Fractional quantum anomalous Hall effects realized in twisted bilayer ${\mathrm{MoTe}}_2$ and multilayer-graphene-based moiré heterostructures have captured a tremendous growth of interest. In this Letter, we propose that rhombohedral multilayer graphene coupled with an artificial kagome superlattice potential is a new platform to realize various fractional topological phases. Taking Bernal bilayer graphene as the simplest example, when it is placed on top of a prepatterned ${\mathrm{SiO}}_2$ substrate with periodic arrays of holes arranged into kagome lattice, the system would be subject to a tunable kagome superlattice potential once an electrostatic voltage drop between the top and bottom gates is applied. Then, we theoretically study the electronic band structures, topological properties, and quantum geometric properties of the Bloch states of Bernal bilayer graphene coupled with a realistic kagome superlattice potential, which is well benchmarked by transport measurements in the weak superlattice-potential regime. We find that the system may exhibit nearly ideal topological flat bands in a substantial region of the parameter space spanned by superlattice constant and electrostatic potential strength. When these topological flat bands are fractionally filled, exact diagonalization calculations suggest that the system would exhibit rich fractional topological phases at $1/3$, $2/3$, $2/5$, $3/5$, and $1/2$ fillings including both fractional Chern insulators and anomalous composite Fermi liquids under zero magnetic field. We also find that Halperin-type FCI states may emerge from the Chern-number-2 flat bands of trilayer graphene coupled with kagome superlattice potential.

Entangled photon sources (EPSs) are essential for quantum science and technology. Despite advancements in integrated optical platforms like thin-film lithium niobate, a scalable, high-performance, chip-scale EPS has remained elusive. We address this by demonstrating an electrically pumped, post-selection-free polarization EPS, achieved through hybrid integration of a distributed feedback laser with a thin-film lithium niobate chip, which integrates periodically poled lithium niobate waveguides, a beam splitter, and a polarization rotator combiner. By injecting current into the chip, we realize a high-performance EPS with a bandwidth of 73 nm and an entanglement pair generation rate of $4.5\times {10}^{10}\mathrm{pairs}/\mathrm{s}/\mathrm{mW}$. The polarization entanglement shows Bell-state fidelities above 96% across frequency-correlated modes. This compact, integrated EPS enables key applications, including high-speed quantum key distribution via wavelength division multiplexing, satellite-based quantum communication, and entanglement-based quantum metrology.

Recent developments in nanotechnology have enabled us to investigate the dynamic properties of van der Waals materials on a piezoelectric substrate. Here, we report on the dynamics of charge density wave in ${\mathrm{NbSe}}_3$ nanowires induced by surface acoustic waves (SAWs). Clear peaks in the differential resistance were observed at the resonant frequency of the SAW device. These peaks, known as “Shapiro steps,” are typically observed by applying an rf current to ${\mathrm{NbSe}}_3$ nanowires. We found that the Shapiro steps induced by SAWs show several features distinct from the ones induced by an rf current. Our detailed study revealed that a strain induced by SAWs plays a significant role in the Shapiro steps. The result clearly demonstrates the importance of the strain in charge density wave materials and paves the way for strain-induced device applications.

Elastic edge states, formed by interfacing different topological phases and appealing for various cutting-edge applications based on surface acoustic waves, often exhibit limits due to the lack of strong topological protection. Here, we overcome this difficulty by engineering a synthetic three-dimensional (3D) Dirac semimetal phase in a 2D elastic metamaterial. By tuning a geometry parameter, we drive topological transitions, which can be mapped into Dirac points in hybrid 3D, i.e., 2D plus a synthetic dimension. Gapless adiabatic spectral flows are found along the synthetic momentum loops when they encircle the Dirac points, emerging as the surface-arc states in hybrid 3D, that restores the bulk-edge correspondence in elastic systems. Experimental measurements confirm the bulk Dirac points, surface-arc states linking oppositely charged Dirac points, and the emergent gapless spectral flows. This Letter brings novel quantum-inspired phenomena to elastic systems and may inspire applications in topological control of mechanical waves and dynamics.

