Papers

We investigate the superconducting pairing symmetry and its doping evolution in pressurized La$_3$Ni$_2$O$_7$. For the undoped compound, the most favorable pairing state is found to be $s_{\pm}$-wave, characterized by sign reversal of the gap functions between the Fermi pockets. A detailed analysis of the pairing interactions reveals that this unconventional state originates from repulsive interactions mediated by the magnetic odd modes of the bilayer nickelate. Upon hole doping, the $\gamma$ Fermi pocket expands, which amplifies the intrapocket repulsions on this pocket. These repulsions, driven by the magnetic even modes, gradually dominates the pairing interactions and ultimately drive a transition in pairing symmetry from $s_{\pm}$-wave to $d_{xy}$-wave in the heavily hole-doped regime. In stark contrast, the $s_{\pm}$-wave pairing persists under electron doping, even deep into the heavily electron-doped regime where a Lifshitz transition occurs. This finding suggests that the $\gamma$ Fermi pocket is not essential for the emergence of superconductivity in bilayer nickelates. In fact, the $s_{\pm}$-wave pairing becomes more robust in the absence of the $\gamma$ pocket, as spin fluctuations are strongly enhanced by the favorable nesting between the $\alpha$ and $\beta$ pockets — a condition guaranteed by Luttinger's theorem and the Fermi surface topology. We believe that exploring the doping evolution of superconducting pairing will open a new realm for testing the pairing mechanism in pressurized La$_3$Ni$_2$O$_7$.

Altermagnets are unconventional spin split magnets arising from the zero spin-orbit coupled limit. They host a magnetic multipolar order parameter yet direct real-space observation of these multipoles has remained elusive. Here we use polarized-neutron diffraction to reconstruct the three-dimensional magnetization density of the prototypical altermagnet MnF$_2$. By exploiting symmetry-selective magnetic reflections, we separate the dominant spherical Mn$^{2+}$ contribution from the much weaker anisotropic Mn magnetization and the covalent spin polarization of the fluorine ligands. The reconstructed spin density reveals a finite fluorine ion moment together with an anisotropic Mn magnetization consistent with the symmetry-allowed altermagnetic rank-5 magnetic multipole $O_{52}$(magnetic triacontadipole). These results provide direct real-space evidence of ferroic multipolar order in an altermagnet and establish polarized-neutron diffraction as a powerful probe of hidden magnetic multipoles in quantum materials.

We propose and study a model of moire heterobilayer systems where the twist angle remains uniform and well defined only within a finite range, but deforms randomly at larger distances. The local twist angle is then subject to a certain probability distribution that penalizes large fluctuations around its mean value. Within the framework of the replica trick, we show that disorder averaging produces a nontrivial correlation with alternating sign between replicas, maximized only close the boundary of each local domain and along certain directions. We show that for the low-energy moire bands, exactly the same correlation can be generated in a dual model where fermions are coupled to non-Hermitian disorder, which can evade Anderson localization dynamically. This duality provides a new perspective to investigate twist-angle disorder in moire systems, and unveils some of the essential differences between twist-angle disorder and conventional disorder.

We consider the effect of twist-angle disorder on the single-particle properties of twisted bilayer systems. These materials are a natural playground for studying how tiny, uncontrolled spatial variations may become unusually consequential; a local change in the twist geometry can give rise to spatially-correlated alterations of the parent Hamiltonian, which in turn affect the coarse-grained properties of the substrate such as transport and ordering tendencies. In analogy to electrodynamics, where the magnetic field is given by the curl of the vector potential, we model the twist angle as the curl of the relative displacement between the two bilayers. We find that geometric scattering constraints imposed here by the twist structure substantially suppress momentum relaxation relative to mean-rate-matched white noise. We quantify these effects and show that the problem can be mapped onto a non-linear sigma model (NLSM).

