Papers

We formulate a theory of pseudogap formation generated by dynamic finite nesting vector ${\bf Q}$ fluctuations with characteristic oscillation frequency $\omega_0$, and damping $\gamma$. Starting from a Hamiltonian describing electrons coupled to a classical Gaussian random field, we introduce the double - series representations of the single - particle Green's function within an Abelian (commuting) approximation to the exact SU(2) time evolution of the pseudogap problem. The resulting propagator naturally acquires a generalized Bogoliubov structure in which every stochastic scattering history is characterized by an effective dynamic gap, leading to a coherent superposition of dynamically broadened sidebands with complex Poisson weights. A central result of the theory is the emergence of a dynamically generated decoherence scale $\Gamma_{\rm eff}$ governing the crossover between two qualitatively different pseudogap regimes. For $\omega_0>\Gamma_{\rm eff}$ the fluctuating field is resolved coherently and the double-series representation provides a controlled description of dynamic sideband formation. Conversely, when $\Gamma_{\rm eff}\gtrsim\omega_0$, coherence is progressively lost and the theory crosses over to the quasistatic fluctuating - gap regime described by the exact continued-fraction solution. The coherent and quasistatic descriptions are therefore interpreted as two complementary asymptotic limits of the same microscopic dynamic pseudogap model. The detailed results of numerical calculations for electron spectral density and density of states supporting our approach are presented for different sets of model parameters confirming the general picture of this crossover.

Ensemble nitrogen-vacancy (NV) centers in diamond enable robust vector magnetometry in unshielded environments, yet deployment remains bottlenecked by complex calibration and a reliance on external data references. Conventional statistical machine learning requires an exorbitantly large volume of training data and suffers from severe simulation-to-reality mismatches. To address this, we introduce a physics-guided hybrid machine learning framework that embeds the Zeeman splitting directly into the learning pipeline. Our physics-guided model significantly reduces the average tracking error demonstrating a 372-fold precision improvement over purely statistical baselines. Furthermore, our hybrid architecture pairs a sparse physical measurement with scalable synthetic data generation, seamlessly incorporating real-world hardware non-idealities. When deployed to decode uncalibrated, raw experimental ODMR data, our framework delivers exceptional predictive accuracy for the scalar magnetic field. This work paves the way toward self-calibrated sensors while establishing a machine learning training method applicable to other data-scarce physical systems

We extend the Luttinger-Ward free energy functional to disordered superconductors and superfluids with arbitrary scattering mechanisms, including both impurity disorder and the presence of interfaces. The disorder is taken into account within the self-consistent $t$-matrix approximation, thus allowing for arbitrary impurity scattering strengths. It is shown that both the interface and the impurity scattering self-energy appear in the functional only implicitly, through self-consistently determined fermionic propagators. The free energy functional is formulated in terms of a generalized integral in the complex energy plane, which encompasses formulations both in terms of retarded/advanced propagators and in terms of Matsubara Green's functions by appropriately choosing the integration path. It can be applied, e.g., to spatially non-uniform and hybrid systems, triplet and other unconventional condensates, and strongly-correlated Fermi liquids. A particularly useful formulation in terms of the quasiclassical propagators is applied to unconventional non-uniform singlet and triplet superconductors and superfluids in an external Zeeman magnetic field.

Functionalities of ferroelectric materials are governed by the spatial organization and coupling of polarization, strain, lattice rotation, and structural order accessible via atomically resolved scanning transmission electron microscopy (STEM) images. Quantitative interpretation of atomic-resolution STEM data has conventionally relied on locating atomic columns and converting their fitted coordinates into local structural descriptors. Here, we develop a field-based approach in which atomic-resolution images are represented by spatially varying latent Bragg fields, whose amplitudes and phases provide continuous maps of crystalline order, lattice displacement, strain, rotation, and mode-specific residual structure. The observed atomically resolved images are decoded from the latent fields. We apply this framework to image series of Sm-substituted BiFeO3 spanning 0-20% Sm and crossing the composition-driven boundary between the R3c ferroelectric phase and the orthorhombic, nonpolar Pnma phase. Conventional atom-resolved parameterization is used as an independent validation, showing that reconstructed Bragg amplitude tracks local atomic-column intensity and that field-derived shear reproduces unit-cell angular distortions obtained from atom fitting. The combined analysis reveals a systematic evolution from extended ferroelectric domains at low Sm concentration, through the appearance and growth of localized regions with period-doubled Pnma order at intermediate compositions, to a connected Pnma-dominated state at high Sm content. The period-doubled order is accompanied by enhanced shear and lattice rotation and by progressive reorganization of the ferroelectric domain structure. These results establish latent-field reconstruction as a physically interpretable complement to atom finding and provide a unified framework for resolving composition-driven phase evolution in ferroic materials.

