Papers

This review examines the theory of superconductivity in systems with singular dynamical electron-electron interaction and contrasts it with a conventional BCS superconductivity. Examples include metals near a Quantum Critical Point, quantum dots and system near a localization (Mott) transition. We show, that the singular interaction destroys the traditional separation of energy scales, invalidating the significance of Cooper logarithm, and, as the consequence, the whole BCS framework. We explore the universal model with dynamical interaction $\Gamma (\Omega) \propto 1/|\Omega|^\gamma$ (the $\gamma$-model) and analyze the competition/interplay between the tendency towards pairing and towards non-Fermi liquid behavior. We show that superconductivity still develops once the pairing interaction exceeds a certain threshold, but the origin of the pairing is qualitatively different from that in BCS theory. We show that the gap equation at $T=0$ has an infinite set of topologically distinct solutions. These solution disappear one by one once the pairing interaction becomes non-singular (massive). We review the physics underlying these phenomena and outline future directions.

Accurate initialization of polymer architectures remains a critical yet underappreciated determinant of reliability in molecular dynamics simulations of soft matter systems. Errors in coordinate generation and connectivity assignment frequently introduce artificial stresses, topological inconsistencies, and numerical instabilities that propagate throughout simulation trajectories. Here, we present a topology-preserving Python framework for generating star and cyclic polymer architectures with deterministic bond connectivity, exact ring closure, excluded volume enforcement, and spatial-hashing-based overlap detection. The algorithm produces LAMMPS-compatible data files under atom style full without reliance on third-party libraries. We demonstrate that the generated structures exhibit mechanical stability at initialization, suppressed artificial energy spikes, and consistent thermodynamic behavior during equilibration. Benchmark comparisons against naive random placement schemes reveal significant reductions in overlap-induced instabilities and improved reproducibility of structural and dynamical observables. The presented framework establishes initialization as a controlled physical boundary condition rather than a stochastic preprocessing step, thereby enhancing the reliability and reproducibility of polymer molecular dynamics simulations.

The pair-density wave (PDW) state, characterized by Cooper pairing at finite momentum, is a long-sought superconducting phase whose possible realization in Kagome metals is particularly intriguing in the strongly correlated regime. We investigate superconductivity in the extended $t$-$J$ model on the Kagome lattice and show that the symmetry-enforced sublattice structure of the Bloch wavefunctions gives rise to a rich landscape of unconventional pairing states. When the chemical potential is tuned to a sublattice-pure ($p$-type) van Hove singularity (vHS), a PDW state inevitably emerges. Near the $m'$-type vHS, which features opposite mirror eigenvalues to the conventional $m$-type vHS, intraband chiral, uniform, and nematic pairing states compete. When further-neighbor hoppings drive the $p$- and $m'$-type vHSs towards near degeneracy, phase frustration in the interband pairing channel stabilizes a chiral interband state. Our results reveal the previously overlooked $m'$-type vHS as a distinct route to unconventional superconductivity rooted in electronic correlations and mirror-symmetry-constrained Bloch wavefunctions.

Kagome lattice crystal systems present interesting symmetry-protected band structure features such as flat bands, van Hove singularities, and linearly dispersing Dirac/Weyl points that provide a rich playground for strongly correlated electron physics. Motivated by the rich properties and charge density wave evolution through the 1-6-6 series of compounds, we present our results in single crystal growth and characterization of the of Lu$_{1-y}$Y$_y$(Nb$_{1-x}$Ta$_x$)$_6$Sn$_6$ double-alloy system, including evolution of the charge density wave transition, electrical transport behavior and resultant phase diagrams. Using a novel growth technique, the synthesis of high quality crystals with extended length along the crystallographic $c$-axis allows us to follow the gradual suppression of charge density wave (CDW) order with Y substitution, and observe quantum oscillations in both magnetoresistance and magnetization throughout the series. We review the evolution of Fermi surfaces, effective masses and quasiparticle dispersion through the alloy series, revealing a decrease in size of Fermi surfaces that trends with both substitutions, and a scaling between effective mass and Fermi wavevector that suggests a regime with Dirac-like dispersion. The ability to fine-tune crystallographic, ground state and electronic dispersion properties of the \lit\ system with minimal impact of disorder opens a path torward further understanding the nature of the kagome lattice and its novel states and interactions.

