Cilia and flagella are highly conserved biological motors that drive the motility of diverse eukaryotic cells. In the microscopic world, an organism's swimming kinematics are generally assumed to be a direct, instantaneous proxy for its underlying motor force output. However, as organisms scale in size—such as during the evolutionary transition to multicellularity—this fundamental assumption may break down. Using the multicellular alga Volvox as a model biophysical system, we perform direct, time-resolved force measurements during free-swimming collisions to deconvolve a swimmer's inertial impact force from its motor's propulsive force. We discover a $\sim 30\mathrm{Hz}$ propulsive pulse, which serves as the mechanical signature of collective ciliary action and hydrodynamic synchronization. Crucially, we demonstrate that while this high-frequency motor output drives a fluctuating velocity in the smaller V. carteri, it is mechanically filtered by the inertia of the larger V. ferrisii, resulting in a smooth swimming trajectory. Our work reveals that as organisms grow larger, their own mass acts as a mechanical low-pass filter. This fundamentally decouples high-frequency motor dynamics from whole-organism swimming kinematics, highlighting how physical constraints shape the mechanobiology of motility as organisms evolve toward complex multicellularity.

Locally noncentrosymmetric materials are attracting significant attention due to the unique phenomena associated with sublattice degrees of freedom. The recently discovered heavy-fermion superconductor ${\mathrm{CeRh}}_2{\mathrm{As}}_2$ has emerged as a compelling example of this class, garnering widespread interest for its remarkable temperature-magnetic-field phase diagram, which features a field-induced first-order superconductor-to-superconductor phase transition with nontrivial dependence on the field direction and high critical fields, as well as antiferromagnetic and potentially higher multipole orders. To investigate the complex interplay of the ordered phases in ${\mathrm{CeRh}}_2{\mathrm{As}}_2$, we develop a theoretical framework based on symmetry analysis applied to a Bogoliubov–de Gennes Hamiltonian and Landau methods. This approach allows us to propose probable symmetries of the superconducting states and elucidate their close relationship with magnetism. Among other results, we find that the near degeneracy of two pairing symmetries is naturally explained if and only if intralayer spin-orbit coupling is large compared to interlayer hopping. Intriguingly, we find that the first-order transition can be interpreted as a transition between coexistence phases of the same superconducting order parameters, albeit with distinct admixtures. This line may end in a critical end point below the superconducting critical temperature. Our approach accurately reproduces current experimental phase diagrams for varying temperature as well as out-of-plane and in-plane magnetic field, both if the transition to a magnetic phase occurs below the superconducting critical temperature and if it occurs above. Furthermore, we calculate the magnetic susceptibility and the specific heat and compare these quantities to recent experimental results.

Mounting evidence indicates that some of the gravitational wave signals observed by ground-based observatories might arise from eccentric compact object binaries, increasing the urgency for accurate waveform models for such systems. While for noneccentric binaries, surrogate models are efficient and accurate, the additional features due to eccentricity have posed a challenge. In this work, we present a method for decomposing eccentric numerical relativity waveforms, making them amenable to surrogate modeling techniques. We parametrize the inspiral in the radial-phase domain, factoring out eccentricity-induced dephasing and thus enhancing compressibility and accuracy. This is combined with a second surrogate for the merger ringdown in the time domain and a technique to take advantage of the approximate periodicity with radial oscillations during the inspiral. We apply this procedure to the (2, 2) mode for nonspinning black hole binaries and demonstrate that the resulting surrogate, NRSurE_q4NoSpin_22, is able to faithfully reproduce the underlying numerical relativity waveforms, with maximum mismatches of $6\times {10}^{-4}$ and median mismatches of $4\times {10}^{-5}$. This technique paves the way for high-accuracy parameter estimation with eccentric models, a key ingredient for astrophysical inference and tests of general relativity.

