We study the spatiotemporal patterns of density fluctuations in ${}^{16,24}\mathrm{O}$ and ${}^{48}\mathrm{Ca}$ using nuclear interactions from chiral effective field theory and the time-dependent coupled-cluster method. We find that two-particle–two-hole excitations generate small-amplitude fluctuations that are fast, short-ranged, and of stochastic character.

We present a framework for treating mesoscopic anisotropic and nonadditive impurity–bath interactions, ubiquitous in realistic quantum impurity problems, which are often neglected in conventional approaches relying on additive, spherically symmetric pseudopotentials. To illustrate this general approach, we focus on the specific impurity problem of a Rydberg atom immersed in a Bose-Einstein condensate, where the internal-state degeneracy of the Rydberg impurity gives rise to configuration-dependent nonadditive potentials. With increasing interaction strength, anisotropy-induced partial-wave mixing generates distinct polaron and molaron resonances, allowing for radially and angularly excited bound states to become accessible. This approach captures the anisotropy and nonadditivity characteristic of a Rydberg impurity immersed in a quantum bath, and is broadly applicable to a host of quantum impurity problems beyond the Fröhlich paradigm.

Optical waveguides conventionally rely on wavelength-scale low-index spacing or cladding to isolate neighboring channels, fundamentally limiting photonic integration density. Here, we show that such spatial separation is not a prerequisite for independent waveguiding. By introducing deep-subwavelength metal perturbations ($\sim {\lambda }_0/25$) onto the surfaces of a dielectric slab, we realize multiple dielectric guiding channels with zero physical spacing. This behavior arises from perturbation-engineered suppression of supermode index splitting, achieved by selectively modifying the symmetric mode while leaving the antisymmetric mode nearly unchanged. We validate this mechanism through full-wave simulations and microwave experiments in both straight and bent geometries. Extending this concept to the optical regime, we design silicon-on-insulator waveguides incorporating hybrid silver-silicon perturbations, achieving ultralong coupling lengths ($L_c\ge 1000{\lambda }_0$) across a broad bandwidth from 1495 to 1565 nm. Owing to the minimal metal volume, propagation losses remain significantly lower than those of conventional hybrid plasmonic systems. This metal-dielectric hybrid waveguide system enables ultradense photonic integration and provides new insights into controlling optical coupling.

The superconducting diode effect (SDE) is a fascinating nonreciprocal phenomenon where the critical current is different for opposite current directions. It is widely believed that realizing SDE requires breaking both inversion symmetry and time-reversal symmetry (TRS), which are usually achieved via heterostructure engineering and applying external magnetic fields. Here, we report a pressure-induced magnetic-field-free SDE in ${\text{NbSe}}_2$ flakes without any heterostructures. We show that pressure alone breaks the inversion symmetry, as confirmed by the second harmonic generation. Crucially, upon applying an out-of-plane magnetic field ($B$), the SDE exhibits even-in-B behavior, implying the absence of explicit TRS breaking. This finding challenges the prevailing theoretical paradigm and demonstrates that a magnetic-field-free SDE can emerge without explicitly breaking TRS. Thereby, our Letter establishes pressure engineering as a powerful tool for inducing nonreciprocal superconductivity and designing versatile, magnetic-field-free superconducting devices.

With the aid of a microscopic theory we derive an effective Hamiltonian that controls quantum dynamics of Andreev states in superconducting nanojunctions out of equilibrium. Resolving the corresponding Schrödinger-like equation we obtain the “wave functions” for Andreev levels and evaluate electric current across the junction in the presence of an external voltage bias. We demonstrate that quantum interference of Andreev states may yield pronounced coherent oscillations of the supercurrent as a function of the Josephson phase in junctions with barrier transmissions slightly below unity. Further implications of this novel effect are expected for junctions with diffusive barriers.

We study the $ab$-plane and $c$-axis charge dynamics of ${\mathrm{La}}_4{\text{Ni}}_3{\mathrm{O}}_{10}$ using optical spectroscopy. While a pronounced Drude profile, i.e., metallic response, is observed in the $ab$-plane optical conductivity ${\sigma }_1^{ab}(\omega )$, the $c$-axis optical spectra ${\sigma }_1^c(\omega )$ exhibit semiconducting behavior. The zero-frequency extrapolation of the optical conductivity ${\sigma }_1(\omega \to 0)\equiv 1/{\rho }_{\mathrm{dc}}$ leads to a resistivity anisotropy ${\rho }_c/{\rho }_{ab}$ exceeding 1000 at low temperatures, which is much larger than the values in iron-based superconductors but comparable to those in high-$T_c$ cuprates. The interband response is also highly anisotropic, showing salient orbital selectivity for light polarized in the $ab$ plane and along the $c$ axis. The interband-transition peaks in both ${\sigma }_1^{ab}(\omega )$ and ${\sigma }_1^c(\omega )$ are located at lower energies compared to density-functional-theory predictions, signifying considerable electronic correlations. By investigating the spectral weight transfer, we find that above the density-wave transition, Coulomb correlations have a marked impact on the charge dynamics of ${\mathrm{La}}_4{\text{Ni}}_3{\mathrm{O}}_{10}$, whereas in the density-wave state, a gap opens with the Ni-$d_{z^2}$ orbital being involved.