It is well established that in time-dependent quantum systems, integrability preserving time-dependent interaction strengths are identical to the renormalization group (RG) trajectories of the corresponding static model when time `$t$' in the driven model is identified with the logarithm of the cutoff `$\log\Lambda$' of the static model. We refer to this integrability preserving driving as the RG protocol. In this work we extend the class of time-dependent integrable models to include non-Hermitian quantum models with time-dependent interaction strengths. Using the recently formulated generalized Bethe ansatz framework [P. R. Pasnoori, Phys. Rev. B 112, L060409 (2025)], we show that the constraints imposed by integrability are more general: The interaction strengths of the static model that flow in the RG follow the respective RG trajectories in the corresponding time-dependent model as described above. In addition, the interaction strengths of the static model that are RG invariant can either be constant or have a specific time-dependence in the corresponding time-dependent model which is constrained by integrability. Thus we establish that in the context of time-dependent non-Hermitian systems, the set of integrability preserving time-dependent strengths is larger than the set corresponding to the RG protocol.

Additive friction stir deposition (AFSD) is attractive for naval and aerospace sustainment because it enables high rate, solid state near net shape fabrication and repair of large metallic components. However, full part scale thermomechanical simulations remain computationally demanding because of the moving heat source, progressive material deposition, and evolving geometry. This work presents a physics-based and geometry-aware reduced order framework for rapid prediction of temperature and residual stress fields in part scale AFSD builds. The transient temperature field is represented using a tensor product quadratic B spline basis on a fixed Cartesian background grid, while arbitrary part geometries are embedded using a signed distance function (SDF) and a smooth material indicator. Residual stresses are recovered through an inherent strain formulation in which an offline thermo elasto plastic representative volume element (RVE) simulation supplies a calibrated eigenstrain field that is spatially scaled using the part scale peak temperature history. The thermal formulation is evaluated against published numerical and experimental AFSD data and two sample multilayer builds are simulated as demonstrations. For a four layer thin-wall build, the thermal solution requires approximately 22 s compared to 806 s for the finite element model, while the complete thermo-mechanical framework requires approximately 86.4 s compared to 2,406 s. For a larger 20 layer hollow cylindrical build, the reduced order thermal simulations requires 0.148 to 0.152 h compared with 1.8 h for the finite element model, corresponding to thermal speed-ups of approximately 11.8 to 12.2 times. The complete thermomechanical framework requires 0.346 h compared to 5.4 h for the full finite element analysis, providing an overall speed-up of approximately 15.6 times.

High-temperature vacuum annealing near a metal's melting point drives controlled grain growth, but it normally requires an expensive turn-key vacuum induction furnace. We retrofit a bare commercial radio frequency (RF) induction generator with computer power control through LabVIEW, dual-wavelength optical temperature feedback, and a high-vacuum quartz-tube chamber with inert-gas backfill. A machined graphite crucible doubles as a susceptor, an RF-absorbing element that heats the specimen it encloses. The only requirement is a monotonic analog power-control input, so the retrofit transfers between generators. Our reference build uses a 6 kW solid-state generator. Surprisingly, nickel annealed in this system produced high-quality electron backscatter diffraction (EBSD) patterns with zero specimen preparation. Samples went directly from the furnace to the electron microscope without grinding, polishing, or etching. The EBSD maps indexed hundreds of equiaxed grains delineated by deep thermal grooves. A modified sample assembly extends the furnace to ceramics that do not couple to the RF field. It coarsened yttria-stabilized zirconia (YSZ) grains in 45 min at 2500{\deg}, compared with 228h at 1600{\deg} in a conventional box furnace. For a fixed configuration, the power-temperature calibration is linear ($R^2$ = 0.991) from 1200 to 1400{\deg}. Eight 12h nickel anneals at 1200{\deg} reproduced their soak temperature to 1201.2 $\pm$ 1.3{\deg}, and 40h soaks at 1325{\deg} remained stable. Complete design files, a bill of materials, control software, and data are openly available. This gives laboratories an affordable route to near-melting-point annealing with direct anneal-to-EBSD characterization.