Universal power laws have been scrutinized in physics and beyond, and a long-standing debate exists in econophysics regarding the strict universality of the nonlinear price impact, commonly referred to as the square-root law (SRL). The SRL posits that the average price impact $I$ follows a power law with respect to transaction volume $Q$, such that $I(Q)\propto Q^{\delta }$ with $\delta \approx 1/2$. Some researchers argue that the exponent $\delta$ should be system specific, without universality. Conversely, others contend that $\delta$ should be exactly $1/2$ for all stocks across all countries, implying universality. However, resolving this debate requires high-precision measurements of $\delta$ with errors of around 0.1 across hundreds of stocks, which has been extremely challenging due to the scarcity of large microscopic datasets—those that enable tracking the trading behavior of all individual accounts. Here we conclusively support the universality hypothesis of the SRL by a complete survey of all trading accounts for all liquid stocks on the Tokyo Stock Exchange over eight years. Using this comprehensive microscopic dataset, we show that the exponent $\delta$ is equal to $1/2$ within statistical errors at both the individual stock level and the individual trader level. Additionally, we rejected two prominent models supporting the nonuniversality hypothesis: the Gabaix-Gopikrishnan-Plerou-Stanley and the Farmer-Gerig-Lillo-Waelbroeck models [Gabaix et al., Nature (London) 423, 267 (2003).; Q. J. Econ 121, 461 (2006).; Farmer et al., Quant. Finance 13, 1743 (2013)]. Our Letter provides exceptionally high-precision evidence for the universality hypothesis in social science and could prove useful in evaluating the price impact by large investors—an important topic even among practitioners.

The intricate competition between coexisting charge density waves (CDWs) can lead to rich phenomena, offering unique opportunities for phase manipulation through electromagnetic stimuli. Leveraging time-resolved x-ray diffraction, we demonstrate ultrafast control of a CDW in ${\mathrm{EuTe}}_4$ upon optical excitation. At low excitation intensities, the amplitude of one of the coexisting CDW orders increases at the expense of the competing CDW, whereas at high intensities, it exhibits a nonmonotonic temporal evolution characterized by both enhancement and reduction. This transient bidirectional controllability, tunable by adjusting photoexcitation intensity, arises from the interplay between optical quenching and phase-competition-induced enhancement. Our findings, supported by phenomenological time-dependent Ginzburg-Landau theory simulations, not only clarify the relationship between the two CDWs in ${\mathrm{EuTe}}_4$, but also highlight the versatility of optical control over order parameters enabled by phase competition.

The acoustic spin Hall effect (ASHE) enables the generation of spin current via lattice vibrations driven by surface acoustic waves (SAWs) in heavy metals. Here, we report its reciprocal counterpart—the inverse ASHE—in which an alternating (ac) spin current induces coherent lattice vibrations that propagate SAWs. By injecting ac spin currents into a heavy metal via interfacial spin backflow in a heavy metal-ferromagnet bilayer, we successfully detect such spin-current-induced nonlocal SAWs over distances up to $400\mathrm{\mu m}$ in an ${\mathrm{LiNbO}}_3$ substrate. As the previously unobserved reciprocal element in spin-lattice interactions, the inverse ASHE completes the framework of spin-phonon interconversion and uncovers a phonon-mediated pathway for long-range spin transport, even through nonmagnetic insulators.

Higher-order interactions provide a nuanced understanding of the relational structure of complex systems beyond traditional pairwise interactions. However, higher-order network analyses also incur more cumbersome interpretations and greater computational demands than their pairwise counterparts. Here, we present an information-theoretic framework for determining the extent to which a hypergraph representation of a networked system is structurally redundant and for identifying its most critical higher orders of interaction that allow us to remove these redundancies while preserving essential higher-order structure.

Communication in quantum networks suffers notoriously from photon loss. Resulting errors can be mitigated with a suitable measurement herald at the receiving node. However, waiting for a herald and communicating the measurement result back to the sender in a repeat-until-success strategy makes the protocol slow and prone to errors from false heralds such as detector dark counts. Here, we implement an entanglement herald at the sending node by employing a cascaded two-photon emission of a single atom into two optical fiber cavities: the polarization of one photon is entangled with the spin of the atom, and the second photon heralds entanglement generation. We show that heralding improves the atom-photon entanglement in-fiber efficiency and fidelity to 68(3)% and 87(2)%, respectively. We highlight the potential of our source for noise-limited long-distance quantum communication by extending the range for constant fidelity or, alternatively, increasing the fidelity for a given distance.

The $\mathrm{SNO}+$ Collaboration reports the first evidence of ${}^8\mathrm{B}$ solar neutrinos interacting on ${}^{13}\mathrm{C}$ nuclei. The charged current interaction proceeds through ${}^{13}\mathrm{C}+{\nu }_e{\to }^{13}\mathrm{N}+e^{-}$ which is followed, with a 10 minute half life, by ${}^{13}\mathrm{N}{\to }^{13}\mathrm{C}+e^{+}+{\nu }_e$. The detection strategy is based on the delayed coincidence between the electron and the positron. Evidence for the charged current signal is presented with a significance of $4.2\sigma$. Using the natural abundance of ${}^{13}\mathrm{C}$ present in the scintillator, 5.7 metric tons of ${}^{13}\mathrm{C}$ over 231 days of data were used in this analysis. The ${5.6}_{-2.3}^{+3.0}$ observed events in the data set are consistent with the expectation of ${4.7}_{-1.3}^{+0.6}$ events. This result is the second real-time measurement of CC interactions of ${}^8\mathrm{B}$ neutrinos with nuclei and constitutes the lowest energy observation of neutrino interactions on ${}^{13}\mathrm{C}$ generally. This enables the first direct measurement of the CC ${\nu }_e$ reaction to the ground state of ${}^{13}\mathrm{N}$, yielding an average cross section of $({16.1}_{-6.7}^{+8.5}(\mathrm{stat}\mathrm{.}{)}_{-2.7}^{+1.6}(\mathrm{syst}\mathrm{.}))\times {10}^{-43}{\mathrm{cm}}^2$ over the relevant ${}^8\mathrm{B}$ solar neutrino energies.

