Papers

The potential energy landscape, PEL, theory stands as one of the most successful frameworks for understanding supercooled liquids and glassy systems. A central element of this theory is the configurational entropy, Sc, which is traditionally represented by a symmetric Gaussian distribution. However, the asymmetric nature of the potential energy of inherent structures, Eis, poses a challenge to such a representation across wide regions of configurational space. In addition, the Gaussian distribution fails to represent fragile to strong transition, FST, observed in various fluids. In this work, we demonstrate that an asymmetric distribution, specifically the Gamma distribution, provides effective description of both Sc and Eis over broad ranges of density and temperature, T. The FST is interpreted through shifts of the Eis distribution and the curvature change of the Eis vs 1/T relation. In terms of energy changes, the FST is comparable to a liquid-liquid phase transition. Moreover, the revised PEL framework yields an equation of state that incorporates a singular term diverging at a glassy or jammed state, an important feature for accurately describing the pressure behavior of these systems.

Machine learning models have become firmly established across all scientific fields. Extracting features from data and making inferences based on them with neural network models often yields high accuracy; however, this approach has several drawbacks. Symbolic regression is a powerful technique for discovering analytical equations that describe data, providing interpretable and generalizable models capable of predicting unseen data. Symbolic regression methods have gained new momentum with the advancement of neural network technologies and offer several advantages, the main one being the interpretability of results. In this work, we examined the application of the deep symbolic regression algorithm SEGVAE to determine the properties of two-dimensional materials with defects. Comparing the results with state-of-the-art graph neural network-based methods shows comparable or, in some cases, even identical outcomes. We also discuss the applicability of this class of methods in natural sciences.

Since the first evidence of luminescence of organic polymers in STM junctions, efforts have been invested in elucidating how to leverage the voltage, anchoring chemistry, and molecular structure to optimize emission power and efficiency. Understanding the fundamentals underlying current-driven molecular emission is important not only for OLED engineering, but also to control luminescence at the atomic scale toward the mastering of single or localized photon sources. However, the difficulty in isolating the separate roles of the variables at play in molecular junction experiments, has precluded a general comprehension of their distinctive effects on the emitted power and the quantum yield. In the present report, we use time-dependent electronic structure simulations based on quantum electrodynamics to disentangle the incidence of bias, electronic coupling and molecular length on device performance, with polyphenylene-vinylene as a case study. A careful validation demonstrates that our approach can achieve quantitative agreement with available experimental data. Through its application we identify the applied bias as the main factor determining emission power. The quantum efficiency, however, is influenced only minimally by bias and electronic coupling, and is instead dominated by polymer length, on which it depends exponentially. Thus, using longer polymer chains emerges as the primary strategy for achieving higher efficiencies. Our results thereby provide key prescriptions for designing single-molecule electroluminescent platforms.

We demonstrate a dual nanopore platform (DNP) containing a top 2D MoS2 pore in series with a 3 to 5 nm thick SiN pore, vertically separated by 30 nm, with diameters of 1.0 and 3.0 nm, respectively. This platform enables independent probing of analytes by each pore, thereby providing complementary information. We measure translocations of single amino acids (AA) and evaluate current blockades recorded across the two pores upon applying voltage. Small diameters ensured tight passage of individual AAs through the nanopores and provided a good signal-tonoise ratio (RMS current noise of 16 pA_RMS and SNR = 6). We focus on measurements of O-Phospho-L-tyrosine at 400 mV, demonstrating single amino acid detection and a good quantitative agreement with the calculated open pore and blocked currents. Based on these results, future device performance can benefit from slightly smaller pores, specifically the SiN pore, higher voltages and electrolyte concentration, and lower system noise.

Silicon spin qubits offer long coherence times, a compact footprint and compatibility with industrial CMOS manufacturing. Here, we investigate spin qubits hosted in quantum dots fabricated in a state-of-the-art 300 mm nanoelectronics foundry and demonstrate substantially enhanced coherence, achieving a Hahn-echo time of $T_2^{\text{Hahn}} = 4\,\mathrm{ms}$ for singlet–triplet oscillations. Employing noise spectroscopy and noise correlation measurements, we identify detuning noise with an amplitude of $\delta \varepsilon_{\mathrm{rms}} = 2.2\,\mu\mathrm{eV}$ (integrated over 90 s) and observe strong zero-phase correlations between two spatially separated spin qubits. The singlet–triplet basis intrinsically rejects these common-mode fluctuations, yielding a pronounced suppression of dephasing. Our results suggest that exploiting the versatility of silicon quantum dots to adapt the qubit encoding to the microscopic noise landscape represents a promising strategy for advancing scalable quantum information processing.