Valley, as a ubiquitous degree of freedom in lattices, has found wide applications in both electronic and classical-wave devices in recent years. However, achieving valley-polarized states, a prerequisite for valley-based operations, still remains challenging. Here, we propose and experimentally demonstrate a universal non-Hermitian mechanism for valley filtering using only uniform background dissipation, which creates a propagation length contrast between valleys through their intrinsic group velocity differences. We implement this concept in an acoustic crystal, observing switchable and robust valley polarization of sound through large-scale field mapping. Remarkably, our approach is solely based on uniform loss, without the need for any special lattice structures, tailored excitations, or external fields. We further provide designs of our non-Hermitian valley filter on photonic and electronic platforms. Our results offer a simple and effective solution to valley-polarized state generation and may advance the development of novel valley-based devices in both classical and quantum regimes.

Monolayer transition-metal dichalcogenides (TMDs) provide a platform for realizing Wigner crystals and enable their detection via exciton spectroscopy. We develop a microscopic theoretical model for excitons interacting with the localized electrons of the Wigner crystal, including their vibrational motion. In addition to the previously observed exciton-Umklapp feature, the theory reproduces and explains the higher-band attractive-polaron resonances recently reported experimentally. Our model further uncovers that the appearance of two equal-strength and parallel attractive polarons, as commonly observed in ${\mathrm{WSe}}_2$ and ${\mathrm{WS}}_2$, is a signature of strong correlations in the electronic system. Altogether, our results demonstrate that accounting for electronic interactions is essential to reproducing and interpreting the exciton-polaron spectra of TMDs.

The coupling between electronic excitations and lattice deformation in van der Waals ferroelectrics is governed by a competition between the electron deformation potential and the inverse piezoelectric effect. While theory predicts that piezoelectric screening should drive a polar-axis contraction in monolayer group-IV monochalcogenides, we demonstrate that, in multilayer tin monosulfide (SnS), the deformation potential provides the dominant contribution, driving a polar-axis expansion even within ferroelectric domains. By correlating polarization-resolved second-harmonic generation microscopy with ultrafast reflectance spectroscopy and first-principles calculations, we resolve the anisotropic lattice response and disentangle intrinsic photostrictive strain from extrinsic thin-film interference artifacts. These results establish a microscopic hierarchy of photostrictive mechanisms and position stacking-engineered SnS as a platform for ultrafast optomechanical transduction.

Quantum magic, quantified by nonstabilizerness, measures departures from stabilizer structure and underlies potential quantum speedups. We introduce an efficient classical framework for computing stabilizer Rényi entropies and stabilizer nullity of generic $N$-qubit wave functions. The method combines the fast Walsh-Hadamard transform with an exact partition of Pauli operators, reducing the average cost per sampled Pauli string from $\mathcal{O}(2^N)$ to $\mathcal{O}(N)$. We further develop a Monte Carlo estimator with Clifford preconditioning and find that the required number of samples shows no visible growth with $N$ in our benchmarks. Applying the method to $T$-doped random Clifford circuits, we identify the scrambling ratio $\eta$ (Clifford gates per $T$ gate) as the key parameter governing magic growth. Each $T$ gate approaches its dilute-limit nonstabilizerness power with only modest Clifford scrambling. Our approach enables quantitative studies of magic in highly entangled states and long-time nonequilibrium dynamics.

We introduce a thermodynamic work-extraction task that describes the energy storage enhancement of quantum systems. This task induces majorizationlike conditions that provide a necessary and sufficient characterization of state conversions in general quantum resource theories. When applied to specific resources, these conditions reduce to the majorization conditions under unital channels and provide a thermodynamic version of Nielsen’s theorem in entanglement theory. We show how this result establishes the first universal resource certification class based on thermodynamics, and how it can be employed to quantify general quantum resources based on work extraction.

Elucidating the emergence of irreversible macroscopic laws from reversible quantum many-body dynamics remains challenging, particularly in disordered media. Here, in a doubly disordered electron-nuclear spin network in nitrogen-doped diamond, we uncover an emergent decoherence law for ${}^{13}\mathrm{C}$ polarization, $M(t)=e^{-\sqrt{R_{p}t}}{e}^{-R_{d}t}$, that persists over $>500\mathrm{s}$ and across broad Hamiltonian regimes. We trace the law to two interdependent, electron-mediated channels: direct depolarization by a fluctuating electron bath and an indirect pathway governed by polarization transport within the dilute nuclear network, which is anomalous and subdiffusive. Combining Floquet engineering with all-optical modulation of the electron environment, we demonstrate deterministic control of the channels and the ability to selectively eliminate either one. Disorder, typically viewed as detrimental, here proves protective by generating rare electron-free clusters that trap polarization and dominate late-time decay.