We address a recent Comment [I. Nikolov et al., arXiv:2608.13579 (2026)] proposing crystalline mosaicity as an alternative explanation for the asymmetric nuclear magnetic resonance (NMR) spectra reported in our study [S. Suetsugu et al., Nat. Phys. 22, 1251–1256 (2026)]. We show that this scenario requires substantial temperature- and site-dependent distributions of crystallographic orientations and additional site-dependent distributions of the electric field gradient (EFG) asymmetry parameter, none of which follow from ordinary crystalline mosaicity. We therefore conclude that crystalline mosaicity cannot account for the observed site-selective spectral asymmetry and does not provide an alternative explanation for the central spectroscopic observation underlying our interpretation.

How many memories can a local learning rule protect, and what fixes the number? Physical learning rules train resistive networks through local measurements, and the standard rules conserve a mass-like function of the conductances, a law whose general form was posed as an open problem with the expectation that no useful solution theory exists. We answer it, in the direction the expectation ran against, and the answer is a capacity theory. The Tellegen identity behind the conserved mass localizes: the feedback state is pinned to zero at the inputs, so every sector of the circuit that the input electrodes separate carries its own private conserved mass, by an argument consuming only Kirchhoff's law and that boundary condition, hence valid for arbitrary nonlinear branch laws. The number of independent sector masses is a topological property of the circuit, bounded by the number of output electrodes. An untrainable element can destroy the mass of its own sector and of no other, which says where fixed nonlinear components may be placed; per-edge learning rates select which functionals are conserved and never how many; and adjoint coupled learning, which clamps its outputs before measuring, drains every output-carrying sector at a rate set by the squared output multipliers. In linear circuits we then classify the identities: exact rational computation over all 502 circuits on up to five vertices with two inputs and one or two outputs, and hundreds of larger ones, yields a closed-form count, proved on that family and conjectured in general, with the sector statement a theorem at every circuit size. The anticipated series-parallel polynomial laws appear as exactly the series-class cubic differences, and the number the opening question asks for is a budget: one designed mass per sector, the differences the topology donates, and one broadcast scalar for each protected functional beyond.

Even for tension-dominated fracture propagation, porous materials may deform plastically adjacent to the propagating fracture. As is common for porous materials, existing phase-field models typically employ a non-associative flow rule for plasticity, and a Helmholtz free energy based on strain and fluid pressure. This work revisits the hydromechanically coupled formulation of the phase-field model for fracture in poro-elastoplastic media by analyzing the strength surface and fracture driving force. Our analyses show that these common choices of flow rule and free energy will lead to a discontinuous strength surface across the tension-compression transition. A non-associative flow rule introduces a jump at the strength surface, while treating fluid pressure-rather than fluid content-as the independent variable in the Helmholtz free energy omits a coupling term from the phase-field driving force, also breaking continuity. Incorporating an associative Drucker-Prager flow rule and this omitted coupling term ensures a continuous strength surface and the accurate fracture driving force. The proposed model exhibits improved accuracy in hydromechanical responses when compared against the analytical solution of the Kristianovich-Geertsma-de Klerk hydraulic fracturing benchmark. Numerical simulations of hydraulic fracturing and biaxial compression in poro-elastoplastic media show that the model can reproduce both shear-dominated fractures induced by mechanical disturbance and tension-dominated fractures driven by fluid injection in saturated porous media.

We derive a channel-resolved Lee-Huang-Yang correction and construct an extended GrossPitaevskii model for one-dimensional polar spin-1 quantum droplets. The fluctuation contribution separates into density and spin channels, which supports self-bound droplets even when the spinindependent mean-field interaction is repulsive. Stationary solutions exhibit a continuous crossover from soliton-like to flat-top droplets, accompanied by saturation of the chemical potential and peak density as the particle number increases. Within the parameter range examined here, linear Bogoliubov analysis together with weak-perturbation dynamics supports the stability of both droplet types. A quadratic-Zeeman quench reveals a finite-size crossover in breathing dynamics and distinct nonequilibrium roles of the density and spin fluctuation channels. Representative head-on collisions further show that the finite-size crossover modulates phase-sensitive nonlinear scattering, with in-phase impact producing coalescence-like central retention and out-of-phase impact favoring quasi-elastic separation. The analysis clarifies how density and spin fluctuations shape equilibrium structure and nonequilibrium response in low-dimensional polar spinor droplets.