Self-propelled microparticles create flow fields that determine how they interact with surfaces, external flows, and each other. These flow fields fall into distinct classes–pushers, pullers, and neutral swimmers–each exhibiting fundamentally different collective behaviors. In all existing synthetic systems, this hydrodynamic character is permanently set during fabrication, making it impossible to explore how adaptive switching between these classes might enable new functions or emergent phenomena. Here we demonstrate that the hydrodynamic character of a microswimmer can be programmed and switched on demand. Using patterned laser heating of surface-bound nanoparticles, we create tailored temperature gradients that drive controllable boundary flows at the particle surface. By changing the illumination pattern in real time, we dynamically transform the swimmers flow field continuously tuning from pusher to puller, while the particle continues to swim. Flow measurements confirm quantitative agreement with theory and allow us to simultaneously track how symmetry, power consumption, and efficiency change across modes. This control over hydrodynamic modes opens experimental access to questions that have remained largely theoretical: How do adaptive swimmers respond to crowding or confinement? Can mixtures with tunable pusher-puller ratios reveal new collective states? Our approach provides a platform to address these questions and explore the morphological developments of active matter systems under external physical constraints.

We provide a field-theoretical description of thermal nucleation in a one-dimensional ferromagnetic superfluid, a quantum-gas analogue of false-vacuum decay. The rate at which ground-state domains nucleate follows an Arrhenius law, with an exponential factor determined by a saddle-point of the energy functional – the critical droplet or instanton – and a magnitude fixed by small fluctuations about this configuration. We evaluate both contributions over the full parameter space, using a Gel'fand-Yaglom approach to reduce the calculation of the fluctuation spectrum to an initial-value problem. In addition, we obtain a closed-form expression for critical droplets close to the coexistence line, and use it to formulate an effective theory of domain nucleation and growth as a Kramers escape problem for the droplet size. Our results determine the parametric dependence of the nucleation rate and predict its signature in experimental images of a nucleating gas, increasing the rigor of comparisons between nucleation theory and experiment.

Organic mixed conductors (OMCs) represent a promising class of materials for applications in bioelectronics, physical computing, and thermoelectrics. Rather unparalleled, OMCs feature dynamics spanning multiple length and time scales, involving an intricate coupling between electronic, ionic, and mass transport. These characteristics set them notably apart from traditional semiconductors and hinder the description by conventional semiconductor theory. In this work, we approach the charge carrier modulation of OMCs using statistical mechanics. We discuss OMCs from a thermodynamic perspective and contrast them with established semiconductor materials, highlighting key differences in their collective charge carrier dynamics. This motivates our description of OMCs as a lattice gas, which we analyze within the grand canonical ensemble. The model exhibits a first-order phase transition analogous to a classical vapor$\unicode{x2013}$liquid transition, governed by temperature and chemical potential. In doing so, it captures the formation of distinct low- and high-density carrier phases, consistent with recently reported experimental observations. It also illustrates how metastability near the phase boundary can give rise to history-dependent characteristics in device operation, a similarly well-reported effect in OMC transistors. This work is intended as a simple motivation for studying OMCs through the lens of statistical mechanics, offering a more natural description than traditional semiconductor models developed for materials of fundamentally distinct character.

We simulate the formation of cyclical arms in star polymers, focusing on the effects of solvent quality on their resulting linking complexity and gyration radius. We find that polymers circularized in bad solvent present a higher degree of linking among arms with respect to those circularized in good solvent. When both are transported to good solvent, this results in a smaller gyration radius of the former with respect to the latter. This effect is magnified when the polymers present a sufficiently small number of arms (or functionality $f$): in this case, in bad solvent, all arms tend to clump together on one side of the central core, due to circularization, and can hence all interact with each other. Instead, when $f$ is large enough, the whole surface of the core is wetted by the arms, whose distribution becomes radially symmetric. This hinders interactions between faraway arms and reduces the probability of inter-arm linking. Interestingly, we find that both the critical $f_c$ at which the clump transition happens and the minimal arm length $n_c$ for which the transition appears depend on the core size: the grafting density of the arms must be larger than a certain constant $\rho_g^c$, while their length must be sufficient to stretch for, at least, half of the core's circumference.