Subdiffusive fractional Brownian motions produce localized aggregation when particles are stopped at exponentially distributed times. In applications where clumping and long-distance dispersal events are observed simultaneously, such as in some instances of seed dispersal, this model fails to describe the tails of the data. The resulting redistribution kernel has only an exponentially decaying tail, whereas a heavier tail is needed for modeling the long-distance dispersal observed. Here we propose a model in which subdiffusive particles stop at exponentially distributed times, but with a rate parameter that is Gamma distributed. This heterogeneity in stopping rates causes the density of final radial positions to have a heavy-tailed distribution. Our model retains the strong localized clumping characteristic of subdiffusive fractional Brownian motion while simultaneously generating the heavy tails required for realistic long-distance dispersal.

Stationary wave functions at the integer quantum Hall transition are known to be multifractal, but the exact form of the multifractality spectrum has remained a subject of debate. While conformal field theory arguments predict a parabolic law, numerical simulations show deviations from parabolicity. We resolve this discrepancy by pointing out that powers of the local wave intensity fail to obey the Gaussian Free Field and Abelian Fusion Hypothesis assumed in earlier analysis. Rather, due to the non-Abelian nature of the underlying effective field theory, wave intensity correlators are dressed by insertions of background charge distributed uniformly in space. An exact expression for the $q$-moments of point-contact generated eigenstates is presented. Numerical tests are performed for the critical Chalker-Coddington network model on a rectangular torus. Our results are in precise agreement with the predictions of conformal symmetry realized as a level-4 current algebra.

We investigate the intensity stability of the superradiant laser. Our study focuses on the architecture where a continuous beam of atoms in an electronically excited state crosses the mode of a high-finesse Fabry-Perot cavity, which has been proposed as a new architecture of an active optical clock. We show that such superradiant laser can become unstable and develop chaotic behavior. We derive an analytical criterion for this instability and find that it may only occur when the lifetime of photons in the cavity is significantly shorter than the lifetime of atoms. This criterion allows for refining the necessary parameters to run a superradiant laser as a frequency reference in the optical domain. In particular, we point-out the consequences of the instability on intensity fluctuations and laser linewidth. On the other hand, we also point out that the superradiant laser, when in the unstable regime, can become an interesting playground for studying chaos. At the mean-field level, there is a direct mapping to the Bénard instability associated with fluid turbulence; however quantum fluctuations associated with photon out-coupling and atom re-filling substantially modify the expected behaviors. Finally, we point-out the existence of a regular self-pulsing regime at large atom numbers.

Fermions with opposite spins occupying half-filled conjugate Chern bands exhibit interaction physics distinct from their multi-component Landau-level counterparts with the same chirality. This is largely due to unavoidable inter-species collisions that preclude the Halperin-type wavefunctions available in multi-component Landau levels. In this work, we propose and evaluate a variational wavefunction for a fractional quantum spin Hall state with Z_4 topological order in a pair of conjugate Landau levels. This Z_4 topological order has previously been shown to be the minimal topological order compatible with charge conservation, $S_z$ conservation, time-reversal symmetry, and the fractional spin Hall conductance 1/2 suggested by previous twisted MoTe$_2$ experiments. Our construction is based on the condensation of an anyonic exciton formed by the neutral fermionic excitations in a decoupled pair of Moore-Read Pfaffian state and its conjugate. By coupling the chiral and anti-chiral Ising conformal field theories associated with the two spin species, we introduce a variational mass parameter in the Z_4 trial wavefunction that captures the inter-spin-species s-wave pairing of composite fermions alongside the intra-spin-species p-wave pairing. We assess the energetics of this trial state using Monte Carlo sampling on a spherical geometry. Because the coupled state intrinsically involves Landau-level mixing, we explicitly evaluate the resulting kinetic energy penalty. Our phase diagram reveals that the proposed Z_4 state becomes energetically favorable in a sizable region of parameter space, over both the decoupled pair of conjugate Pfaffian states and an alternative exciton condensate state. These results provide a concrete microscopic wavefunction realization of this Z_4 fractional quantum spin Hall phase, and propose a route to constructing additional families of such states.

