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.

The decay $B^{\pm }\to K_{\mathrm{S}}^0{\pi }^{\pm }$, with a $CP$ asymmetry expected to be close to zero in the standard model, is theoretically clean and sensitive to potential new physics. An analysis of the decays $B^{\pm }\to K_{\mathrm{S}}^0{\pi }^{\pm }$ and $B^{\pm }\to K_{\mathrm{S}}^0{K}^{\pm }$ is performed using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$. The $CP$ asymmetries are determined to be ${\mathcal{A}}^{CP}(B^{\pm }\to K_{\mathrm{S}}^0{\pi }^{\pm })=-0.028\pm 0.009\pm 0.009$ and ${\mathcal{A}}^{CP}(B^{\pm }\to K_{\mathrm{S}}^0{K}^{\pm })=0.118\pm 0.062\pm 0.031$, and the branching fraction ratio is measured to be $\mathcal{B}(B^{\pm }\to K_{\mathrm{S}}^0{K}^{\pm })/\mathcal{B}(B^{\pm }\to K_{\mathrm{S}}^0{\pi }^{\pm })=0.055\pm 0.004\pm 0.002$, where the first uncertainties are statistical and the second are systematic. These results are the most precise measurements of these quantities to date. A search for the rare decay $B_c^{\pm }\to K_{\mathrm{S}}^0{K}^{\pm }$ is also performed. No significant signal is observed, and the upper limit on the product of the branching fraction ratio $\mathcal{B}(B_c^{\pm }\to K_{\mathrm{S}}^0{K}^{\pm })/\mathcal{B}(B^{\pm }\to K_{\mathrm{S}}^0{\pi }^{\pm })$ and the fragmentation-fraction ratio $f_c/f_u$ is set to be 0.015 (0.016) at the 90% (95%) confidence level.

The continuous spectrum of double beta decay ($\beta \beta$) provides a sensitive probe to test the predictions of the standard model and to search for signatures of new physics beyond it. We present a comprehensive analysis of the ${}^{136}\mathrm{Xe}$ $\beta \beta$ spectrum utilizing $39.1\pm 0.7\mathrm{kg}·\mathrm{yr}$ of ${}^{136}\mathrm{Xe}$ exposure from the PandaX-4T experiment. The analysis yields the most precise measurement to date of the ${}^{136}\mathrm{Xe}$ two-neutrino double beta decay ($2\nu \beta \beta$) half-life, $(2.14\pm 0.05)\times {10}^{21}\mathrm{years}$, the uncertainty of which is reduced by a factor of 2 compared to our previous result. We measure the parameter ${\xi }_{31}^{2\nu }$, defined as the ratio between the subleading and leading components of the ${}^{136}\mathrm{Xe}$ $2\nu \beta \beta$ nuclear matrix element, to be ${0.59}_{-0.38}^{+0.41}$, which is consistent with theoretical predictions. We also search for Majoron-emitting modes of ${}^{136}\mathrm{Xe}$ $\beta \beta$, establishing the most stringent limit for the spectral index $n=7$.

The mechanical response of yield-stress materials below the yield point remains a subject of debate. Two of the most widely used constitutive models for these materials offer fundamentally conflicting views: one permits plastic flow at all stress levels, while the other assumes entirely recoverable viscoelasticity below yield. Using parallel superposition rheometry, we test the subyield behavior of a microgel and an emulsion. When residual slip effects are properly accounted for, both fluids exhibit bounded, periodic strain responses, offering compelling evidence that they do not flow in the studied regime. Our results indicate that the subyield regime is underpinned by nonlinear viscoelasticity and underscore the need for improved constitutive relations that capture such effects without treating yielding as a precursor for nonlinearity.

Multistable order parameters provide a natural means of encoding nonvolatile information in spatial domains, a concept that forms the foundation of magnetic memory devices. However, this stability inherently conflicts with the need to move information around the device for processing and readout. While in magnetic systems, domains can be transported using currents or external fields, mechanisms to robustly shuttle information-bearing domains across neutral systems are scarce. Here, we experimentally realize a topological boundary ratchet in an elastic metamaterial, where digital information is encoded in buckling domains and transported in a quantized manner via cyclic loading. The transport is topological in origin: neighboring domains act as different topological pumps for their Bogoliubov excitations, so their interface hosts topological boundary modes. Cyclic loading renders these modes unstable through interdomain pressure, which in turn drives the motion of the domain wall. We demonstrate that the direction of information propagation can be controlled through adjustable mechanical constraints on the buckling beams, and numerically investigate buckling-based domain-wall logic circuits in an elastic metamaterial network. The underlying tight-binding structure with low-order nonlinearities makes this approach a general pathway toward racetrack memories in neutral systems.