Diffusion of particles in complex fluids and gels is difficult to describe and often lies beyond the scope of the classical Stokes-Einstein relation. One of the main lines of research over the past few decades has sought to relate diffusivity to a fundamental dissipative property of the fluid: the wave-vector-dependent shear viscosity function. Here, we use linear response theory to extend this viscosity function framework to rod-like particles. Using a dimer (two-bead particle) as a minimal rod-like probe, we derive explicit expressions for its diffusion coefficients parallel and perpendicular to its axis in terms of the viscosity function. We show that this description captures the full range of behaviors, from nearly isotropic diffusion of the rod-like probe to highly anisotropic, reptation-like motion. The method is based on a microscopic statistical-mechanical treatment of the Smoluchowski dynamics, yet leads to simple final formulas, providing a practical tool for interpreting diffusion experiments on rod-like tracers in complex fluids. We also clarify the limitations of this approach, emphasizing that the present formulation is primarily suited to complex liquids like polymer solutions and only indirectly applicable to gels.

Discrete time crystals (DTCs) have emerged as a novel non-equilibrium phenomenon. Nevertheless, analytical quantification for disordered DTCs remains challenging, leaving uncertainties about their behaviors in large scale systems amid current debates on the stability of (Floquet-)many-body localization. In this work, we introduce an analytical framework to calculate the values of key observables in a strongly disordered DTC without fitting parameter. The perturbatively obtained closed-form formulae show quantitative agreement with numerical simulations for inverse participation ratios for eigenstate localization in Fock space, Edwards-Anderson parameters for spin-glass orders, mutual information for long-range entanglement, and the steady-state amplitudes of autocorrelators for period-doubled oscillations. Meanwhile, we demonstrate that eigenstate resonances render the scaling for the deviation of physical observables from their unperturbed values as $O(\lambda)$, in contrast to non-resonant situations with suppressed deviation $O(\lambda^2)$. Our newly developed scheme adopts resolvent perturbation formalism, which can directly prescribe arbitrarily higher-order corrections without iterations. With such advantages, we analytically prove that quasienergy corrections for pairwise cat eigenstates are identical up to order $O(\lambda^{(L/n_{\text{op}})-1})$, where perturbations of strength $\lambda$ involve at most $n_{\text{op}}$-spin terms. Such spectral pairing deviations quantify the DTC lifetime as $\tau_* \sim (1/\lambda)^{L/n_{\text{op}}}$. We further show that the analytical framework applies to generic DTC models with dominant Ising interaction and a given number of qubits, offering a unified scheme to quantify physical observables for systems beyond numerically accessible sizes, with or without disorders.

Infinite projected entangled-pair states (iPEPS) provide a powerful variational framework for two-dimensional quantum matter and have been widely used to capture bosonic topological order, including chiral spin liquids. Here we extend this approach to fermionic topological order by variationally optimizing $U(1)$-symmetric fermionic iPEPS for a fractional Chern insulator (FCI), with bond dimensions up to $D=9$. We find evidence for a critical bond dimension, above which the ansatz faithfully represents the FCI phase. The FCI state is characterized using bulk observables, including the equal-time single-particle Green's function and the pair-correlation function, as well as the momentum-resolved edge entanglement spectrum. To enable entanglement-spectrum calculations for large iPEPS unit cells, we introduce a compression scheme and show that the low-lying part of the spectrum is already well converged at relatively small cutoff dimensions.

