The latent space approach to complex networks has revealed fundamental principles and symmetries, enabling geometric methods. However, the conditions under which network topology implies geometricity remain unclear. We provide a mathematical proof and empirical evidence showing that multiscale self-similarity in complex networks is a crucial factor of latent geometry. Using degree-thresholding renormalization, we prove that a general class of ensembles of random scale-free networks in Riemannian manifolds of constant curvature and of any dimension are self-similar when interactions are pairwise. Hence, both nonvanishing local clustering in the thermodynamic limit and self-similarity are required to imply geometricity. Our findings highlight that correlated links can lead to a finite clustering coefficient without self-similarity, and therefore without inherent latent geometry. The implications are significant for network mapping and ensemble equivalence between graphs and continuous spaces.

Using particle based simulation of a model glass former, we demonstrate a transition from brittle yielding to ductile yielding in amorphous solids by introducing quenched disorder in the form of randomly pinned particles. The well-annealed samples, which exhibit brittle yielding, undergo a transition to increasingly ductile yielding with increasing pinning concentrations while exhibiting an enhanced stress overshoot. Extensive finite size analysis is performed to demonstrate the critical nature of the transition at a finite pinning concentration and the various scaling exponents obtained are found to be in good agreement with the reported values for the random field Ising model universality class. Finally, we establish a connection between inherent disorder strength of amorphous solids that controls the nature of the yielding and quenched disorder strength due to particle pinning.

We apply the phenomenological renormalization group to resting-state fMRI time series of brain activity in a large population. By recursively coarse graining the data, we compute scaling exponents for the series variance, log probability of silence, and largest covariance eigenvalue. The scaling exponents clearly exhibit linear interdependencies in the form of scaling relations and inherent variability of values closely related to the structure of correlations of brain activity. The scaling relations between the exponents are derived analytically. We find a significant correlation of exponents with clinical (gray matter volume) and behavioral (cognitive performance) traits. Akin to scaling relations near critical points in thermodynamics, our results suggest that this interdependency is intrinsic to brain organization, and may also exist in other complex systems.

One can theoretically conceive of processes in which quantum operations are composed cyclically in a way that is incompatible with a well-defined causal order. Some of these processes can be realized within standard quantum temporal evolutions on systems that are delocalized in time. In this Letter, we introduce the “circuit (super)operator,” a tool that allows one to express how a (possibly cyclic) quantum circuit transforms under arbitrary changes of subsystem decompositions. This framework concisely captures the link between causally indefinite processes and their temporal realizations. We apply it to the quantum switch, a paradigmatic example of a causally indefinite process, and consider two distinct temporal realizations. These correspond to the “causal perspectives” or “causal reference frames” of the two parties involved, describing the process from their respective viewpoints. Surprisingly, we show that these causal perspectives cannot be related by a change of subsystem decomposition, i.e., they cannot be seen as two equivalent descriptions of the same process.

As a paraxial wave packet is reflected or refracted from a planar interface separating two material media, it experiences spatial and angular shifts of its center position with respect to predictions of the geometrical ray picture. These in-plane and out-of-plane beam shifts are known as Goos-Hänchen and Imbert-Fedorov shifts, respectively. We discover a universal link between the phase-space nonseparability of an incident wave packet of any degree of spatial coherence and the reflected beam shifts. We unveil coherence Goos-Hänchen and coherence Hall effects, absent in the fully coherent limit. While the former effect can trigger a pronounced enhancement of the spatial Goos-Hänchen shift, the latter enables control of the spatial Imbert-Fedorov shift, from complete cancellation at a certain incidence angle to dramatic enhancement of the shift to giant magnitudes for nearly incoherent incident wave packets. Our results are equally applicable to optical, x-ray, and neutron, as well as matter waves, and they showcase novel phenomena in wave-matter interactions.

Plasma-based acceleration linear collider designs consist of many plasma stages where a drive beam drives a wake that accelerates a witness beam. Misalignment between the drive and witness beams can lead to the hosing instability, large emittance growth, and difficulty colliding beams at the final focus. The extreme charge and small spot size of a linear collider class electron beam causes the plasma ions to collapse within their transit time, leading to nonlinear focusing forces. It is shown that drive-beam-induced ion motion can be used to eliminate witness beam hosing and realign it with the drive beam. Fully self-consistent qpad simulations of an initial plasma stage with quasiadiabatic plasma density ramps at the entrance and exit show it is possible to simultaneously match the witness beam in the presence of ion motion while eliminating its centroid offset, at the expense of $\sim 4\%$ emittance growth. The energy spread growth is limited to $<1\%$ and the energy transfer efficiency is 50%.