Vacuum ultraviolet photoemission spectroscopies are very information-rich experiments, but due to their surface sensitivity, data are often collected on an initially uncharacterized surface. Traditional raster-grid approaches for locating optimal measurement regions can be time-consuming. In this work, we introduce AARDVARK, a generalizable framework for sample exploration that leverages dimensionality reduction and Gaussian process regression to guide initial sample searches in spatially-resolved photoemission experiments. By utilizing UMAP as a target for a Gaussian process, the algorithm efficiently identifies boundaries of spectroscopically distinct regions, dynamically adapting to variations in sample characteristics. The algorithm enables real-time decision making in measurement selection, optimizes data acquisition, and presents a robust framework for future autonomous sample exploration in photoemission experiments.

Nonlinear multiphoton conversion processes are theoretically and experimentally challenging systems in quantum optics and related areas. These phenomena bring remarkable quantum properties and can be of fundamental relevance in quantum information and computation applications. Based on recent experimental advances and the possible uses in generalized three-photon squeezing, we investigate degenerate three-photon parametric down-conversion generated inside a cavity fed by a classical pump. In addition, we consider that the process is stimulated by a coherent driving mode and subjected to dissipation by spontaneous emission of the cavity. A treatment using phase-space methods and stochastic differential equations is applied and the stability conditions of its steady states are found. We find that the system does not exhibit multistability, instead it has a limited parameter region leading to a single stable steady branch, alongside multiple unstable branches. Focusing on the stable steady states and linearizing the dynamics around them, we calculate the spectral densities of the quadrature variables. We identify and characterize the squeezing of three-photon down-conversion. Moreover, since the quasi-probability differential equations of the higher-order multiphoton processes have higher-order derivatives, hindering their mapping into stochastic differential equations, we make use of a positive Wigner function approach to calculate two-dimensional spectral densities associated with three-time correlation functions, with the goal of studying non-Gaussian properties of the system.

We argue that the variance of the information content ($C$), an information-theoretic quantity, can be naturally interpreted as a measure of statistical complexity. We show that $C$ satisfies widely accepted criteria for statistical complexity measures: it vanishes for both ordered and equiprobable states, while attaining maxima in intermediate regimes, typically shifted toward order. This interpretation establishes direct connections with thermodynamics and phase transitions: for systems obeying Boltzmann–Gibbs statistics, $C$ is extensive and directly proportional to energy fluctuations and heat capacity. Moreover, unlike other statistical complexity measures, it attains a maximum at continuous phase transitions, as illustrated for the two-dimensional Ising model. Applications to chaotic maps and fractional Gaussian noise further indicate that $C$ captures nontrivial dynamical structure in different classes of correlated systems.

We propose a spintronic memcapacitance effect based upon altermagnetic multiferroic materials. We identify the rare-earth vanadates RVO$_3$ as a concrete platform, with all key parameters tied to measured properties. Under an oscillating electric field, the resulting charge and spin currents trace pinched hysteresis loops that close tangentially at zero field – the hallmark of memcapacitive, type-2 memdevice behavior – with charge current densities exceeding, by a factor of about 3.6, the lowest deterministic switching current density reported for optimized spin-transfer-torque magnetic tunnel junctions. We model the system theoretically as a dimerized two-orbital $d$-wave altermagnetic lattice via a Su–Schrieffer–Heeger-type bond modulation, in the spirit of the spin-dependent Rice–Mele model, thereby coupling the altermagnetic order to field-switchable charge and spin polarizations. The associated polarization loops close tangentially at zero field and yield a sign-changing, history-dependent “butterfly” differential capacitance, identifying the device as a genuine memcapacitor. Both responses are protected by the same inversion symmetry, so charge and spin channels switch simultaneously with no separate control needed. These results establish altermagnetic multiferroics, realized concretely in RVO$_3$, as an efficient, non-volatile platform for combined electric and spintronic memory.