The effects of inter-defect interaction and impurity disorder on defect thermodynamics, local ion coordination, and oxidation in acceptor-doped wide-gap ABO3 perovskites are explored using the developed statistical theory and Monte Carlo simulations. The results demonstrate that under realistic energy parameters the interaction between oxygen vacancies and impurities generally has a greater impact on the studied properties than inter-vacancy correlations. The influence of inter-vacancy interaction significantly depends on dopant content x: inter-site vacancy repulsion becomes noticeable at sufficiently high x, whereas on-site correlations can be pronounced within a narrow doping range at moderate x values. It is found that a non-uniform impurity allocation, which can result from a sample preparation procedure, considerably affects oxygen-vacancy distribution, and has a weaker effect on short-range order and oxidation. It is also shown that inter-defect interaction reduces the hole concentration, increases the oxidation enthalpy, and can result in their non-trivial dependence on x. The obtained results agree with experimental data on local ion coordination and help to explain the behavior of hole conductivity in the considered perovskites. The findings of this study contribute to understanding the fundamental properties of acceptor-doped oxides, facilitating the development of new materials for clean energy applications.

Atomic cells made by anodically bonding silicon and borosilicate glasses are widely used in atomic devices. One inherent problem in these cells is that the silicon material blocks beams with wavelengths shorter than 1000 nm, which limits available optical accesses when alkali metal atoms are involved. In this work, we investigate the possibility of the silicon carbide material as an alternative of silicon materials in fabricating anodically bonded cells. We demonstrate that the optical, thermal and mechanical properties of silicon carbide help to improve the performance of atomic devices in certain applications.

We study a non-Hermitian extension of the Creutz ladder with generic non-reciprocal hopping. By mapping the ladder onto two decoupled non-Hermitian Su–Schrieffer–Heeger (SSH) chains, we uncover a rich structure in parameter space under different boundary conditions. Under periodic boundary conditions, the spectrum admits a fine-tuned line in parameter space with entirely real eigenvalues, while deviations from this line induce a real–complex spectral transition without crossing exceptional points. In contrast, an exact analytical diagonalization under open boundary conditions reveals extended regions in parameter space with purely real or purely imaginary spectra, separated from complex spectral domains by exceptional lines. The intersections of these exceptional lines define triple-junction points where distinct spectral regimes meet, giving rise to a structured phase diagram that is absent under periodic boundary conditions. We further show that flat bands in this system can occur both as Hermitian diabolical points and as non-Hermitian exceptional points, known as exceptional flat bands, where the dynamics is more stringent than in the Hermitian case, leading to distinct spectral and dynamical signatures.

We propose a ground state entanglement probe for gapped, two-dimensional quantum many-body systems that involves taking powers of reduced density matrices in a particular geometric configuration. This quantity, which we denote by $\omega_{\alpha,\beta}$, is parameterized by two positive real numbers $\alpha, \beta$, and can be seen as a “Rényi-like" generalization of the modular commutator – another entanglement probe proposed as a way to compute the chiral central charge from a bulk wave function. We obtain analytic expressions for $\omega_{\alpha,\beta}$ for gapped ground states of non-interacting fermion Hamiltonians as well as ground states of string-net models. In both cases, we find that $\omega_{\alpha,\beta}$ takes a universal value related to the chiral central charge. For integer values of $\alpha$ and $\beta$, our quantity $\omega_{\alpha,\beta}$ can be expressed as an expectation value of permutation operators acting on an appropriate replica system, providing a natural route to measuring $\omega_{\alpha,\beta}$ in numerical simulations and potentially, experiments.

We investigate the dynamical phases that emerge in collective spin models subjected to a spatially non-uniform periodic drive. Taking the paradigmatic Lipkin-Meshkov-Glick (LMG) model as a concrete platform, we establish that a rich landscape of dynamical phases emerges when two regions of the system are driven with different field strengths, $h_1$ and $h_2$. Remarkably, despite the `all-to-all' nature of the interactions, the system can be driven into dynamical phases characterized by distinct kinds of discrete time crystal (DTC) orders in different parts of the system. Apart from these coexisting DTCs, tuning the driving field leads to the emergence of phases where DTCs coexist with Floquet-synchronized or oscillatory phases; the former has been dubbed a chimera DTC. Finally, we demonstrate that a tunable set of global DTC phases emerges when $h_1$ and $h_2$ are proximate. Crucially, these dynamical regimes can be observed both for experimentally relevant finite-size systems and in the thermodynamic limit. Our results establish spatially structured driving as a powerful route to realize non-equilibrium phase coexistence in collective spin systems.