Magneto-optical trapping of molecules has thus far been restricted to molecules with ${}^2\mathrm{\Sigma }$ electronic ground states. These species are chemically reactive and only support a simple laser cooling scheme from their first excited rotational level. Here, we demonstrate a magneto-optical trap (MOT) of aluminum monofluoride (AlF), a deeply bound and intrinsically stable diatomic molecule with a ${}^1{\mathrm{\Sigma }}^{+}$ electronic ground state. The MOT operates on the strong $A^1\mathrm{\Pi }\leftarrow X^1{\mathrm{\Sigma }}^{+}$ transition near 227.5 nm, whose $Q(J)$ lines are all rotationally closed. We demonstrate a MOT of about $6\times {10}^4$ molecules for the $J=1$ level of AlF, more than ${10}^4$ molecules for $J=2$ and 3, and with no fundamental limit in going to higher rotational levels. Laser cooling and trapping of AlF is conceptually similar to the introduction of alkaline-earth atoms into cold atom physics, and is key to leveraging its spin-forbidden $a^3\mathrm{\Pi }\leftarrow X^1{\mathrm{\Sigma }}^{+}$ transition for precision spectroscopy and narrow-line cooling.

We use a quantum-logic spectroscopy (QLS) protocol to control the quantum state of a ${\mathrm{CaH}}^{+}$ ion in a cryogenic environment in which reduced thermal radiation extends rotational state lifetimes by an order of magnitude over those at room temperature. By repeatedly and adaptively probing the molecule, detecting the outcome of each probe via an atomic ion, and using a Bayesian update scheme to quantify confidence in the molecular state, we demonstrate state preparation and measurement (SPAM) in a single quantum state with infidelity less than $6\times {10}^{-3}$ and measure Rabi flopping between two states with greater than 99% contrast. The protocol does not require molecule-specific lasers and can be generalized, paving the way for high-fidelity quantum control of many other molecular ions.

The energy spectrum of cosmic rays above 2.5 EeV has been measured across the declination range $-90°\le \delta \le +44.8°$ using $\sim 310000$ events accrued at the Pierre Auger Observatory from an exposure of $(104900\pm 3100){\mathrm{km}}^2\mathrm{sr}\mathrm{yr}$. No significant variations of energy spectra with declination are observed, after allowing or not for nonuniformities across the sky arising from the well-established dipolar anisotropies in the arrival directions of ultrahigh-energy cosmic rays. The instep feature in the spectrum at $\simeq 10\mathrm{EeV}$ reported previously is now established at a significance above $5\sigma$. Within the statistics, the energy spectra are indistinguishable across declinations so disfavoring an origin for the instep from a few distinctive sources.

We investigate the intercalation of epoxy resin into a Weyl semimetal, ${\mathrm{WTe}}_2$, by using a scanning tunneling microscopy. We show that intercalant molecules have self-similar height variations with the silver-mean quasiperiodicity and also that they create phason and soliton defects to yield a mean coherence length of 15 sequential order. In addition, we unravel that weak quasiperiodic potentials imposed by the intercalation layer drive a ${\mathrm{WTe}}_2$ surface to have an enhanced conductance near the Fermi level while keeping its semimetal phase, providing a direct verification of theoretical prediction.

Edge states reflect the key physical properties yet are difficult to probe individually, particularly when several states are present at an edge. We present momentum resolved tunneling spectroscopy between a quantum well and a quantum wire to extract the dispersions of the quantum Hall edge states. Momentum and energy selective tunneling allows for separately addressing the different states even if they are spatially overlapping. This delivers the edge state velocities over broad ranges of magnetic field and density, in excellent agreement with a hard wall model. This technique provides a basis for future edge state selective spectroscopy on quantum materials.