Muon spin rotation (${\mu }^{+}\mathrm{SR}$) was used to investigate the magnetic properties of cobalt-intercalated $2H-{\mathrm{NbSe}}_2$ (${\mathrm{Co}}_{1/4}{\mathrm{NbSe}}_2$). ${\mathrm{Co}}_{1/4}{\mathrm{NbSe}}_2$ is predicted to be an altermagnet, and while neutron diffraction has proposed its magnetic structure, the microscopic details of this remain unclear. Therefore, a local probe investigation of the magnetism in ${\mathrm{Co}}_{1/4}{\mathrm{NbSe}}_2$ is essential. Our results reveal a sharp second-order transition to a full-volume-fraction, homogeneous magnetic order below $T_{\mathrm{N}}=168\mathrm{K}$. The moments are aligned antiparallel along the $c$ axis, consistent with neutron diffraction and altermagnetism. ${\mu }^{+}\mathrm{SR}$ reveals that the state remains stable under a $c$-axis magnetic field up to $0.78\mathrm{T}$, with magnetization measurements suggesting that this robust regime extends to at least 5 T. Within the time sensitivity of ${\mu }^{+}\mathrm{SR}$, no precursor slow magnetic fluctuations were detected above $T_{\mathrm{N}}$, which is important for interpreting the band splitting in the paramagnetic state reported by photoemission studies.

Electron-phonon interactions play a central role in determining charge and heat transport in condensed matter systems, but in disordered and low-dimensional materials, this coupling can be strongly suppressed, leading to nontrivial transport phenomena. One striking manifestation is the appearance of bistable current-voltage ($I\text{−}V$) characteristics, where an imbalance between electrical heating and electron-phonon cooling yields multiple nonequilibrium steady states. In this work, we experimentally investigate this phenomenon in amorphous $a\text{−}{\mathrm{Y}}_x{\mathrm{Si}}_{1-x}$ thin films, where disorder can be tuned by thermal annealing. We identify the critical disorder at which bistability emerges and characterize the associated jumps in nonlinear $I\text{−}V$ curves. To interpret these results, we develop a microscopic derivation of the phenomenological hot-electron model and extend it by incorporating electric-field-assisted hopping and phonon-mediated intergrain transitions, allowing quantitative agreement with experimental data across different disorder regimes. Complementary numerical simulations confirm the robustness of our extended framework. Our combined experimental, analytical, and numerical results provide a comprehensive description of electron-phonon decoupling and its impact on transport in disordered systems, offering a platform for studying nonequilibrium phases.

The behavior of charged vesicle suspensions, commonly encountered in biological and industrial contexts, is largely governed by screened electrostatic repulsions. However, the addition of depletants such as polymers can induce attractive interactions and lead to gel formation. Here, we investigate the rheology and yielding behavior of such a vesicle gel, relevant to a class of consumer products. The combination of experiments and Brownian dynamics simulations enables us to establish connections between macroscopic rheology and microstructural features. Oscillatory tests reveal a predominantly elastic response at small deformations, followed by yielding upon increasing the strain amplitude. With increasing shear rate, the flow curves feature a yield stress regime, followed by shear thinning and, eventually, a Newtonian-like response (viscosity plateau). We find that, in both oscillatory and shear-rate-controlled tests, the yielding transition is accompanied by nonmonotonic trends in structural heterogeneity. Fitting the flow curves with the recently introduced three-component model reveals that structural heterogeneity peaks near the crossover from the yield stress plateau to shear thinning, while homogeneity is recovered in the Newtonian-like regime. Numerical creep tests exhibit rich phenomenology, including Andrade-like deformation, delayed yielding, and resolidification, whose persistence even above the dynamic yield stress highlights the ductile nature of gels with competing attractive and repulsive interactions. Overall, our study highlights distinctive rheological and structural features of gels with competing attractive and repulsive interactions, providing insight into how microscopic heterogeneity controls yielding and flow.