Quantum geometry has emerged as a unifying concept across condensed matter physics, underlying phenomena from nonlinear topological response to flat-band superconductivity. While usually formulated within band theory, quantum geometry remains meaningful in disordered interacting systems~\cite{resta1999electron}. Here we show that the first negative moment of the optical conductivity – proportional to the zero temperature quantum Fisher information as a bound on the multipartite entanglement – provides an experimental probe of quantum geometry across the three-dimensional metal-insulator quantum phase transition in phosphorus-doped silicon. We extract a quantum geometric length $\ell$ that characterizes the local wavefunctions. Far from the transition, this length is almost coincident with the Bohr radius of the hydrogenic phosphorus donors, reflecting their atomic-scale quantum geometry. Approaching the transition, $\ell$ is enhanced, but does not diverge continuously like a correlation length; it jumps discontinuously to infinity at the critical point. This reflects the UV domination of the sum rule in three dimensions that renders it insensitive to the critical fluctuations driving the diverging dielectric constant and correlation length. Its enhancement demonstrates a “puffing" of the donor polarizability volume of quantum geometric origin, which yields a quantum geometric corrected Clausius-Mossotti description in closer agreement with the diverging dielectric response and provides a quantum mechanical foundation for the century-old Herzfeld metallization criterion.

Molecular dynamics simulation of plasma-surface interactions requires an interatomic potential that is simultaneously accurate, computationally efficient, and able to describe many elements and bonding types in reactive systems. In principle, a foundation model for machine-learned interatomic potential (MLIP) can meet these demands. We explore the use of the Universal Models for Atoms (UMA) model, developed by Meta FAIR, for the interactions of oxygen plasma species on a multilayer of WS$_2$, a promising 2D material. Starting from the pretrained uma-s-1p1 model under the Open Catalyst 2020 (OC20) task, we apply an iterative fine-tuning loop. Even in the absence of fine-tuning, the pretrained model reproduces the production-scale observables of interest, namely, chemisorbed S and O coverage under 15 eV O$^+$ and O$_2^+$ bombardment. These results were obtained without spin polarization and Hubbard $U$ correction. Nonetheless, fine-tuning with spin polarization and a Hubbard $U$ correction reduces the energy and force mean absolute error (MAE) to $4.5\times10^{-3}$ eV/atom and $0.076$ eV/angstrom, respectively.

We show that an integer quantum Hall setup proximized by superconductors can exhibit subgap thermoelectric effects in the linear-response regime when triplet superconducting correlations are present. We devise a minimal setup that enables a nonzero Seebeck effect mediated by Andreev processes and predict that the corresponding Seebeck coefficient can reach values on the order of $k_B/e$ in the middle of the quantum Hall plateau. We analytically show that both triplet correlations and spin polarization are essential for the emergence of the thermoelectric effect, which arises despite the linear band dispersion of the edge states. We characterize the dependence of the thermoelectric response on the Hamiltonian parameters and the system's temperature regime.

Nonreciprocal interactions underpin diverse nonequilibrium phenomena, yet the effects of quenched nonreciprocity in extended systems remain largely unexplored. We study a $2d$ Ising model with randomly distributed nonreciprocal bonds at density $p$, finding a continuous nonequilibrium transition down to $T=0$ with finite $p_c$. A gauge-invariance argument yields $p_c(T)\leq1/2$, and mean-field theory predicts a qualitatively correct phase diagram. Unlike equilibrium disordered models, the zero-temperature dynamics remains active, with athermal rare-region reversals and logarithmic "activated" coarsening.

