We develop a mean-field theory of the stability of fractional Chern insulators based on the dipole picture of composite fermions (CFs). We construct CFs by binding vortices to Bloch electrons and derive a CF single-particle Hamiltonian that describes a Hofstadter problem in the enlarged CF Hilbert space, with the trace-condition term emerging naturally in the small-$q$ limit as part of the CF Hamiltonian. Going beyond the small-$q$ limit, we apply our theory to twisted ${\mathrm{MoTe}}_2$ and calculate its CF band structures. The resulting CF phase diagram matches closely with that from exact diagonalization, and the projected many-body wave functions achieve exceptionally high overlaps with the latter. Our theory provides both a microscopic understanding and a computationally efficient tool for identifying fractional Chern insulators.

We consider unconventional magnets with and without spin-singlet $s$-wave superconductivity and demonstrate the emergence of spin triplet states due to light drives. In particular, we find that a high-frequency linearly polarized light drive induces a spin-triplet density in $d$-wave altermagnets which does not exist in the static regime and can directly reveal the strength of the altermagnetic field. In this high-frequency regime, we also show that linearly polarized light enables the formation of odd-frequency spin-triplet superconducting correlations possessing $d$-wave and $s$-wave parities, which can be controlled by the light drive and accessed by measuring the spin density. Moreover, for low-frequency linearly and circularly polarized light drives, we obtain that the types of superconducting correlations are broadened due to the presence of Floquet bands, enabling spin-triplet pairs in $d$- and $p$-wave unconventional magnets, which are absent in the static phase.

Traveling fronts ubiquitous in physics, chemistry, and biology are prone to transverse cellular deformations due to diffusive or convective instabilities. Here, we show both theoretically and experimentally that new patterns can be obtained if the destabilization is triggered around a front locked radially by advection. Specifically, angularly shifting sun-ray-like patterns can develop around an autocatalytic front frozen by radial advection. These patterns arise from a diffusive instability that occurs when the autocatalyst $X$ and the reactant $Y$ diffuse at different rates. The properties of these shining-star structures can be controlled by tuning the flow rate $Q$ and the ratio of diffusion coefficients $\delta$ as evidenced by linear stability analysis, nonlinear simulations, and experiments on the chlorite-tetrathionate reaction.

Supermassive black hole (SMBH) binary systems are an unavoidable outcome of galaxy mergers. Their dynamics encode valuable information about their formation and growth, the composition of their host galactic nuclei, the evolution of galaxies, and the nature of gravity. Many SMBH binaries with separations pc-kpc have been found, but closer (subparsec) binaries remain to be confirmed. Identifying these systems may elucidate how binaries evolve past the “final parsec” until gravitational radiation drives them to coalescence. Methods to discover and characterize SMBH binaries can shed light on these important questions and potentially open new multimessenger channels. Here we show that SMBH binaries in nonactive galactic nuclei can be identified and characterized by the gravitational lensing of individual bright stars, located behind them in the host galaxy. The rotation of “caustics”—regions where sources are hugely magnified due to the SMBH binary’s orbit and inspiral—leads to quasiperiodic lensing of starlight (QPLS). The extreme lensing magnification of individual bright stars produces a significant variation in the host galaxies’ luminosity; their lightcurve traces the orbit of the SMBH binary and its evolution, analogous to the waveforms recorded by gravitational-wave (GW) detectors. QPLS probes the population of sources observable by pulsar timing arrays and space detectors (LISA, TianQin), offering advance warning triggers for merging SMBHs for coincident or follow-up GW detections. SMBH population models predict 1–50 $[190–5000](n_{\star }/{\mathrm{pc}}^{-3})$ QPLS binaries with period less than 10[40] yr with comparable masses and redshift $z<0.3$, where $n_{\star }$ is the stellar number density. Additionally, stellar and orbital motion will lead to frequent instances of single or double flares caused by SMBHBs with longer periods. This novel signature can be searched for in a wealth of existing and upcoming time-domain photometric data: identifying quasiperiodic variability in galactic lightcurves will reveal an ensemble of binary systems and illuminate outstanding questions around them.

We investigate how material diffusion processes affect the temporal evolution of the radii of DNA droplets formed from DNA nanoparticles whose phase-separation ability can be enzymatically degraded. The droplets are immobilized so as to disallow Brownian coalescence, and their size is tracked using confocal fluorescent microscopy. Without enzymes, we observe very slow Ostwald ripening in rough agreement with the Lifshitz-Slyozov-Wagner theory. With enzymes, we observe a dynamic radius distribution in which time and radius decouple, leading to an unusual behavior in which the average radius remains constant despite the total droplet volume decreasing. Our Letter provides insights into the statistical dynamics of phase-separated droplets, with relevance to both biological condensates and materials applications.