Two-dimensional material platforms now host a remarkable array of exotic correlated phases, from unconventional superconductivity to fractional Chern insulators. Probing magnetic order in these systems is essential for understanding their underlying physics, yet dilute spin densities render conventional magnetic probes ineffective. Spin waves, or magnons, in quantum Hall ferromagnets (QHFM) have proven effective for probing the magnetic order in various symmetry-broken quantum Hall (QH) phases in graphene systems, but previous works have been limited to homojunction configurations within a single material. Here, we demonstrate magnon transmission across a monolayer-bilayer graphene quantum Hall ferromagnet heterojunction - the first magnon transmission across quantum Hall ferromagnet heterojunctions, using one material as a magnon source to probe magnetic order in a distinct material. Generating magnons in monolayer graphene (MLG) at $\nu$ = 1, we detect their transmission through bilayer graphene (BLG) via nonlocal voltage measurements, revealing spin order in BLG symmetry-broken quantum Hall states. The transmission exhibits hallmark magnon signatures: a sharp onset at the Zeeman energy and systematic variation with Landau level filling, including suppression at $\nu$ = 4 and 8 where spin polarization vanishes. Our findings establish heterojunction magnon transmission as a powerful, modular probe of magnetic order, opening new avenues for investigating exotic quantum states across the rapidly expanding family of two-dimensional materials.

Fractional changes in entropy are often associated with strong electron correlations or non-Abelian anyons in topological systems. We show that neither condition is necessary – a system of free electrons on a ring scattering off a repulsive point-like impurity undergoes a $k_B\ln\sqrt 2$ entropy change as the impurity strength is increased. This effect arises from a shift of allowed single-particle momenta from integer quantization to half-integer quantization, induced by the impurity. We show that this fractional entropy change is universal across a broad class of single-particle dispersions, demonstrating that such signatures can arise without strong correlations or topological order.

In this report, we have shown that, in an otherwise geometrically frustrated lattice, the underlying interactions compete to stabilize different magnetic phases. In conjunction with fluctuations, these interactions may lead to the formation of unusual ordered phases, providing a pathway for understanding the fluctuation-driven order-by-disorder phenomenon. This competition is further modified by the presence of inherent structural disorder in a frustrated two-dimensional lattice. Furthermore, due to the local nature of the additional structural disorder, the majority of the samples evolve toward glassy dynamics, which can not only mimic spin-liquid-like behavior but also make it difficult to identify genuine spin-liquid candidates experimentally.

Orbital-lattice coupling in transition-metal oxides is usually discussed within a given bonding framework, where orbital occupation is intertwined with local coordination, strain, or symmetry breaking. Here, we show that orbital occupation can also select the bonding framework itself, thereby determining structural dimensionality. Using first-principles calculations, we identify CrO as a prototype in which the single active $3d\,e_g$ electron of high-spin Cr$^{2+}$ gives rise to two competing orbital-structure states. The $d_{x^2-y^2}$ occupation favors a three-dimensionally connected covalent phase, whereas the $d_{z^2}$ occupation stabilizes a weakly coupled layered phase. Constrained-occupation calculations show that increasing the $d_{z^2}$ filling continuously contracts the in-plane lattice while expanding the structure along the layer normal. The two phases exhibit distinct magnetic ground states and ferroelastic responses. Moreover, the layered phase is robust against exchange-correlation functional and on-site ($U$) variations, remains dynamically stable down to the monolayer limit, and has a low exfoliation energy of 46 meV/Angstrom^2. Extending the analysis across related $3d$ binary oxides reveals a filling-dependence relation between accessible orbital filling and the preference for 2D or 3D connected bonding motifs, providing a microscopic basis for exploring low-dimensional oxide materials.

Local electronic states of vortices in an s $\pm$ d wave nematic superconductor are studied both in the absence and presence of twin boundaries. The Bogoliubov-de Gennes theory for a tight-binding model is used with its nematicity represented by the anisotropy in the transfer integrals and attractive interactions between the nearest-neighbor sites. We evaluate s and d wave components of the pair potentials and the local density of states, and analyze the effects of nematicity on the vortex core structures with/without twin boundaries. We find that a single vortex trapped at the twin boundary is composed of a bound pair of fractional vortices accompanied by weakly-induced s $\pm$ id wave components, despite that such s $\pm$ id wave components do not appear in a zero magnetic field. The calculated spatial structures of the local electronic states are compared with the vortex image measured by STM experiments in an iron-based superconductor FeSe.

