Identifying optimal strategies for efficient spatial exploration is crucial, both for animals seeking food and for robotic search processes, where maximizing the explored area is a fundamental requirement. Here, we propose position resetting as an optimal protocol to enhance spatial exploration in active matter systems. Specifically, we show that the area covered by an active Brownian particle depends nonmonotonically on the resetting rate, demonstrating that resetting can optimize spatial exploration. Our results are based on experiments with active granular particles undergoing Poissonian resetting and are supported by simulations of active Brownian dynamics. The covered area is analytically predicted for both large and small resetting rates, leading to a scaling relation between the optimal resetting rate and the self-propulsion speed.

Geometric incompatibility, the inability of a material’s rest state to be realized in Euclidean space, underlies shape formation in natural and synthetic thin sheets. Classical Gauss and Mainardi-Codazzi-Peterson incompatibilities explain many patterns in nature, but they do not exhaust the mechanisms that frustrate thin elastic sheets. We identify a new incompatibility that forbids smooth stretching-free configurations, even when the rest state of the elastic sheet locally satisfies the Gauss and Mainardi-Codazzi-Peterson compatibility conditions. We demonstrate this principle in a model of surface growth with positive Gaussian curvature, where a geometric horizon forms, leading to the onset of frustration. Experiments, simulations, and theory show that the sheet responds by nucleating periodic d-cone-like dimples. We show that this obstruction to stretching-free configurations is topological, and we point to open questions concerning the origin of frustration.

Living organisms employ diverse strategies to navigate confined environments. Inspired by translocation observations on California blackworms (Lumbriculus variegatus), we combine biological experiments and active-polymer simulations to examine how confinement and stiffness govern translocation. Active filaments translocate fastest when the channel width is comparable to their diameter, with escape time determined by propulsion speed, filament length, and channel geometry. In wider channels, activity and flexibility induce reorientation-dominated conformational changes that prolong escape. A single dimensionless ratio linking confinement to stiffness captures the transition from axis-aligned escape with short wall deflections for stiffer filaments to reorientation-controlled motion with bloblike shapes for flexible filaments. These results provide a unified physical framework for active translocation in confinement and suggest design principles for flexible robotic filaments in complex environments.

Organisms adapt to volatile environments by integrating sensory information with internal memory, yet their information processing is constrained by resource limitations. Such limitations can fundamentally alter optimal estimation strategies in biological systems. For example, recent experiments suggest that organisms exhibit phase transitions between memoryless and memory-based estimation strategies depending on energy availability and sensory reliability. However, a theoretical understanding of how resource limitations induce these transitions is still missing. This Letter presents an analytical characterization of the resource-induced phase transitions in optimal estimation strategies. Our results identify the conditions under which resource limitations alter estimation strategies and analytically reveal the mechanism underlying the emergence of discontinuous, nonmonotonic, and scaling behaviors. These results provide a theoretical foundation for understanding how limited resources shape information processing in biological systems.

We investigate the impact of nonunique decompositions of mixed states on energy transfer. Mixed states generally have nonunique decompositions into pure states in quantum theory and, by definition, in other nonclassical probabilistic theories. We consider energy transfers constituting deterministic energy harvesting, wherein the source transfers energy to the harvester but not entropy. We use the possibility of nonunique decompositions to derive that, if source states in a set jointly lead to deterministic energy harvesting for the given harvesting system and interaction, then that set can be expanded to include both mixtures and superpositions of the original states in the set. In the Jaynes-Cummings model, we show that source states supported on specific Fock states and their superpositions achieve exact deterministic energy harvesting, while coherent states with fixed $|\alpha |$ and their superpositions achieve approximate deterministic energy harvesting. More generally, the results link the defining feature of a nonclassical probability theory with the ability to achieve energy transfer without entropy transfer.

Violations of Lorentz invariance, a cornerstone of modern physics, are predicted by theories of quantum gravity and by extensions of general relativity involving new vector or tensor fields. In the weak-field limit, such a violation would primarily manifest as a nonzero value for the post-Newtonian parameter ${\alpha }_1$, which is identically zero in general relativity. We present a new test of local Lorentz invariance by searching for this signature in the orbits of the LAGEOS and LAGEOS II satellites. By applying a phase sensitive detection technique to the mean argument of latitude, derived from about 30 years of satellite laser ranging data, we isolate the periodic signal potentially induced by a preferred reference frame aligned with the cosmic microwave background. Our analysis yields a new constraint $|{\alpha }_1|\sim 2\times {10}^{-5}$. This result improves upon the previous best limit from lunar laser ranging and provides the most stringent constraint to date on preferred-frame effects in Earth’s gravity.