The recently introduced random purification channel, which converts $n$ copies of an arbitrary mixed quantum state into $n$ copies of the same uniformly random purification, has emerged as a powerful tool in quantum information theory. Motivated by this development, we introduce a channel-level analogue, which we call the random Stinespring superchannel. This consists in a procedure to transform $n$ parallel queries of an arbitrary quantum channel into $n$ parallel queries of the same uniformly random Stinespring isometry, via universal encoding and decoding operations that are efficiently implementable. When the channel is promised to have Choi rank at most $r$, the procedure can be tailored to yield a Stinespring environment of dimension $r$. We present two applications of the random Stinespring superchannel, one in quantum Shannon theory and one in quantum learning theory. In quantum Shannon theory, we prove a channel-level analogue of Uhlmann's theorem for quantum divergences. In quantum learning theory, our construction shows that tomography of quantum channels reduces to tomography of isometries. This yields a simple channel learning algorithm, based on existing isometry learning protocols, that matches the performance of the two recently proposed channel tomography algorithms. Complementarily, whereas the optimality of these algorithms had previously been established only up to a logarithmic factor in the dimension, we close this gap by removing this logarithmic factor from the lower bound. Taken together, our results fully establish the optimality of these recently introduced channel learning algorithms, showing that the optimal query complexity of learning a quantum channel with input dimension $d_A$, output dimension $d_B$, and Choi rank $r$ is $\Theta(d_A d_B r)$.

We develop theoretical methods to predict the effects of paramagnetic impurities on the microwave response of conventional spin-singlet superconductors. Our focus is on superconducting devices and resonators with low concentrations of impurities and exchange interactions with conduction electrons. We connect the sub-gap quasiparticle spectrum generated by pair-breaking to the frequency and temperature dependence of the conductivity for superconductors operating at microwave frequencies. We report theoretical results for superconducting device performance – dissipation, quality factor and frequency shift anomalies – based on self-consistent calculations of the current response and penetraion of the electromagnetic field at the vacuum-superconducting interface. Key results include the prediction of a non-monotonic anomaly in the low-frequency superfluid fraction and penetration depth at very low temperatures related to the sub-gap quasiparticle spectrum. Dissipation of microwave power is predicted from intra- and inter- impurity band transitions at GHz frequencies at low temperatures, including a physical mechanism responsible for residual resistance. We predict anomalies in the resonant frequency, $f(T)$, and quality factor, $Q(T)$, of high-Q SRF cavities operating in the GHz range at low-temperatures that are sensitive to non-magnetic and paramagnetic impurity disorder.

Orbital-Free Density Functional Theory (OFDFT) has re-emerged as a viable alternative to Kohn-Sham DFT, driven by recent advances in kinetic energy density functionals (KEDFs). Nonlocal (NL) KEDFs have significantly extended OFDFT's applicability, particularly for bulk solids, but their high computational cost and dependence of system-specific parameters limit their universality. In this work, we propose a semilocal KEDF at the Generalized Gradient Approximation (GGA) level that achieves accuracy comparable to state-of-the-art NL and meta-GGA functionals, while remaining entirely parameter-free. Our construction revives the Thomas-Fermi-von Weizsacker (TFvW) framework by modulating the relative contributions of TF and vW terms through physically motivated constraints and preserving the exact second-order gradient expansion. Despite its simple form, the proposed functional (KGE2) performs remarkably well across both extended systems (metals and semiconductors) and finite systems (clusters), without any need for parameter tuning. These results mark a step toward a transferable, computationally efficient, and general-purpose KEDF suitable for large-scale OFDFT simulations.

Transport properties of strongly correlated materials have contributions from quasiparticle excitations such as electrons and holes as well as emerging collective excitations such as plasmonic sound-like modes which are sustained by interactions. As was shown in Phys. Rev. B 106, 205127, the thermal excitation of the long-lived plasmons in graphene provides a substantial contribution to heat and momentum transport in the interaction-dominated regime. Detailed information on these excitations is therefore necessary for the quantitative understanding of hydrodynamic transport. On the other hand, dynamics of graphene plasmons is usually studied using Dirac perturbation theory, thus neglecting the effects of a finite Brillouin zone and higher-order perturbative corrections. Both these effects can be however significant for strong-interacting systems including free-standing graphene with the effective coupling constant of the order of alpha=2. In this paper, we studied the behavior of plasmons in half-filled free standing graphene using unbiased Quantum Monte Carlo calculations. We confirm the existence of well-defined resonance peaks for plasmons around the Gamma-point. Comparison with the Random-phase-approximation (RPA) calculation for the honeycomb lattice shows that RPA yields more stable plasmon modes, while QMC shows enhanced broadening due to non perturbative interaction effects. To account for this effect, we generalize the lattice RPA calculations by dressing the fermionic propagator by a constant lifetime. As a result, the plasmon frequencies are shifted towards higher energies and the spectrum is broadened, yielding a better agreement with QMC. Our findings highlight the need to account for both a finite Brillouin zone and strong interaction effects when developing theories of electronic transport in free-standing graphene.