We propose a quantum algorithm for computing one-quasiparticle excitation energies in the thermodynamic limit by combining numerical linked-cluster expansions (NLCEs) and the variational quantum eigensolver (VQE). Our approach uses VQE to block diagonalize the cluster Hamiltonian through a single-unitary transformation. This unitary is then postprocessed using the projective cluster-additive transformation (PCAT) to ensure cluster additivity, a key requirement for NLCE convergence. We benchmark our method on the transverse-field Ising model (TFIM) in one and two dimensions, and with longitudinal field, computing one-quasiparticle dispersions in the high-field polarized phase. We compare two cost function classes, trace minimization and variance based, demonstrating their effectiveness with the Hamiltonian variational ansatz (HVA). For pure TFIM, $\lceil N/2\rceil$ layers of HVA suffice: $\mathrm{NLCE}+\mathrm{VQE}$ matches exact diagonalization. For TFIM with longitudinal field, where parity symmetry breaks and PCAT becomes essential, both $\lceil N/2\rceil$ and $N$ layers of HVA converge with increasing cluster size, with $N$ layers providing improved accuracy. Our results establish PCAT as a cluster-additive framework that extends variational quantum algorithms to excited-state calculations in the thermodynamic limit via NLCE. While demonstrated with VQE, the PCAT postprocessing approach, which requires only low-energy eigenspace information, applies to any quantum eigenstate preparation method.

We establish a quantitative relation between the altermagnetic spin splitting and different higher-order multipoles of the charge and magnetization density around the magnetic atoms. Magnetic multipoles such as octupoles or triakontadipoles have been suggested as potential ferroic order parameters for $d$- and $g$-wave altermagnetism, respectively, based mainly on qualitative symmetry arguments. We use first-principles-based electronic structure calculations to establish a clear quantitative relation between the strength of the altermagnetic spin splitting and the magnitude of certain local multipoles. We vary the magnitude of these multipoles either by applying an appropriate constraint on the charge density or by varying a corresponding structural distortion mode, using two simple perovskite materials, ${\mathrm{SrCrO}}_3$ and ${\mathrm{LaVO}}_3$, as model systems. Our analysis indicates that in general the altermagnetic spin splitting is not exclusively determined by the lowest-order nonzero magnetic multipole, but results from a superposition of contributions from different multipoles with comparable strength, suggesting the need for a multicomponent order parameter to describe altermagnetism. We also discuss different measures to quantify the overall spin splitting of a material, without relying on features that might be specific to only individual bands.

We theoretically explore a dynamical generalization of the Aubry-André model in two dimensions formed by superimposing two square-lattice potentials. Motivated by the rich physics emerging at different twist angles between the two lattices at equilibrium, we introduce periodic twisting by continuously rotating one of the lattices with respect to the other in the plane. We demonstrate that the distinct time-dependent twisting in this system gives rise to an intricate form of periodic multifrequency driving that changes with the distance from the rotation axis. We find that the incommensurate nature of the potential no longer plays the pivotal role as it does in the static case. Rather, the tunneling can be understood in terms of a local, spatially varying dynamical localization effect, which we show to yield ring-shaped states localized within the bulk that have interesting transport signatures. Quantifying the eigenstates with the Bott index and local Chern marker, we find that there is a zoo of states with nontrivial topological signatures, the most ubiquitous of which result in relatively uniform ring-shaped regions of the Chern marker. We investigate the origin of these effects from various angles and identify that hybridization between different delocalized ring states plays a vital role. Finally, we discuss possible experimental realizations in quantum simulation settings. Our results open an avenue of investigation with periodic twisting inducing a spatially varying multifrequency drive.

