Papers

This study presents a method for deterministic Er3+ doping of x-cut TFLN using focused ion beam (FIB) implantation with sub-100 nm spatial precision, enabling seamless integration of active rare-earth ions into this technologically relevant platform for lithium niobate integrated nanophotonics. Photoluminescence (PL) measurements from implanted regions reveal Stark-split 4f-4f transitions consistent with bulk Er-doped lithium niobate, indicating similar lattice occupation. Temperature-dependent PL measurements from 300 K to 5 K exhibit conventional behaviour down to approximately 50 K, followed by a marked decrease in the emission intensity and lifetime. This anomaly is attributed to a suppression of the pyroelectric response in LiNbO3 at low temperatures, which affects local electric fields and, consequently, Er3+ emission. The sensitivity of the PL response to the modulation frequency and polarization of the 980 nm excitation light is also consistent with possible mechanisms linking thermal effects and internal fields arising in the thin film. The results demonstrate a method for the targeted doping with Er3+ ions into the most widely used cut of TFLN for integrated photonic devices and provide further important considerations for their exploitation in cryogenic quantum devices.

As a critical component of power supply systems, low-voltage distribution net-works directly affect grid stability and user power supply reliability, yet they face significant threats from lightning-induced faults. Transient simulations are more economical and adaptable for investigating lightning-induced faults in low-voltage distribution networks than experiments. A hybrid Variable Time Step (VTS)-Partial Element Equivalent Circuit (PEEC) method, has been validat-ed in previous study, is used for Lightning-induced Electromagnetic Pulse (LEMP) simulation and fault analysis. The lightning-induced faults in ex-tended unequal-length double-circuit low-voltage distribution networks are ana-lyzed in this paper. The impact of lightning stroke location on overvoltage and fault risk is the primary focus of this study. Key findings indicate that, for ground strokes in front of the center of one double circuit, similar three-phase negative and bipolar oscillatory waveforms that are linked to fault initiation emerge. Closer strokes promote bipolar waveforms with the main peak negative as well as higher overvoltages and fault risk. These results provide essential insights for under-standing lightning-induced fault mechanisms, thereby laying a foundation for formulating more targeted and effective lightning protection measures.

Contemporary schemes for waveform-resolved characterization are constrained by setup-specific requirements, which severely limits their adaptability and fails to establish standard procedures for routine in-line diagnostic. This work reports a comprehensive experimental demonstration that relative yield measurements from a broad variety of media and nonlinear observables, combined with our family of open-source reconstruction algorithms (CRIME and lazyCRIME), allow for robust waveform retrieval with attosecond accuracy on a standard workstation in just minutes. We have further adapted this framework to multiple configurations – including non-invasive, simultaneous waveform characterization during an attosecond transient absorption spectroscopy (ATAS) experiment – showcasing the low-cost and non-intrusive nature of the new pulse characterization approach. Together, this work establishes an easy-to-implement universal characterization scheme for in-line diagnostic of ultrashort pulses that is readily accessible to the broader ultrafast science community.

We demonstrate dark-field x-ray microtomography in a compact, laboratory-based system capable of resolving attenuation, phase, and anisotropic scattering signals with micrometer-scale resolution across centimetre-scale samples. The method is based on two-directional beam tracking (2DBT), which requires only a single optical element and is compatible with standard x-ray sources and detectors. We validate the system's capabilities through imaging of a custom-built phantom, a fibre-reinforced composite and ex-vivo biological tissues, including a bovine intervertebral disc, a rat heart, and a porcine meniscus. The results show that dark-field tomography provides complementary information to attenuation as well as to phase tomography, by revealing sub-resolution features such as fibre orientation and microstructural heterogeneity at length scales that are well below the voxel size. A key element of our system is its sensitivity to scattering along two orthogonal directions in the image plane, enabling the measurement of scattering anisotropy with a single exposure. As well as simple and robust, our approach is sensitive and precise. These findings demonstrate the potential of 2DBT for non-destructive and three-dimensional structural characterisation of samples and materials in engineering, materials science and biomedical applications.