We report high-resolution synchrotron X-ray diffraction and X-ray resonant magnetic scattering (XRMS) studies of the low-temperature crystal and magnetic structures of DyCuAs$_2$, a member of the \RE{}CuAs$_2$ family exhibiting a resistivity minimum above the antiferromagnetic transition temperature. Synchrotron diffraction measurements reveal that DyCuAs$_2$ preserves tetragonal symmetry down to low temperature within the experimental resolution, although pronounced anomalies in both lattice parameters $a$ and $c$ are observed near the antiferromagnetic transition temperature, $T_{\mathrm N}\approx7$~K, indicating strong magnetoelastic coupling. XRMS measurements at the Dy $L_3$ edge establish commensurate antiferromagnetic ordering below $T_{\mathrm N}$ with AFM Bragg peaks at \qq{} = (0, 0, 0.5). Representation analysis and calculations of the AFM Bragg peak intensities identify the magnetic structure as the $\Gamma_{10}$ representation, consisting of in-plane Dy moments stacked along the \cc{} axis in a $++--$ sequence. The magnetic structure is therefore identical to that previously reported for SmCuAs$_2$. Comparison among DyCuAs$_2$, SmCuAs$_2$, and GdCuAs$_2$ suggests that in-plane AFM order and the associated magnetic frustration on the tetragonal lattice are closely connected to the emergence of the resistivity minimum in the \RE{}CuAs$_2$ family. At the same time, the enhanced lattice response and stronger magnetic-field sensitivity observed in DyCuAs$_2$ imply that magnetoelastic and spin-orbit interactions additionally play important roles in determining the robustness of this anomalous transport behavior.

In this work, an implantation-free ohmic contact technology based on selectively MOCVD-regrown Si-doped n$^+$ layers is demonstrated for enhancement-mode vertical $\beta$-Ga$_2$O$_3$ U-trench MOSFETs. The regrown n$^+$ contact structure eliminates the need for implantation-based ohmic contact formation while maintaining excellent electrical characteristics. A multi-energy nitrogen-ion-implanted current blocking layer (CBL) followed by 1100~$^\circ$C activation annealing in N$_2$ ambient for 30 min was employed to achieve normally-OFF operation. Transmission line model measurements yielded a low specific contact resistivity of $2.65 \times 10^{-7}~\Omega\cdot$cm$^2$. The fabricated devices exhibited a threshold voltage of approximately 5~V, an ON/OFF current ratio of $1.15\times10^{6}$, a peak current density of 158A/cm$^2$, and a specific ON-resistance of 120.9~m$\Omega\cdot$cm$^2$. Three-terminal OFF-state breakdown voltages ranging from 920 to 980~V were achieved at $V_{GS}=0$~V. Multi-finger MOSFETs show current scaling to 0.25 A. These results demonstrate that selectively MOCVD-regrown n$^+$ contact layers provide a promising implantation-free approach for realizing high-performance vertical $\beta$-Ga$_2$O$_3$ power MOSFETs.

Rare-earth van der Waals magnets provide a route to combining strong spin-orbit coupling, large magnetic moments, and reduced dimensionality in bulk crystals. We report a comparative study of the dysprosium oxyhalides DyOX (X = Cl, Br, I), which realize square-bilayer networks of Dy3+ moments separated by a tunable van der Waals gap. Structural refinements show that increasing the halide ionic radius strongly expands the inter-bilayer spacing while leaving the local bilayer geometry nearly unchanged. Magnetization and heat-capacity measurements reveal two low-temperature anomalies in all three compounds: antiferromagnetic order at TN ~ 7-10 K and a broader anomaly near TQ ~ 27-30 K. Single-crystal magnetization on DyOCl and DyOBr establishes a strong hard-c-axis anisotropy, consistent with crystal-field analysis of DyOCl, which yields an XY-like ground-state g tensor. Neutron diffraction shows long-range antiferromagnetic order in DyOCl, whereas DyOBr and DyOI exhibit sharp magnetic scattering coexisting with Warren-like diffuse features, consistent with robust in-plane correlations and imperfect inter-bilayer registry. Inelastic neutron scattering on DyOCl identifies crystal-field excitations near 25-30 meV and an additional magnetic mode near 10 meV whose temperature dependence is tied to the high-temperature anomaly. Taken together, these results establish DyOX as a tunable family of quasi-two-dimensional rare-earth magnets and point to candidate multipolar physics associated with low-lying crystal-field states. Direct probes of quadrupolar order, such as resonant x-ray scattering or elastic-constant measurements, will be required to determine the order parameter at TQ.

