Heralded storage of photons is crucial for advancing quantum networks. Previous realizations have primarily relied on single atoms strongly coupled to optical cavities. In this work, we present the experimental realization of heralded storage using a Rydberg superatom, a mesoscopic atomic ensemble operating in the strong blockade regime. In our approach, an input photon is initially stored in the superatom via electromagnetically induced transparency. Subsequently, a second photon is emitted conditioned on the success of the first photon’s storage. Because of the collectively enhanced interaction, both the storage and the emission of the herald photon can be rather efficient in principle. As a demonstration of this technique, we use it to entangle two remote Rydberg superatoms. This method obviates the need for an intermediate node, which is commonly employed in traditional interference-based remote entanglement schemes. Our results showcase the potential of performing cavity-QED-like experiments with Rydberg superatoms. This work opens pathways for numerous applications in quantum networks and linear optical quantum computing.

Polarized neutron scattering experiments reveal anisotropy of magnetic correlations in the candidate Kitaev material $\alpha \text{−}{\mathrm{RuCl}}_3$. The anisotropy of the inelastic response at the magnetic Bragg positions is opposite to the expectation for a simple Heisenberg model. Near the antiferromagnetic propagation vector, there are no low-energy transversal magnon modes and the response is always uniaxially polarized. These observations directly prove the fully anisotropic and bond-directional character of the magnetic interaction in $\alpha \text{−}{\mathrm{RuCl}}_3$. However, other findings disagree with a simple or strongly dominant Kitaev component.

Decay properties of the neutron-deficient Sg isotopes were studied at the gas-filled recoil separator TASCA at GSI, Darmstadt by using the ${}^{52}\mathrm{Cr}+{}^{206,208}\mathrm{Pb}$ reactions. We report on the discovery of the new isotope ${}^{257}\mathrm{Sg}$. Its ground state, tentatively assigned to have $9/2^{-}$[734] configuration, was observed to decay by both spontaneous fission and $\alpha$-particle emission with a half-life of ${12.6}_{-2.3}^{+3.7}\mathrm{ms}$. The alpha decay from this high-spin state was followed by fission of ${}^{253}\mathrm{Rf}$ after $11\mathrm{\mu }\mathrm{s}$. In ${}^{259}\mathrm{Sg}$, we observed strong evidence for the occurrence of a $K$-isomeric state for the first time in superheavy nuclei with 106 protons. The current experimental findings, discussed within the experimental systematics and theory, indicate that hitherto unseen features of the shell effect on the fission process may be found in the neutron-deficient superheavy nuclei.

The dynamics of edge-core coupling is critically important to the optimization of magnetically confined fusion plasmas. Since early proposals, there has been persistent speculation that inward propagation of turbulence from the boundary is a possible means to energize the edge-core coupling region. However, the detailed mechanism of this process has remained a mystery until recent experiments observed that regular, intense gradient relaxation events generated blob-void pairs very close to the last closed flux surface. Blobs ($\tilde{n}>0$) propagate outward and detach from the bulk plasma, while voids ($\tilde{n}<0$) propagate inward, and so stir the core plasma. Here, we demonstrate that this heretofore ignored process of void emission can drive a broad turbulent layer of width $\sim 100{\rho }_s$, for typical parameters. The mechanism is the Cherenkov emission of drift waves from inward-propagating voids. The model shows promise to resolve several questions surrounding the shortfall problem and the strong turbulence in the edge-core coupling region.

Nonlinearities in King plots (KP) of isotope shifts (IS) can reveal the existence of beyond-standard-model (BSM) interactions that couple electrons and neutrons. However, it is crucial to distinguish higher-order standard model (SM) effects from BSM physics. We measure the IS of the transitions ${{}^{3}P}_0\to {{}^{3}P}_1$ in ${\mathrm{Ca}}^{14+}$ and ${{}^{2}S}_{1/2}\to {}^2{D}_{5/2}$ in ${\mathrm{Ca}}^{+}$ with sub-Hz precision as well as the nuclear mass ratios with relative uncertainties below $4\times {10}^{-11}$ for the five stable, even isotopes of calcium (${}^{40,42,44,46,48}\mathrm{Ca}$). Combined, these measurements yield a calcium KP nonlinearity with a significance of $\sim {10}^3\sigma$. Precision calculations show that the nonlinearity cannot be fully accounted for by the expected largest higher-order SM effect, the second-order mass shift, and identify the little-studied nuclear polarization as the only remaining SM contribution that may be large enough to explain it. Despite the observed nonlinearity, we improve existing KP-based constraints on a hypothetical Yukawa interaction for most of the new boson masses between $10\mathrm{eV}/{\mathrm{c}}^2$ and ${10}^7\mathrm{eV}/{\mathrm{c}}^2$.

