Papers

Cellular structures must organize themselves within strict physical constraints, operating with finite resources and well-defined boundaries. Classical systems demonstrate only passive responses to boundaries, from surface energy minimization in soap films to strain distributions in elastic networks. Active matter fundamentally alters this paradigm - internally generated stresses create a bidirectional coupling between boundary geometry and mass conservation that enables dynamic control over network organization. Here we demonstrate boundary geometry actively directs network deformation in reconstituted microtubule-kinesin systems, revealing a programmable regime of shape transformation through controlled boundary manipulation. A coarse-grained theoretical framework reveals how boundary geometry couples to internal stress fields via mass conservation, producing distinct dynamical modes that enable engineered deformations. The emergence of shape-preserving and shape-changing regimes, predicted by theory and confirmed through experiments, establishes boundary geometry as a fundamental control parameter for active materials. The control principle based on boundaries advances both the understanding of biological organization and enables design of synthetic active matter devices with programmable deformation.

Atomically thin oxides are increasingly recognized as an emerging class of 2D materials, yet their multifunctional properties have been far less investigated compared to other layered materials. Among these, gallium oxide is distinguished by its ultrawide bandgap, thermal stability, and mechanical rigidity, positioning it as a candidate material for nanoelectromechanical systems. In this study, the tribological, transport, and electromechanical properties of beta-Ga2O3 nanosheets were probed using atomic force microscopy (AFM)–based techniques. Friction force microscopy (FFM) was used to investigate interfacial sliding, and a dependence of friction on external bias was observed, which was attributed to defect-mediated charge trapping. Van der Pauw Hall measurements were conducted up to 400 $^{\circ}$C, through which the ultrawide bandgap nature of beta-Ga2O3 was confirmed, as electronic transport remained suppressed despite high thermal activation. Piezoresponse force microscopy (PFM) was further applied, and a measurable converse electromechanical response on the order of a few pm/V was revealed, consistent with oxygen-vacancy–induced symmetry breaking. By integrating tribological, electrical, and electromechanical measurements, it was demonstrated that beta-Ga2O3 nanosheets present a unique platform in which insulating stability, bias-tunable interfacial mechanics, and defect-enabled electromechanical activity coexist, offering new opportunities for multifunctional oxide nanodevices.

Exciton polariton condensates (EPCs) have emerged as a paradigmatic platform for investigating nonequilibrium quantum many-body phenomena, particularly due to their intrinsic open-dissipative nature and strong nonlinear interactions governed by the interplay between stimulated scattering and reservoir-mediated damping. Recent advances in Feshbach resonance engineering now enable precise tuning of interaction strengths, opening new avenues to explore exotic nonlinear excitations in these driven-dissipative systems. In this work, we systematically investigate the quench dynamics and stability of dark solitons in repulsive one-dimensional EPCs under sudden parameter variations in both nonlinear interaction strength g and pump intensity P. Through a Hamiltonian variational approach that incorporates reservoir damping effects, we derive reduced equations of motion for soliton velocity evolution that exhibit remarkable qualitative agreement with direct numerical simulations of the underlying open-dissipative Gross Pitaevskii equation. Our results reveal three distinct dynamical regimes: (i) stable soliton propagation at intermediate pump powers, (ii) velocity-dependent soliton breakup above critical pumping thresholds, and (iii) parametric excitation of soliton trains under simultaneous interaction quenches. These findings establish a quantitative framework for understanding soliton dynamics in nonresonantly pumped EPCs, with implications for quantum fluid dynamics and nonequilibrium Bose Einstein condensates.

A magnetic field typically suppresses superconductivity by either breaking Cooper pairs via the Zeeman effect or inducing vortex formation. However, under certain circumstances, a magnetic field can stabilize superconductivity instead. This seemingly counterintuitive phenomenon is associated with magnetic interactions and has been extensively studied in three-dimensional materials. By contrast, this phenomenon, hinting at unconventional superconductivity, remains largely unexplored in two-dimensional systems, with moiré-patterned graphene being the only known example. Here, we report the observation of re-entrant superconductivity (RSC) at the epitaxial (110)-oriented LaTiO3-KTaO3 interface. This phenomenon occurs across a wide range of charge carrier densities, which, unlike in three-dimensional materials, can be tuned in-situ via electrostatic gating. We attribute the re-entrant superconductivity to the interplay between a strong spin-orbit coupling and a magnetic-field driven modification of the Fermi surface. Our findings offer new insights into re-entrant superconductivity and establish a robust platform for exploring novel effects in two-dimensional superconductors.