We propose twisted bilayers of certain group IV and IVB trigonal transition metal dichalcogenides (TMDs) ${\mathrm{MX}}_2$ ($\mathrm{M}=\mathrm{Zr}$, Hf, Sn and $\mathrm{X}=\mathrm{S}$, Se) as moiré materials. In monolayer form, these TMDs have conduction band minima near the three inequivalent Brillouin zone $M$ points and negligible spin-orbit coupling, implying six flavors of low-energy conduction band states. The flavor sectors decouple at the single-particle level and in twisted bilayers are accurately described by emergent moiré-periodic Hamiltonians that we derive from small-unit-cell density functional theory calculations. Because the valley-projected Hamiltonians have large valley-dependent mass anisotropies and are time-reversal invariant, spontaneous valley polarization is signaled in transport by anisotropy instead of by the anomalous Hall and magnetic circular dichroism signals commonly observed in graphene and $K$-valley TMD-based moiré multilayers.

Coupled lasers offer a promising approach to scaling the power output of photonic devices for applications demanding high frequency precision and beam coherence. However, maintaining coherence among lasers remains a fundamental challenge due to desynchronizing instabilities arising from time delay in the optical coupling. Here, we depart from the conventional notion that disorder is detrimental to synchronization and instead propose an interpretable mechanism through which heterogeneity in the laser parameters can be harnessed to promote synchronization. Our approach allows for stabilization of prespecified synchronous states that, while abundant, are often unstable in systems of identical lasers. The results show that stable synchronization enabling coherence can be frequently achieved by introducing intermediate levels of random mismatches in any of several laser constructive parameters. Our results establish a principled framework for enhancing coherence in large laser networks, offering a robust strategy for power scaling in photonic systems.

Observations of gravitational waves from binary black hole mergers, including the recent signals GW231123 and GW230529, have revealed multiple progenitor black holes in the so-called upper and lower mass gaps, respectively. It is generally assumed that massive stars cannot form black holes in the upper mass gap because pair instabilities in the late stage of stellar evolution disrupt the stars, whereas the lower mass gap refers to the gap between the maximum allowed neutron-star mass and the smallest black hole mass expected to form in supernova explosions. Here we explore a premature collapse scenario in which upper mass gap stars collapse and form black holes before they reach the late stage of stellar evolution. The mechanism for triggering a premature collapse is the capture of a smaller black hole, possibly primordial in nature. A similar capture scenario can occur to produce black holes in the lower mass gap. At least for massive stars, typical stellar rotation rates would likely result in rapidly rotating black holes in such a scenario, naturally explaining the rapid spins inferred from GW231123. Even though our estimates hinge on several parameters with rather large uncertainties, they suggest that, at least in galactic disks, the likelihood of such a capture is small for stars in the upper mass gap, but may lead to a significant population of black holes in the lower mass gap and, in fact, even below the lower mass gap.

With data collected in a dedicated energy scan from 2.3864 up to 3.0800 GeV, the BESIII Collaboration provides the first complete energy-dependent measurements of the $\mathrm{\Lambda }$ electromagnetic form factors in the timelike region. By combining double-tag and single-tag events from the $e^{+}{e}^{-}\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}\to p{\pi }^{-}\overline{p}{\pi }^{+}$ reaction, we achieve a complete decomposition of the spin structure of the reaction at five energy points, with high statistical and systematic precision. Our data reveal that while the modulus of the ratio between the electric and magnetic form factor, $R(q^2)=|G_E(q^2)/G_M(q^2)|$, remains fairly constant across the considered energy range, the relative phase $\mathrm{\Delta }\mathrm{\Phi }(q^2)={\mathrm{\Phi }}_E(q^2)-{\mathrm{\Phi }}_M(q^2)$ changes by more than 90° between 2.396 and 2.6544 GeV. Using a fit to our data based on dispersion relations, the complex form factor ratio is determined as a function of $q^2$, and the preferred solution has multiple zero-crossings in the complex plane. From the derivative of the ratio at $q^2=0$, the root-mean-squared charge radius of the $\mathrm{\Lambda }$ is obtained. The two most probable solutions yield a negative root-mean-squared charge radius, indicating an asymmetric charge distribution where the $ds$ quark pair lies close to the center of the $\mathrm{\Lambda }$ hyperon.