Vacuum package integrity in micro- and nanoelectromechanical resonators is commonly assessed through the quality factor Q, although Q probes residual-gas damping rather than the surface-state evolution that can govern frequency aging. Here, we disentangle the pressure responses of Q and the resonance frequency f0 in a 64.21 MHz Al0.7Sc0.3N-on-silicon cross-sectional Lamé-mode resonator between 0.01 to 760 Torr. Measurements at 25 {\deg}C and at the 68.8{\deg}C frequency turnover, where first-order thermal sensitivity is suppressed, reveal widely separated equilibration timescales. Following each pressure step, Q reaches a reversible, history-independent steady value on the pressure-control timescale and approaches a fitted pressure-independent ceiling of 8.5e4 below approximately 1 Torr. By contrast, f0 responds measurably down to 1e-5 Torr and remains history-dependent, relaxing for hours at fixed pressure. The transients follow stretched-exponential kinetics, consistent with a broad distribution of surface relaxation rates, and individual pressure steps produce fractional frequency shifts as large as 1.9 ppm. Ten-hour phase-locked measurements show a common short-term time-deviation floor near 1e-10 s from 0.01 to 100 Torr, whereas residual deterministic relaxation dominates at long averaging times; at 760 Torr, gas damping degrades short-term tracking through the reduced Q. These results establish gas-damping equilibrium and frequency equilibrium as distinct states. Quality-factor saturation alone is therefore insufficient to qualify vacuum packaging for precision mechanical frequency references; package specifications must also constrain surface-mediated frequency aging.

External parameters such as temperature, pressure, and chemical doping can induce structural phase transitions in materials. Although such transitions usually involve a change in symmetry, an uncommon exception is the isostructural phase transition, which is first order yet preserves the symmetry of the parent structure. Using first-principles calculations, we show that $AM_2$Al$_9$ compounds ($A$ = Ba, Ca, Sr, or Eu; $M$ = Fe, Co, or Ni) undergo pressure-induced isostructural phase transitions. At the transition pressure, these systems exhibit a pronounced volume collapse while retaining the same crystal symmetry and space group ($P6/mmm$). Bonding analysis based on the integrated crystal orbital Hamilton population (ICOHP) shows that the transition is driven by a redistribution of bonding character between intralayer and interlayer atomic bonds. Because isostructural transitions are rare in single crystals, $AM_2$Al$_9$ provides a promising platform for investigating critical phenomena under pressure and for deepening our understanding of symmetry-preserving structural transitions.

The coupling of excitons to lattice vibrations is typically treated via phenomenological models that artificially separate long-range Fröhlich and short-range Holstein interactions. Recent analytical work has established that, in the delocalized limit, Fröhlich scattering is suppressed by electron–hole interference. Here we present a model-space Bethe–Salpeter framework to evaluate exciton–phonon coupling across the extended-to-localized crossover. We establish a fundamental distinction between the inclusive exciton–phonon coupling weight, obtainable via an exact completeness sum rule without summation over excited states, and the exclusive intraband (internal-state-preserving) scattering amplitude that governs low-energy decoherence. We prove an exact symmetry theorem: for an inversion-symmetric relative-coordinate Hamiltonian with equal electron and hole masses, the intraband Fröhlich vertex vanishes identically, protecting the exciton from low-energy polar phonon scattering. When mass asymmetry is introduced, the finite-momentum relative wavefunction acquires a complex phase twist that breaks this protection. By analyzing the long-wavelength limit, we derive a controlled small-$q$ activation law showing that the intraband vertex scales as $F_{00}(q) \propto \Delta q^2 \langle r^2 \rangle$, where $\Delta$ parameterizes the mass asymmetry. Finally, we compute the second-order polaron self-energy shift and demonstrate that mass asymmetry dramatically enhances phonon dressing, confirming that the symmetry theorem directly governs the many-body energy renormalization of the exciton. These results provide a rigorous conceptual framework for understanding the competition between long-range and local exciton–phonon coupling in polar semiconductors.

