High-precision quasisimultaneous collinear/anticollinear laser spectroscopy was performed to measure the $5s{}^2{S}_{1/2}\to 5p{}^2{P}_{1/2}$ ($D1$), the $5s{}^2{S}_{1/2}\to 5p{}^2{P}_{3/2}$ ($D2$), and the three $4d\to 5p$ transitions in naturally abundant ${\mathrm{Sr}}^{+}$ isotopes. For absolute transition frequencies, an uncertainty as low as $600\mathrm{k}\mathrm{Hz}$ was achieved, while common-mode rejection allowed us to extract isotope shifts with uncertainties down to a level of $200\mathrm{k}\mathrm{Hz}$, 1 order of magnitude better than previously achieved. Similarly, the uncertainties of the hyperfine-structure coefficients for ${}^{87}\mathrm{Sr}$ of the $5p$ states and the $4d{}^2{D}_{3/2}$ levels are improved. A King-plot analysis yielded a field-shift ratio of the $D2$ and $D1$ lines of $F_{\mathit{\text{D}}\text{2}}/F_{\mathit{\text{D}}\text{1}}=1.004\left(5\right)$, which lies within the theoretically allowed region and can be used as a benchmark for atomic structure theory calculations. We use the information from all stable isotopes in the investigated transitions to compare field-shift and mass-shift constants obtained by various techniques regularly used in the literature, ranging from King plots with purely experimental input to ab initio atomic structure calculations by state-of-the-art theory. We show that in the region above $N=50$, the charge radii are strongly dependent on the approach being used.

We propose a simple scalable scheme for the dissipative generation of entangled states of multiple emitters coupled to a waveguide. Our approach exploits collective interactions arising from the formation of subradiant and superradiant excited states, combined with the quantum Zeno effect. We show that, starting from an arbitrary initial state, the system deterministically evolves toward a W-type entangled steady state, with an infidelity that scales inversely with the cooperativity. The protocol is scalable to an arbitrary number of emitters. We further analyze the impact of additional experimental imperfections and present a detailed implementation based on trapped ${}^{133}\mathrm{Cs}$ atoms.

Scalable trapped-ion quantum computing is commonly realized with modular chips that feature distinct zones with specific functionalities, such as storage, state preparation, and gate execution. To execute a quantum circuit, the ions must be transported between these zones. This process is called ion shuttling. To achieve reliable computation results, the shuttling process must be optimized. However, as the number of ions increases, this becomes a high-dimensional optimization problem where optimal solutions cannot be computed efficiently. We demonstrate, to the best of our knowledge, the first use of reinforcement learning (RL) for the optimization of ion shuttling. RL is well suited for such scenarios, as it enables learning a strategy through direct interaction with the problem. We show that our RL approach outperforms current state-of-the-art heuristic techniques, yielding a reduction in shuttling operations of up to $36.3\%$. Furthermore, we show that our method is easily applicable to various chip architectures. Our approach offers a versatile method to study shuttling efficiency during chip design and, therefore, a highly relevant tool for future, more complex architectures.

Altermagnets are a novel class of magnetic systems characterized by their momentum-dependent spin splitting without net magnetization. In this work, we extend established Euclidean tight-binding models of altermagnets to regular hyperbolic lattices in two spatial dimensions defined on a discretized Poincaré disk. Using hyperbolic crystallography and Abelian hyperbolic band theory, we show that the inclusion of next-nearest-neighbor hopping is sufficient to induce spin splitting in minimal tight-binding models of bipartite hyperbolic lattices. While certain families and special cases of hyperbolic lattices remain antiferromagnetic, we identify an entire family and a special case that generically permit spin splitting in this framework. Hence, altermagnetism is inherent to certain hyperbolic lattices. Since Abelian hyperbolic band theory yields a momentum space that is at least four dimensional, we classify the leading spin-splitting harmonics using four-dimensional atomic orbitals. As an outlook, we apply non-Abelian hyperbolic band theory to the $\{10,5\}$ lattice. Although its Abelian spectrum is spin degenerate, two selected higher-genus supercells exhibit spin splitting. This finding suggests that spin degeneracy does not necessarily persist within all translation representation sectors.