We measured the invariant mass of the ${\eta }^{\prime }(958)$ meson through the ${\eta }^{\prime }\to \gamma \gamma$ decay channel to search for possible character change of ${\eta }^{\prime }$ in a nuclear medium. The measured invariant-mass spectra were analyzed by fitting realistic spectral functions. An enhancement was observed in the lower tail of the ${\eta }^{\prime }$ mass peak for low-momentum ($P_{\gamma \gamma }<1\mathrm{GeV}/\mathrm{c}$) events. Three statistical methods were applied to assess the significance of the enhancement. All methods yield a statistical significance above $3.7\sigma$. The spectral fitting indicates a mass reduction of ${57.5}_{-27.8}^{+5.7}{\mathrm{MeV}/\mathrm{c}}^2$. Our result provides the first evidence for an in-medium spectral modification of the ${\eta }^{\prime }$ meson obtained through a direct measurement of its invariant mass.

We experimentally generate sine-Gordon-like solitons in a spin-1 spinor BEC utilizing a robust and reproducible local phase-imprinting scheme. We find that the soliton velocity can be tuned by the effective quadratic Zeeman shift. This enables the investigation of controlled soliton interactions, in which we observe the characteristic elastic collision behavior of the integrable sine-Gordon model. The spatial displacement—the so-called phase shift—between incoming and outgoing solitons, the signature of their pairwise interaction, is found to be in quantitative agreement with numerical spin-1 simulations within the error bars. These results establish spinor BECs as a highly controllable experimental platform for studying aspects of the dynamics of sine-Gordon-like models.

A resonant phase shifter should rotate a complex optical field without changing its magnitude, but loss and coupling usually make resonant phase tuning change the intensity as well. We introduce a pole-zero synthesis rule that produces a full $2\pi$ phase winding at a chosen scattering magnitude for a selected matrix element $S_{ij}$. The rule traces a closed iso-$|S_{ij}|$ contour that encloses a scattering zero and excludes the relevant pole; Cauchy’s argument principle fixes the phase winding, and the contour fixes the amplitude. For a single isolated resonance, this contour is an Apollonius circle, giving a closed-form design. We realize the rule either by finite-time complex-frequency waveform excitation of a static resonator or by adiabatic comodulation of detuning with damping or coupling at a real carrier. We also discuss the extra control-dimensionality needed for simultaneous multichannel operation.

Experiments show that the Weyl semimetal ${\mathrm{PtBi}}_2$ hosts unconventional superconductivity in its topological surface states. Hence, the material is a candidate for intrinsic topological superconductivity. Measurements indicate nodal gaps in the center of the Fermi arcs. We derive that anisotropic electron-phonon coupling on Weyl semimetal surfaces, combined with statically screened Coulomb repulsion, is a microscopic mechanism for this nodal pairing. The dominant solution of the linearized gap equation shows nodal gaps when the surface state bandwidth is comparable to the maximum phonon energy, as is the case in ${\mathrm{PtBi}}_2$. We further predict that, if the screening of Coulomb interaction on the surface is enhanced by Coulomb engineering, the superconducting gap becomes nodeless, and the critical temperature increases.

A sudden change in material properties creates a temporal interface and forces a propagating wave to change its frequency while preserving its wave number. In contrast to monoatomic lattices with a single-frequency–wave-number pair, polyatomic lattices support multiple frequencies for each wave number. More importantly, polyatomic lattices can host nontrivial topological characteristics. To date, experimental observations are limited to topologically trivial monoatomic phononic systems. Here, we utilize analytical, numerical, and experimental methods to examine polyatomic phononic lattices subject to temporal interfaces. In particular, we realize phononic lattices demonstrating single-frequency shift (i.e., mode conservation) and multifrequency splitting (i.e., mode conversion) following a temporal interface. Accordingly, we generalize temporal analogs of Snell’s law and Fresnel equations. Moreover, we utilize Bloch mode overlaps to obtain a phononic time lens and a classical analog of dynamic quantum phase transitions for phonons. Such overlap determines the probability of mode conversion or conservation after a temporal interface and, more importantly, can carry hidden topological characteristics. Our methodology paves the way for the use of temporal interfaces in probing phonon band topology and the realization of advanced acoustic devices.