We present a numerical formulation for the resolution of finite systems of interacting edge dislocations and wedge disclinations. The approach is based on a finite element discretization of a fourth-order elliptic boundary value problem arising from the mechanical equilibrium equations of plane-strain linear elasticity in the presence of kinematic incompatibilities. The numerical implementation follows a continuous interior penalty discontinuous Galerkin framework and relies on the solution of a finite set of local cell problems. Our method is validated against analytical benchmarks and used to explore several non-trivial dislocation-disclination configurations, illustrating how translational and rotational incompatibilities shape the stress state of the body.

Let $\mathbf{c}=(\lambda,\alpha,\mu,\nu)\in\mathbb{R}^{4}$ denote the four running couplings of four-dimensional nonplanar Euclidean scalar $\varphi^{4}$ theory, and let $B(\mathbf{c})=\sum_{p\ge2}\sum_{|\mathbf{m}|=p}\beta(\mathbf{m})\mathbf{c}^{\mathbf{m}}$ be its formal beta-function series. Assuming the factorial coefficient bounds $|\beta(\mathbf{m})|\le (p-1)!C^{p-1}$ for $|\mathbf{m}|=p$, we construct an explicit summation rule $\mathcal{S}$, given by a cut Borel–Laplace transform whose cut is placed by a scale-covariant real-analytic gauge. We prove that it assigns a well-defined real value to $B$ on an explicit nonempty open domain, in fact on all of $\mathbb{R}^{4}$. The summed function $\mathcal{S}B$ is linear and real, real-analytic on $\mathbb{R}^{4}\setminus\{0\}$, $C^\infty$ on $\mathbb{R}^{4}$ with Taylor series $B$ at the origin, and Gevrey-$1$ asymptotic to $B$ to all orders with an explicit remainder bound. At optimal truncation the remainder is $O(e^{-\eta/(C\|\mathbf{c}\|_\infty)})$ for any $\eta<1$. We show that $\mathcal{S}B$ reproduces the classical Borel sum and the ordinary sum of a convergent series up to errors of the same exponentially small order. Exact reproduction is impossible for any linear rule defined on the whole admissible class: regularity forces all weights to equal $1$, leading to divergence. Finally, we prove optimality under the stated hypothesis. Admissible series may diverge at every $\mathbf{c}\ne0$, and their Borel transforms may have the circle $|\tau|=1/(C\|\mathbf{c}\|_\infty)$ as a natural boundary, so classical Borel-type summation need not be available on the class. Moreover, there exist two functions indistinguishable at the level of the coefficient bounds yet differing by exactly $(2\pi/C)e^{-1/(C\|\mathbf{c}\|_\infty)}$. All constants are explicit and all arguments are self-contained.

Flows in random networks are known to exhibit heavy-tailed statistics, giving rise to anomalous transport in a range of biological, environmental and engineered systems. Yet, how structure determines flow remains an open question. Here we derive a dual network approach that relates flow statistics and network properties. Conditional statistics in a range of networks reveal the existence of two interlaced subnetworks with distinct hydraulic behaviors. Based on this hidden structure, we derive a universal analytical approach that predicts heavy-tailed flow statistics based on network topology and disorder distribution across a range of random networks.