We study symmetry preserving adiabatic and Floquet dynamics of one-dimensional systems. Using quasiadiabatic evolution, we establish a correspondence between adiabatic cycles and invertible defects generated by spatially truncated Thouless pump operators. Employing the classification of gapped phases by module categories, we show that the Thouless pumps are classified by the group of autoequivalences of the module category. We then explicitly construct Thouless pump operators for minimal lattice models with $\text{Vec}_G$, Rep($G$), and Rep($H$) symmetries, and show how the Thouless pump operators have the group structure of autoequivalences. The Thouless pump operators, together with Hamiltonians with gapped ground states, are then used to construct Floquet drives. An analytic solution for the Floquet phase diagram characterized by winding numbers is constructed when the Floquet drives obey an Onsager algebra. Our approach points the way to a general connection between distinct Thouless pumps and distinct families of Floquet phases.

Deterministic pseudo random number generators (PRNGs) used in generative artificial intelligence (GAI) models produce predictable patterns vulnerable to exploitation by attackers. Conventional defences against the vulnerabilities often come with significant energy and latency overhead. Here, we embed hardware-generated true random bits from spin-transfer torque magnetic tunnel junctions (STT-MTJs) to address the challenges. A highly parallel, FPGA-assisted prototype computing system delivers megabit-per-second true random numbers, passing NIST randomness tests after in-situ operations with minimal overhead. Integrating the hardware random bits into a generative adversarial network (GAN) trained on CIFAR-10 reduces insecure outputs by up to 18.6 times compared to the low-quality random number generators (RNG) baseline. With nanosecond switching speed, high energy efficiency, and established scalability, our STT-MTJ-based system holds the potential to scale beyond 106 parallel cells, achieving gigabit-per-second throughput suitable for large language model sampling. This advancement highlights spintronic RNGs as practical security components for next-generation GAI systems.

Electrides are materials in which some of the electrons are localized at the interstitial sites rather than around the atoms or along atomic bonds. Most elemental electrides are either alkali metals or alkaline-earth metals because of their low ionization potential. In this work, we report that elemental silicon becomes an electride at pressures exceeding 400 GPa. With ab initio molecular dynamics (MD) simulations, we study this behavior for silicon, sodium, potassium, and magnesium at high pressure and temperature. We performed simulations for liquids and ten crystal structures. Charge density and electron localization functions (ELF) are analyzed for representative configurations extracted from the MD trajectories. By analyzing a variety of electride structures, we suggest the following quantitative thresholds for the ELF and charge density in each interstitial site to classify high-pressure electrides: (1) the maximum ELF value should be greater than 0.7, (2) there should be at least 0.9 electrons near the ELF basin, and (3) the Laplacian charge density, $\nabla^2 \rho(\mathbf{r}_0)$, should be negative with magnitude greater than $10^{-3}\ e/\mathrm{bohr}^5$. Finally, we compute X-ray diffraction patterns to determine the degree to which they are affected by the electride formation. Overall, this framework could become a benchmark for future theoretical and experimental studies on electrides.

The optical selection rule states that opposite parity between the valence and conduction bands is required for optical absorption to occur. However, monolayer hexagonal transition metal dichalcogenides (h-TMDs) such as $ \mathrm{MoS}_{2} $ exhibit pronounced optical absorption despite their nominally dipole-forbidden d-d transitions. In this Letter, we elucidate a parity inversion mechanism through which obstruction-driven band inversion promotes dipole-allowed optical transitions near the band edge in monolayer h-TMDs. By comparing trivial and obstructed atomic limit phases, we show that intersite interactions between hybridized d orbitals induce parity inversion. Our results provide a novel approach to tuning optical properties through parity control, bridging the gap between topology and light-matter interaction.

Competition between short- and long-range interactions underpins many emergent phenomena in nature. Despite rapid progress in their experimental control, computational methods capable of accurately simulating open quantum many-body systems with complex long-ranged interactions at scale remain scarce. Here, we address this limitation by introducing an efficient and scalable approach to dissipative quantum lattices in one and two dimensions, combining matrix product operators and time-dependent variational Monte Carlo. We showcase the versatility, effectiveness, and unique methodological advantages of our algorithm by simulating the non-equilibrium dynamics and steady states of spin-$\frac{1}{2}$ lattices with competing algebraically-decaying interactions for as many as $N=200$ sites, revealing the emergence of spatially-modulated magnetic order far from equilibrium. This approach offers promising prospects for advancing our understanding of the complex non-equilibrium properties of a diverse variety of experimentally-realizable quantum systems with long-ranged interactions, including Rydberg atoms, ultracold dipolar molecules, and trapped ions.