Exactly solvable models of topologically ordered phases with non-abelian anyons typically require complicated many-body interactions which do not naturally appear in nature. This motivates the "inverse problem" of quantum many-body physics: given microscopic systems with experimentally realistic two-body interactions, how to design a Hamiltonian that realizes a desired topological phase? Here we solve this problem on a platform motivated by Rydberg atoms, where elementary two-level systems couple via simple blockade interactions. Within this framework, we construct Hamiltonians that realize topological orders described by non-abelian quantum double models. We analytically prove the existence of topological order in the ground state, and present efficient schemes to prepare these states. We also introduce protocols for the controlled adiabatic braiding of anyonic excitations to probe their non-abelian statistics. Our construction is generic and applies to quantum doubles $\mathcal{D}(G)$ for arbitrary finite groups $G$. We illustrate braiding for the simplest non-abelian quantum double $\mathcal{D}(S_3)$.

Motivated by the ubiquity of decoherence in quantum hardware and the growing role of imaginary-time evolution (ITE) in quantum algorithms, we investigate how many-body correlations generated by imaginary-time filtering are modified by local decoherence. We introduce measurement-dressed imaginary-time evolution (MDITE), which alternates ITE with projective-measurement channels, producing a competition between low-energy filtering and local dephasing. By developing a new efficient quantum Monte Carlo method, we uncover MDITE mixed-state transitions with spontaneous-symmetry-breaking signatures in the driving of 1D transverse-field Ising and 2D columnar dimerized Heisenberg Hamiltonians in the resulting density matrices. In the continuous limit, the Choi-Jamiolkowski mapping yields a tractable equilibrium description with conformal criticality that qualitatively captures the phase transitions. At finite protocol parameters, however, the four-point correlator violates the conformal cross-ratio form and the critical exponents deviate from their continuous-limit values, signaling the loss of conformal symmetry and richer nonequilibrium criticality. Our results establish MDITE as a controlled setting for exploring mixed-state phases and critical phenomena driven by the interplay between imaginary-time filtering and decoherence.

3D-printed materials are used in many different industries (automotive, aviation, medicine, etc.). Most of these 3D-printed materials are based on ceramics or polymers whose mechanical properties vary with frequency. For numerical modeling, it is crucial to characterize this frequency dependency accurately to enable realistic finite-element simulations. At the same time, the damping behavior plays a key role in product development, since it governs a component's response at resonance and thus impacts both performance and longevity. In current research, inverse material characterization methods are getting more and more popular. However, their practical validation and applicability on real measurement data have not yet been discussed widely. In this work, we show the identification of two different materials, POM and additively manufactured sintered ceramics, and validate it with experimental data of a well-established measurement technique (dynamic mechanical analysis). The material identification process considers state-of-the-art reduced-order modeling and constrained particle swarm optimization, which are used to fit the frequency response functions of point measurements obtained by a laser Doppler vibrometer. This work shows the quality of the method in identifying the parameters defining the viscoelastic fractional derivative model, including their uncertainty. It also illustrates the applicability of this identification method in the presence of practical difficulties that come along with experimental data such as boundary conditions and noise.

Homodyne Quadrature interferometers (HoQI) are an interferometric displacement sensing scheme proven to have excellent noise performance, making them a strong candidate for sensing and control schemes in gravitational wave detector seismic isolation. Like many interferometric schemes, HoQIs are prone to nonlinear effects when measuring displacements. These nonlinearities, if left unsuppressed, would substantially limit the use cases of HoQIs. This paper first shows a means of measuring and quantifying nonlinearities using a working HoQI and a mechanical resonator. We then demonstrate a method for real-time correction of these nonlinearities and several approaches for accurately calibrating the correction technique. By correcting in real time, we remove one of the biggest obstacles to including HoQIs in upgrades to future gravitational wave detectors. Finally, we discuss how to post correct data from HoQIs, suppressing even further the nonlinearity-induced errors, broadening the appeal of such sensors to other applications where measurement data can be reconstructed after the fact. We demonstrate all of this on a working HoQI system and show the measured suppression of nonlinear effects from each of these methods. Our work makes HoQIs a more broadly applicable tool for displacement sensing.