Time materials are materials with acoustic, electromagnetic, or elastic properties that change while waves are propagating through them. Waves can scatter from such temporal inhomogeneities, but due to causality, they cannot reflect back in time. As a result, time-scattered wave fields do not resemble space-scattered wave fields—which are spatially mirrored—but instead look like copies of the original signal traveling back in time. Consequently, they can form an ingredient for physical solvers of inverse problems that rely on time-reversal transformations. Here, we investigate the use of time reflections for calculating so-called focusing wave fields. We establish a one-to-one mapping between focusing wave fields and the transmitted wave fields produced by time scattering. This mapping is then used to construct a space-time medium where the time scattering anticipates the space scattering and “computes” the exact inverse transmission response for the space scattering. We demonstrate the construction with a simple numerical example of a single pulse encountering a series of time boundaries before reaching a spatial inhomogeneity. The time boundaries scatter the single pulse into a focusing wave field that subsequently focuses through the spatial inhomogeneity. With certain mild assumptions, the transmitted wave has both the same wave shape and amplitude as the original pulse, yielding a transmission coefficient of unity.

Discrete nonlinear systems support a rich variety of localized and extended wave phenomena, with their dynamics sensitively dependent on the symmetries of the underlying interaction forces within the lattice. Odd elasticity, emerging in effective models of active materials, breaks the action-reaction symmetry of the local interactions and gives rise to new wave behavior. We investigate the existence and stability of traveling waves in a nonlinear lattice with odd elasticity, where the coupling force between adjacent units depends asymmetrically on the deformations of the coupled units (nonreciprocal or asymmetric elastic coupling). We demonstrate the existence of periodic and quasiperiodic traveling waves and analyze their spectral stability using the master stability framework. In particular, we identify the onset of Eckhaus instability based on the curvature of the associated master stability curve. This approach enables a quantitative analysis of size effects, specifically the bounds on lattice sizes for which a given traveling wave is stable. The stability analysis for quasiperiodic waves is based on an effective description of the envelope of the response through a rotating-wave approximation, which agrees well with direct numerical simulations. Our findings establish a unified framework for understanding wave propagation characteristics in nonlinear lattices, for both periodic and quasiperiodic wave profiles. We highlight, qualitatively and quantitatively, the role of odd elasticity on the existence and stability of nonlinear traveling waves in dissipative systems, and discuss how localization and stability depend on the interplay between nonlinearity, dissipation, and nonreciprocity.

A series of glass-shell $\mathrm{D}{}^3\mathrm{He}$ gas-filled implosions was carried out on the OMEGA Laser Facility. In these experiments, the thicknesses of the glass shells were varied from 4.2 to 9.4 $\mu \mathrm{m}$, producing implosions that spanned from shock-to-compression-dominated emission. Data from several diagnostics were used to infer the conditions and nuclear yields for the $\mathrm{D}{}^3\mathrm{He}$-p and DD-n reactions during shock and compression burns. From the inferred yields and ion temperatures, the deuterium fractions in the hot spot during both emission phases were estimated. It is found that there is a substantial surplus ($\sim 5\%$) of deuterium in the hot spot compared to the initial fill fraction during both shock and compression phases for all implosion types. This is the first measurement indicating persistent species separation throughout both phases of inertial confinement fusion (ICF) implosions. In ICF implosions, deviations from a 50:50 species ratio will decrease the fusion rate, directly impacting performance. Future ICF implosion design work would benefit from including models that capture multi-ion dynamics.

Free-electron interactions with optical near fields are conventionally described as one-dimensional energy ladders, in which multicolor photon-exchange pathways can become spectrally degenerate. In this work, we show that coupling a single free electron to commensurate two-color optical vortices can unfold this degeneracy, realizing a tunable synthetic lattice spanned by the electron energy and orbital angular momentum (OAM). The resulting single-particle dynamics map the free-electron light interaction onto an effective tight-binding Hamiltonian whose primitive hopping vectors and coupling anisotropy are controlled by the optical OAM charges and near-field amplitudes. We use this construction to emulate a Lifshitz transition in the synthetic quasienergy band structure, identified by a topological reconnection of the zero-quasienergy contour and the associated Van Hove singularity in the density of states. We further show that the generated electron state exhibits tunable intraparticle energy-OAM mode nonseparability, which serves as a diagnostic of the synthetic-lattice geometry. These results establish free electrons as a tunable platform for synthetic-band engineering, combining electron-wavefunction control with ultrafast electron-microscopy and nanoscale near-field techniques.