We report the structure of a modulated phase in the ferroelectric nematic material RM734 under cationic-polymer-coated planar confinement. This phase emerges continuously from the nematic phase upon cooling and transforms into the ferroelectric nematic phase via a first-order transition. Compelling optical evidence, including thickness-dependent periodicity, a sinusoidal variation of the orientation angle, and periodic variations in phase retardance and image intensity, demonstrates that this modulated phase is the theoretically predicted double splay nematic phase. In this phase, splay deformations alternate along two orthogonal directions oriented at 45° to the substrate surfaces, resulting in a maximum modulation wavelength twice the cell thickness. Our experiments with various ionic coatings reveal that only cationic polymer coatings effectively promote this phase configuration, highlighting the crucial role of electrical screening. These findings further provide insights into its distinctive topological defects within confined geometries.

Several small polycyclic aromatic hydrocarbons (PAHs) with closed-shell electronic structure have been identified in the cold, dark environment Taurus Molecular Cloud 1. We measure efficient radiative cooling through the combination of recurrent fluorescence (RF) and IR emission in the closed-shell indenyl cation (${\mathrm{C}}_9{\mathrm{H}}_7^{+}$), finding good agreement with a master equation model including molecular dynamics trajectories to describe internal-energy-dependent properties for RF. We find that ${\mathrm{C}}_9{\mathrm{H}}_7^{+}$ formed with up to $E_c=5.85\mathrm{eV}$ vibrational energy, which is $\approx 2\mathrm{eV}$ above the dissociation threshold, radiatively cool rather than dissociate. The efficient radiative stabilization dynamics are likely common to other closed-shell PAHs present in space, contributing to their abundance.

Two-dimensional Dirac semimetals feature flatband edge states but a zero Chern number, while Chern insulators support one-way edge states associated with a nonzero Chern number. Here, we demonstrate a two-dimensional photonic crystal combining the response of a semimetal and of a Chern insulator, termed a Chern semimetal. This photonic semimetal is characterized by a nonzero Chern number, simultaneously hosting both a flatband edge state and a one-way edge state. We experimentally realize such a photonic Chern semimetal using a gyromagnetic photonic crystal with programmable magnetic bias, tailoring its second-neighbor coupling within each sublattice. We also verify the ability to control over the light speed while preserving topological protection. Our findings open new avenues toward exploring topological phases and their applications across fermionic and bosonic systems, providing an exciting platform for nanophotonic applications and a playground for topological physics discoveries.

Indentation tests are classical tools to determine material properties. For biological samples such as cysts of cells, however, the observed force-displacement relation cannot be expected to follow predictions for simple materials. Here, by solving the Pogorelov problem of a point force indenting an elastic shell for a purely nonlinear material, we discover that complex material behavior can even give rise to new scaling exponents in this force-displacement relation. In finite-element simulations, we show that these exponents are surprisingly robust, persisting even for thick shells indented with a sphere. By scaling arguments, we generalize our results to pressurized and prestressed shells, uncovering additional new scaling exponents. We find these predicted scaling exponents in the force-displacement relation observed in cyst indentation experiments. Our results thus form the basis for inferring the mechanisms that set the mechanical properties of these biological materials.

We perform three-photon photoassociation to obtain high resolution spectra of ${}^{87}\mathrm{Rb}$ trilobite dimers for the principal quantum numbers $n=22$, 24, 25, 26, and 27. The large binding energy of the molecules in combination with a relative spectroscopic resolution of ${10}^{-4}$ provides a rigorous benchmark for existing theoretical models. A recently developed Green’s function framework, which circumvents the convergence issues that afflicted previous studies, is employed to theoretically reproduce the vibrational spectrum of the molecule with high accuracy. The relatively large molecular binding energy is primarily determined by the low-energy $S$-wave electron-atom scattering length, thereby allowing us to extract the ${}^3{S}_1$ scattering phase shift with unprecedented accuracy, at low-energy regimes inaccessible to free electrons.

Chiral and axial materials offer platforms for intriguing phenomena, such as cross-correlated responses and chirality-induced spin selectivity. However, quantifying the properties of such materials has generally been considered challenging. Here, we demonstrate that the spatial distribution of the electron chirality, represented by ${\mathrm{\Psi }}^{†}{\gamma }^5\mathrm{\Psi }$ with the four-component Dirac field $\mathrm{\Psi }$, characterizes the chirality and axiality of materials. Furthermore, we reveal that spin-derived electric polarization can serve as an effective indicator of material polarity. We present quantitative evaluations of electron chirality distribution and spin-derived electric polarization based on first-principles calculations. Additionally, we propose that electron chirality can be directly observed via circular dichroism in photoemission spectroscopy, which measures the difference between right- and left-handed circularly polarized light. Electron chirality and spin-derived electric polarization provide a new framework for quantifying chirality, axiality, and polarity in asymmetric materials, paving the way for the exploration of novel functional materials.