We present the physical design and systematic optimization of a high-performance storage ring tailored for the generation of high-power coherent radiation, with particular emphasis on the extreme ultraviolet (EUV) regime. The proposed ring adopts a Double Bend Achromat (DBA) lattice configuration and integrates 12 superconducting wigglers to significantly enhance radiation damping and minimize the natural emittance. And a bypass line is adopted to generate high power coherent radiation. Comprehensive linear and nonlinear beam dynamics analyses have been conducted to ensure beam stability and robustness across the operational parameter space. The optimized design achieves a natural emittance of approximately 0.8 nm and a longitudinal damping time of around 1.4 ms, enabling the efficient buildup of coherent radiation. Three-dimensional numerical simulations, incorporating the previously proposed angular dispersion-induced microbunching (ADM) mechanism, further confirm the system's capability to generate high-power EUV coherent radiation, with output powers reaching the order of several hundred watts. These results underscore the strong potential of the proposed design for applications in coherent photon science and EUV lithography.

We present a Monte Carlo method for simulating the inception of electric discharges in gases. The input consists of an unstructured grid containing the electrostatic field. The output of the model is the estimated probability of discharge inception per initial electron position, as well as the estimated time lag between the appearance of the initial electron and discharge inception. To obtain these quantities electron avalanches are simulated for initial electron positions throughout the whole domain, also including regions below the critical electric field. Avalanches are assumed to propagate along field lines, and they can produce additional avalanches due to photon and ion feedback. If the number of avalanches keeps increasing over time we assume that an electric discharge will eventually form. A statistical distribution for the electron avalanche size is used, which is also valid for gases with strong electron attachment. We compare this distribution against the results of particle simulations. Furthermore, we demonstrate examples of inception simulations in 2D Cartesian, 2D axisymmetric and 3D electrode geometries.

Cathodoluminescence (CL) enables optical-frequency analysis of samples with nanometer resolutions, originating from the interaction of a focused electron beam with radiative electronic states, or directly with the optical modes of the sample. Here we decompose the various mechanisms underlying CL generation and emission from an archetype spherical resonator using its spectral, angular and spatially resolved features. We investigate radiation of optical whispering-gallery modes in regimes of coherent and incoherent luminescence. The use of different experimental regimes allows us to disentangle the different contributions to the CL in spheres, namely, photon absorption, generation and radiative leakage, and conclude that the photon generation occurs precisely on the sphere's surface. In addition, the spheres serve as high-NA collimating lenses for CL, resulting in mode quality unprecedented for CL in free space. We believe that such collimated and directed CL in free space will enhance existing quantum measurements of CL and facilitate new ones, such as high-rate electron-photon entangled pairs, CL from quantum emitters, and homodyne analysis of CL.

Multispecies ecosystems modelled by generalized Lotka-Volterra equations exhibit stationary population abundances, where large number of species often coexist. Understanding the precise conditions under which this is at all feasible and what triggers species extinctions is a key, outstanding problem in theoretical ecology. Using standard methods of random matrix theory, I show that distributions of species abundances are Gaussian at equilibrium, in the weakly interacting regime. One consequence is that feasibility is generically broken before stability, for large enough number of species. I further derive an analytical expression for the probability that $n=0,1,2,...$ species go extinct and conjecture that a single-parameter scaling law governs species extinctions. These results are corroborated by numerical simulations in a wide range of system parameters.

We present an analytical theory of second harmonic generation (SHG) in hybrid structures combining a nonlinear 2D crystal with a dielectric metasurface waveguide. The theory describes the excitation spectrum and enhancement of SHG at both leaky mode and quasi-bound state in the continuum (quasi-BIC) resonances in terms of the material parameters. For low-loss systems, the SHG efficiency at leaky resonances is determined by their radiative broadening, governed by the relevant Fourier harmonics of the metasurface polarizability, whereas the SHG enhancement at quasi-BIC resonances is ultimately limited by inhomogeneous broadening and absorption in the system. We also describe the emergence and polarization properties of second harmonic diffracted beams. These beams appear even if both the 2D crystal and the meta-waveguide are centrosymmetric owing to the nonlocal mechanism of SHG. The developed framework provides a systematic theoretical basis for optimizing the resonant nonlinear frequency conversion in hybrid 2D-material-metasurface platforms and identifies the fundamental limitations of the SHG efficiency.