In altermagnets, the magnon bands are anisotropically spin split in reciprocal space without relativistic or dipolar spin-spin interactions. In this Letter, we theoretically study magnons and phonons coupled by spin-lattice interaction in a two-dimensional square-lattice $d$-wave altermagnet. We show that phonon-chirality-selective magnon-phonon hybridization can be caused by interfacial Dzyaloshinskii-Moriya interaction leading to the emergence of hybrid quasiparticles that possess finite phonon angular momentum. These hybrid quasiparticles are called magnon polarons and consist of spin-polarized magnons and chiral phonons. Their phonon angular momentum texture follows the $d$-wave character of the magnon spin texture, opening up the possibility of phononic counterparts to the electronic response effects in altermagnets, such as a phonon angular momentum splitter effect, i.e., the generation of a transverse phonon angular momentum current induced by a temperature gradient—the bosonic analog of the spin-splitter effect.

We present experimental results of the flow of programmable robots through a bottleneck. With these agents, velocity and force can be decoupled—a unique feature allowing us to show that, in the absence of physical contact and pushing from behind, and despite the development of clogs, moving faster always improves the flow of discrete systems through bottlenecks. Conversely, the flow is reduced if the robots are allowed to push. This result indicates that the pressure build-up within the system is a necessary condition to observe the effect previously known as faster-is-slower, a generic phenomenon emerging in a variety of discrete systems flowing through a narrowing which we argue should rather be called stronger-is-slower.

Wigner negativity and genuine multipartite entanglement (GME) are key nonclassical resources that enable computational advantages and broader quantum-information tasks. In this Letter, we prove two theorems for multimode continuous-variable systems that relate these nonclassical resources. Both theorems show that sufficient Wigner negativity—either a sufficiently-large Wigner negativity volume along a suitably chosen two-dimensional slice, or a sufficiently large nonclassicality depth of the center-of-mass mode of a system—certifies the presence of GME. Moreover, violations of the latter inequality provide lower bounds of the trace distance to the set of non-GME states. Our results also provide sufficient conditions for generating GME by interfering a state with the vacuum through a multiport interferometer, complementing long-known necessary conditions. Beyond these fundamental connections, our methods have practical advantages for systems with native phase-space measurements: they require only measuring the Wigner function over a finite region, or measuring a finite number of characteristic function points. Such measurements are frequently performed with readouts common in circuit and cavity quantum electrodynamic systems, trapped ions and atoms, and circuit quantum acoustodynamic systems. As such, our GME criteria are readily implementable in these platforms.

We reveal a nontrivial crossover of subsystem fluctuations of quantum jumps in continuously monitored many-body systems, which have a trivial maximally mixed state as a steady-state density matrix. While the fluctuations exhibit the standard volume law $\propto L$ following Poissonian statistics for sufficiently weak measurement strength, anomalous yet universal scaling law $\propto L^{\alpha }$ ($\alpha \sim 2.7$ up to $L=20$) indicating super-Poissonian statistics appears for strong measurement strength. This drastically affects the precision of estimating the rate of quantum jumps: for strong (weak) measurement, the estimation uncertainty is enhanced (suppressed) as the system size increases. We demonstrate that the anomalous scaling of the subsystem fluctuation originates from an integrated many-body autocorrelation function and that the transient dynamics contributes to the scaling law rather than the Liouvillian gap. The measurement-induced crossover is accessed only from the postselection-free information obtained from the time and the position of quantum jumps and can be tested in ultracold atom experiments.

Programmability is a unifying paradigm for enacting families of quantum transformations via fixed processors and program states, with a fundamental role and broad impact in quantum computation and control. While there has been a shift from viewing open systems solely as a source of error to treating them as a computational resource, their programmability remains largely unexplored. In this Letter, we develop a framework that characterizes and quantifies the programmability of Lindbladian semigroups by combining physically implementable retrieval maps with time-varying program states. We identify quantum programmable classes enabled by symmetry and stochastic structures, including covariant semigroups and fully dissipative Pauli Lindbladians with finite program dimension. We further provide a necessary condition for physical programmability that rules out coherent generators and typical dissipators generating amplitude damping. For such nonphysically programmable cases, we construct quasisampling protocols with finite resources. Finally, we introduce an operational programming cost, defined via the number of samples required to program the Lindbladian, and establish its core structural properties. These results provide a notion of programming cost for Lindbladians, bridge programmable channel theory and open system dynamics, and yield symmetry-driven compression schemes and actionable resource estimates for the semigroup simulation and control in noisy quantum technologies.