The Landau-Lifshitz-Gilbert (LLG) equation has been the cornerstone of modeling the dynamics of localized spins, viewed as classical vectors of fixed length, within nonequilibrium magnets. When light is employed as the nonequilibrium drive, the LLG equation must be supplemented with additional terms that are usually conjectured using phenomenological arguments for direct optomagnetic coupling between localized spins and (real or effective) magnetic field of light. However, direct coupling of magnetic field to spins is $1/c$ smaller than coupling of light and electrons; or both magnetic and electric fields are too fast for slow classical spins to be able to follow them. Here, we displace the need for phenomenological arguments by rigorously deriving an extended LLG equation via Schwinger-Keldysh field theory (SKFT). Within such a theory, light interacts with itinerant electrons, and then spin current carried by them exerts spin-transfer torque onto localized spins, so that when photoexcited electrons are integrated out we arrive at a spin-only equation. Unlike the standard phenomenological LLG equation with local-in-time Gilbert damping, our extended one contains a non-Markovian memory kernel whose plot within the plane of its two time arguments exhibits fractal properties. By applying the SKFT-derived extended LLG equation, as our central result, to a light-driven ferromagnet as an example, we predict an optically induced magnetic inertia term. Its magnitude is governed by a spatially nonlocal and time-dependent prefactor, leading to the excitation of coherent magnons at sharp frequencies in and outside of the band of incoherent (or thermal) magnons.

We study the snapping instability of a spherical elastic shell induced by a viscous flow, the umbrella flipping problem when life is at low Reynolds numbers. We combine precision desktop-scale experiments, fluid-structure simulations, shell theory, fluid mechanics, and scaling analysis to determine the instability threshold as a function of the geometrical and material parameters of the system. Building on these findings, we devise a snapping-based valve that passively and abruptly alters the hydraulic resistance of a channel, offering robust flow control without active components. Beyond the application, our Letter presents what we believe to be a prototypical example of fluid-induced elastic instability in viscous flow, providing a foundation for future explorations in soft hydraulics and flow-responsive structures.

Ultrastable glasses (USGs) exhibit strikingly different properties from liquid-cooled normal glasses (NGs), yet their molecular dynamics remain poorly understood. Using $\beta$-detected NMR of implanted spin-polarized ${}^8{\mathrm{Li}}^{+}$, we directly track the depth and temperature dependence of the $\gamma$ relaxation—phenyl ring twisting—in highly monodisperse atactic styrene oligomers. Near the bulk glass transition temperature $T_{\mathrm{g}}$, USGs show much faster surface dynamics but slower bulk dynamics than an NG. Cooling below $T_{\mathrm{g}}$ reveals a sharp crossover at $T^{*}$, where surface dynamics vitrify on tens to hundreds of nanosecond timescales and become slower than in the bulk. The NG further displays two distinct $T^{*}$ values near the surface, pointing to heterogeneous local structure. Despite these differences, all dynamics obey entropy-enthalpy compensation, suggesting a common molecular mechanism. These results show that preparation and thermal history lock styrene oligomeric glasses into distinct regions of the potential energy landscape, giving rise to fundamentally different glassy dynamics.

A quantum memory is an essential element for quantum computation, quantum networks, and quantum metrology. Previously, a single-qubit quantum memory with a coherence time of about an hour has been realized in a dual-species setup where a coolant ion provides sympathetic cooling for a memory ion of a different species. However, the frequent random position hopping between the ions in the room-temperature trap limits the technique to be applicable only to single-qubit storage. Here, we report a multi-ion quantum memory in a cryogenic trap based on the dual-type scheme and demonstrate a coherence time above two hours for a qubit encoded in the decoherence-free subspace, i.e., two-ion entangled states, after correcting the dominant leakage error. Our scheme alleviates the necessity of an ultrastable frequency reference for the stored qubit, and it has a preferable scalability owing to the same mass of the metastable-state memory ions and the ground-state coolant ion.

Altermagnets have been identified as the third category of magnetic materials, exhibiting momentum-dependent spin splitting characterized by even powers of momentum. In this Letter, we show that when subjected to elliptically polarized light, these materials serve as an exemplary framework for the dynamic generation of topological bands featuring higher-order spin-orbit coupling (SOC). Notably, while the generated Zeeman field remains invariant to the particular altermagnetic ordering, the induced higher-order SOCs are related to the magnitude and symmetry of the altermagnetic order. Specifically, we show that an altermagnet exhibiting ${\mathbf{k}}^{2n}$-spin splitting can generate odd-in-$\mathbf{k}$ spin-orbit couplings up to ${\mathbf{k}}^{2n-1}$. In the limit of circularly polarized light, the only correction is $k^{2n-1}$, with all lower-order contributions being nullified. Interestingly, light-induced SOCs significantly impact the low-energy band topology, where their Chern numbers change by $\mathrm{\Delta }C=\pm 1$, 2, 3 for $d$, $g$, $i$-wave altermagnets. Finally, we find a critical field in which a persistent spin texture is realized, a highly desirable state with predicted infinite spin lifetime. Our Letter showcases light as a powerful, controllable tool for engineering complex and exciting phenomena in altermagnets.