We report a direct demonstration of quantum-enhanced sensing in the Fourier domain by comparing single- and two-photon interference in a fiber-based interferometer under strictly identical noise conditions. The simultaneous acquisition of both signals provides a common-mode reference that enables a fair and unambiguous benchmark of quantum advantage. Spectral analysis of the interferometric outputs reveals that quantum correlations do not increase the amplitude of the modulation peak, but instead lower the associated noise floor, resulting in the expected 3 dB improvement in signal-to-noise ratio. This enhancement persists in the sub-shot-noise regime, where the classical signal becomes indistinguishable from the spectral background while the two-photon contribution remains resolvable. These observations establish quantum supersensitivity in the Fourier domain as an operational and broadly applicable resource for precision interferometric sensing.

Inertial confinement fusion implosion design requires simultaneous optimization of strongly coupled target and driver parameters across high-dimensional design spaces. Existing automated design approaches typically rely on nondifferentiable radiation-hydrodynamics codes treated as black boxes, making optimization increasingly expensive as dimensionality grows. In this work, we present a differentiable simulation approach for high-dimensional inverse design of inertial confinement fusion implosions. Automatic differentiation through a differentiable implosion physics model, driven by an external pressure pulse, provides gradients of implosion objectives with respect to design parameters, enabling gradient-based optimization. The framework is applied to 25 kJ OMEGA-scale direct-drive implosions, optimizing 500-parameter laser pulses across sampled target geometries. The optimized pulse recovers a near-isentropic rise to peak power without that structure (i.e., pulse shape) being imposed. Neural-network pulse parametrizations are additionally explored as a means of accelerating design-space exploration. These results establish differentiable implosion modeling as a promising tool for inertial confinement fusion design, while motivating further work on adjoint robustness and higher-fidelity differentiable simulators.

Guiding relativistically intense laser pulses in low-density plasmas enables extended acceleration lengths in laser-plasma accelerators (LPAs), allowing for the production of multi-GeV electron beams. Quantitative interpretation of such experiments is often limited by substantial uncertainties in key plasma parameters, particularly the transverse density profile of hydrodynamic optical-field-ionized channels. Distinct plasma density distributions can produce similar terminal beam energies, complicating efforts to infer the underlying interaction physics from measurements at the accelerator exit alone. By combining longitudinally resolved electron beam diagnostics with independent measurements of laser spectral evolution in a 10 GeV LPA, we establish a multiobservable constraint on plasma density profiles. Once plasma down ramps are taken into account, excellent agreement is observed with simulation over the entire accelerator length for two plasma channel sizes. The validated simulations indicate that extending the accelerator length to 65 cm would increase the electron beam energy to 15 GeV. They also point the way to achieving $\sim 20\mathrm{GeV}$ electron beams in $\sim 70\mathrm{cm}$ via linear matching using the same 24 J laser energy.

We identify an instability mechanism in pressure-driven viscoelastic channel flows bounded by porous walls. Unlike the elastoinertial center mode in impermeable channels or the classical porous-wall mode in Newtonian flows, the instability uncovered here is wall localized and arises from the coupling of polymeric stress transport with interfacial momentum leakage. Elastic normal stresses concentrate disturbances at the fluid-porous interface, while permeability simultaneously enables slip-driven stress amplification and dissipative leakage, producing a wall-confined elastoinertial mode. The resulting instability occurs at Reynolds and Weissenberg numbers well below classical thresholds and exhibits a nonmonotonic dependence on permeability. In the strongly elastic limit, the onset is governed by interfacial stress localization rather than inertial amplification, rendering inertia nonessential. These findings show that permeability not only shifts stability boundaries but also reorganizes the instability mechanism itself, establishing a boundary-driven route to transition in porous-bounded viscoelastic flows.