We demonstrate that the charge value of transport mechanisms heavily impacts the validity of thermodynamic uncertainty relations (TURs). Specifically, we show within the framework of full counting statistics, that the recently established quantum TUR can be violated by the presence of transport processes that carry more than one charge, like Andreev reflection processes in normal metal-superconductor junctions. We propose a modified quantum TUR, which incorporates the charge value and demonstrate that this charge-dependent quantum TUR can only be violated if the highest charge transport process exceeds this charge value. In particular, we establish that the breaking of the quantum TUR solely originates from the charge value of the highest charge transport process. Namely, our analytical considerations do not invoke the existence of superconductivity, and these considerations generally hold for non-interacting electronic transport which can be described by the scattering formalism.

Murunskite K$_2$Cu$_3$FeS$_4$ is a representative sulfosalt, isostructural to the pnictides, but with electronic properties more similar to the insulating parent compounds of the cuprates. We use it as a bridge to compare the chemical and physical roles of metal and ligand orbitals in cuprates and pnictides. In cuprates, ionicity, covalency, and metallicity are tightly interwoven to give rise to high-temperature superconductivity (SC). Their most remarkable property is the interaction of an ionically localized hole on the copper (Cu) with a Fermi liquid (FL) on the oxygens (O), which is critically important for understanding all key properties of these materials. The localization is due to strong correlations on the Cu $3d$ orbital. We describe a scenario in which the localized hole gives rise both to SC by Cooper scattering of O holes, and to Fermi arcs, as observed in cuprate spectroscopy, the latter by a purely kinematic projection of the static local disorder, without invoking any residual interactions between the mobile O FL carriers. In the pnictides, the orbitals responsible for binding and metallic conduction appear to be separate. The Fe $3d$ $e_{g}$ orbitals hybridized with the ligands set the lattice spacing. The $3d$ $t_{2g}$ orbitals overlap directly between the Fe atoms, resulting in several electronic bands appearing at the Fermi level. The ensuing Fermi liquid exhibits both charge and magnetic correlations. We argue that a similar SC scenario as in the cuprates is plausible in the pnictides, except that a light FL scatters on a slow nearly-antiferromagnetic (AF) one, rather than on localized holes as in the cuprates.

In a recent experiment [Nature 642, 58 (2025)], a new record for the superconducting critical temperature $T_c$ among infinite-layer nickelates has been reported in doped SmNiO$_2$. Here, we use the cutting-edge dynamical vertex approximation (D$\Gamma$A), and qualitatively as well as quantitatively reproduce the $T_c$ vs. doping dome for this compound. Encouraged by this, we go further and identify a path towards realizing even higher $T_c$'s by changing the cation along the line Nd$\rightarrow$Sm$\rightarrow$Y$\rightarrow$Lu with matching substrates. The successively smaller cation radius allows for smaller lattice constants of the substrate. This in turn increases the in-plane hopping and thus eventually $T_c$.

Layered magnetic and strongly correlated materials present a rich platform for condensed matter physics with intrinsic properties intertwined by magnetism and low-dimensionality. A suspended light-emitting 2D antiferromagnetic membrane forms a highly controllable hybrid system in which the interplay between spin ordering, optical and mechanical degrees of freedom can be uniquely explored. NiPS$_3$ hosts excitons responsible for a puzzling luminescence down to a few atomic layers, linked to its zigzag antiferromagnetic order. The nature of these excitons remains unclear. Here we report on the magnetic excitons of a suspended few-layer NiPS$_3$ membrane. We reveal nematic zigzag states and study the optical transitions induced by the magnon-mediated motion of the excitation in the magnetic lattice, resulting in magnon-dressed excitons. We observe a strain tuning of these emission lines, dependent on their microscopic origin, with rates that sign a strong localization of the magnetic excitons, fading with the number of magnon-mediated hops.