Quantum capacitance (QC) has recently emerged as a promising tool for parity readout in topological qubits based on Majorana bound states (MBSs). Here, we show that this capability can be extended further: by employing an auxiliary quantum dot (QD) as a sensor, we demonstrate that QC measurements simultaneously resolve two fundamental figures of merit of the device, the ground-state energy splitting and the MBS overlap, thus providing direct access to the underlying internal degrees of freedom. Using a low-energy effective model, we provide analytic expressions for these two figures of merit that can be determined from the relative position and magnitude of the QC maxima in the even and odd parity sectors as functions of the auxiliary-QD energy. We further validate these results with a microscopic model of QD-based Kitaev chains and qubits, demonstrating their applicability in a wide range of MBS-based devices. Our results establish QC as a probe of MBS quality and a tool for topological-device optimization that preserves fermion parity.

The Fermi polaron, formed by an impurity interacting with a surrounding Fermi sea, exemplifies the canonical quasiparticle concept as a cornerstone in our description of quantum many-body systems across a wide range of energy scales. Experiments on atomic quantum gases have provided profound insights into the universal nature of the Fermi polaron. While most previous studies have focused on the case of zero impurity momentum, finite-momentum properties have remained largely uncharted. Here, we investigate the moving Fermi polaron by combining a novel Raman acceleration scheme with high-precision radio-frequency spectroscopy, exploring the quasiparticle dispersion relation over a wide range of momenta. We compare our measurements of energy shifts and spectral linewidths with a microscopic theory and reach quantitative agreement for all momenta. For low momenta, we find the energy of the moving polaron to be fully consistent with the Fermi liquid picture of a dressed particle with a constant effective mass. At high momenta, the polaron approaches the behavior of a weakly interacting bare particle, featuring small energy shifts and weak broadening. For intermediate momenta, broadening is generally larger and, most strikingly, the behavior differs for attractive and repulsive polarons. While the repulsive polaron exhibits a smooth connection between both regimes along with a monotonic change of the energy shift, the attractive case shows a peculiar non-monotonic behavior. With increasing momentum, the attractive polaron enters a regime where its energy deviates from the constant effective mass expression and broadening suddenly increases. By comparing this observation with theory, we show that this abrupt behavior coincides with the attractive polaron entering a molecule-hole continuum, where it is no longer the ground state. We interpret this as a motion-induced polaron-molecule transition.

Thermodynamic uncertainty relations establish fundamental bounds between current fluctuations and entropy production in nonequilibrium systems. In hybrid normal superconducting conductors, transport is governed by the coexistence of quasiparticle transmission and Andreev reflection, where electron hole conversion transfers charge through the superconducting condensate. Using the Anantram Datta scattering formalism, we decompose the charge current and zero-frequency noise into Andreev, quasiparticle, and interference contributions. Although the interference term prevents a simple additive bound at the level of individual noise components, we show that the nonequilibrium excess noise admits a positive representation. This allows us to prove a hybrid quantum thermodynamic uncertainty relation valid for an arbitrary real superconducting gap. Our result extends the pure Andreev quantum TUR to regimes where quasiparticle and Andreev processes coexist, clarifying how superconducting coherence reshapes current fluctuations while preserving a universal dissipation precision constraint in hybrid quantum conductors.