By combining artificial intelligence and fluid physics, we discover a closed-form closure for 2D turbulence from small direct numerical simulation data. Large-eddy simulation with this closure is accurate and stable, reproducing direct numerical simulation statistics, including those of extremes. We also show that the new closure could be derived from a fourth-order truncated Taylor expansion. Prior analytical and artificial-intelligence-based work only found the second-order expansion, which led to unstable large-eddy simulation. The additional terms emerge only when interscale energy transfer is considered alongside standard reconstruction criterion in the sparse-equation discovery.

The construction of cavity quantum electrodynamic systems is pivotal for advancing the development of quantum emitters, yet it is fundamentally constrained by the trade-off between a cavity’s quality factor ($Q$) and its mode volume ($V$) in conventional cavities. This causes a bottleneck for single-photon sources when improving the key performance metrics of brightness, purity, and indistinguishability. Here, we overcome this limitation by invoking nonradiative states in the plasmonic metasurface that decouples $Q$ and $V$. Quasibound states in the continuum regulate electromagnetic field confinement in time ($Q$) while anapole states enable strong electromagnetic field confinement in space ($V$). This independent manipulation over $Q$ and $V$ allows us to separately control Purcell factor and cavity linewidth, leading to concurrent improvements of brightness and indistinguishability. Working at room temperature, single-photon emission from two-dimensional hexagonal boron nitride integrated with the plasmonic metasurface is raised by about 3 orders of magnitude. Furthermore, maximal chiral emission is also demonstrated via coordinated spatiotemporal regulation. Our findings pave the way for practical application of compact quantum emitters, and provide new insights into light-matter interaction.

We demonstrate that the machine learning of density functionals allows one to determine simultaneously the equilibrium chemical potential across simulation datasets of inhomogeneous classical fluids. Minimization of a loss function based on an Euler-Lagrange equation yields both the universal one-body direct correlation functional, which is represented locally by a neural network, as well as the system-specific unknown chemical potential values. The method can serve as an efficient alternative to conventional computational techniques of measuring the chemical potential. It also facilitates using canonical data from Brownian dynamics, molecular dynamics, or Monte Carlo simulations as a basis for constructing neural density functionals, which are fit for accurate multiscale prediction of soft matter systems in equilibrium.

The emergence of the arrow of time in quantum many-body systems stems from the inherent tendency of Hamiltonian evolution to scramble quantum information and increase entanglement. While, in principle, one might counteract this temporal directionality by engineering a perfectly inverted Hamiltonian to reverse entanglement growth, such a scenario is fundamentally unstable because even minor imperfections in the backward evolution can be exponentially amplified, a hallmark of quantum many-body chaos. Therefore, successfully reversing quantum many-body dynamics demands a deep understanding of the underlying structure of quantum information scrambling and chaotic dynamics. In this Letter, by using solid-state nuclear magnetic resonance on a macroscopic ensemble of randomly interacting spins, we measure the out-of-time-ordered correlator and validate key predictions of scramblon theory, a universal theoretical framework for information scrambling. Crucially, this theory enables us to isolate and mitigate errors in the out-of-time-ordered correlator caused by imperfections in the backward evolution. As a result, this protocol uncovers the anticipated exponential behavior of quantum many-body chaos and extracts the quantum Lyapunov exponent in a many-body experimental system for the first time. Our results push the fundamental limits of dynamical reversibility of complex quantum systems, with implications for quantum simulation and metrology.

The ambient-pressure superconductivity in ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$ thin films via compressive epitaxial strain provides a highly accessible platform for diverse characterization techniques, facilitating the studies of high-temperature superconductivity. Here, we systematically map the phase diagram and reveal the superconducting dome with an electron-hole crossover in compressively strained ${\mathrm{La}}_{3-x}{\mathrm{Sr}}_x{\mathrm{Ni}}_2{\mathrm{O}}_{7-\delta }$ thin films by simultaneously tuning Sr doping and oxygen content. The maximum transition temperature ($T_c$) coincides with an anomalous sign change in the Hall coefficient ($R_H$), reminiscent of electron-doped cuprates, which may signal a Fermi surface reconstruction. Beyond the superconducting dome, a $\ln 1/T$ insulating regime and a $T$-linear resistivity regime are also resolved, resembling behaviors observed in cuprates and infinite-layer nickelates. This work reveals a dome-shaped relationship between $T_c$ and $R_H$ and establishes a key framework for understanding unconventional superconductivity in nickelate systems.

