We present the first lattice QCD determination of the electromagnetic form factors of the exotic tetraquark $T_{bb}(bb\overline{u}\overline{d})$ with quantum numbers $I(J^P)=0(1^{+})$. The extracted form factors encode information about its internal structure, including the charge distribution and the magnetic dipole moments, determined separately for the light and heavy quarks. Our results provide evidence in favor of it being a bound state consisting of a compact heavy diquark $[bb]$ in a color-antitriplet with spin one and a light antidiquark $[\overline{u}\overline{d}]$ in a color-triplet with spin zero. The charge radius of $T_{bb}$ is found to be significantly smaller than the combined charge radii of $B$ and $B^{*}$ mesons. These two comprise the lowest-lying threshold $B{B}^{*}$ in the channel that we are considering, and their electric charge form factors are also determined. The computations were performed on a single ensemble, generated by the Coordinated Lattice Simulations effort, with $N_f=2+1$ dynamical quarks and a lattice spacing of approximately $a\approx 0.064\mathrm{fm}$ at the pion mass $m_{\pi }\approx 290\mathrm{MeV}$.

We present a mechanism for self-induced Floquet states involving acoustic and optical modes in synthetic antiferromagnets. By driving optical modes off-resonantly with radio frequency fields in the canted antiferromagnetic state, limit cycles arising from the predator-prey dynamics of the acoustic and optical mode populations can appear. The cyclic growth and decay of these mode populations induce a time-periodic modulation of the canted state, which subsequently generates Floquet states. These states appear as a rich frequency comb in the power spectrum of magnetization oscillations.

We demonstrate that the slot between parallel metal gates placed above a two-dimensional electron system (2DES) forms a plasmonic cavity with unconventional mode quantization. The resonant plasmon modes are excited when the slot width $L$ and the plasmon wavelength $\lambda$ satisfy the condition $L=\lambda /8+n\times \lambda /2$, where $n=0,1,2\dots$. The lowest resonance occurs at a surprisingly small cavity size, specifically one eighth of the plasmon wavelength, which contrasts with the conventional half-wavelength Fabry-Perot cavities in optics. This unique quantization rule arises from a nontrivial phase shift of $-\pi /4$ acquired by the 2D plasmon upon reflection from the edge of the gate. The slot plasmon modes exhibit weak decay into the gated 2DES region, with the decay rate being proportional to the square root of the separation between the gate and the 2DES. The absorption cross section by such slots reaches $\sim 50\%$ of the fundamental dipole limit without any matching strategies and is facilitated by field enhancement at the metal edges.

Quantum correlations in Bell and prepare-and-measure experiments are central resources for probing nonclassicality and enabling device-based quantum information protocols. In the absence of shared public randomness (i.e., without run-to-run mixing), even qubit correlation sets are typically nonconvex, making standard convex characterizations inadequate. Here we derive qubit-specific constraints from uncertainty relations, yielding a state-independent consistency test for observed statistics in both prepare-and-measure and Bell scenarios. The test captures explicit nonconvex boundaries in representative correlation families and enables correlation-based device inference by constraining (and sometimes uniquely determining) unitary-invariant measurement parameters even away from extreme points. Moreover, incorporating the inferred qubit constraints as additional conditions in a moment-matrix relaxation strengthens separability tests and can certify entanglement even for Bell-local correlations within the independent-device model. These tools provide a practical route to characterize and leverage low-dimensional quantum devices, including certification, randomness generation, and entanglement verification.

A major challenge in extracting information from current and upcoming surveys of cosmological large-scale structure (LSS) is the limited availability of computationally expensive high-fidelity simulations. We introduce calibrated neural quantile estimation, a new simulation-based inference (SBI) method that leverages a large number of approximate simulations for training and a small number of high-fidelity simulations for calibration. This approach guarantees an unbiased posterior regardless of approximate simulation accuracy, while achieving near-optimal constraining power when the approximate simulations are reasonably accurate. As a proof of concept, we demonstrate that cosmological parameters can be inferred at field level from projected 2-dimensional dark matter density maps up to $k_{\max }\sim 1.5h/\mathrm{Mpc}$ at $z=0$ by training on $\sim {10}^4$ particle-mesh simulations with transfer function correction and calibrating with $\sim {10}^2$ particle-particle (PP) simulations. The calibrated posteriors closely match those obtained by directly training on $\sim {10}^4$ expensive PP simulations, but at a fraction of the computational cost. Our method offers a practical and scalable framework for SBI of cosmological LSS, enabling precise inference across vast volumes and down to small scales.