The way living tissues respond to external mechanical forces is crucial in physiological processes like embryogenesis, homeostasis or tumor growth. Providing a complete description across length scales which relates the properties of individual cells to the rheological behavior of complex 3D-tissues remains an open challenge. The development of simplified biomimetic tissues capable of reproducing essential mechanical features of living tissues can help achieving this major goal. We report in this work the development of a microfluidic device that enables to achieve the sequential assembly of biomimetic prototissues and their rheological characterization. We synthesize prototissues by the controlled assembly of Giant Unilamellar Vesicles (GUVs) for which we can tailor their sizes and shapes as well as their level of GUV-GUV adhesion. We address a rheological description at multiple scales which comprises an analysis at the local scale of individual GUVs and at the global scale of the prototissue. The flow behavior of prototissues ranges from purely viscous to viscoelastic for increasing levels of adhesion. At low adhesion the flow response is dominated by viscous dissipation, which is mediated by GUV spatial reorganizations at the local scale, whereas at high adhesion the flow is viscoelastic, which results from a combination of internal reorganizations and deformation of individual GUVs. Such multiscale characterization of model biomimetic tissues provides a robust framework to rationalize the role of cell adhesion in the flow dynamics of living tissues.

Comparing abstract concepts (such as electric circuits) with familiar ideas (plumbing systems) through analogies is central to practice and communication of physics. Contemporary research highlights self-generated analogies to better facilitate students' learning than the taught ones. "Spontaneous" and "self-generated" analogies represent the two ways through which students construct personalized analogies. However, facilitating them, particularly in large enrollment courses remains a challenge, and recent developments in generative artificial intelligence (AI) promise potential to address this issue. In this qualitative study, we analyze around 800 student responses in exploring the extent to which students spontaneously leverage analogies while explaining Morse potential curve in a language suitable for second graders and self-generate analogies in their preferred everyday contexts. We also compare the student-generated spontaneous analogies with AI-generated ones prompted by students. Lastly, we explore the themes associated with students' perceived ease and difficulty in generating analogies across both cases. Results highlight that unlike AI responses, student-generated spontaneous explanations seldom employ analogies. However, when explicitly asked to explain the behavior of the curve in terms of their everyday contexts, students employ diverse analogical contexts. A combination of disciplinary knowledge, agency to generate customized explanations, and personal attributes tend to influence students' perceived ease in generating explanations across the two cases. Implications of these results on the potential of AI to facilitate students' personalized analogical reasoning, and the role of analogies in making students notice gaps in their understanding are discussed.

Parity mixing in photoionization, i.e. when emitted electrons have different parities but the same energy, causes interference observable only in angle-resolved measurements. The interference typically manifests as a symmetry violation in the photoelectron angular distributions. The traditional, based on HHG, RABBITT scheme with high-order harmonics separated by twice the seed field energy, precludes parity mixing. On the contrary, a free-electron laser provides a possibility to generate even harmonics. Using triple the fundamental frequency as a seed, one obtains a comb of alternating even and odd harmonics, separated by three times the initial frequency [Nature 578, 386-391 (2020)] (2-SB RABBITT). In this setup, there are two sidebands between the main photoelectron lines, versus one in the traditional scheme. In the paper, we examine the general properties of a two-sideband scheme and analyze the symmetry breakdown of photoelectron angular distributions for various polarization geometries of the incident pulse. We found a crucial difference in symmetries between 2-SB RABBITT and other photoionization schemes with parity mixing. Illustrative calculations are carried out for neon with pulse parameters typical for modern facilities. The possibility to reconstruct the temporal profile of the pulse from the angle-resolved measurements is discussed.