The viscoelastic instability of cross-slot flow was first observed experimentally almost half a century ago and reproduced numerically two decades ago, yet its physical origin remains unresolved. We revisit this problem for two-dimensional creeping flow of Oldroyd-B fluid by combining direct numerical simulations, global stability analysis, structural sensitivity analysis, and energy-budget analysis. Our simulations reproduce the canonical pitchfork bifurcation, and the stability analysis consistently predicts the threshold and perturbation growth rates. The leading eigenmode consists of a chiral velocity–stress perturbation that tilts and rotates the birefringent strand generated by the extensional flow. Structural sensitivity and energy-budget analyses identify narrow high-extension-rate ridges within the extensional flow as both the spatial core and energetic source of the instability. In these ridges, the stress-based wavemaker co-localizes with large positive disturbance polymeric stress power density, indicating localized transfer of stored elastic energy to the disturbance flow. Analyses of cross-slot variants with rounded corners and with a centered cylinder further reveal that neither sharp corners nor a free central stagnation point is the essential destabilizing ingredient; rather, the instability originates from elastic-energy release in extension-dominated regions characteristic of cross-slot flow.

This article describes recent progress in understanding highly stable glasses prepared by physical vapor deposition and provides perspective on further research directions for the field. For a given molecule, vapor-deposited glasses can have higher density and lower enthalpy than any glass that can be prepared by the more traditional route of cooling a liquid, and such glasses also exhibit greatly enhanced kinetic stability. Because vapor-deposited glasses can approach the bottom of the amorphous part of the potential energy landscape, they provide insights into the properties expected for the ideal glass. Connections between vapor-deposited glasses, liquid-cooled glasses, and deeply supercooled liquids are explored. The generality of stable glass formation for organic molecules is discussed along with the prospects for stable glasses of other types of materials.

Altermagnets host momentum-dependent spin splitting without net magnetization, a symmetry-enforced band phenomenon whose photonic analogues have so far been realized only in square lattices governed by fourfold rotation. Here we introduce a photonic altermagnet on a hexagonal lattice whose helicity splitting is governed by mirror rather than rotational symmetry. Elliptical chiral elements of alternating handedness, placed at the vertices of a regular hexagon, leave the two opposite-chirality sublattices connected only by chirality reversal combined with a mirror reflection. Full-wave simulations reveal mirror-related splitting of the two opposite-helicity branches in the band structure and isofrequency contours, with the channels exchanged when the ellipse orientation is reversed. Using a finite photonic crystal slab, we show that such splitting separates a linearly polarized beam into handedness-resolved channels, thus enabling beam splitting and direction-selective helicity filtering with target-helicity output fractions above 0.85 and output paths continuously tunable through the ellipse rotation angle. These results extend photonic altermagnetism to a previously unexplored lattice-symmetry class and establish mirror-symmetric chiral textures as building blocks for altermagnetism-inspired on-chip chiral photonics.

The interplay of superconductivity, band topology, and spontaneous time-reversal-symmetry breaking (TRSB) is expected to enable topological superconducting boundary states. FeTe0.55Se0.45 provides a promising single-material platform because it combines superconductivity, nontrivial band topology, and spontaneous magnetization in the superconducting state. Here we report evidence for a boundary-mediated superconducting transport response in exfoliated Fe(Te,Se) devices. Polar Kerr measurements show that TRSB emerges below TKerr < Tc and coexists with superconductivity across multiple compositions, providing an independent symmetry-breaking scale for transport. Using crystallographically sharp, continuous edges and side-surface-dominant contacts, we find that topological FeTe0.55Se0.45 exhibits an anomalous conductance plateau absent in topologically trivial FeTe0.40Se0.60 and Fe1.02Te0.55Se0.45 under comparable measurements. This plateau requires uninterrupted sharp edges connecting source and drain, persists over micrometer-scale separations far exceeding the bulk coherence length, shows strongly suppressed thermal broadening, and collapses when the drain is moved to the top surface. Its temperature evolution follows the TRSB scale: the plateau remains weakly broadened below T*Kerr and disappears near TKerr rather than Tc. These doping-selective, edge-geometry-dependent, TRSB-correlated, and long-range nonlocal signatures establish experimental criteria for identifying boundary-mediated superconducting transport in FeTe0.55Se0.45 and motivate phase-sensitive and theoretical studies of its microscopic origin.

