entangled $J_{\rm eff}=\frac{1}{2}$ Co$^{2+}$ moments with a substantial unquenched orbital contribution, consistent with local $XY$ anisotropy seen in the isostructural Na$A''$Co$_2$F$_7$ ($A''$ = Ca, Sr) analogues. $\mu$SR and $^{23}$Na NMR measurements reveal progressive slowing of spin fluctuations below $\sim10$ K, culminating in a partially frozen state with persistent low-temperature dynamics that deviates from a canonical spin glass. Comparison with the isostructural bond-disordered pyrochlore NaCdCu$_2$F$_7$, which realizes a random-singlet state, reveals a fundamentally different response of spin-orbit-entangled Co$^{2+}$ moments to bond disorder. These results identify spin-orbit coupling as a key ingredient governing the fate of bond-disordered frustrated pyrochlore magnets.

Chaotic quantum systems can retain spatial memory through scarred eigenstates, but whether these static structures control scrambling remains unclear. This work establishes a morphology-resolved connection between scarred eigenstates and eigenstate-resolved OTOCs in a peanut-shaped quantum billiard. Scalar localisation diagnostics, including differential entropy and continuum participation ratios, detect anomalous concentration but discard spatial architecture. A scale-normalised density overlap, in contrast, directly compares probability density profiles, revealing families of orthogonal eigenstates with nearly identical spatial morphology. Comparing the complete OTOC time traces of these orthogonal eigenstates reveals that morphological recurrence has dynamical content: moderate density overlap yields no universal prediction, whereas strongly recurring morphologies exhibit nearly identical OTOC growth and saturation. Thus, scarred structures act as spatial templates for operator growth, not merely static violations of ergodicity. This morphology-resolved framework turns eigenstate shape into a quantitative predictor of scrambling and provides a scale-controlled diagnostic of weak ergodicity breaking in quantum chaos.

The three-dimensional (3D) Ising model is a foundational model in statistical physics and critical phenomena, yet its analytical intractability has long impeded the precise determination of universal critical exponents. While high-precision estimates have been obtained through classical numerical methods and conformal bootstrap techniques, a direct quantum simulation of the 3D Ising criticality remains challenging, requiring nontrivial connectivity, sufficient system size, and high spectral resolution. In this work, assisted by the state-operator correspondence of conformal field theory, we perform a digital quantum simulation of the 3D Ising critical exponents using a multiply-connected 9-qubit superconducting quantum processor with a Platonic lattice geometry. Employing an extended variational quantum eigensolver equipped with a phase-based loss function, we variationally prepare the low-energy eigenstates of the transverse-field Ising model on a cubic Platonic lattice encoded in an 8-qubit register. The four lowest eigenenergies are extracted via Fourier-transform analysis and high-precision numerical fitting, agreeing with the exact diagonalization values up to +/- 0.001. The resulting scaling dimension Delta_epsilon = 1.5850 and critical exponent nu = 0.7067 match well with theory.

Thermoelectric (TE) materials enable the direct conversion of heat into electricity and are attractive for sustainable energy applications. For practical deployment, TE materials must combine high efficiency with low cost, non-toxicity, and scalability. In this work, we optimize the TE performance of low-cost and robust Fe$_2$VAl-based full-Heusler compounds through high-entropy engineering: a synergistic combination of heavy-element doping and controlled off-stoichiometry results in substitutional disorder on all lattice sites, triggering one of the lowest lattice thermal conductivities, $\kappa_\text{L}\sim2.3$ W m$^{-1}$ K$^{-1}$, reported so far for full-Heusler systems. The resulting materials exhibit improved values of the average figure of merit $zT_\text{ave}\approx 0.3$ from $300-500$ K. To demonstrate reproducibility and technological relevance, a full TE module (TEM) based on the optimized alloys was fabricated and characterized. Scaled-up material batches were synthesized by hot pressing, exhibiting TE properties in excellent agreement with laboratory-scale samples, with only slightly increased resistivities in absence of post-annealing treatments. Owing to the excellent mechanical workability of Fe$_2$VAl-based materials, the TEM legs were directly brazed onto copper electrodes, enabling robust module fabrication. A ($6\times 6$)-leg TEM was assembled and systematically characterized. The device exhibits the highest output power and one of the highest conversion efficiencies reported to date for Fe$_2$VAl-based generators over the broad temperature range of $300-673$ K, underscoring the potential of this material system for scalable TE energy harvesting.