Accurate thermal analysis is crucial for modern spacecraft, driving demand for reliable modeling tools. This research advances space thermal modeling by improving the simulation accuracy and efficiency of radiative heat transfer, the dominant mode of heat exchange in space. To this end, we incorporate diffuse reflectivity using the Gebhart method, which computes radiative exchange factors (REFs) from geometric view factors. The view factors, obtained via Monte Carlo ray tracing (MCRT), require post-processing to mitigate statistical errors. Critically, existing correction schemes cannot simultaneously enforce closure and reciprocity for open systems. This research addresses this gap by proposing two novel enforcement methods: (i) a least-squares optimization with non-negativity rectification (NNR) and small positive value avoidance (SPVA), and (ii) an iterative enforcement algorithm. To ensure consistency across different discretization levels, this work also introduces the multi-node surface model relations to formalize the connection between sub-face, face, and node representations of view factors and REFs. A simple case study demonstrates a substantial reduction in mean absolute error (MAE): the least-squares method achieves an 81% MAE reduction, while the iterative method offers the best balance of accuracy (56% MAE reduction) and computational efficiency. A second case study shows that including diffuse reflections decreases the steady-state temperature of a plate by $4^{\circ}C$, reinforcing that reflected radiation reduces net absorption. This work introduces and validates computationally efficient methods for integrating diffuse reflectivity into space thermal analyses and for consistently coupling multi-node surface radiative models. The results enable more accurate and robust thermal predictions for spacecraft systems.

Caribou is a versatile data acquisition (DAQ) system developed within several collaborative frameworks (CERN EP R&D, DRD3, AIDAinnova, and Tangerine) to support laboratory and test-beam characterization of novel silicon pixel detectors. It combines a custom Control and Readout (CaR) board with a Xilinx Zynq System-on-Chip (SoC) running project-wide shared firmware and software stacks. The system architecture emphasizes reusability, flexibility, and ease of integration. The CaR board provides essential interfaces such as programmable power supplies, voltage and current references, high-speed ADCs, and configurable I/O lines for detector control and readout. The SoC runs an embedded Linux distribution built with PetaLinux and integrates two main components: Peary, a C++ embedded DAQ application providing hardware abstraction, configuration management, logging, and multi-device control through Command Line (CLI) and Python interfaces; and Boreal, a common Caribou FPGA firmware framework offering reusable modules and automated build workflows for user-specific bit files. The next major milestone in Caribou's evolution is the transition to version 2.0, based on a Zynq UltraScale+ System-on-Module (SoM) architecture. This paper presents the recent progress and future prospects of the project and describes recent hardware, firmware, and software developments preparing the system for the upcoming CaR board v2.0.

Ionization by a sequence of extreme ultraviolet pulses is investigated based on the rigorous numerical solution of the time-dependent Schrödinger equation, when the driving laser field is treated exactly. This goes beyond the typically used first-order nondipole approximation and reveals the effects of radiation pressure to its full extent. Specifically, we observe the comb structures in both the momentum and the energy distributions of photoelectrons. The comb peaks are shifted, however, depending on the emission angle of electrons. While similar effect is observed already in the first-order nondipole approximation, with increasing the laser field strength the discrepancy with our exact results becomes more pronounced. Also, we observe the additional substructure of the comb peaks arising in the angle-integrated energy distributions of photoelectrons. Finally, as our numerical calculations account for the atomic potential in the entire interaction region, we observe the loss of coherence of comb structures with increasing the number of laser pulses, that we attribute to rescattering.

Achieving state-of-the-art optical data storage requires raising device capacity well above commercial standards. This requires media structured at a much smaller scale and enabling readout at a shorter wavelength. Current CDs, DVDs and Blu-rays are read with visible light, and are based on metallic reflection gratings and phase-change recording layers structured at the few-hundred-nm scale. Herein, we introduce 10-nm structured silicon as a promising UV-readable data storage platform. Recording on it harnesses the amorphous-to-crystalline phase-change of silicon, the two phases presenting well-constrasted UV optical properties. Furthermore, the phase-change contrast is strongly enhanced in the Vacuum UV thanks to the distinct interband plasmon resonances of the amorphous and crystalline nanostructures, which have an epsilon-near-zero and surface plasmonic character, respectively. Silicon nanogratings with a 10 nm width and a 20 nm period resonate near the wavelength of 120 nm, at which phase-change induces a 600% maximum optical transmittance contrast. This paves the way toward UV-readable data storage platforms with a 10 to 100 times increased data density, which could be implemented by harnessing the well-established silicon nanotechnology.