Attosecond pulses from free-electron lasers have opened the doors to atomic site-specific studies of bound electronic dynamics on their natural, subfemtosecond timescales. Key to their success has been electron beam shaping techniques enabling the generation of subfemtosecond current spikes with peak currents on the order of 10 kA. We demonstrate in an rf linac the generation of current spikes with extreme chirps on the order of $350\mathrm{MeV}/\mu \mathrm{m}$, directly competitive with the chirps expected from beam-driven plasma wakefield accelerators. Leveraging chirp-taper compensation, we use these highly chirped beams to generate hard x-ray attosecond pulses with bandwidths exceeding 30 eV, a factor of 2 beyond previous demonstrations. We simultaneously present the first explicit experimental evidence of chirp-taper compensation in an attosecond x-ray free-electron laser, finding that optimal tapering improves the bandwidth and pulse energy by factors of 2 and 5, respectively, for our conditions. In addition to the immediate utility of such broadband hard x-ray pulses, electron beams with such extreme chirps can be utilized for unique new experimental modalities by performing further compression after the undulators. Such postlasing compression can enable subsequent superradiant light emission at longer wavelengths or direct excitation of quantum systems with the beam’s intense space-charge field for unique attosecond pump-probe possibilities.

Given the rapid advances in quantum computing hardware, establishing strategies for verifying the correctness of quantum computations has become increasingly important. Exploiting the fact that the axial anomaly in gauge theories is exact to all orders in perturbation theory, we propose the axial anomaly as a nontrivial benchmark for quantum simulations of lattice gauge theories. We simulate axial charge production in ${\mathbb{Z}}_N$ lattice gauge theories on the trapped-ion quantum computer “Reimei.” After taking the U(1), infinitesimal time, and infinite volume limits, we successfully reproduce the anomaly coefficient within statistical uncertainties, even without error mitigation. Our results demonstrate that the axial anomaly can be simulated on current quantum computers and serves as a verification test of quantum computations.

Understanding the emergence of macroscopic irreversible hydrodynamics from the reversible unitary dynamics of isolated quantum many-body systems remains a fundamental challenge. Conventional approaches often force spin density dynamics into purely diffusive models, obscuring the microscopic interplay of pressure, spin current, and local friction. Furthermore, reconciling true irreversibility with strictly unitary evolution raises fundamental questions about the role of the observer's temporal resolution. In this paper, we introduce a fully data-driven framework based on generalized extended dynamic mode decomposition integrated with the Mori-Zwanzig projection. By expanding the observable dictionary to explicitly include spin currents, we directly extract the Navier-Stokes hydrodynamic coefficients from a chaotic XXZ spin chain across varying temporal coarse-graining scales. Our unconstrained extraction reveals a clear physical dichotomy: The mechanical elasticity $\left(c^2\right)$ is intrinsically derived from the exact unitary dynamics, preserving strict microscopic reversibility. In contrast, the macroscopic friction $\left(\gamma \right)$ and kinematic viscosity $\left(\nu \right)$ exhibit zero net dissipation, oscillating rapidly around zero in the exact-derivative limit. We demonstrate that genuine macroscopic transport cannot be established without finite temporal coarse graining. By introducing a finite observation timescale $(\mathrm{\Delta }{t}_{\mathrm{cg}}>0)$, the system passes through a distinct crossover timescale where these reversible fluctuations average out, establishing an intermediate functional regime that yields strictly positive friction and viscosity. We further show that the coarse-grained generator constitutes a predictive reduced model requiring only $O\left(N\right)$ macroscopic observables, and that the sign of the emergent friction is inherited from the causal, forward-in-time direction of the coarse-grained inference: Time-symmetric estimators yield zero net dissipation at any coarse-graining scale. Our results demonstrate that macroscopic friction in isolated quantum systems is not an absolute property, but an emergent phenomenon dictated by the temporal resolution and the causal direction of the observer's coarse-grained description.