This work presents a novel digital image correlation (DIC) framework for full-field measurements of displacement, strain, and damage, based on a phase field (PF) approach. The idea is to take advantage of the ability of the PF method to track complex crack morphologies and to provide a natural way in DIC to perform damage and crack measurements from experimental speckle images, in addition to displacement and strain fields. Moreover, incorporating the damage variable into DIC can improve the displacement accuracy near the crack tip, and can avoid the need of user-defined masks when dealing with cracked samples, which is advantageous when cracks become complex and the manual application of masks becomes challenging. The theoretical formulation of the proposed framework, namely PF-DIC, was presented in detail in the paper, along with a finite element implementation. Numerical examples have demonstrated the capability of the proposed PF-DIC in terms of capturing different types of cracks while providing similar measurement accuracy to that of masked DIC. Additionally, it is shown that the PF-DIC can be easily adapted to selectively identify critical cracks under specific loading conditions or mechanisms for damage assessment and diagnostic purposes. The proposed DIC framework can be used to characterize material defects, support structural health monitoring, and enable a potential unification of PF simulations and experimental fracture measurements

The exact time-space correlation function of the $1D$ Glauber-Ising model, quenched to temperature $T=0$ and on a semi-open lattice of finite size $N$, is obtained. This also allows to deduce the exact empty-interval probability of the dual $1D$ coagulation-diffusion process on a periodic finite ring and to reproduce the long-time decay of the particle concentration. These results are consistent with the generic expectations of dynamical finite-size scaling theory.

The amplitudes of light modes in a homogeneous interface layer are investigated around the critical conditions (CC) in a total reflection geometry. CC occur when the normal wave vector vanishes; the resulting divergence upon variation of the angle of incidence is characterized by a critical exponent -0.5. Absorption replaces the divergence with a finite peak whose width and height are derived analytically. The high relevance of the amplification for Evanescent Wave Dynamic Light Scattering (EWDLS) is demonstrated using published experimental data. The relation to surface plasmon resonance (SPR) is briefly discussed. An outlook connects the amplitude divergence to a critical analysis of the Distorted Wave Born Approximation (DWBA) presented in a companion paper.

This study investigates the potential of high-speed nanoindentation in collaboration with data analytics and phase volume fractions to achieve micromechanical characterization of heterogeneous rocks. While micromechanical characterization can be performed using mechanical testing alone, integrating chemical analysis-such as elemental mapping techniques-provides essential phase identification. This enables more accurate interpretation of phase-specific mechanical properties. However, incorporating chemical analysis increases the complexity of the process. Hence, this study proposes data-driven micromechanical characterization and mapping of heterogeneous rocks based primarily on mechanical data and limited dependence on chemical analysis. In this study, Mancos shale rock is analyzed using high-speed nanoindentation to determine the mechanical properties at the microscale. Subsequently, a suite of unsupervised statistical learning techniques, such as Uniform Manifold Approximation and Projection (UMAP) with k-means Clustering, Gaussian Mixture Model (GMM), Dirichlet Process Mixture Model (DPMM), and Density-Based Spatial Clustering of Applications with Noise (DBSCAN), are applied to the nanoindentation data. Additionally, an automated image processing and segmentation technique was developed and tested. The results from each technique have been systematically compared against the conventional chemo-mechanical approach using two metrics: weighted error and spatial error. Based on the results, UMAP with k-means clustering is the most appropriate technique, while DBSCAN, DPMM, and image segmentation techniques are more suitable as secondary approaches. This study demonstrates the capability of high-speed nanoindentation combined with machine learning techniques for micromechanical characterization with reduced analytical complexity and improved workflow efficiency.