We explore the correlated dynamics underlying the formation of the quantum Peregrine soliton, a prototypical rogue-wave excitation, utilizing interaction quenches from repulsive to attractive couplings in an ultracold bosonic gas confined in a one-dimensional box trap. The latter emulates the so-called semiclassical initial conditions and the associated gradient catastrophe scenario facilitating the emergence of a high-density, doubly localized waveform. The ensuing multiorbital variant of the Peregrine soliton features notable deviations from its mean-field sibling, including a reduced peak amplitude, wider core, absence of the side density dips, and earlier formation times. Moreover, Peregrine soliton generation yields coherence losses, while experiencing two-body bunching within each of its sides, which show anti-bunching between each other. Controllable seeding of the Peregrine soliton is also demonstrated by tuning the atom number or the box length, while reducing the latter favors the generation of the time-periodic Kuznetsov-Ma breather. Our results highlight that correlations reshape the morphology of rogue waves in the genuinely quantum, nonintegrable realm, while setting the stage for the emergent field of quantum dispersive hydrodynamics.

Random ensembles of pure states have proven to be extremely important in various aspects of quantum physics such as benchmarking the performance of quantum circuits, testing for quantum advantage, studying many-body thermalization, and the black hole information paradox. Although generating a truly random quantum ensemble is experimentally challenging, approximate realizations are equally valuable and are known to emerge naturally in a variety of physical models, including Rydberg setups. These are referred to as approximate quantum state designs, and verifying their degree of randomness can be a measurement-intensive task, similar to performing full quantum state tomography on many-body systems. In this theoretical work, we present a measurement scheme and analysis techniques to validate the degree of randomness of a quantum ensemble generated by a simulated experimental setup. This is achieved by translating the information residing in the complex many-body state into a succinct representation of classical data using projective measurements in randomly chosen bases, which is then processed using methods of statistical inference such as maximum-likelihood estimation and neural networks, benchmarked against the predictions of shadow tomography. Our scheme only requires individually addressed single-qubit operations to be performed in order to be employed, making it applicable for a range of physical platforms.

We study the dynamics of light interacting with a near-resonant atomic medium using the truncated Wigner and positive $P$ phase-space representations. By mapping the atomic degrees of freedom via the Jordan-Schwinger transformation, we first analyze the system under unitary evolution before extending the treatment to include an optical reservoir. While both methods capture the main features of the light-matter dynamics, our results demonstrate that the truncated Wigner approximation deviates significantly at higher interaction strengths and in regimes where reservoir-induced noise is prominent.

We investigate the Lotka-Volterra model for predator-prey competition with a finite carrying capacity that varies periodically in time, modeling seasonal variations in nutrients or food resources. In the absence of time variability, the ordinary differential equations have an equilibrium point that represents coexisting predators and prey. The time dependence removes this equilibrium solution, but the equilibrium point is restored by allowing the predation rate also to vary in time. This equilibrium can undergo a parametric resonance instability, leading to subharmonic and harmonic time-periodic behavior, which persists even when the predation rate is constant. We also find period-doubling bifurcations and chaotic dynamics. If we allow the population densities to vary in space as well as time, introducing diffusion into the model, we find that variations in space diffuse away when the underlying dynamics is periodic in time, but spatiotemporal structure persists when the underlying dynamics is chaotic. We interpret this as a competition between diffusion, which makes the population densities homogeneous in space, and chaos, where sensitive dependence on initial conditions leads to different locations in space following different trajectories in time. Patterns and spatial structure are known to enhance resilience in ecosystems, suggesting that chaotic time-dependent dynamics arising from seasonal variations in carrying capacity and leading to spatial structure might also enhance resilience.

Multiswarm systems, where two or more swarms of mobile agents occupy the same region of space with different parameters and goals, occur in a variety of biological, engineering, and defense applications. Composites of multiple swarms can produce hybrid spatiotemporal patterns, which compared to single swarming systems, are relatively unexplored. In this work, we develop a framework for studying the collision of countermoving swarms, each with its own preferred, stable velocity before collision. We show that redirection of such swarms after collision occurs when a stable velocity synchronized state of the multiswarm composite exists. Using a rigid-body approximation, we are able to extract how scatter-redirection transitions scale with swarm parameters in a variety of scenarios from reciprocal and nonreciprocal systems to symmetric and antagonistic parameter values. Our results compare well to simulations of both particle modeled agents and wheeled robots.