We study a mobile impurity coupled to a Kitaev chain with chemical-potential disorder and ask whether the impurity behavior distinguishes different regimes of the host system. Exact diagonalization calculations for small periodic chains shows that in the deep topological regime the impurity localizes only partially, with a smooth increase of $\mathrm{IPR}_d$, whereas in the deep trivial regime it undergoes a much sharp transition to nearly single-site localization. For open chains at strong interaction, DMRG shows edge-localized impurity density near the Kitaev sweet spot. With increasing chemical potential, the impurity weight spreads into the bulk and eventually becomes almost uniform. We explain the edge preference analytically from the Majorana-dimer structure: a bulk impurity rearranges two neighboring dimers, while an edge impurity affects only one. Disorder competes with this clean edge bias and can pin the impurity in the bulk. Thus, the impurity is sensitive to the regime of the host system, although we do not find a strict one-to-one correspondence between the impurity localization pattern and the host topology. Instead, the disorder-averaged behavior suggests only an indirect correlation between impurity localization and the underlying phase of the chain.

Water confined within nanoscale capillaries exhibits phase behaviour and transport properties that differ substantially from bulk, and these effects are commonly interpreted as consequences of geometric confinement and reduced dimensionality. Here we show that confinement topology alone is insufficient to predict the behaviour of nanoconfined water. Using machine learning interatomic potentials with first-principles accuracy, we compute the density-temperature phase diagram of water confined within bilayer graphene nanocapillaries and compare AA and AB stacking arrangements, which differ only by a lateral shift of 1.4 Å. Despite this minimal structural change, AA stacking can stabilise different ice polymorphs, can increase the melting temperature by more than 100 K, can enhance proton transfer, and alters the onset of superionic behaviour relative to AB stacking. We trace these effects to stacking-induced changes in the hydrogen-bond network associated with modifications to the lateral free energy landscape and neighbouring O-O separations. Our results demonstrate that even subtle atomistic variations in the confining walls can qualitatively reshape the physical and chemical behaviour of nanoconfined water, with implications for the interpretation and control of fluids under angstrom-scale confinement.

Defect and heteroatom engineering offer powerful routes for tuning the electronic and magnetic properties of graphene, yet the role of specific peripheral nitrogen topologies around graphene voids remains insufficiently understood. Here, spin-polarized first-principles calculations were performed to investigate how four heterocyclic – like peripheral nitrogen configurations – pyridinic, pyridazinic, pyrrolic, and pyrazolic modify the structural stability, charge redistribution, electronic structure, and magnetic response of graphene containing a central void. Among the four peripheral N configurations, the pyridinic N provides the most favorable structural-energetic balance among the investigated motifs. Bond-length analysis reveals that nitrogen topology strongly controls local lattice reconstruction. Charge-density, charge-density-difference, and Bader analyses demonstrate that the peripheral N atoms act as electron-accumulating centers and reshape the local electronic environment around the vacancy rim. Spin-resolved band structures show that pyridinic, pyridazinic, and pyrrolic configurations retain metallic or near-metallic defect-state character, whereas pyrazolic graphene opens a narrow band gap. Magnetic analysis further reveals that pyrazolic graphene is spin-compensated, with zero net magnetization, unlike the other systems, which possess finite spin-polarized moments. Spin-density and SPDOS analyses indicate that the magnetism originates from N-modulated vacancy-edge states involving both N 2p and neighboring C 2p orbitals. These findings establish peripheral nitrogen topology not merely as a structural defect descriptor, but as a deterministic defect-chemical switch, offering a metal-free route to pattern active spintronic and semiconducting domains directly into the graphene lattice through controlled vacancy-edge nitrogen coordination.