Current interstitial techniques of tumor ablation face challenges that ultrasound technologies could meet. The ablation radius and directionality of the ultrasound beam could improve the efficiency and precision. Here, a 9gauge MR-compatible dual-mode ultrasound catheter prototype was experimentally evaluated for Ultrasound Imageguided High Intensity Focused Ultrasound (USgHIFU) conformal ablations. The prototype consisted of 64 piezocomposite linear array elements and was driven by an open research programmable dual-mode ultrasound platform. After verifying the US-image guidance capabilities of the prototype, the HIFU output performances (dynamic focusing and HIFU intensities) were quantitatively characterized, together with the associated 3D HIFU-induced thermal heating in tissue phantoms (using MR thermometry). Finally, the ability to produce robustly HIFU-induced thermal ablations in in-vitro liver was studied experimentally and compared to numerical modeling. Investigations of several HIFU dynamic focusing allowed overcoming the challenges of miniaturizing the device: mono-focal focusing maximized deep energy deposition, while multi-focal strategies eliminated grating lobes. The linear-array design of the prototype made it possible to produce interstitial ultrasound images of tissue and tumor mimics in situ. Multi-focal pressure fields were generated without grating lobes and transducer surface intensities reached up to Isapa =14 W$\bullet$cm -2 . Seventeen elementary thermal ablations were performed in vitro. Rotation of the catheter proved the directionality of ablation, sparing non-targeted tissue. This experimental proof of concept demonstrates the feasibility of treating volumes comparable to those of primary solid tumors with a miniaturized USgHIFU catheter whose dimensions are close to those of tools traditionally used in interventional radiology, while offering new functionalities.

Real-time and accurate monitoring of humidity and pH is of great significance in daily life and industrial production. Existing humidity and pH measurement suffer from limitations such as low sensitivity, signal crosstalk, complex system structures, and inability to achieve real-time monitoring. In this work, the surface of a polarization maintaining fiber (PMF) was functionalized with a composite humidity-sensitive polymer composed of polyvinyl alcohol (PVA) and carbon nanosheets (CNs). A humidity-sensitive film with a microporous structure was prepared on the PMF cladding through high-temperature rapid film formation and laser processing, enhancing humidity sensitivity and stability. To enable pH sensing, poly(allylamine hydrochloride) (PAH) and poly (acrylic acid) (PAA) were successively adsorbed onto the PMF surface via electrostatic self-assembly, forming a pH-sensitive nanofilm structure. By connecting a temperature-compensated PMF within the same Sagnac loop and combining it with a multi-wavelength matrix, simultaneous real-time monitoring of humidity, pH, and temperature was achieved, effectively solving the issue of temperature crosstalk and extending toward a universal optical fiber multi-parameter measurement platform.

Biological tissues exhibit diverse mechanical and rheological behaviors during morphogenesis. While much is known about tissue phase transitions controlled by structural order and cell mechanics, key questions regarding how tissue-scale nematic order emerges from cell-scale processes and influences tissue rheology remain unclear. Here, we develop a minimal vertex model that incorporates a coupling between active forces generated by cytoskeletal fibers and their alignment with local elastic stress in solid epithelial tissues. Combining theory and simulations, we show that this feedback loop induces an isotropic–nematic transition, leading to an ordered solid state that exhibits soft elasticity. Further increasing activity drives collective self-yielding, that is the ability to spontaneously transition form elastic to plastic deformations, with tissue flows that are correlated across the entire system. We argue that this remarkable state, that we dub plastic nematic solid, is uniquely suited to facilitate active tissue remodeling during morphogenesis. It fundamentally differs from the well-studied fluid regime where macroscopic elastic stresses vanish and the velocity correlations remain short-ranged. Altogether, our theoretical results reveal a rich spectrum of tissue states jointly governed by activity and passive cell deformability, with important implications for understanding tissue mechanics and morphogenesis.