Waves propagating through weakly disordered smooth linear media undergo a universal phenomenon called branched flow. Branched flow has been observed and studied experimentally in various systems by considering coherent waves. Recent experiments have reported the observation of optical branched flow by using an incoherent light source, thus revealing the key role of coherent phase-sensitive effects in the development of incoherent branched flow. By considering the paraxial wave equation as a generic representative model, we elaborate a stochastic theory of both coherent and incoherent branched flow. We derive closed-form equations that determine the evolution of the intensity correlation function, as well as the value and the propagation distance of the maximum of the scintillation index, which characterize the dynamical formation of incoherent branched flow. We report accurate numerical simulations that are found in quantitative agreement with the theory without free parameters. Our theory highlights the important impact of coherence and interference on branched flow, thereby providing a framework for exploring branched flow in nonlinear media, in relation to the formation of freak waves in oceans.

The current experimental and theoretical values of the ionization energy of metastable ${}^4\mathrm{He}$ [$(1s)(2s){{}^{3}S}_1$] differ by $9\sigma$, which prevents the determination of the alpha-particle charge radius from spectroscopic measurements in ${}^4\mathrm{He}$. To help clarify the origin of this discrepancy, we report on a precision measurement of hyperfine-resolved transitions from the $(1s)(2s){{}^{3}S}_1$ metastable state of ${}^3\mathrm{He}$ to high $np$ Rydberg states converging on the $F^{+}=0$, 1 hyperfine levels of the ${}^3{\mathrm{He}}^{+}$ $(1s{)}^2{S}_{1/2}$ ground state. Rydberg-series extrapolation using multichannel quantum-defect theory (MQDT) enabled the determination of the ionization energy of the $(1s)(2s){{}^{3}S}_1$ state of ${}^3\mathrm{He}$ [$E_{\mathrm{I}}({}^3\mathrm{He})/h=1152788844.6154(77{)}_{\mathrm{stat}}(25{)}_{\mathrm{sys}}\mathrm{MHz}$] and of the corresponding isotopic shift [$(E_{\mathrm{I}}({}^4\mathrm{He})-E_{\mathrm{I}}({}^3\mathrm{He}))/h=53898.093(9)\mathrm{MHz}$]. The MQDT analysis also permitted the quantification of singlet-triplet mixing in the $np$ series induced by the hyperfine interaction. From the isotopic shift of the ionization energy of He, the difference $\delta r^2$ between the squared charge radii of the helion and alpha particles is determined to be $1.060(10){\mathrm{fm}}^2$.

We address the challenge of incorporating non-Markovian electronic friction effects in quantum-mechanical approximations of dynamical observables. A generalized Langevin equation is formulated for ring-polymer molecular dynamics rate calculations, which combines electronic friction with a description of nuclear quantum effects for adsorbates on metal surfaces. An efficient propagation algorithm is introduced that captures both the spatial dependence of friction strength and non-Markovian frictional memory. This framework is applied to a model of hydrogen diffusing on Cu(111) derived from ab initio density functional theory calculations, revealing significant alterations in rate constants and tunneling crossover temperatures due to non-Markovian effects. Our findings explain why previous classical molecular dynamics simulations with Markovian friction showed unexpectedly good agreement with experiment, highlighting the critical role of non-Markovian effects in first-principles atomistic simulations.

Quadratic quasinormal modes encode fundamental properties of black hole spacetimes. They are also one of the key ingredients of nonlinearities of general relativity in the ringdown stage of binary black hole coalescence. In this Letter, we classify all possible quadratic coupling channels of quasinormal modes for a generic Kerr black hole and use a frequency-domain pseudospectral code with hyperboloidal slicing to calculate these couplings. After accounting for all the channels in systems with reflection symmetry, our results become consistent with those extracted from numerical simulations and time-domain fits. This agreement provides a compelling example demonstrating the success of black hole second-order perturbation theory. We also explore potential applications of our calculations in future ringdown data analysis by carrying out a detectability survey for various quadratic modes. We find that a few of them are observationally relevant for third-generation ground-based detectors like Cosmic Explorer, as well as the spaceborne Laser Interferometer Space Antenna.