Spacetime can undergo complex nonlinear evolution, as governed by the Einstein field equations, and a central challenge is to understand the geometric structures that arise, persist, and interact throughout its evolution. Using a formulation of Einstein equations that parallels nonlinear electrodynamics of continuous media, we show that general relativity admits gravitational field connections—two-surfaces and associated field lines whose connectivity is maintained by the spacetime dynamics. This gravitational frozen-in behavior is enabled by an ideal Ohm-type condition for the gravitational field. We further show that the same framework naturally leads to a conserved “gravitational magnetic” flux. A conserved gravitational helicity also emerges, with a clear topological interpretation in terms of gravitational field-line structures. These results identify well-defined topological constraints on admissible spacetime evolution and provide an organizing principle underlying the nonlinear dynamics of spacetime.

We report the first measurement of the semileptonic decay $D_s^{+}\to K^0{\mu }^{+}{\nu }_{\mu }$, using a sample of $e^{+}{e}^{-}$ annihilation data corresponding to an integrated luminosity of $7.33{\mathrm{fb}}^{-1}$ collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector at the BEPCII collider. The branching fraction of the decay is measured to be $\mathcal{B}(D_s^{+}\to K^0{\mu }^{+}{\nu }_{\mu })=(2.89\pm 0.27_{\mathrm{stat}}\pm 0.12_{\mathrm{syst}})\times {10}^{-3}$, where the first uncertainty is statistical and the second is systematic. Based on a simultaneous fit to the partial decay rates in $q^2$ intervals measured in $D_s^{+}\to K^0{\mu }^{+}{\nu }_{\mu }$ and $D_s^{+}\to K^0{e}^{+}{\nu }_e$ decays, the product value of the form factor $f_{+}^{K^0}(0)$ and the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cd}|$ is measured to be $f_{+}^{K^0}(0)|V_{cd}|=0.140\pm 0.008_{\mathrm{stat}}\pm 0.003_{\mathrm{syst}}$, which is the most precise determination to date. In addition, lepton flavor universality is tested for the first time with $D_s^{+}\to K^0{\ell }^{+}{\nu }_{\ell }$ decays in full and separate $q^2$ intervals. No violation is found.

Conventional femtosecond coherent laser spectroscopy predominantly focuses on the temporal phase coherence through time- or frequency-resolved methods. In this Letter, we suggest an alternative experimental framework based on spatial phase coherence. The intrinsic spectral dispersion of wave vectors in femtosecond pulses and sample dimensions exceeding the laser wavelength creates a compelling basis to establish spatial phase coherence as a novel approach to femtosecond laser spectroscopy. Using rotational Raman coherence in air as a case study, we analyze the transverse spatial distribution of the third-order signal generated by the rotational wave packet. Our findings reveal apparent temporal shifts and distortions in time-resolved signals that arise in conventional measurements lacking sensitivity to spatial phase coherence. Moreover, we demonstrate that spatial phase coherence can serve as a useful tool for thermometric applications, showcasing its sensitivity to temperature variations. These discoveries open new avenues in femtosecond laser spectroscopy, including an alternative single-shot detection scheme, a new form of Raman coherence imaging, and molecular species quantification during overlapping fractional revivals.

The Landau theory of superfluidity associates the low-temperature flow of the normal component with the phonon wind. This picture does not apply to superfluids in which Galilean invariance is broken either by disorder, porous media, or lattice potential, and the phonon wind is no longer solely responsible for depletion of the superfluid component. Based on Popov’s hydrodynamic action with anharmonic terms, we present a general theory for low-temperature ($T$) dependence of the superfluid stiffness, which reproduces the Landau result as a special case when several parameters of the hydrodynamic action are fixed by Galilean invariance. We validate our theory with numerical simulations of interacting lattice bosons. In a broader context, our approach reveals universal low-temperature thermodynamics of superfluids with an intrinsic connection between finite-$T$ and finite-size ($L$) effects implying universal scaling, $T^{d+1}$ and $1/L^{d+1}$, respectively, for a large class of thermodynamic quantities. We discuss the experimental detection of this law, and compare our prediction to the existing literature.

The three-dimensional $S=\frac{1}{2}$ system ${\mathrm{Y}}_3{\mathrm{Cu}}_2{\mathrm{Sb}}_3{\mathrm{O}}_{14}$ consists of two inequivalent ${\mathrm{Cu}}^{2+}$ sites, each forming an edge shared triangular lattice. Our magnetic susceptibility $\chi (T)$, specific heat $C_p(T)$, ${}^{89}\mathrm{Y}$ nuclear magnetic resonance (NMR), muon spin relaxation ($\mathrm{\mu }\mathrm{SR}$), and electron spin resonance (ESR) measurements on this system confirm the absence of any long-range magnetic ordering and the persistence of spin dynamics down to 0.077 K. In ${}^{89}\mathrm{Y}$ NMR, we find an anomaly at about 120 K, which we suggest arises from a fraction of the spins condensing into a singlet (a valence bond solid, or VBS) state. A plateau in the muon relaxation rate is observed between 60 K and 10 K (signifying the VBS state from a fraction of the spins) followed by an increase and another plateau below about 1 K (presumably signifying the quantum spin liquid state from all the spins). Our density functional theory calculations find a dominant antiferromagnetic interaction along the body diagonal with inequivalent Cu(1) and Cu(2) ions alternately occupying the corners of the cube. All other near-neighbor interactions between the Cu ions are also found to be antiferromagnetic and are thought to drive the frustration.