Atomically precise phosphine-stabilized gold nanoclusters are commonly characterized by single-crystal X-ray diffraction, yet the extent to which these static structures represent finite-temperature behavior remains unclear. To explore the free-energy landscapes, equilibrium populations, and isomerization kinetics of these nanoclusters in the gas phase, we establish a general framework that combines molecular dynamics simulations based on a machine-learned interatomic potential with Markov state models (MSMs). Analysis of the MSMs indicates that experimentally reported crystal structures frequently correspond to minor metastable states or transient configurations rather than the dominant finite-temperature structures. Increasing ligand coverage systematically alters both the thermodynamics and kinetics of structural rearrangements, driving the transition from planar to three-dimensional gold cores while accelerating isomerization dynamics. Moreover, catalytically accessible geometries are often only minor members of the equilibrium ensemble, highlighting a trade-off between structural stability and surface accessibility. These results emphasize that ligand-protected nanoclusters need to be viewed as dynamic ensembles and their finite-temperature behavior cannot be fully captured by their corresponding crystallographic structures alone.

State convertibility represents a fundamental concept used to determine whether a transformation is possible given a specific set of resources. Within the field of Thermodynamics, where physical process are required to preserve a reference state typically in microcanonical or canonical form, this translates into the notions of majorization and thermo-majorization —criteria that require constructing and comparing state-dependent Lorenz curves. In this work, we firstly unify and extend these notions to an arbitrary and possibly time-dependent reference distribution $g(t)$, introducing the concept of $g(t)$-majorization; we then introduce a dual picture whereby state convertibility is turned into a one-dimensional convex-order problem, which allows us to demonstrate that a transition is admissible if and only if the associated real-valued distributions of relative populations $ k_j(t)/g_j(t)$ are connected by a martingale. Building on it, we then derive an exact fluctuation theorem for a reference-relative entropy production whose average violation certifies, through a $\chi^{2}$-divergence bound, the mismatch between an assumed and the true reference evolution—a model-independent diagnostic that requires no independent characterization of the latter and turns an observed breakdown of the fluctuation relation into a certified lower bound on the reference error.

These notes develop four interconnected ways of reading a quantum circuit. A circuit for us begins as an operational composition of gates; then, it becomes a diagram whose local equalities may be used as calculations; next, it becomes a protected process once errors, syndromes, and logical degrees of freedom are separated; and finally, it becomes geometric when its connectivity, topology, and boundary data are treated as physical design parameters. The development begins at the level of bits and qubits before appealing to Deutsch's and Grover's algorithms as basic examples of quantum circuits. With the basics in hand, we interpret quantum circuits diagramatically, leading us to compact closed string diagrams and the ZX-calculus. After that, we consider how to correct quantum circuits by introducing the Knill–Laflamme condition, homological surface codes, and related concepts with a view towards thinking of these as operations on diagrams. The lectures eventually arrive at the properties of hyperbolic quantum codes and the prospect of physical superconducting circuits emulating the negatively-curved lattices needed to support those codes. These mathematical ideas and physical experiments, taken together, represent one way to impart a geometric layer onto quantum circuits. By the very end, we bring the ideas nearly full circle by assessing the extent to which these device physics experiments operationalize the basic ZX diagrams encountered much earlier in the story. While the later material reports on original research, and while the discussion becomes increasingly mathematical as the sections progress, no prior knowledge of quantum information, quantum computing, or quantum error correction is actually assumed.

In layered materials, spacing and stacking-order extent are usually locked. Here we show that in swollen suspensions of stiff, charged nanosheets they decouple, and that this defines a distinct regime, apart from the crystalline- and Wigner-swelling regimes such systems usually occupy. The mean spacing stays sharp and salinity-tunable while scattering-weighted stacking spans only two to three layers. We demonstrate this in a near-perfect model material, so the behaviour is intrinsic, not defect-driven. X-ray and neutron scattering, sedimentation and a Donnan analysis show the spacing is held by a parameter-free osmotic restoring slope below one pascal per nanometre. Because the slope is so weak, the spacing sits at equilibrium while faults relax slowly, a quenched metastable registry whose ageing-like relaxation of low-dimensional periodic order has not, to our knowledge, been realised before. The same decoupling is expected across stiff, swollen nanosheets, from clays to oxide nanosheets and graphene oxide.