We demonstrate that charge teleportation serves as a superior observable for Quantum Energy Teleportation (QET)-based cryptographic primitives. While following the LOCC protocol structure of earlier proposals, we show that decoding key bits via local charge rather than energy provides exact bit symmetry and enhanced robustness: by Local Operations and Classical Communication (LOCC) on an entangled many-body ground state, Alice's one-bit choice steers the sign of a local charge shift at Bob, which directly encodes the key bit. Relative to energy teleportation schemes, the charge signal is bit-symmetric, measured in a single basis, and markedly more robust to realistic noise and model imperfections. We instantiate the protocol on transverse-field Ising models, star-coupled and one-dimensional chain, obtain closed-form results for two qubits, and for larger systems confirm performance via exact diagonalization, circuit-level simulations, and a proof-of-principle hardware run. We quantify resilience to classical bit flips and local quantum noise, identifying regimes where sign integrity, and hence key correctness, is preserved. These results position charge teleportation as a practical, low-rate QKD primitive compatible with near-term platforms.

Membraneless droplets or liquid condensates formed via liquid-liquid phase separation (LLPS) play a pivotal role in cell biology and hold potential for biomedical engineering. While membraneless droplets are often studied in the context of interactions between passive components, it is increasingly recognized that active matter inclusions, such as molecular motors and catalytic enzymes in cells, play important roles in the formation, transport and interaction of membraneless droplets. Here we developed a bacteria-polymer active phase separation system to study the nonequilibrium effect of active matter inclusions on the LLPS dynamics. We found that the presence of bacterial active matter accelerated the initial condensation of phase-separated liquid droplets but subsequently arrested the droplet coarsening process, resulting in a stable suspension of membraneless active droplets packed with motile bacterial cells. The arrested phase separation of the bacterial active droplet system presumably arises from anti-phase entrainment of interface fluctuations between neighboring droplets, which reduces the frequency of inter-droplet contact and suppresses droplet coarsening. In addition, the active stresses generated by cells within the droplets give rise to an array of nonequilibrium phenomena, such as dominant long-wavelength fluctuations and enhanced droplet transport with short-term persistent motion due to spontaneous symmetry breaking. Our study reveals a unique mechanism for arrested phase separation and long-term stability in membraneless droplet systems. The bacteria-polymer active phase separation system opens a new avenue for studying the dynamics of membraneless active droplets relevant to non-equilibrium LLPS in cells and in biomedical engineering applications.

We propose a framework based on the postulate of quantum vacuum self-consistency, where classical backgrounds – spacetime, gauge fields, and the Higgs condensate – are macroscopic order parameters of a single quantum state, sustained by the vacuum expectation values of the fluctuations they support. Using a background-field, heat-kernel approach, we derive the coupled low-energy effective equations for the metric, gauge, and Higgs fields as vacuum equations of state. This recovers the Einstein, Yang–Mills, and Higgs equations, augmented by the higher-derivative operators required for quantum consistency, with all couplings running coherently under a single RG flow. The framework is embedded in a UV-complete theory of higher-derivative gravity (quantized with the fakeon prescription for unitarity) coupled to the Standard Model (SM). We assume the combined system flows to an asymptotically safe fixed point in the UV, rendering the theory predictive. A solvable O(N) model is used to explicitly demonstrate how the vacuum gap equations constrain both the condensate and curvature. The framework yields robust phenomenological predictions: (1) The loop-induced $R^2$ term drives Starobinsky-type inflation, with $n_s \simeq 1 - 2/N_e$ and $r \simeq 12/N_e^2$. (2) Short-distance corrections to gravity are quantified and satisfy laboratory bounds. (3) The speed of gravitational waves is luminal, consistent with GW170817. The combination of asymptotic safety with the vacuum gap equations correlates IR observables in gravity and particle physics, constraining SM parameters from the properties of the UV fixed point. The theory is testable across cosmology and precision gravity, reducing to General Relativity and the SM at low energies with controlled corrections.