Numerous experimental and computational studies have been conducted in the past few decades to understand the swimming performance of fish, and to identify the optimal kinematic strategies for a swimming fish or fish-like robot. Many of these studies model the swimmer in a `tethered' condition, in which the swimmer is held fixed while it is subjected to a free stream. Its performance is then quantified using power expenditure, thrust generation, and efficiency. However, the dynamics of a tethered swimmer are different from those of a self-propelled swimmer, whose performance is best measured using its steady-state swimming speed in still fluid and its efficiency. It is an open question whether the conclusions drawn from studies of tethered swimmers can be directly applied to free swimmers. In this study, we use an unsteady panel method to systematically compare the swimming performance of a tethered fin and that of a self-propelled fin attached to a virtual drag-producing body to investigate how their performance varies over a set of prescribed kinematics. After validating the numerical model against previous experimental results, we show how the pitch amplitude, heave amplitude and the phase offset between them affect the efficiency and thrust generation in the tethered case, and how they affect the speed and efficiency in the self-propelled case. We find that the kinematic strategies that optimize the performance of a tethered swimmer do not necessarily optimize the performance of a self-propelled swimmer.

Every crystal is a Bravais lattice decorated by a basis, so the dipolar ordering of the fourteen Bravais lattices is the natural starting point for any systematic theory of dipolar magnetism in three dimensions. We determine it here in a single common framework: the interaction tensor is Ewald-summed, the classical ground state is obtained by minimising the lowest Luttinger–Tisza band over the entire Brillouin zone, and the linear spin-wave spectrum with its zero-point corrections is computed for every lattice whose order is collinear. Three results emerge that are not properties of individual lattices but of the landscape. First, two structural principles — the exact tracelessness of the dipolar tensor in three dimensions, and its identical vanishing at $\mathbf k=0$ for every cubic-symmetric lattice — explain the ordering type, the absence of first-order cubic anisotropy, and the systematics of the zero-point moment reduction. Second, exactly one lattice defeats the Luttinger–Tisza construction: for face-centred orthorhombic the optimal eigenvector is not circular, the single-$\mathbf k$ state is a spin-density wave of non-constant length, and the tabulated energy is a strict lower bound; direct supercell minimisation gives the true ground state. Third, optimising each family over its free metric parameters collapses the whole of Bravais space onto only four attractors, with body-centred tetragonal the global optimum and a single interior optimum at rhombohedral $\alpha=62.42^\circ$ lying below face-centred cubic. Three independent published benchmarks are reproduced.

The extreme persistence of per- and polyfluoroalkyl substances (PFAS) in the environment is rooted in their three-dimensional molecular conformation. The helical twist adopted by perfluoroalkyl chains due to hyperconjugation involving their recalcitrant C-F bonds governs their resistance to degradation, yet a quantitative, continuous metric for helicity has remained absent. Here we introduce a data-driven framework that quantifies backbone helicity using three statistical descriptors: void-state (binary occupancy) spatial autocorrelations, local backbone principal component analysis, and persistent homology. We further validate each statistical descriptor against geometric dihedral benchmarks and DFT-calculated Vibrational Circular Dichroism (VCD) spectra. The framework is initially established on a homologous series of perfluorocarboxylic acids (FC2 through FC16) and their hydrogenated analogues, then extended across perfluorosulfonic acids, fluorotelomer alcohols, polyfluoroalkyl hexanoic acid analogues, and longer-chain PFOA and PFOS analogues. Agreement between statistical, geometric, and spectroscopic definitions of helicity is established for PFCAs and extended to structurally distinct subfamilies, including PFOA analogues of varying fluorine content and perfluorosulfonic acids, demonstrating that the descriptors are robust to changes in headgroup chemistry and fluorine substitution pattern. The framework provides a chemistry-agnostic toolset for incorporating backbone conformation into predictive models of PFAS environmental fate and degradation reactivity.