End-to-end pumps utilizing edge-localized states offer a promising route to operate as connecting buses, supplying efficient and robust connectivity between non-neighboring elements in a network. Here, we investigate a finite quasiperiodic Fibonacci-type photonic chain and demonstrate its ability for end-to-end pumping, with only small and simple changes to the system. First, we use a tight-binding formalism to numerically show that a localized pumping state can be transferred between opposite ends of the system, with only a small structural change to the chain. Then, we experimentally implement this end-to-end pump in an array of coupled optical waveguides, where light propagation is effectively described by the tight-binding model under the paraxial approximation, enabling direct correspondence between theory and experiment. We numerically simulate and experimentally demonstrate pumping by injecting light into a single waveguide at one end of the setup, which activates a localized pumping state. As the light propagates along the waveguide array, it is also pumped to the other end. We further show that pumping remains robust against structural deformation, such as controlled defects in the waveguide array. Our results establish that quasiperiodic Fibonacci-type photonic lattices are a robust and experimentally viable platform for disorder-resilient state transfer.

We investigate the nonequilibrium dynamics of core-hole excitations in a one-dimensional fermionic few-body system consisting of a spin-polarized Fermi bath coupled to a single heavy mobile impurity. The bath is initially prepared in a particle-hole configuration by emptying a selected bath single-particle orbital, while the impurity is displaced with respect to the center of the bath confinement potential. The quench dynamics are initialized by suddenly switching on the impurity-bath interaction. To resolve the resulting dynamics, we combine two complementary ab initio approaches, namely, the MultiLayer MultiConfiguration Time-Dependent Hartree method for mixtures and a multichannel Born-Oppenheimer framework. We show that the postquench response is governed by the interaction strength, impurity confinement, mass imbalance, and the location of the initially prepared hole within the Fermi sea. The density evolution and impurity center-of-mass motion reveal a competition between mixing and demixing of impurity and bath, while the von Neumann entropy demonstrates the buildup of pronounced many-body correlations. Most importantly, the occupation dynamics of the initially emptied orbital identifies deep core holes as substantially more robust against refilling than bulk or edge vacancies. Our results establish core-hole excitations as robust dynamical many-body features in trapped ultracold fermions and provide a controlled route toward probing orthogonality response, correlation buildup, and hole refilling in real time.

The size and organization of biomolecular condensates formed by liquid-liquid phase separation are set by multiple cellular mechanisms that are not yet fully understood. Here, we identify a transport-driven mechanism: Stochastic binding of phase-separating proteins to cytoskeletal motor proteins, followed by active redistribution along filament networks, generates an effective long-range repulsion that arrests coarsening and selects a finite condensate size. A minimal diffusion-transport model, analyzed by linear stability theory and three-dimensional simulations, reveals a transition from macroscopic to microphase separation at remarkably low binding/release fractions, corresponding to minute motor-bound populations. Tuning motor binding rates $b$ or transport velocities enables sublinear control of condensate sizes ($L\sim b^{-1/4}$) from a few hundred nanometers up to the micron scale. The selected length scale is robust to the intrinsic shot noise of the binding-release reactions. In anisotropic cytoskeletal environments, transport asymmetry drives morphological transitions from spherical to cylindrical condensates, independently of the thermodynamic parameters. This mechanism provides a versatile, spatiotemporally programmable route to condensate organization and informs the design of synthetic active emulsions with tunable architectures.

Demonstrating the practical utility of noisy intermediate-scale quantum hardware for recurrent tasks in computer-aided drug discovery is of paramount importance. We tackle this challenge by performing three-dimensional hydration-site prediction in protein pockets on a quantum computer. Formulating the water placement problem as a quadratic unconstrained binary optimization, we use a hybrid approach coupling a classical three-dimensional reference-interaction site model to an efficient quantum optimization solver to run various hardware experiments up to 123 qubits. Matching the precision of classical approaches, our results reproduced experimental predictions on real-life protein-ligand complexes. Furthermore, through a detailed resource estimation analysis, we show that accuracy can be systematically improved with increasing number of qubits, indicating that full quantum utility is within reach as devices scale in the near term. The method has potential for assisting simulations of protein-ligand complexes for drug lead optimization and setup of docking calculations.