A central concept in quantum information processing is genuine multipartite entanglement (GME), a type of correlation beyond biseparability, that is, correlations that cannot be explained by statistical mixtures of partially separable states. GME is relevant for characterizing and benchmarking complex quantum systems, and it is an important resource for applications such as quantum communication. Remarkably, it has been found that GME can be activated from multiple copies of biseparable quantum states, which do not possess GME individually. Here, we experimentally demonstrate unambiguous evidence of such GME activation from two copies of a biseparable three-qubit state in a trapped-ion quantum processor. These results not only challenge notions of quantum resources but also highlight the potential of using multiple copies of quantum states to achieve tasks beyond the capabilities of the individual copies.

Manipulating the quantum noise of continuous-wave lasers through squeezing has reshaped optical interferometry. However, progress in optical frequency comb interferometry with pulsed squeezed sources has been limited, despite the role of frequency combs in ultraprecise optical metrology. Here, we introduce a new time-domain approach to characterizing squeezed femtosecond light pulses using dual-comb interferometry. Time-domain interferograms are generated via multiheterodyne beating between the modes of a Kerr soliton-squeezed frequency comb and a coherent state comb. The interferogram noise reveals phase-dependent squeezing and antisqueezing, dipping as much as $3.8\pm 0.2\mathrm{dB}$ below the shot noise level at alternating zero crossings. We model this nonstationary quantum noise as a periodic optical displacement of the squeezed comb by the coherent comb. These results support a route toward quantum-enhanced dual-comb timing applications and high-speed quantum state tomography with dual-comb interferometers.

The discrepancy between quantum distinguishability in Hilbert space and classical distinguishability in probability space is expressed by the gap between the quantum and classical Fisher information matrices (QFIM and CFIM, respectively). This intrinsic quantum obstruction is generally not saturable and plays a central role in both fundamental insights and practical applications in modern quantum physics. Here, we develop a geometrical framework for this gap by introducing the notion of the semiclassical geometric tensor (SCGT). We relate this quantity to the quantum geometric tensor (QGT), whose real part equals the QFIM. We prove the matrix inequality between QGT and SCGT, which sharpens the standard inequality between QFIM and CFIM and provides novel multiparameter information bounds: the real part of the SCGT reproduces the CFIM plus an additional nonnegative contribution capturing quantum obstruction. This further motivates a natural extension of the Berry phase to the semiclassical setting.

We provide a new perspective on the cosmological constant by exploring the background-independent Wheeler-DeWitt quantization of general relativity. The Chern-Simons-Kodama state of quantum gravity, a generalization of the Hartle-Hawking and Vilenkin states, has a striking structural similarity to the topological field theory of the quantum Hall effect. As a result, we study the gravitational topological $\theta$ sectors in analogy to Yang-Mills theory. We find that the cosmological constant $\mathrm{\Lambda }$ is intimately linked to the $\theta$ parameter by $\theta =12{\pi }^2/(\mathrm{\Lambda }{\ell }_{\mathrm{Pl}}^2)\text{mod}2\pi$ due to the fact that Chern-Simons-Kodama state must live in a particular $\theta$ sector. This result is shown in the canonical, nonperturbative formalism. Furthermore, we explain how the physics of the Hamiltonian constraint is analogous to the quantum Hall effect, with the cosmological constant playing the role of a quantum gravitational Hall resistivity. These relations suggest that $\mathrm{\Lambda }$ is topologically protected against perturbative graviton loop corrections, analogous to the robustness of quantized Hall conductance against disorder in a metal.

Holographic complexity, as the bulk dual of quantum complexity, encodes the geometric structure of black hole interiors. Motivated by the complexity $=$ anything proposal, we introduce the spectral representation for generating functions associated with codimension-one and codimension-zero holographic complexity measures. These generating functions exhibit a universal slope-ramp-plateau structure analogous to the spectral form factor in chaotic quantum systems. In such systems, quantum complexity evolves universally, displaying long-time linear growth followed by saturation at late times. By employing the generating function formalism, we show that this universal behavior has two origins: a particular pole structure of the matrix elements of the generating functions in the energy eigenbasis and random matrix universality in spectral statistics. Using the residue theorem, we prove that the existence of this pole structure is a necessary and sufficient condition for the linear growth of holographic complexity measures. Furthermore, we show that the late-time saturation plateau arises directly from the spectral level repulsion, a hallmark of quantum chaos.

We propose a novel probe of the nucleon’s transversity distribution $h_1^q$ using the one-point energy correlator (OPEC), an infrared-and-collinear safe jet substructure observable. We demonstrate that in transversely polarized $p^{\uparrow }p$ collisions, the OPEC exhibits a single-spin asymmetry (SSA) with a clean $\sin ({\varphi }_s-{\varphi }_n)$ angular dependence. This method probes SSA over a much wider kinematic range in the angular scale ${\theta }_n$ compared to traditional measurements of hadron transverse momentum $j_{\perp }$, establishing a complementary and systematically distinct channel to study the nucleon’s three-dimensional structure at the RHIC and the future electron-ion collider.