Whether brain dynamics operate near a critical regime remains a central question in neuroscience, with potential implications for information processing and computational flexibility. However, conventional approaches are susceptible to artifacts introduced by temporal correlations, spatial dependencies, and subsampling, which can create the illusion of scaling in noncritical systems. Here we introduce an analytical and numerical framework centered on the covariance matrix and its spectrum, combined with a phenomenological renormalization group (PRG) approach, and extended to incorporate colored inputs, temporal and spatial correlations, and robust inference and control strategies for empirical data. Applying this framework to pooled resting-state fMRI, we find that collective brain activity is slightly subcritical yet close to criticality. The extracted exponents are robust and align with predictions from recurrent firing-rate models in the long-time correlation limit. Beyond these results, our Letter provides methodological tools for more reliable tests of criticality in neuroscience and complex systems.

Isomer depletion serves as a prerequisite for a variety of important applications. Several mechanisms are proposed to trigger the isomer depletion. In the previous work [Chiara et al., Nature (London) 554, 216 (2018).], isomer depletion with an exceptionally high probability in ${}^{93m}\mathrm{Mo}$ was reported and attributed to nuclear excitation by electron capture (NEEC). However, contradictory probability values were subsequently reported from both experimental and theoretical aspects. This Letter reports a new and more precise measurement of the isomer depletion of high-energy ${}^{93m}\mathrm{Mo}$ ions during the slowing-down processes in lead and carbon foils via a low-background beam-based experimental approach. By employing a purified isomer beam, the depletion probabilities are determined to be $2.0(2)\times {10}^{-5}$ in lead and $4.7(13)\times {10}^{-6}$ in carbon, agreeing well with the inelastic nuclear scattering calculations. We conclude that the observed isomer depletion in ${}^{93m}\mathrm{Mo}$ arises from inelastic nuclear scattering rather than the previously proposed NEEC mechanism.

Solitons are the cornerstone of nonlinear physics. The integrability of nonlinear equations is the basis of this universal concept. However, most multidimensional systems lack integrability, a fundamental limitation that challenges the existence of solitons in high dimensions. A remarkable exception would be the lump soliton, a two-dimensional solution of the Kadomtsev-Petviashvili (KP) equation with the unique property of propagating unperturbed in three-dimensional space. Due to the difficulty of implementing the KP dynamics in any physical system, lump solitons have never been observed. Here, we report the first experimental observation of the lump soliton. The lump is realized in nonlinear optics, in a photorefractive crystal under the action of paraxial diffraction and defocusing nonlinearity, ruled by the $(2+1)\mathrm{D}$ nonlinear Schrödinger (NLS) equation. We tailor the input field shape and the nonlinearity to realize the hydrodynamic KP integrable regime of the NLS equation. The lump emerges as a self-localized wave that propagates unaltered with a transverse velocity. We confirm its integrable nature by reporting, for the first time, the elastic collision of lumps in two dimensions. As the first experimental evidence of integrable solitons in high dimensions, our observation paves the way for a new era in the study of nonlinear systems.

An acoustic standing wave acts as a lattice of evenly spaced potential energy wells for subwavelength-scale objects. Trapped particles interact with each other by exchanging waves that they scatter from the standing wave. Unless the particles have identical scattering properties, their wave-mediated interactions are nonreciprocal. Pairs of particles can use this nonreciprocity to harvest energy from the wave to sustain steady-state oscillations despite viscous drag and the absence of periodic driving. We show, in theory and experiment, that a minimal system composed of two acoustically levitated particles can access four distinct dynamical states, two of which are emergently active steady states. Under some circumstances, these emergently active steady states break spatiotemporal symmetry and therefore constitute a classical time crystal.

Landau quantization of two-dimensional free electrons and massless Dirac fermions plays a key role underlying many quantum phenomena in condensed matter physics. It usually requires the magnetic field, which arranges the charge carriers associated with the harmonic oscillation on a ladder of discrete Landau levels with a dissipationless edge state. Nevertheless, the presence of intrinsic dissipation and absence of a pseudomagnetic field in thermal diffusion precludes the observation of Landau quantization. Here, we report a recipe of creating a synthetic gauge serving as a pseudomagnetic field and achieve Landau quantization on real- and imaginary-valued spectra, on both of which complex pseudo-Landau levels are identified as isometric ladders. We experimentally observe the macroscopic quantum thermal Hall-like effect induced by dissipation, which is distinguished by a plateaulike effective thermal resistance. Our findings open up a unique paradigm for manipulating heat transfer and create an insightful platform for exploring dissipative non-Hermitian physics.