A simplification of the VV10 van der Waals density functional [J. Chem. Phys. 133, 244103 (2010)] is made by an approximation of the integrand of the six-dimentional integral in terms of a few products of three-dimensional density-like distributions and potential-like functions of the interelectronic distance only, opening the way for its straightforward computation by fast multipole methods. An even faster computational scheme for molecular systems is implemented where the density-like distributions are fitted by linear combinations of usual atom-centered basis functions of Gaussian type and the six-dimensional integral is then computed analytically, at a fraction of the overall cost of a typical calculation. The simplicity of the new approximation is commensurate with that of the original VV10 functional, and the same level of accuracy is seen in tests on molecules.

The Global Natural Orbital Functional (GNOF) provides a straightforward approach to capture most electron correlation effects without needing perturbative corrections or limited active spaces selection. In this work, we evaluate both the original GNOF and its modified variant GNOFm on a set of twelve 5- and 6-membered molecular rings, systems characterized primarily by dynamic correlation. This reference set is vital as it comprises essential substructures of more complex molecules. We report complete-basis-set limit correlation energies for GNOF, GNOFm, and the benchmark CCSD(T) method. Across the Dunning basis sets, both functionals deliver a balanced and accurate description of the molecular set, with GNOFm showing small but systematic improvements while preserving the overall robustness of the original formulation. These results confirm the reliability of the GNOF family and its ability to capture dynamic correlation effects.

We investigate energy propagation in a one-dimensional stub lattice in the presence of both disorder and nonlinearity. In the periodic case, the stub lattice hosts two dispersive bands separated by a flat band; however, we show that sufficiently strong disorder fills all intermediate band gaps. By mapping the two-dimensional parameter space of disorder and nonlinearity, we identify three distinct dynamical regimes (weak chaos, strong chaos, and self-trapping) through numerical simulations of initially localized wave packets. When disorder is strong enough to close the frequency gaps, the results closely resemble those obtained in the one-dimensional disordered discrete nonlinear Schrödinger equation and Klein-Gordon lattice model. In particular, subdiffusive spreading is observed in both the weak and strong chaos regimes, with the second moment $m_2$ of the norm distribution scaling as $m_2 \propto t^{0.33}$ and $m_2 \propto t^{0.5}$, respectively. The system's chaotic behavior follows a similar trend, with the finite-time maximum Lyapunov exponent $\Lambda$ decaying as $\Lambda \propto t^{-0.25}$ and $\Lambda \propto t^{-0.3}$. For moderate disorder strengths, i.e., near the point of gap closing, we find that the presence of small frequency gaps does not exert any noticeable influence on the spreading behavior. Our findings extend the characterization of nonlinear disordered lattices in both weak and strong chaos regimes to other network geometries, such as the stub lattice, which serves as a representative flat-band system.

We develop a deep reinforcement learning framework for controlling a bio-inspired jellyfish swimmer to navigate complex fluid environments with obstacles. While existing methods often rely on kinematic and geometric states, a key challenge remains in achieving efficient obstacle avoidance under strong fluid-structure interactions and near-wall effects. We augment the agent's state representation within a soft actor-critic algorithm to include the real-time forces and torque experienced by the swimmer, providing direct mechanical feedback from vortex-wall interactions. This augmented state space enables the swimmer to perceive and interpret wall proximity and orientation through distinct hydrodynamic force signatures. We analyze how these force and torque patterns, generated by walls at different positions influence the swimmer's decision-making policy. Comparative experiments with a baseline model without force feedback demonstrate that the present one with force feedback achieves higher navigation efficiency in two-dimensional obstacle-avoidance tasks. The results show that explicit force feedback facilitates earlier, smoother maneuvers and enables the exploitation of wall effects for efficient turning behaviors. With an application to autonomous cave mapping, this work underscores the critical role of direct mechanical feedback in fluid environments and presents a physics-aware machine learning framework for advancing robust underwater exploration systems.