We study classical Heisenberg spins interacting through the dipole–dipole interaction on the eleven Archimedean and eight Laves planar lattices at canonical geometry, which reduce to fifteen distinct vertex sets. For each lattice we compute the Fourier-space interaction matrix $\Am(\bk)$, extract the Luttinger–Tisza ordering wave vector $\bk_{0}$, determine the classical ground state by unconstrained minimization on the commensurate magnetic cell, and evaluate the linearized spin-wave dispersion $\varepsilon_{i}(\bk)$ along the high-symmetry path of the (magnetic) Brillouin zone together with the Holstein–Primakoff moment reduction. The ground states fall into three classes: five are collinear, two are non-collinear at angles commensurate with the lattice symmetry, and eight cant at transcendental angles, which we determine to thirty digits. Across the family, failure of the Luttinger–Tisza strong condition coincides exactly with the appearance of incommensurate canting, with no exceptions in either direction. Truncating the interaction range shows that whether a lattice cants is fixed by the local coordination geometry, whereas the value of the canting angle is set by the long-range tail. The quantum corrections are governed by the magnon spectrum through the size of the magnetic basis and are uncorrelated with frustration, so that the frustration and fluctuation classifications are independent; the corner-sharing lattices host the narrowest low-energy branches. The results constitute a spectral atlas of dipolar Heisenberg systems on the full family of $1$-uniform planar tilings and their duals, and provide predictions for inelastic neutron scattering in materials whose magnetic ions occupy Archimedean or Laves lattices, and for artificial arrays of dipolar-coupled nanomagnets.

Environmental modification of dipole interactions has long been explored in energy transport. Here we consider the effects of a tunable graphene monolayer upon nearly H-type or J-type molecular aggregates, concentrating on the inversion of one type of coupling to the other. Modelling the graphene as being deposited on a metallic substrate, we find that as the surface conductivity of the graphene is varied, there is a corresponding change in the parameter region over which coupling inversion is predicted. This provides a route towards observing the predicted coupling inversion in a real system by dynamically changing the surface conductivity during a single run of an experiment.

Modern electronic systems require tens of clock and carrier frequencies, each synthesized by a dedicated phase-locked loop from a shared reference, imposing routing, power and synchronization burdens that grow with every domain. Optical frequency combs solved this problem in photonics, whereas electronics has lacked an equivalent source in its native radiofrequency domain. Here we report broadband phononic frequency combs in ferroelectric hafnia-zirconia nanoelectromechanical resonators built from complementary metal-oxide-semiconductor (CMOS) oxides. Lithographically defined detuning of a 2:1 internal resonance selects the generation mechanism: two-tone-seeded wave mixing yields more than 170 lines distributed over two octaves, with mutual coherence verified for representative pump and generated lines, whereas an autonomous Hopf route yields hierarchical combs of more than 200 lines through torus and period-doubling dynamics, in agreement with slow-flow bifurcation theory. Geometric scaling extends comb generation across 0.44 GHz to 2.1 GHz. Heterodyne measurements, analyzed using the modified Allan deviation (MDEV), establish a two-timescale law. The mechanism governs short-term stability: seeded combs inherit the white-phase-noise scaling of their pumps, whereas autonomous combs acquire the phase diffusion of a free-running oscillator, with the one-second MDEV increasing from 1e-11 to 1e-8. The material governs long-term stability: in air and without active thermal control, the temperature-compensated stack suppresses the random-walk drift that dominates uncompensated resonators. These results establish mechanism- and material-level design rules for operating a single resonator as chip-scale frequency infrastructure, from multi-clock generation to radiofrequency parallel processing.

Dzyaloshinskii-Moriya (DM) interaction is a source of chiral magnetic physics, and it manifests microstructural symmetry which could link to exotic magnetic and electronic properties such as altermagnetism. For a new paradigm in magnetism and spintronics, it is crucial to have control on the DM interaction as well as ordering of the DM vectors which characterize the DM interaction. Here, we report on a strong interlayer DM interaction emerged in Co/Ru magnetic superlattices whose structural symmetry is unambiguously broken by alternating mechanical strains developed using the peculiar technique of our stress mechanism. Moreover, theoretical analyses reveal that our magnetic superlattices host a staggered order of the DM vectors. Our results indicate that the spatially varying strains with our breakthrough technique are quite effective in breaking the symmetry of the system and prove that it can control the DM interaction strength as well as the DM vector order.