The spin dynamics of localized electrons in bulk semiconductors is governed by the interplay of effective nuclear field fluctuations, spin exchange between electrons, and spin transitions into the conduction band. Using spin noise spectroscopy, we reveal this interplay for donor-bound electrons in a CdTe/CdMgTe quantum well and spectrally separate electron spin relaxation and dephasing in zero magnetic field. We identify a specific regime of the electron spin dynamics, where temperature-induced activation of spin-independent hopping leads to a monotonic acceleration of electron spin relaxation. This behavior contrasts with bulk CdTe crystals, where the motional narrowing effect is observed. We attribute this difference to the significantly larger inhomogeneous broadening of the donor-related trion resonance in our quantum well compared to bulk samples. The theoretical analysis of the spin noise power and the strength of the spin exchange interaction provides the estimation of the donor concentration in our unintentionally doped structure.

We identify the transition from the oscillatory Rabi regime to the localized Zeno/Anti-Zeno regime in continuous measurement and feedback of a qubit as a quantum analogue of Motility-Induced Phase Separation (MIPS). A mapping between a biased monitored qubit and a classical “Run-and-Tumble" active particle is studied. We demonstrate that the competition between coherent Rabi driving (analogous to active motility) and measurement-induced feedback bias (analogous to persistence) mimics the behavior of biological swimmers. This framework provides a picture of measurement-induced phase transitions using the language of active matter and offering a novel pathway for designing dissipative noisy quantum systems.

Gallium alloys are promising materials in biomedical engineering, electronics, and wireless communications, thanks to their good conductivity, non toxicity and their ability to sustain large deformations. They can be transported in capillaries using purely electric means by continuous electrowetting (CEW). Current models of CEW-driven flows do not address the transient response to fast changes in the excitation, crucial in many applications. Here, we present a theory that describes the CEW-driven oscillatory motion of a drop of Eutectic Gallium-Indium alloy inside a capillary. We consider inertia, viscosity and the transient response of the electrical circuit consisting of the drop plus the electrolyte where it is immersed. The theory describes fairly well the experimental drop velocity and explains the existence of an optimal frequency that maximizes the velocity.

Moiré superlattices in van der Waals materials have revolutionized the study of electronic and excitonic systems by creating periodic electrostatic potentials. Extending this concept to magnetic materials promises new pathways in merging spintronics with photonics. While moiré magnetism has been revealed with near-field probes and nonlinear optical techniques, the coupling of these magnetic textures to optical excitations - magneto-moiré excitons - remains unexplored. Here, we report the observation of magneto-moiré excitons in twisted bilayer CrSBr, correlated with moiré spin textures that emerge below a critical twist angle of ~2{\deg}. The nanoscale moiré spin texture imprints distinct signatures onto the optical spectrum, shifting the exciton energy via a periodic magnetic exchange field. First-principles calculations corroborate that these signatures arise from one-dimensional spin textures governed by the balance of exchange interactions and domain wall energy. Our results demonstrate that moiré magnetism can be used to engineer nanoscale excitonic energy landscapes, providing a new platform for magneto-optical sensing, quantum transduction, and control of non-collinear magnetism and topology through light.

Gelatin is often used as an analog for studying soft and biological materials in order to understand the mechanics of behavior of biological tissue in events like traumatic brain injuries. The material properties of gelatin change with the ratio of water to gelatin powder used to make a given sample. Characterizing the relationship between this ratio and the material properties of gelatin is crucial to enable its use in mechanics experiments. In this work, compression tests were performed on a texture analyzer on samples which ranged from a 2:1 to 20:1 ratio of water to gelatin powder. In this range, instantaneous stiffnesses were well fit via power law in this ratio and decreased from 277 +/- 30 kPa to 4.34 +/- 0.64 kPa. The dominant (longest) timescales of the samples were well fit via a sigmoid function in this ratio and increased from 29.8 +/- 1.0 s to 621 +/- 92 s. The resulting ratio-property relationships offer a functional way to design gelatin samples for use in mechanics experiments.