Colloidal smectics – layered structures formed in dense suspensions of rod-like particles – often exhibit grain boundaries, across which the layer orientation changes by $90^{\circ}$. Motivated by this feature, we develop a layer-based topological framework that treats orthogonal grain boundaries as constituents of the ground state rather than as exceptional defect structures. Extending the layer-based approach for ordinary smectics, we reduce the smectic structure to layers, half-layers, and domain walls. We classify the topology of defects and their combination rules based on this structure. In two dimensions, point defects are described by semi-directed cycle graphs. Although the disclination charge remains a valid topological invariant, it does not uniquely classify defects, as distinct graphs may share the same charge. In three dimensions, line defects are classified by their transverse graph structure, while point defects exhibit qualitatively different behavior. In particular, we show that the hedgehog disclination charge is not a topological invariant, but instead varies continuously under smooth deformations of the layer structure.

We investigate the non-equilibrium work statistics originating from a sudden quench in a bosonic Josephson junction. In particular, by employing the Holstein-Primakoff approximation, the work statistics are analytically characterized in the weak-interaction regime, where the dynamics map onto a time-dependent quantum harmonic oscillator. For a junction initialized in the ground state of the pre-quench Hamiltonian, we demonstrate that the work statistics are governed by a negative binomial distribution, as occurs in fully-connected models driven across a critical point. Furthermore, we also consider initial superposition states containing quantum coherences in the energy basis. To characterize the corresponding work distributions, we employ Kirkwood-Dirac quasiprobabilities (KDQ). Even in the simplest case, when the junction is initialized in a superposition of the ground and second excited states, the KDQ distribution of work exhibits negative or complex values, reflecting non-classical features. Moreover, the coherence content of the initial state can be optimized to enhance the extractable work extracted from the quench, beyond classical bounds. Finally, we propose an experimental interferometric protocol to directly measure the characteristic function of the work distribution in experimentally accessible settings.

We study the dynamics of recombination, optical orientation, and optical alignment of excitons in ensembles of CsPbI$_{3}$ nanocrystals (NCs), synthesized in a glass matrix. In large NCs with size exceeding 16 nm, the low-energy photoluminescence is contributed by the emission of indirect in real space excitons formed by spatially separated electrons and holes, which are localized at the NC/glass interface. The recombination dynamics of an ensemble of such excitons extends from tens of nanoseconds to microseconds and exhibits a power-law dependence. Their optical alignment and optical orientation reveal a peculiar spin dynamics caused by excitons influenced by the exchange interaction, varying by orders of magnitude. We develop a theory of the polarized photoluminescence of triplet excitons, taking into account the interplay between the electron-hole exchange interaction, their Zeeman effect, and their hyperfine interaction with the nuclei. This model reveals that for the excitons with the smallest exchange splitting we reach the regime, where the exciton fine structure becomes dominated by the hyperfine interaction with the random nuclear spin fluctuations in the NCs.

We have developed a machine learning model for critical cooling rates for metallic glasses based on computational properties. We compare results for features derived from easy-to-compute functions of elemental properties to more complex physically motivated properties using ab initio, machine-learning potentials, and empirical potential molecular dynamics methods. The established approach enables property acquisition across a diverse range of alloys. Analysis of various features for 34 alloys from 20 chemical systems shows that the best model for critical cooling rates was learned from one elemental property-based feature and three simulated features. The elemental property-based feature is an ideal entropy value based on alloy stoichiometry. The simulated features were acquired from estimates of energies above the convex hull, changes in heat capacity, and the fraction of icosahedra-like Voronoi polyhedra. Models were assessed through a demanding cross validation test based on repeatedly leaving out full chemical systems as test sets and had an $R^2$ of 0.78 and a mean average error of 0.76 in units of $[log_{10}(K/s)]$. We demonstrate with Shapley additive explanation analysis that the most impactful features have physically reasonable influence on model predictions. The established methodology can be applied to other high-throughput studies of material properties of diverse compositions.