We introduce a chiral tubular magnonic crystal formed by a ferromagnetic nanotube with a periodically modulated interfacial Dzyaloshinskii–Moriya interaction (DMI). Using a plane-wave formalism adapted to the cylindrical geometry, we calculate the spin-wave band structure including exchange, nonlocal dipolar coupling, and interfacial DMI. We show that the tubular geometry qualitatively modifies the role of periodic DMI compared with planar chiral magnonic crystals. Besides producing the usual nonreciprocal frequency shift, curvature converts part of the interfacial DMI into an effective anisotropy-like internal field. This creates a sign-dependent frequency landscape along the tube, so that DMI-covered regions can act either as potential wells or barriers for the lowest-frequency modes. As a result, flat and weakly dispersive bands appear in both Damon–Eshbach-like and backward-volume-like configurations, with the latter having no direct counterpart in planar systems. Our results identify periodically engineered DMI in nanotubes as a route for controlling nonreciprocal spin waves, localized modes, and flat magnonic bands in curved architectures.

Magnetically coupled damped rotational degrees of freedom can give rise to tribological loss when excited by a relative sliding motion, linking friction to the dynamics of magnetic moments. We analytically investigate such magnetic friction by studying a recently introduced simplified model for a rigid magnetic rotor array sliding over a commensurate magnetic substrate. Here, the array rotors can rotate about an axis perpendicular to the sliding direction and are damped by microscopic shaft friction, while the substrate magnets have a fixed in-plane orientation. The simplified model reduces the collective rotor dynamics of this setup to a set of coupled nonlinear differential equations, which can be studied by the corresponding energy landscape in the quasi-static regime. We find that the parameter plane spanned by layer separation and time can be divided into distinct chambers, in which the structure of the energy landscape remains invariant. Using these chambers, we identify the layer separation intervals corresponding to different dynamical states and recover the emergence of a regime where the moment alignment alternates globally while exhibiting peak dissipation. Additionally, we derive the leading nontrivial orders of the collective magnetic friction in the regimes of small and large gaps between the array and the substrate. For the alternating regime, we find that friction can be computed by tracking energy jumps from unstable to stable critical points at the chamber boundaries. These results provide an analytical foundation for the observed dynamics and dissipation in sliding rotor arrays. Because the simplified model is scale-free, our conclusions transfer across a broad range of microscopic and macroscopic length scales.

Planar $k$-uniform states have maximally mixed reductions on every $k$-site interval of a ring. We introduce planar $k$-purity—the mean purity of those intervals—as a faithful cost function for this simultaneous constraint. For a Haar-random pure state of $n$ parties with local dimension $p$, the joint purity of two intervals depends only on their overlap. An exhaustive four-replica calculation therefore yields the complete cyclic covariance kernel and a closed variance for every $1\le k\le\lfloor n/2\rfloor$. In the balanced qubit case, $k=\lfloor n/2\rfloor$ and $N=2^n$, the variance is asymptotic to $20/(3nN^2)$ for even $n$ and $6/(nN^2)$ for odd $n$. A site-factorized permutation representation gives all raw moments and permits exact finite-sum evaluation of the skewness. Fixed-seed simulations validate nonbalanced qubit and qutrit cases, while balanced-qubit simulations through $n=10$ validate the parity formulas and finite-size skewness. Balanced planar and absolute balanced purity have the same Haar mean but different fluctuations; the planar variance is approximately $2.83$ times larger at $n=10$. Thus subsystem incidence, although invisible to every one-cut marginal distribution, controls the collective fluctuations of geometrically related cuts. Together with universal attainability and a linear number of interval constraints at balance, this provides a geometry-aware benchmark for multipartite entanglement beyond AME existence regimes.

During many biological processes, cell aggregates spread on substrates in a process of active wetting. The existing models of tissue spreading, however, do not explicitly capture the state of partial wetting, in which the cell aggregate reaches a non-zero contact angle. Here, modeling cell aggregates as active polar liquid droplets, we predict a transition between partial and complete wetting. This transition emerges from the competition between tissue surface tension and active traction forces, which is captured in an active Young-Dupré equation. The active wetting transition is discontinuous, and it features a region of parameters in which both partial and complete wetting are possible. Unlike in passive wetting, the transition depends on dynamical parameters such as the tissue viscosity and substrate friction. Finally, adding contractile intercellular active stresses leads to higher contact angles and even full dewetting. Overall, our work predicts an active wetting transition for tissues and it captures the partial wetting states often seen in experiments.