The Riviera model mimics a densifying settlement along the coastline. In the lattice version, houses are built sequentially in empty sites with the constraint that every newly built house has at least one empty neighboring site. The distribution of clusters of adjacent houses does not obey a closed set of evolutionary equations, but the void-cluster-void distribution does. We compute the latter and extract the cluster distribution from it. In the jammed state, when all voids have length one, the cluster distribution takes a simple closed form and exhibits factorial decay with cluster size. For finite systems, we use a static approach that directly analyzes jammed states. If the coastline is a finite segment, we determine the statistics of the number of empty sites in the jammed state (the average, variance, and higher cumulants). We also study a continuum version in which houses are built along the line, subject to a minimum separation from at least one neighboring house.

Boundary conformal field theory (BCFT) contains universal data that are usually accessed microscopically by imposing spatial boundaries on the lattice. In non-Hermitian many-body systems, however, changing boundary conditions can qualitatively reorganize spectra and eigenstates, and their boundary criticality remains elusive. Here, we introduce a periodic-chain spectroscopy to extract universal boundary quantities, such as the Affleck-Ludwig $g$-factor, directly from non-Hermitian bulk-critical quantum chains, avoiding the need to engineer microscopic open boundaries and circumventing subtle boundary effects in non-Hermitian systems. We illustrate our method with a $\mathcal{PT}$-symmetric Ising realization of the real nonunitary Yang-Lee CFT and reveal a universal negative excited-to-ground ratio, which has no counterpart in unitary critical theories and provides a microscopic signature of nonunitarity. For the genuinely complex fixed points of the non-Hermitian five-state Potts chain, we extract intrinsically complex boundary coefficients, verify the exact Kramers-Wannier duality relation, and select the consistent analytic-continuation branch of the boundary states. Our results establish a route to nonunitary BCFT universal data using only knowledge of the bulk critical system, opening a window into non-Hermitian boundary criticality.

Countless biological and physical systems experience fluctuations that exhibit non-trivial temporal correlations. The Unified Colored-Noise Approximation (UCNA) is a framework providing an approximate description of such stochastic dynamics with colored noise, valid in the limits of vanishing and infinite correlation time of the noise. We first pinpoint and address some criticalities in its original derivation, recasting the result through a time-scale separation procedure. By using our approach, we derive the next-to-leading order correction to the dynamics in both limiting regimes, and highlight the relevant physical scalings of these approximations. Our result helps frame the limits of validity of both the original and the refined formulas, especially in comparison with those derived through different approximation procedures. We show our findings in two paradigmatic examples, a quartic potential and a stochastic logistic growth with multiplicative noise.

We present a structural analysis of glasses formed by mix of SiO2 and B2O3 glass formers with soda and lime modifiers (Na2O and CaO), which provide a good testing ground for Stochastic Agglomeration Theory. With local structural units properly identified, we can reproduce the one-parameter glass transition temperature T_g (z) curve for the family of (0.75-z) SiO_2 + 0.15 Na_2O + 0.10 CaO + z B_2O_3 glasses studied experimentally by Smedskjaer et al.

