We report a nondissipative optomechanical approach to separate the spin and orbital components of transverse energy flows of light beams. Focusing on uniformly polarized paraxial fields, the method relies on detecting the radiation-pressure-induced reorientation of the optical axis in anisotropic media—specifically, liquid crystals. Within a perturbative analytical approach, we demonstrate the selective encoding of the transverse spin and orbital components of the Poynting vector into orthogonal orientational elastic modes, whose relative weights are mediated by the Gouy phase. The spatial distributions of spin and orbital momentum can therefore be retrieved without resorting to point-by-point measurements using absorbing or scattering probe particles. Analytical results are supported by a fully self-consistent numerical solution coupling Maxwell’s equations and Landau-de Gennes nematodynamics in three dimensions. This exact framework captures higher-order and nonparaxial effects beyond the analytical perturbative regime and allows us to validate the predicted Gouy-phase-mediated optomechanical response. These results establish a practical route toward optomechanical imaging of the internal momentum structure of light, fostering momentum-resolved optical metrology and light-matter interaction studies with structured beams.

Fluctuating hydrodynamics provides a framework connecting mesoscopic fluctuations with macroscopic transport behavior. To bridge mesoscopic and macroscopic transport from microscopic dynamics, we introduce a wave-number-dependent viscosity, defined via the equilibrium correlation of time-averaged Fourier components of the fine-grained shear stress field. Two-dimensional molecular dynamics simulations reveal its small-wave-number divergence characteristic of the renormalized viscosity, while its large-wave-number behavior determines the bare viscosity, thereby establishing a link between mesoscopic and macroscopic transport based on microscopic dynamics.

We classify gapped phases and characteristic nodal points of non-Hermitian band structures on two-dimensional nonorientable parameter spaces. Such spaces arise in a wide range of physical systems in the presence of nonsymmorphic parameter space symmetries. For gapped phases, we find that nonorientable spaces provide a natural setting for exploring fundamental structural problems in braid group theory, such as torsion and conjugacy. Gapless systems, which host exceptional points (EPs), explicitly violate fermion doubling, even in two-band models. We demonstrate that EPs traversing the nonorientable parameter space exhibit non-Abelian charge inversion. These braided phases and their transitions leave distinct signatures in the form of bulk Fermi arc degeneracies, offering a concrete route toward experimental realization and verification.

We employ the operational quasiprobability (OQ) as a work distribution, which reproduces the Jarzynski equality and yields the average work consistent with the classical definition. The OQ distribution can be implemented through two simple experimental settings: the end-point measurement and the two-point measurement. Using this framework, we demonstrate the explicit contribution of coherence to the work, which can be formulated by the second-law-type relation. In a two-level system, we show that nonjoint measurability, a generalized notion of measurement incompatibility, can increase the amount of extractable work beyond the classical bound imposed by jointly measurable measurements. We further prove that the real part of Kirkwood-Dirac quasiprobability (KDQ) and the OQ are equivalent in two-level systems, and they are non-negative for binary unbiased measurements if and only if the measurements are jointly measurable. In a three-level nitrogen-vacancy center system, the OQ and the KDQ exhibit different amounts of negativities while enabling the same work extraction, implying that the magnitude of negativity is not a faithful indicator of nonclassical work. These results highlight that coherence and nonjoint measurability play fundamental roles in the enhancement of work.

Complex fluids such as colloids and emulsions are ubiquitous in biopharmaceuticals, manufacturing, and the oil industry, but controlling their viscosity can pose a significant challenge. Low viscosities are ideal for mixing, high viscosities are helpful for pharmaceuticals, and switchable viscosities are useful for smart materials. One strategy to make multipurpose fluids is to make nonequilibrium modifications to the microstructure of colloids and emulsions using external fields, which can result in emergent changes in their rheological characteristics. We introduce an experimental technique, electrorheoimaging (ERI), which directly visualizes microstructure during rheological measurements while simultaneously applying an electric field. We also introduce a continuous phase that lowers electrohydrodynamic thresholds and enables experiments at modest field strengths, revealing behaviors previously inaccessible in laboratory settings. Using this combination of technique and material design, we observe shear-induced banding that only appears in the presence of electric depending on the frequency of the electric field, at either high or low shear rates. These microstructural transitions produce dramatic, reversible viscosity modulation—not only increases, but also decreases, including negative intrinsic viscosities. Frequency control enables instantaneous switching among multiple effective viscosities spanning a 30-fold range, establishing ERI as a powerful tool for probing and controlling rheology in field-responsive soft materials.

We study asymptotic properties of supercritical Galton-Watson (GW) branching processes in the asymptotic where the mean of the offspring distribution approaches 1 from above. We show that the population-size distribution of the GW branching processes at a sufficiently large generation in this asymptotic can be approximated by a compound Poisson-gamma distribution. Numerical experiments revealed that the compound Poisson-gamma models were in good agreement with the corresponding GW models for sufficiently large generations under a reasonable parameter regime. Our results can be regarded as supporting the use of the compound Poisson-gamma model as a model for cascaded multiplication processes.