The bulk-boundary correspondence (BBC), a cornerstone of topological physics that links bulk topology to boundary response, has long been established within the framework of line-gap topology. Recently, the BBC concept has been extended to non-Hermitian point gaps, addressing a crucial gap in our understanding of topological phases. Here, we report the first observation of higher-dimensional point-gap BBC using our versatile acoustic platform. We implement a compact two-dimensional point-gap topological insulator characterized by a nontrivial open-bulk Chern number, whose spectrum maps intuitively onto a momentum-resolved Su-Schrieffer-Heeger model. Experimentally, we directly visualize the iconic point-gap spectrum characteristic via a mixed-dimensional acoustic setup (one real-space, one synthetic-momentum). Most notably, using two real two-dimensional samples with distinct boundary conditions, we observe topological edge states and the bipolar non-Hermitian skin effect, respectively. Together, these complementary observations constitute decisive evidence for the point-gap BBC and complete a crucial missing pillar in non-Hermitian topological physics.

We demonstrate that the chiral ${\mathbb{Z}}_p$ toric code—the quintessential model of topological order—hosts additional, emergent topological phases when perturbed: descendant fractional quantum Hall-like states, which we term Hall-on-Toric. These hierarchical states feature fractionalized ${\mathbb{Z}}_p$ charges and increased topological ground-state degeneracy. The Hall-on-Toric phases appear in the vicinity of the transitions between deconfined ${\mathbb{Z}}_p$ phases with different background charge per unit cell, in a fixed nontrivial flux background. We confirm their existence through extensive infinite density matrix renormalization group (iDMRG) simulations, analyzing the topological entanglement entropy, entanglement spectra, and a generalized Hall conductance. Remarkably, the Hall-on-Toric states remain robust even in the absence of $U(1)$ symmetry. Our findings reinforce the foundational interpretation of star and plaquette defects as magnetic and electric excitations, and reveal that this perspective extends to a much deeper level.

Ferrons are a type of quasiparticle corresponding to elementary excitations of the ferroelectric order. Analogously to how magnons modulate and transport magnetization, ferrons modulate and transport electric polarization. Here, we introduce multiferrons as elementary excitations with both electric and magnetic character. Multiferrons lead to a tilt and elliptical precession of the polarization and at the same time create a magnetization through the mechanism of dynamical multiferroicity. Using first-principles calculations for ${\mathrm{LiNbO}}_3$, we show that the electric polarization of multiferrons is perpendicular to the equilibrium ferroelectric polarization, whereas the magnetization is parallel to it. Our calculations further demonstrate that multiferrons carry net electric and magnetic quadrupole and octupole moments, which we term multipolons. These multipolons could couple to internal multipolar degrees of freedom, for example in altermagnets, or to external probes such as neutrons, leading to potentially experimentally observable phenomena following coherent or thermal excitation of multiferrons.

Uncovering the underlying complex network structure with high-order topologies from observational data is a fundamental challenge across diverse domains. Can we provide a versatile and precise approach for inferring full-order structure solely from node states? To address this issue, we propose a data-driven likelihood optimization framework for reconstructing the underlying topological structures. Our approach captures state transition relationships in binary time series generated by Markovian dynamics and employs the difference of convex algorithm to efficiently handle the optimization problem of full-order reconstruction. Experiments demonstrate that our approach excels in reconstructing a full-order simplicial network and achieves high accuracy across different experimental conditions, highlighting its potential to uncover complex interactions.

The accurate computation of low-energy spectra of strongly correlated quantum many-body systems, typically accessed via Green’s functions, is a long-standing problem posing enormous challenges to numerical methods. When the spectral decomposition is obtained from Fourier transforming a time series, the Nyquist-Shannon theorem limits the frequency resolution $\mathrm{\Delta }\omega$ according to the numerically accessible time domain size $T$ via $\mathrm{\Delta }\omega =2\pi /T$. In tensor network methods, increasing the domain size is exponentially hard due to the ubiquitous spread of correlations, limiting the frequency resolution and thereby restricting this ansatz class mostly to one-dimensional systems with small quasiparticle velocities. Here, we show how this limitation can be overcome by augmenting the time series with complex-time Krylov states. With the example of the critical $S-1/2$ Heisenberg model and light bipolarons in the two-dimensional Su-Schrieffer-Heeger model, we demonstrate the enormous improvements in accuracy, which can be achieved using this method.