The majority of superconductors have more than one Fermi surface, on which the electrons pair below the critical temperature, yet their behavior can be well described by a single-band Bardeen-Cooper-Schrieffer theory. This is mostly due to interband scattering, especially in superconductors in the dirty limit, rigidly linking the pairing amplitude of the bands. This has limited experimental studies of the complex physics of multiband superconductivity. Here, we utilize the fact that elementary Pb—as a clean limit system—has two Fermi surfaces that are only weakly coupled by interband scattering, allowing the formation of two separate condensates. By studying stacking fault tetrahedra with a millikelvin scanning tunneling microscope, we show how to locally tune interband coupling ranging from weak to strong coupling and modify the superconducting order parameters from two well separated gaps to one merged gap around defects. The experiments critically test the theory of multiband superconductors and give a route to access a wide range of predicted quantum effects in these systems.

We introduce the concept of purely electronic chirality (PEC), which arises in the absence of structural chirality. In condensed matter physics and chemistry, chirality has conventionally been understood as a mirror-image asymmetry in crystal or molecular structures. We demonstrate that certain electronic orders exhibit chirality-related properties without atomic displacement. Specifically, we investigate quadrupole orders to realize such purely electronic chirality with handedness that can be tuned by magnetic fields. As a representative example, we analyze a model featuring 120° antiferro quadrupole orders on a distorted kagome lattice, predicting various chirality-related responses in the nonmagnetic ordered phase of URhSn. Furthermore, as a phonon analog, chiral phonons can emerge in achiral crystals through coupling with the PEC order. Our results provide a distinct origin of chirality and a fundamental basis for exploring the interplay between electronic and structural chirality.

We report a systematic and accurate approach for deriving the bulk free energy surface (FES), a function of temperature, polarization, and strain, from the first-principles density functional theory (DFT) of proper ferroelectrics. The core of our approach is the metadynamics algorithm that extracts the polarization dependence of the FES from all-atom molecular dynamics simulations without an a priori ansatz. The rest of the FES is derived from the metadynamics trajectories that span the relevant phase space. We demonstrate our approach in the case of lead titanate. The errors across the phase transition, due to DFT numerics, all-atom molecular dynamics, and free energy evaluation by enhanced sampling, can be systematically controlled and are of the order of $1\mathrm{meV}/\mathrm{atom}$. The accuracy of the resulting ab initio FES is only limited by the adopted functional approximation of DFT.

Magic numbers lie at the heart of nuclear structure, reflecting enhanced stability in nuclei with closed shells. While the emergence of magic numbers beyond 20 is commonly attributed to strong spin-orbit coupling, the microscopic origin of the spin-orbit potential remains elusive, owing to its dependence on the resolution scale and renormalization scheme of nuclear forces. Here, we investigate the evolution of nuclear shell structure with varying momentum resolution in nuclear interactions derived from chiral effective field theory, using the similarity renormalization group to link different scales. We uncover a novel transition from spin symmetry to pseudospin symmetry as the resolution scale decreases, during which magic numbers emerge naturally. A similar pattern is found in calculations using relativistic one-boson-exchange potentials, underscoring the robustness of the phenomenon. This establishes a direct connection between realistic nuclear forces with a high resolution scale and effective nuclear forces at coarse-grained scales, offering a first-principles explanation for the origin of magic numbers and pseudospin symmetry in nuclear shell structure and new insights into the structure of exotic nuclei far from stability.

Single-electron tunneling in mesoscopic superconducting islands has demonstrated a parity-modulated Coulomb blockade periodicity for decades. Yet, the quasiparticle dynamics mediating the interplay between Cooper-pair condensate coherence and charging energy remains poorly understood. Here, we uncover a new type of superconducting parity effect in a Coulomb blockade system comprising nano-sized Pb islands, investigated via low-temperature scanning tunneling spectroscopy. Our spectroscopic measurements demonstrate parity-dependent Coulomb gaps near the Fermi energy, associated with equidistant Coulomb peaks at higher energies. The parity dependence is distinct from the conventional even-odd Coulomb peak alternations and is validated through a parity transition of a Coulomb charge ring. As corroborated by theoretical simulations, we dub such intriguing phenomenon as the “dynamical” superconducting parity effect, which originates from an emergent tunneling channel facilitated by electron-hole conversion processes, dynamically coupled to Cooper-pair condensation. Our observations underscore the essential role of quasiparticle-mediated Cooper-pair formation in Coulomb blockade transport.