The design and control of soft robots operating in fluid environments requires a careful understanding of the interplay between large elastic body deformations and hydrodynamic forces. Here, we show that this interplay leads to elastohydrodynamic instabilities in a clamped soft robotic arm driven terminally by a constant pressure in a viscous fluid. We model the arm as a Cosserat rod that can stretch, shear, and bend. We obtain invariant, geometrically exact, nonlinear equations of motion by using Cartan’s method of moving frames. Stability to small perturbations of a straight rod is governed by a non-Hermitian linear operator. Eigenanalysis shows that stability is lost through a Hopf bifurcation with the increase of pressure above a first threshold. A surprising return to stability is obtained with further increase of pressure beyond a second threshold. Numerical solutions of the nonlinear equations, using a geometrically exact spectral method, confirm stable limit-cycle oscillations between these two pressure thresholds. An asymptotic analysis in the beam limit rationalizes these results analytically. This counterintuitive sequence of bifurcations underscores the subtle nature of the elastohydrodynamic coupling in Cosserat rods and emphasizes their importance for the control of the viscous dynamics of soft robots.

Recent progress in manipulating individual quantum systems enables the exploration of engines exploiting nonclassical resources. One of the most appealing is the energy provided by the inherent backaction of quantum measurements. While a handful of experiments have investigated the inner dynamics of engines fueled by measurement backaction, powering a task by such an engine is missing. Here, we demonstrate the amplification of microwave signals by an engine fueled by repeated quantum measurements of a superconducting transmon qubit. Using feedback, the engine acts as a quantum Maxwell demon operating without a hot thermal source. Measuring the gain of this amplification constitutes a direct probing of the work output of the engine, in contrast to inferring the work by measuring the qubit state along its evolution. Observing a good agreement between both work estimation methods, our experiment validates the accuracy of the indirect method. We characterize the long-term stability of the engine as well as its robustness to transmon decoherence, loss, and drifts. Our experiment exemplifies the use of energy brought by quantum measurement backaction.

We present a general theoretical framework for group-resetting dynamics in a potential landscape. While traditional resetting models typically focus on a single particle, we consider a group of particles whose collective dynamics govern the resetting. We extend existing resetting theories to cover extreme-value group resetting. This has applications from bacterial evolution under antibiotic pressure to swarm-search optimization. Using renewal theory, we derive a Fokker-Planck equation for the spatial distribution of the group's center of mass, treated as an effective particle. This formalism yields analytical expressions for key observables such as the stationary mean position and variance. We also study a group avoidance problem, where the particles must avoid an undesirable region. Such problems have recently been studied in contexts such as preventing critically high water levels in dams and controlling excessive financial leverage. Our framework offers insights into how resetting can optimize group-level search and avoidance strategies.

To sustain bacterial growth, a fraction of active ribosomes must be allocated to synthesize ribosomal proteins. Two control parameters modulate the growth rate: the fraction of ribosomes allocated to ribosomal protein synthesis and the translation speed. At longer doubling times, which approach the active ribosome lifetime, the limited number of ribosomes poses a significant constraint in allocating ribosomes to ribosomal protein synthesis. We show that, to maintain slow growth while reducing the risk of depletion of the active cellular ribosome population, some bacteria must significantly reduce translation speed below its maximum, as previously observed. This change in the controls is due to a universal shot noise limitation that applies at slow growth rates in all kingdoms of life.

We develop a theoretical framework to elucidate the mechanics and morphogenesis of open vesicles coupled to boundary filaments, capturing their geometric, energetic, and mechanical interplay. Using a spherical harmonics parametrization and constrained energy minimization, we systematically explore equilibrium morphologies as functions of filament length, stiffness, and topology, as well as membrane spontaneous curvature, uncovering a rich spectrum of shapes and transitions. For open vesicles bounded by flexible closed filaments, increasing filament length or spontaneous curvature drives transitions from cuplike to stomatocyte and budded morphologies, both axisymmetric and nonaxisymmetric, with continuous and discontinuous regimes mapped in a phase diagram. For open vesicles partially bounded by open filaments, the coupled filament-membrane system exhibits more complex morphological evolution, including free edge stretching or contraction, localized filament bending, and opening expansion with increasing filament length. The derived force and moment balances at the vesicle edge connect local geometric quantities, such as filament and membrane curvatures, to filament internal forces and membrane tension, providing a direct mechanical interpretation of shape equilibria. Our results reveal how filament geometry, topology, and bending stiffness govern membrane shape transformations and establish a general mechanical framework for coupled filament-membrane systems, such as DNA-vesicle complexes and other filament-mediated membrane structures.