Matter can organize not only through forces, but also through the information its constituents acquire from their surroundings. Here we use perceptive Brownian particles as a minimal model to isolate nonlocal sensing as an organizing principle for nonequilibrium matter. The particles undergo purely Brownian motion, with no mechanical interactions, self-propulsion, alignment, or auxiliary fields. Their only coupling is informational, through diffusivity regulated by density measured over a finite perception zone. Whereas local sensing, when unstable, produces conventional long-wavelength demixing, nonlocal perception restructures the instability spectrum, introducing finite-wavelength patterning and nonlinear bubbling instabilities. More fundamentally, it reshapes the ordering pathway by assembling a cascade of instabilities: macroscopic demixing creates dense domains, finite-wavelength modes pattern them internally, and nonlinear feedback hollows them into void bubbles. This produces hybrid phase separation, where a macroscopic dense phase coexists with a dilute background while retaining ordered internal microstructure, whose symmetry, anisotropy, and length scales are selected by the perception kernel. These results establish information acquisition as a constitutive principle of nonequilibrium matter, capable of governing both phase stability and the dynamical pathways through which order emerges.

Dynamic qubit routing is emerging as a promising architectural path for semiconductor quantum processors. Charge carriers can be rapidly moved around on a chip using traveling-wave potentials known as conveyors, preserving the spin state with high fidelity. Originally developed for spin transport, conveyor-mode shuttling may also offer opportunities for performing qubit operations directly controlled by the motion itself. Here, we demonstrate coherent single- and two-qubit control by conveyor-mode electron shuttling, using two conceptually different approaches. First, conveyor electric-dipole spin resonance (conveyor EDSR) achieves high-fidelity rotations by resonantly shuttling spins through transverse magnetic-field gradients at their mean Larmor frequency. Second, conveyor diabatic gates exploit quantization-axis tilts for tunable bang-bang control. Combining diabatic conveyor transport with exchange activation controlled by the motion directly yields a variety of effective two-qubit interactions selectable via the shuttling speed and distance. These experimental results motivate an architectural paradigm of reconfigurable and transport-driven spin qubits.

Perovskite oxides ABO$_3$ host a rich interplay of charge, spin, lattice, and orbital degrees of freedom, giving rise to diverse quantum phenomena. In low-dimensional ABO$_3$, reduced symmetry can induce exotic quantum effects such as the two-dimensional electron gas and unconventional superconductivity. Using first-principles density functional theory, tight-binding modeling, and symmetry analysis, we show that ultrathin two-dimensional (2D) ABO$_3$ films – exemplified by SrTiO$_3$ – naturally break inversion symmetry, producing a spontaneous out-of-plane bulk photovoltaic (BPV) effect. This differs from previous studies on in-plane BPV current signals and is more applicable and experimentally detectable. Such an effect is highly tunable via thickness, strain, surface termination, crystallographic orientation, and Moiré twisting. These findings are broadly applicable to a wide range of 2D perovskite and other layer-resolved oxides.

An efficient and robust FFT-based solver is proposed for diffusion-type problems with general Neumann and Dirichlet boundary conditions, based on a Chebyshev collocation framework. The method combines Chebyshev polynomial approximations with FFT-based operators to provide a matrix-free implementation of the discrete differential operator at the Chebyshev-Gauss-Lobatto points. The linear system of equations resulting from the Chebyshev discretization is solved using LGMRES. To overcome convergence problems on fine grids, a hierarchical refinement strategy based on modal prolongation is proposed, enabling the solution of very large 3D problems. The methodology is applicable to homogeneous and heterogeneous domains, as well as to linear and nonlinear constitutive equations. The accuracy of the proposed method is analyzed by solving the Poisson equation in homogeneous 1D and 3D domains with general boundary conditions, using manufactured analytical solutions as references. Convergence to the analytical solution is achieved in a few iterations, with smaller errors than those obtained using DCT/DST approaches. Discretizations of up to $256^3$ are achieved thanks to the hierarchical refinement strategy. In the case of heterogeneous domains, the accuracy and efficiency obtained are similar to those of a standard periodic FFT approach. It is found that the computational complexity of the method preserves the FFT scaling, of order $n\log n$, in all the cases studied.