In this Letter, we present a robust method for generating custom-shaped, coherent hard x-ray pulses in regenerative amplifier free-electron lasers (RAFELs) using laser-induced energy modulation of the electron beam. A temporally shaped optical modulation imprints an optical-wavelength energy pattern on the beam, which interacts with the recirculated seed in the x-ray cavity to generate spectral sidebands. These sidebands lie outside the Bragg reflection bandwidth and are extracted as out-coupled radiation, while the seed is retained for continued amplification, enabling a novel mechanism for both output coupling and pulse shaping. This approach allows deterministic control over the spectral and temporal properties of the emitted x-rays, including multicolor generation, twin-pulse structures, pulse duration tuning, and complex temporal waveforms. Importantly, it does not require modification of the RAFEL cavity or optics and is fully compatible with high-repetition-rate operation, offering a practical pathway to deliver coherent, shaped, and on-demand x-ray pulses for advanced time-resolved and nonlinear x-ray science.

Chiral graviton modes are elusive excitations arising from the hidden quantum geometry of fractional quantum Hall states. It remains unclear, however, whether this picture extends to lattice models, where continuum translations are broken and additional quasiparticle decay channels arise. We present a framework in which we explicitly derive a field theory incorporating lattice chiral graviton operators within the paradigmatic bosonic Harper-Hofstadter model. Extensive numerical evidence suggests that chiral graviton modes persist away from the continuum and are well captured by the proposed lattice operators. We identify geometric quenches as a viable experimental probe, paving the way for the exploration of chiral graviton modes in near-term quantum simulation experiments.

The unusual magnetoelectric transport present in Weyl semimetals and 3D topological insula- tors can be compactly understood as manifestations of a background axion field, which itself is determined by the microscopic band structure. In the presence of correlations, an additional axion quasiparticle may emerge as the collective excitations on top of the mean background field. Such modes couple nonlinearly to electric and magnetic fields, giving rise to a dynamical magnetoelectric response. However, unambiguous identification of this collective axion mode is challenging due to its inherent nonlinear dynamics. Here, we propose an all-optical protocol that utilizes a pump-probe setup for verifying and characterizing the transient dynamics of axion fields in three-dimensional insulator systems. In particular, we show that nonlinear Raman processes induce dynamical oscillations of the axion field that depend on the geometry of the incident electromagnetic fields. These oscillations manifest in the polarization and magnetization of the material, hence, can be subsequently measured using time-resolved Kerr rotation spectroscopy. Our results open a pathway toward using multiphoton and quantum pair spectroscopies to identify new correlated phases of quantum matter.

Device-independent quantum key distribution (DIQKD) allows two distant parties to establish a secret key, based only on the observed Bell nonlocal distribution. It remains unclear, however, what the minimal resources for enabling DIQKD are and how to maximize the key rate from a given distribution. In the present Letter, we consider a scenario where several copies of a given quantum distribution are jointly processed via a local and classical wiring operation. We find that, under few assumptions, it is possible to activate device-independent key, that is, starting from a distribution that is useless in a DIQKD protocol, we obtain a positive asymptotic key rate by wiring several copies together. We coin this effect device-independent key activation. Our analysis focuses on the standard DIQKD protocol with one-way postprocessing, and we resort to semidefinite programming techniques for computing lower bounds on the key rate.

Axion dark matter can satisfy the conditions needed to account for all of the dark matter and solve the strong $CP$ problem. The Axion Dark Matter eXperiment (ADMX) is a direct dark matter search using a haloscope to convert axions to photons in an external magnetic field. Key to this conversion is the use of a microwave resonator that enhances the sensitivity at the frequency of interest. The ADMX experiment boosts its sensitivity using a dilution refrigerator and near quantum-limited amplifier to reduce the noise level in the experimental apparatus. In the most recent run, ADMX searched for axions between 1.10 and 1.31 GHz to extended Kim-Shifman-Vainshtein-Zakharov sensitivity. This Letter reports on the results of that run, as well as unique aspects of this experimental setup.

The study of extended $\gamma$-ray sources usually assumes symmetric diffusion of cosmic rays. However, recent observations of multiple sources near single pulsars and significant offsets between TeV halo centroids and their parent pulsars suggest that this assumption is overly simplistic. In this Letter, we demonstrate that asymmetric propagation of cosmic rays near their accelerators may create multiple TeV sources instead of a single symmetric source. This mechanism also explains the large offsets between TeV halo centroids and their parent pulsars. We demonstrate that several perplexing detected sources can be naturally interpreted without invoking additional invisible accelerators.