We study quantum transport through a magnetic barrier in a nodal-line semimetal. When the Fermi energy lies near the nodal ring, the Fermi surface has toroidal geometry. Each cross-section in a plane parallel to the nodal ring consists of two concentric contours, inner and outer, carrying distinct transport channels. We show that a magnetic barrier resolves these two channels: because the contours enclose different momentum-space areas, they accommodate the field-induced transverse-momentum shift unequally, and the inner channel is cut off at a weaker barrier strength than the outer. Using a two-band effective Hamiltonian and a wave-function matching approach, we obtain closed-form, channel-resolved transmission amplitudes. Over a finite window of barrier strength the inner contour is fully blocked while the outer still transmits, so the barrier acts as a channel-selective filter. This sequential quenching shapes the two-terminal conductance, which decreases with barrier strength as the two channels close in turn and terminates once the outer channel is cut off, providing experimentally accessible fingerprints of the toroidal Fermi surface of a nodal-line semimetal.

Quenched disorder can profoundly modify phase transitions. In low-dimensional systems, theory predicts that even weak quenched disorder can round the thermodynamic discontinuities associated with a first-order phase transition. Here, we employ time-domain terahertz spectroscopy to investigate the quasi-two-dimensional trimerized kagome van der Waals magnet family Nb$_3$Cl$_{8-x}$Br$_x$ ($x=0$, 1 and 8). We observe the emergence of an additional phonon branch upon Br substitution, whose spectral weight increases and frequency softens with increasing Br concentration. The temperature evolution of the phonon frequencies reveals a clean first-order transition in Nb$_3$Cl$_8$ characterized by macroscopic phase coexistence and thermal hysteresis. In contrast, the transition in the substitutionally disordered compound Nb$_3$Cl$_7$Br retains its hysteresis while exhibiting a substantially broadened transition with no resolvable macroscopic phase coexistence. These observations reveal disorder-induced fragmentation of the transition into locally favored domains instead of well-defined bulk phases separated by stable phase boundaries. The behavior is consistent with the Imry-Wortis and the Aizenman-Wehr scenarios for the effect of quenched disorder in low-dimensional systems, which destabilizes macroscopic phase coexistence and rounds the thermodynamic discontinuities associated with first-order transitions. Thermal hysteresis persists in the disordered compound despite the lack of resolvable coexistence, indicating that the two features often treated as a single hallmark of first-order character arise distinctly and can be separated by disorder. Moreover, our results establish Nb$_3$Cl$_{8-x}$Br$_x$ as a promising platform for investigating the effects of disorder on first-order transitions in low-dimensional systems.

A chiral superconductor carries chiral Majorana modes along its boundary, and the integer that counts them fixes everything that follows, yet that integer has never been measured together with a local parity observable on one object. Proximitized one-dimensional wires read fermion parity rapidly but diagnose bulk topology through a separate protocol. Here we show that a reconfigurable domain wall between regions of opposite Chern number in an intrinsic two-dimensional chiral superconductor performs both functions. Opened to its contacts the wall is a ballistic channel whose quantized thermal conductance counts its Majorana modes; closed, the same wall is a Fabry–Pérot resonator whose spectrum shifts by half a level spacing when the parity of the enclosed vortices changes, giving a two-level heat conductance. We derive the exact transmission, the elastic heat full counting statistics, and a theorem showing that linear-response heat scattering of a fixed quadratic problem resolves vortex parity but not the fusion channel of well-separated cores. An outside vortex hybridized with the wall is an intrinsic false positive; temperature, geometry and a finite-bias mean–noise test separates it. Rhombohedral-graphene parameters place submicron loops in the resolved regime at millikelvin temperatures, where chiral-domain reconfiguration and noise thermometry are both established.