The growth temperature of directly grown boron-compound masks on patterned sapphire can modify the local accessibility of the underlying sapphire surface and thereby alter the subsequent nucleation behavior of GaN. In this work, we investigate how ammonia-borane-derived boron-compound masks grown at different temperatures shape the GaN nucleation landscape within circular SiO$_2$ openings during the initial stage of epitaxial lateral overgrowth. The preferential nucleation position of GaN changes systematically with mask growth temperature: masks grown at 700–750$^\circ$C produce pronounced edge-biased distributions, whereas higher-temperature masks lead to more inward-shifted and spatially sparse GaN domains. Quantitative analysis of the GaN areal fraction, the number of visibly isolated domains, and the radial distribution of domain centers shows that the mask growth temperature affects both the amount of GaN coverage and the spatial arrangement of GaN domains within each opening. The nonmonotonic change in the number of visibly isolated domains is interpreted as a consequence of competition between reduced lateral merging and reduced effective substrate accessibility, rather than as a direct measure of the number of active nucleation sites. Kinetic Monte Carlo simulations reproduce the essential experimental trends by varying the effective density and radial distribution of substrate-accessible sites. These results suggest that the growth temperature of directly formed boron-compound masks provides a practical means of reshaping the intra-opening GaN nucleation landscape by controlling the spatial distribution and effectiveness of local pathways through which GaN precursors can access the underlying sapphire surface.

Defining magnon topology in strongly frustrated magnets is often hindered by the absence of a simple harmonic magnon vacuum at zero field. Within a classical-spin ground-state search followed by linear spin-wave theory (LSWT), we demonstrate that a representative triangular-lattice K-Gamma-Gamma' model in a dominant-Gamma exchange regime has an in-plane-field-selected compact, noncoplanar seven-site order. This field-selected state provides a controlled classical reference state and hosts magnon bands with field-tunable Chern numbers. Increasing the field drives a Dirac-like band touching that transfers Berry curvature between the fifth and sixth bands, altering the Chern vector from (0, 1, 0, -2, 1, 0, 0) to (0, 1, 0, -2, -1, 2, 0). This topological transition reorganizes the band-resolved thermal Hall conductivity, driving the total $\kappa_{xy}(T)$ through a near-zero crossing once the upper bands are thermally populated. The dynamical structure factor places roughly half of the coherent spectral weight on the Chern-active branches, offering a spectroscopic route to identify the topological branches. These results define a controlled semiclassical benchmark for magnon topology in this pure nearest-neighbor exchange model.

Two-dimensional crystals with densely packed atoms exhibit a range of emerging properties, particularly a wide variety of excitonic behaviors. Thickness-variable layered chromium trihalides with finite surface recombination sites provide an ideal system for understanding how excitons confined in octahedral ligand fields migrate on nanometer length scales, a regime that defies conventional transport probes. In this work, we demonstrate that Cr3+-derived photoluminescence in CrCl3 is spectrally thickness-independent, but its relaxation dynamics are strongly sensitive to thickness and temperature, thereby indicating significant activated migration. A diffusion-coupled surface recombination model reveals an effective out-of-plane diffusivity of 4.5 x 10-6 cm2/s for the ligand-field excitons and a diffusion activation energy of 130 meV. The latter is comparable to the reorganization energy independently estimated from optical Stokes shifts, suggesting that exciton transport is coupled to local lattice relaxation. Furthermore, we show that the relaxation dynamics can be systematically tuned by either enhancing or suppressing surface recombination through controlled surface reactions or encapsulation. This work not only reveals the nanoscopic transport of localized ligand-field excitons but also establishes a spectroscopic transport probe applicable to various 2D materials.

We propose a symmetry-resolved optical probe of intrinsic loop-current chirality in moiré materials, with twisted bilayer graphene as a representative realization. Interlayer interference generates chiral electronic circulation on triangular plaquettes, giving rise to an intrinsic geometric chirality that enters the second-order response through a $C_3$-selected angular harmonic of the Berry curvature and can be isolated by the orbital-angular-momentum difference $\Delta\ell$ of interfering optical vortex beams. When moiré $C_3$ symmetry is preserved, the intrinsic contribution appears in the $\Delta\ell=3$ channel of the helicity-dependent dc photocurrent, whereas $C_3$-breaking perturbations activate additional channels. These results establish angular-momentum-resolved nonlinear optics as a route to probing geometric chirality in moiré and other symmetry-engineered quantum materials.