Single electron spin qubits trapped in SiMOS quantum dots are a promising technology for scaling to thousand- or million-qubit systems due to their compatibility with mature CMOS manufacturing processes. A readout system that combines a single electron transistor with a custom cryogenic CMOS amplification and digitization chain offers key advantages by avoiding the use of bulky RF components or room-temperature interconnects. We present design techniques and simulation results for an optimized qubit-SET cryoCMOS interface, culminating in the design of the QNDR1 ASIC, the first cryogenic readout ASIC designed under the Quandarum project, which targets the development of a many-channel spin qubit based detector for use in high energy physics.

It is natural to expect that the electromagnetic spin-spin interaction has roots in a more fundamental theory: quantum electrodynamics in this case. To show this, we take the non-relativistic limit of the Dirac-Maxwell Lagrangian, using the Foldy-Wouthuysen transformation and derive the Breit interaction by an alternative approach. By adding the Pauli term (i.e., a higher-order interaction between spin and the electromagnetic field), we calculate the correction terms to electromagnetic spin-spin interactions in the non-relativistic limit. Finally, we study some of the physical effects of these terms regarding spin-spin interactions and spin-spin entanglements. Accordingly, we provide theoretical estimates that are not yet accessible with current experiments.

When modeling surfaces of multinary compounds, conventional cleavage planes often cut through strongly bonded polyhedra, resulting in unphysical surface energies. Here, we introduce SALAMI (Symmetric Atomic Layers for Arbitrary Multinary Interfaces), a Python package that generates symmetric, charge-neutral, dipole-free, and low-energy slab models for multinary compounds. SALAMI performs combinatorial searches to selectively remove surface atoms and generate corrugated terminations that preserve optimal coordination environments. We applied this workflow to all symmetrically inequivalent crystallographic orientations with Miller indices up to 2 for two prototypical structures: the solid-state electrolyte Li3PS4 and the transparent conducting oxide ZnSb2O6. Density functional theory calculations reveal that Li3PS4 must preserve all PS4 units to achieve the minimum surface energy. For ZnSb2O6, low-energy surfaces are achieved by partial undercoordination of surface Sb atoms to SbO5 or SbO4 from the bulk SbO6, depending on the surface orientations. Compared to surface models generated with unconstrained coordination, applying constraints to achieve optimal local coordination environments significantly lowers surface energies, shrinking the volume of the predicted Wulff shape by approximately 20%. Our results demonstrate that meticulous control of local coordination environments is necessary for accurately predicting the surface energetics of multinary compounds.

We present a systematic investigation of the stability of the phase diagram of the spinless Falicov-Kimball model on two-dimensional non-bipartite lattices, the triangular and kagome lattices, using Markov-chain Monte Carlo simulations. Three filling or chemical potential conditions are examined: fixed chemical potentials ($\mu_f = \mu_c = U/2$), "generalized" half-filling ($\bar{n}_f = 1/3$, $\bar{n}_c = 2/3$), and conventional half-filling ($\bar{n}_f = \bar{n}_c = 1/2$). For each condition, the effects of a perturbatively small next-nearest-neighbor hopping are studied. On the triangular lattice, Anderson insulator, Mott insulator, and charge-density wave (CDW) phases are found in all cases, with the CDW driven by Coulomb-interaction-mediated nesting. Evidence for a charge-liquid regime is found in the region between the weakly correlated regime and the CDW, characterized by competing charge-ordering wavevectors and the absence of universal scaling behavior, whose extent shrinks progressively from the grand-canonical to the conventional half-filling condition. On the kagome lattice, the CDW phase is completely absent; instead, an insulating ground state, plausibly of the Mott type, is found, with signatures of a possible quantum phase transition at zero temperature. Our results establish the crucial role of lattice geometry and particle-hole symmetry breaking in shaping the phase diagram of correlated electron systems.