We performed high-precision decay-pion spectroscopy of light $\mathrm{\Lambda }$ hypernuclei at the Mainz Microtron (MAMI) using the A1 spectrometer facility. By measuring the monochromatic ${\pi }^{-}$ momentum from the two-body weak decay ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}\to {}^3\mathrm{He}+{\pi }^{-}$ and referencing it to the ${}_{\mathrm{\Lambda }}{}^4\mathrm{H}\to {}^4\mathrm{He}+{\pi }^{-}$ decay, we determined the $\mathrm{\Lambda }$ binding energy of ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$ with unprecedented accuracy. The obtained value, $B_{\mathrm{\Lambda }}{(}_{\mathrm{\Lambda }}^3\mathrm{H})=0.523\pm 0.013_{\mathrm{stat}}\pm 0.075_{\mathrm{syst}}.\mathrm{MeV}$, is consistent with the STAR result, but indicates a significantly deeper binding than inferred from earlier measurements. This result implies a stronger $\mathrm{\Lambda }$-deuteron interaction and provides stringent constraints on hyperon-nucleon interactions.

The lifetime of the $J^{\pi }=2^{+}$ state in the self-conjugate ${}^{88}\mathrm{Ru}$ nucleus has been determined in an experiment performed using rare-isotope beams provided by the new Facility for Rare Isotope Beams. This is the heaviest $N=Z$ nucleus for which such a measurement has been achieved. ${}^{88}\mathrm{Ru}$ was populated by both one-neutron knockout and charge-exchange reactions, and the lifetime of ${14.3}_{-3.4}^{+2.5}\mathrm{ps}$ was determined using the triple-foil plunger technique. The extracted electromagnetic transition strength shows that the quadrupole collectivity has dropped significantly compared with the highly deformed $N=Z$ region around $A\sim 80$. These results are compared with state-of-the-art large-scale shell-model and discrete nonorthogonal shell-model calculations. The theoretical calculations indicate a moderate triaxial deformation and suggest that low-lying states in this nucleus are no longer dominated by strong many-particle many-hole excitations, unlike the lighter, highly deformed $N=Z$ nuclei nearby.

Dodecagonal oxide quasicrystals (OQCs) have so far been limited to a few elemental systems, with no general formation mechanism established. Here, we demonstrate a versatile approach to OQC formation via a host-atom-induced transformation of a metal-oxide honeycomb network. Adsorption of Ba, Sr, or Eu onto the honeycomb layer triggers its reorganization into a dodecagonal tiling, as revealed by low-energy electron diffraction and scanning tunneling microscopy. Full conversion occurs when 73% of the honeycomb rings are occupied. Kelvin probe and UV photoelectron spectroscopy show a linear decrease in work function with increasing host coverage, followed by a sharp increase upon quasicrystal formation due to reduced host dipoles. This transformation mechanism enables the fabrication of structurally precise OQCs, including a new Eu-Ti-O phase that extends the field to lanthanide quasicrystals, forming a 2D grid of localized magnetic moments. The method might offer a more general route to explore lattice-matched substrates for epitaxial growth and may be adapted to other 2D honeycomb materials such as graphene, hexagonal ice, and silica, paving the way for engineered aperiodic systems beyond transition metal oxides.

We report the existence of algebraically localized eigenstates embedded within the continuum spectrum of 2D non-Hermitian systems with a single impurity. These modes, which we term algebraic states in continuum (AICs), decay algebraically as $1/|r|$ from the impurity site, and their energies lie within the bulk continuum spectrum under periodic boundary conditions. We analytically derive the threshold condition for the impurity strength required to generate such states. Remarkably, AICs are forbidden in Hermitian systems and in 1D non-Hermitian systems, making them unique to non-Hermitian systems in two and higher dimensions. To detect AICs, we introduce a local density of states as an experimental observable, which is readily accessible in photonic and acoustic platforms.

Both the minimal size of optically switched magnetic bits and the wavelengths of optically excited spin waves in optomagnonic devices are fundamentally diffraction limited. Here, we propose and experimentally demonstrate a novel method to overcome these limitations by using a specially designed magnetophotonic waveguide structure. This structure enables the creation of a sign-changing profile of the inverse Faraday effect (IFE) induced in the magnetic film by the circularly polarized femtosecond laser pulse tuned to the resonance of the optical TE guided mode. The spatial period of the IFE profile is subdiffractive, which allows for the launch of narrow band exchange-dominated magnetostatic spin waves. As experimentally demonstrated, their wavelengths are around 300 nm, and they can potentially be reduced to 100 nm. This opens new horizons for optomagnetic applications, ranging from logic elements to data processing devices.