The elastic response of mechanical, chemical, and biological systems is often modeled using a discrete arrangement of Hookean springs, representing either finite material elements or even the molecular bonds of a system. However, to date, there is no direct derivation of the relation between a general discrete spring network, with arbitrary geometry, and its corresponding elastic continuum. Furthermore, understanding the network’s mechanical response requires simulations that may be expensive computationally. Here, we report a method to derive the exact elastic continuum model of any discrete network of springs, requiring network geometry and topology only. We identify and calculate the so-called “nonaffine” displacements. Explicit comparison of our calculations to simulations of different crystalline and disordered configurations shows that we successfully capture the mechanics even of auxetic materials. Our method is valid for residually stressed systems with nontrivial geometries, and is an important step in generalizing active stresses on such discrete systems. It is easily generalizable to other discrete models, and opens the possibility of a rational design of elastic systems.

We detail experimental results inferring ionization and temperature for warm dense copper plasmas at several times solid density (15–25 ${\mathrm{g}/\mathrm{cm}}^3$) and temperatures of 10–21 eV. Experiments performed at the OMEGA Laser Facility generate uniform warm dense matter conditions via symmetric shock compression of a buried copper layer. The plasma is probed with a laser-generated x-ray source to collect the K-shell x-ray absorption spectrum. Fitting bound-bound absorption contributions from constituent charge states of copper provides an estimated $\overline{Z}$ of approximately 4–7 for these warm dense copper plasmas. We find that these partially ionized plasmas have K-edge shifts of 12–30 eV and bound-bound resonance $1s\to 3p$ absorption shifts of 4–26 eV with respect to the cold K edge. This study provides necessary experimental data to improve ionization and opacity models in the warm dense matter regime.

The Magnus expansion underpins average Hamiltonian theory (AHT), a central tool in quantum control and sensing that is used to generate efficient approximations of system dynamics. Here, we demonstrate that the conditions for Magnus expansion convergence are violated under typical operating regimes for sensing using solid-state spin systems. We also establish that certain symmetries, such as those found in rapid echo pulse sequences, cancel all higher-order Magnus terms outside standard convergence frameworks. We introduce an exact method to compute the sensor response beyond the AHT regime, and apply it to both broadband and narrow-band magnetometry protocols. Our results clarify AHT limits and enable opportunities in pulse sequence design through symmetry-driven convergence, with implications for entanglement-enhanced sensing and quantum Fisher information estimation in control protocols.

Attosecond pulse trains (APTs) are indispensable for probing electron dynamics at their intrinsic timescales. High-harmonic generation (HHG) has long been a successful and widely used technique in producing extreme ultraviolet APTs. However, in the soft x-ray regime, HHG suffers from low conversion efficiency and lacking flexibility in the waveform and spectrum control. Here in this study, based on the waveform synthesis of the echo-enabled harmonic generation (EEHG) free-electron laser (FEL), we propose a method that can generate soft x-ray APTs with high temporal and spectral tunability. EEHG scheme is well-known in forming phase-locked high-harmonic bunching combs down to the soft x-ray regime. Here, the EEHG scheme is employed to facilitate successive FEL lasing in several different harmonic numbers and then perform the coherent waveform synthesis to generate soft x-ray APTs. Three-dimensional simulation results indicate that reproducible generation of coherent APTs in the soft x-ray regime with peak power of 3.5 GW and micropulse duration of 160 as can be achieved by five-harmonic synthesis. The micropulse duration together with the spectral components of the APTs can be adjusted easily according to the programmable high-harmonic bunching combs in the EEHG scheme. This method has the potential to establish a robust platform for attosecond sciences in the soft x-ray regime, which can enable unprecedented studies of electron dynamics in physical and chemical reactions, biological systems, and quantum materials.

Lanthanides are nowadays extensively used to investigate the properties of strongly correlated matter. Nevertheless, exploiting the Zeeman manifold of a lanthanide atom ground state is challenging due to the unavoidable presence of depolarization collisions. Here, we demonstrate that in the case of the thulium atom, it is possible to suppress this depolarization by a factor of 1000 with a carefully tuned magnetic field, thus opening the way for the efficient use of the Zeeman manifold in quantum simulations.

Mode switching in exciton-polariton condensates represents a significant phenomenon that illustrates the non-Hermitian properties and out-of-equilibrium dynamics of exciton-polaritons. In this research, we experimentally demonstrate controllable mode switching in a tunable ZnO microrod cavity at room temperature, where increasing pump power drives the condensate from one lower polariton branch to another of higher energy. This unconventional up-switching is explained by an imbalance in the densities of the active excitonic reservoirs, governed by both loss and relaxation efficiency. Ultrafast spectroscopy reveals a several-picosecond delay between the condensates, providing direct evidence for this mechanism. Our results provide important insights into the fundamental physics of Bose-Einstein condensation in dissipative systems, enable control of polariton condensation through reservoir engineering, and open routes to room-temperature polaritonic devices exploiting nonlinear switching.