As the largest gravitationally bound objects in the Universe, galaxy clusters have provided the first piece of evidence for the presence of dark matter and may be suitable targets for indirect dark matter searches. Among various signals, the GeV-TeV $\gamma$-ray line has been taken as the smoking-gun signal of the dark matter annihilation and decay, since no known astrophysical or physical process(es) could generate such a peculiar spectrum. With 15.5 years of Fermi-LAT P8R3 publicly available data, we search for the $\gamma$-ray line emission in the directions of 13 massive galaxy clusters at redshifts $z\le 0.028$ with an unbinned likelihood analysis. A $\gamma$-ray line signal at $\sim 43.2\mathrm{GeV}$ has a net test statistic (TS) value of $\approx 30$ if we take into account only the data in the directions of the Virgo, Fornax, and Ophiuchus clusters, three massive clusters with the highest J-factors expected to generate the dark matter annihilation signal. The signal still presents when the data of 10 other nearby massive clusters are also included, though the TS value decreases to $\approx 21$, likely because of their lower signal-to-noise ratios. The absence of this signal in the inner Galaxy disfavors both the instrumental effect and the canonical dark matter annihilation interpretation, and a more sophisticated dark matter model or very peculiar astrophysical scenario might be needed. This $\gamma$-ray line signal, if intrinsic, could be unambiguously verified by the Very Large Area $\gamma$-ray Space Telescope in its first two years of performance.

We show that the tree-level spectrum of heavy particles can be directly extracted from the Wilson coefficients of the corresponding effective field theory at low energies. This procedure is exact when the number of resonances is finite and otherwise approximate. Our results are derived from a new class of analytic dispersion relations that depend nonlinearly on the scattering amplitude and apply to an exceedingly broad class of theories and kinematics.

We apply a tag-and-probe method to precisely measure the absolute branching fraction of the decay ${\eta }_c\to \gamma \gamma$ with the BESIII experiment at BEPCII. Starting with a large initial sample of $(2712.4\pm 14.3)\times {10}^6\psi (3686)$ events, a sample of $0.16\times {10}^6{\eta }_c$ events is tagged via the golden channel $\psi (3686)\to {\pi }^0{h}_c$, $h_c\to \gamma {\eta }_c$, effectively avoiding interference effects. The absolute branching fraction of ${\eta }_c\to \gamma \gamma$ is measured for the first time to be $\mathcal{B}({\eta }_c\to \gamma \gamma )=(2.45\pm 0.48_{\mathrm{stat}}\pm 0.09_{\mathrm{syst}})\times {10}^{-4}$. Using the world average value of the total width of the ${\eta }_c$, the partial decay width of ${\eta }_c\to \gamma \gamma$ is calculated to be $\mathrm{\Gamma }({\eta }_c\to \gamma \gamma )=(7.48\pm 1.48_{\mathrm{stat}}\pm 0.30_{\mathrm{syst}})\mathrm{keV}$.

We report the first searches for charged-lepton-flavor violation in decays of ${\chi }_{bJ}(1P)$ ($J=0$, 1, and 2) to a pair of charged leptons using 158 million $\mathrm{\Upsilon }(2S)$ decays collected with the Belle detector in $e^{+}{e}^{-}$ collisions at the KEKB collider. No significant signal is observed, and we set upper limits on the branching fractions for ${\chi }_{bJ}(1P)$ decays to $e^{\pm }{\mu }^{\mp }$ at the level of ${10}^{-6}$ and to $e^{\pm }{\tau }^{\mp }$ or ${\mu }^{\pm }{\tau }^{\mp }$ at the level of ${10}^{-5}$. Limits on ${\chi }_{b0}(1P)$ decays are translated into bounds on the corresponding Wilson coefficients of scalar operators that mediate charged-lepton-flavor violation.

Decay of a four-level diamond scheme via a cascade is a potential source of entangled photon pairs. A solid-state implementation is the biexciton cascade in a semiconductor quantum dot. While high entanglement fidelities have been demonstrated, the two photons, XX and X, are temporally correlated, typically resulting in poor photon coherence. Here, we demonstrate a high two-photon interference visibility (a measure of the photon coherence) for both XX ($90\pm 2\%$) and X ($80\pm 6\%$) photons. This is achieved by Purcell enhancing the biexciton transition in a low-noise device. We find that the interference visibility follows the well-known quantum optics result upon tuning the XX:X lifetime ratio over 2 orders of magnitude. In addition, we show that the XX purity, 98%, is limited not by quantum optics but by the phonons in the semiconductor matrix via cavity feeding.