Supply networks are essential for modern production, yet their critical properties remain understudied. We present a stochastic model with random production capacities to analyze material flow to a root node, focusing on topology and buffer stocks. The critical demand, where unsatisfied demand diverges, is examined mostly through numerical simulations. Without stocks, minimal production dictates behavior, making topology irrelevant. With stocks, memory effects arise, making topology crucial. Increased local connectivity is beneficial: firms should favor broad, short supply chains over long, narrow ones.

Quantum key distribution (QKD) offers a secure means of communication based on the laws of quantum physics. Despite its remarkable advancements, the current reliance of QKD on attenuated coherent (laser) light sources has imposed a fundamental limit on the secure key rate (SKR) per channel use. This constraint stems from the scarcity of single-photon components within coherent light, inherently bounded by a maximum of $1/e$. Here, we report comprehensive demonstrations of single-photon-source-based high-rate QKD, surpassing the fundamental SKR limit imposed by the weak coherent light. By employing an on-demand, bright single-photon source with an efficiency of 0.71(2), coupled with narrow-bandwidth filtering and random polarization modulation, we demonstrated a field QKD trial over a 14.6(1.1) dB-loss free-space urban channel, achieving a SKR of $1.08\times {10}^{-3}\mathrm{bits}$ per pulse. This SKR surpasses the practical limit of weak coherent-light-based QKD by 79%. These findings unequivocally demonstrate the superior performance of single-photon sources over weak coherent light for QKD applications, marking a pivotal stride towards realizing a global quantum internet.

Valley Hall phases (VHPs) in electronic and classical wave systems have been extensively explored and brought fruitful wave manipulations and associated applications. However, the concept of VHPs is so far restricted to two-dimensional (2D) systems. VHPs in 3D platforms remain an open question, which is not a straightforward extension of theirs 2D counterparts. In this work, we generalize the 2D VHPs into the 3D case in phononic crystals, which are derived from a nodal-line semimetal. The variation of geometric parameters gives rise to band inversion and generates two distinct VHPs possessing a pair of valleys with opposite Berry curvature distributions in the Brillouin zone. Topological surface states protected by the 3-tuple valley Chern numbers emerge at the interface between two different VHPs. Thanks to the configuration of the equal-frequency contour, some intriguing surface wave propagations have been observed experimentally. At the corner surrounded by two VHPs, interestingly, circular propagation of the surface wave exhibits negative refraction to form a closed loop around the corner. Furthermore, 3D partition is demonstrated in a four-channel structure. The 3D VHPs will stimulate other exotic transports, such as 3D collimation and wave guiding, and provide new means for designing 3D acoustic devices.

We singled out the surface and bulk spin dynamics in magnetic hollow nanoparticles by means of nuclear magnetic resonance relaxometry. Experimental ${}^1\mathrm{H}\text{−}\mathrm{NMR}$-dispersion curves (NMR-D), measured across a wide frequency range (${10}^4\mathrm{Hz}<f<3\times {10}^8\mathrm{Hz}$), show the presence of a high-frequency contribution to the longitudinal relaxation rate, evidenced for the first time and ascribed to the surface spin dynamics. The nuclear longitudinal relaxation rates were successfully analyzed by means of a phenomenological model accounting for the two spin populations, i.e., surface and core spins. The fit of the longitudinal NMR-D data by means of this model allowed for the estimation of the hyperfine coupling constant of the surface spins, and of the superparamagnetic $1/{\tau }_N$ and surface-paramagnetic-like $1/{\tau }_C^{\mathrm{surf}}$ spin-spin correlation frequency, the last one being larger by more than 1 order of magnitude. These experimental results provide a substantial contribution to the basic knowledge of spin dynamics in nanoscale systems.

The Worthington jets from bursting bubbles at a gas-liquid interface can break up into small droplets, aerosolizing chemical and biological substances into the atmosphere and impacting both global climate and public health. Despite their importance in contaminant transport, the influence of adsorbed contaminants on bubble-bursting jet dynamics remains poorly understood. Here, we document how an immiscible compound contaminant layer impacts the jet radius, which deviates from the expected jetting dynamics produced by clean bubble bursting. We rationalize the deviation of the jet radius by characterizing the propagation of the capillary waves at the air-oil-water interface. We develop a linearized wave damping model based on the oil thickness profile and the wave dispersion, and we propose a revised Ohnesorge number with a scaling relation that captures the experimental results reasonably well. Our work not only advances the fundamental understanding of bubble bursting jets but also offers valuable insights for predicting bubble-mediated aerosol size distributions and transport of airborne contaminants in realistic environmental scenarios.