Bismuth selenide (Bi2Se3) is a topological insulator with potential applications in thermoelectrics, spintronics, and optoelectronics. However, its response to radiation remains poorly understood. We investigate cumulative X-ray damage in Bi2Se3 using simultane- ous transmission X-ray microscopy (TXM) and X-ray diffraction (XRD) at the Pohang Accelerator Laboratory X-Ray Free Electron Laser (PAL-XFEL) over 27,000 successive pulses. We observe distinct damage mechanisms: rapid hole formation via vaporization within 100 pulses, followed by slower grain refinement and material sputtering over thousands of thermal cycles. Williamson-Hall analysis reveals a progressive transformation from single-crystal to nanocrystalline structure, with grain sizes decreasing from mi- cron to nanometer scale. Finite-element modeling confirms that X-rays penetrate 13.47 {\mu}m, driving local temperatures above 1600 K with subsequent cooling between pulses. Scanning electron microscopy identifies three characteristic morphologies correspond- ing to different thermal histories: sputter streaks, prismatic crystals, and disordered microcrystals. Our results demonstrate that grain-boundary formation creates a feedback mechanism that accelerates damage in later pulses. This work establishes a method- ology for studying radiation damage across multiple length scales and provides insight into topological insulator stability under extreme conditions

We show that the conventional multipolar Hamiltonian is qualitatively modified when the photonic vacuum breaks inversion or time-reversal symmetry. By explicitly applying the Power-Zienau-Woolley transformation, we derive the resulting multipolar Hamiltonians for two idealized chiral photonic environments: a spatial-chiral vacuum, which breaks inversion symmetry, and a temporal-chiral vacuum, which breaks time-reversal symmetry. In the spatial-chiral case, the transformation generates an inversion-breaking self-energy, whereas in the temporal-chiral case it produces an additional Zeeman-like energy. Using a trapped hydrogen-like atom and a charged harmonic oscillator in cavities as minimal examples, we show that these symmetry-dependent terms lead to characteristic spectral shifts. Our work provides a general framework for describing light-matter interactions in chiral quantum electrodynamics and identifying the associated symmetry-dependent effects on cavity-embedded atoms, molecules, and quantum materials.

Mid-circuit measurements provide direct access to trajectory-level observables, revealing dynamical structures in many-body systems that are invisible in ensemble-averaged quantities. We exploit this capability to realize and study an instance of the Floquet-East model on a superconducting quantum processor. Here, the combination of mid-circuit measurements, kinetically constrained unitary operations and hardware noise gives rise to intricate many-body phenomena. Analyzing trajectories obtained from temporally and spatially resolved mid-circuit measurements, we identify dynamical heterogeneity — a hallmark of glassy dynamics. We quantify this emergent behavior by studying the probability of finding inactive space-time regions of a given size. This quantity displays a crossover from area- to perimeter-dominated scaling, which is a characteristic property of glasses and is associated with the proximity to a dynamical first-order phase transition. Our results establish current noisy intermediate-scale quantum devices as scalable testbeds for investigating correlated many-body phenomena at the level of measurement trajectories.

We modify the NN/QFT duality [1] to incorporate the layerwise permutation symmetry of the network, resulting in a $(0\!+\!1)$-dimensional lattice gauge theory, in which each layer of $N$ neurons acts as an $N$-component lattice site, and the weight matrices play the role of gauge fields living on the links. In this framework, we compute the tree-level neuron-neuron propagator which describes the evolution of layer variance in the network, and develop the Feynman diagram machinery to compute interactions in the perturbative expansion in $1/N$. In particular, we obtain a recursive expression for all corrections to the exact propagator at $O(1)$, representing statistical fluctuations in the ensemble of networks, including infinitely-many loop diagrams mediating the interactions from previous layers. We also present a preliminary analysis of neuron scattering amplitudes that contribute order-by-order in $1/N$, which provides a field-theoretic framework for studying higher-point correlations, and by extension information propagation, in deep networks. We remark on some interesting directions for future work at the intersection of neural networks and quantum field theory.

Bose-Einstein condensates have been used successfully as quantum simulators for early-universe particle production. Here we extend this analogy to the interacting theory. To this end, we compute the leading interaction terms expected in a general experimental setup that determine the 3-point correlations. We apply them to cosmologically motivated expanding model universes, but also periodically oscillating ones. While expanding scale factors do not necessarily lead to easily observable signatures due to experimental constraints on the realizable scale factor, periodically driven ones produce resonant correlators that grow linearly over time and lend themselves well to experimental detection. One direct application of this analysis is the experimental study of late-time infrared divergencies often discussed in the context of massless scalars in de Sitter space.