We report the first detection of gamma-ray emission up to ultrahigh-energy (UHE; $>100\mathrm{TeV}$) emission from the prototypical gamma-ray binary system LS I $+61°$ 303 using data from the Large High Altitude Air Shower Observatory. It is detected with significances of $9.2\sigma$ in the Water Cherenkov Detector Array (WCDA, $1.4-30.5\mathrm{TeV}$) and $6.2\sigma$ in the Kilometer Square Array (KM2A, $25-267\mathrm{TeV}$); in KM2A alone we identify 16 photonlike events above 100 TeV against an estimated 5.1 background events, corresponding to a $3.8\sigma$ detection. These results provide compelling evidence of extreme particle acceleration in LS I $+61°$ 303. Furthermore, we observe orbital modulation at $3.9\sigma$ confidence level, between 25 and 100 TeV, with a hint that the orbital modulation is energy dependent. These features can be understood in a composite scenario in which leptonic and hadronic processes jointly contribute.

The Arrhenius model has long provided a framework for describing thermally activated processes in solids, linking temperature to relaxation dynamics through a fixed activation barrier. Yet in molecular glasses, it routinely produces unphysically low preexponential factors, ${\tau }_0^{*}$, raising fundamental questions about the physical meaning of the extracted parameters. Here, we resolve this long-standing paradox by showing that the activation energy decreases linearly with temperature as a consequence of density-driven variations of the barrier. Using a constant-volume approach combining broadband dielectric spectroscopy with pressure-volume-temperature analysis, we separate thermal and density contributions and directly quantify energy barriers. The results confirm theoretical predictions made fifty years ago but never experimentally verified. Neglecting the temperature dependence of activation energy systematically inflates barrier heights and drives anomalously low ${\tau }_0^{*}$ in conventional Arrhenius fits, leading to misleading conclusions about glassy dynamics. This effect is observed for both intramolecular secondary relaxations and intermolecular processes of the Johari-Goldstein relaxation type, highlighting the generality of the mechanism. Our Letter sets a new standard for interpreting secondary relaxation processes and provides a physically justified framework for analyzing thermally activated dynamics across a wide range of amorphous materials.

Mechanical modulation of recoilless nuclear transitions allows the dynamic control of $\gamma$-ray emission and absorption. Accessing modulation frequencies well above the nuclear linewidth enables coherent manipulation of the nuclear response. Here we demonstrate high-frequency control via efficient coupling of a film of enriched ${}^{57}\mathrm{Fe}$ to a 97.9 MHz surface acoustic wave, nearly 2 orders of magnitude higher than the nuclear linewidth. The mechanical drive produces a comb of absorption sidebands in the Mössbauer spectrum, reflecting the periodic time modulation of the nuclear transitions. This constitutes the highest frequency mechanically driven Mössbauer resonance to date. Our solid-state, monolithic platform establishes a new interface between nuclear transitions and high-frequency acoustics, with applications in $\gamma$-ray quantum optics and precision nuclear spectroscopy.

Proximity effects complement conventional materials design by enabling interfacial properties absent in any constituent. Here, we uncover an altermagnetic proximity effect (AMPE), distinct from ferromagnetic and antiferromagnetic proximity, in which the hallmark momentum-alternating spin splitting of an altermagnet is transferred across an interface into an adjacent nonmagnetic layer—a process we term “altermagnetization.” Using first-principles calculations and model analysis, we identify the AMPE in heterostructures based on the prototypical van der Waals altermagnet ${\mathrm{V}}_2{\mathrm{Se}}_2\mathrm{O}$, where a proximitized monolayer PbO acquires altermagnetic band splitting and real-space spin textures, with systematic tunability via interlayer spacing and magnetic configuration. We further demonstrate that the AMPE enables valley-dependent spin splitting in the semiconductor PbS and realizes topological superconductivity in the $s$-wave superconductor ${\mathrm{NbSe}}_2$, both inheriting the altermagnetic spin texture. Finally, we validate the generality and experimental feasibility of the AMPE by realizing it in a broader class of established altermagnets, including ${\mathrm{V}}_2{\mathrm{Se}}_2\mathrm{O}$ derivatives, Ruddlesden-Popper perovskites, and the metallic CrSb. Our results identify the AMPE as a universal proximity mechanism and a versatile platform for engineering emergent quantum phenomena in heterostructures.

Quantum communication in the microwave regime is set to play an important role in distributed quantum computing and hybrid quantum networks. However, typical superconducting quantum circuits require millikelvin temperatures for operation, which poses a significant challenge for large-scale microwave quantum networks. Here, we present a solution to this challenge by demonstrating the successful quantum teleportation of microwave coherent states between two spatially separated dilution refrigerators over a thermal microwave channel in the temperature range up to 4 K. We distribute two-mode squeezed states over this noisy channel and employ the resulting quantum entanglement for quantum teleportation of coherent states with fidelities of $72.3\pm 0.5\%$ at 1 K and $59.9\pm 2.5\%$ at 4 K, exceeding the no-cloning and classical communication thresholds, respectively. We successfully model the teleportation protocol using a Gaussian operator formalism that includes losses and noise. Our analysis shows that the teleportation infidelity mainly stems from a parasitic heating of the cold quantum nodes due to the hot network connection. These results demonstrate the experimental feasibility of distributed superconducting architectures and motivate further investigations of noisy quantum networks in various frequency regimes.

The Shastry-Sutherland model is an effective model of the layered material ${\mathrm{SrCu}}_2({\mathrm{BO}}_3{)}_2$, which exhibits an extremely rich phase diagram as a function of pressure and magnetic field. Motivated by the recent controversy regarding its phase diagram at zero magnetic field, we perform large-scale simulations based on infinite projected entangled-pair states, a two-dimensional tensor network Ansatz to represent the ground state directly in the thermodynamic limit. By employing the latest optimization techniques, we obtain variational states with lower energy than previous results obtained from other methods. Using systematic extrapolations to the exact infinite bond dimension limit, our simulations reveal a narrow quantum spin liquid phase between the plaquette and antiferromagnetic phases in the range $0.785(5)\le J^{\prime }/J\le 0.82(1)$.

We demonstrate numerically the existence of solutions of five-dimensional vacuum gravity describing the formation, in finite time, of an extremal rotating black hole from a preexisting Schwarzschild black hole. This is the first example of a violation of the third law of black hole mechanics in vacuum gravity and demonstrates that the third law is false independently of any matter model. We also demonstrate the existence of solutions describing the formation, in finite time, of an extremal rotating black hole from vacuum initial data that do not contain a black hole.

We report local conductivity imaging of edge states in monolayer graphene by millikelvin microwave impedance microscopy. At the charge-neutrality point, as the magnetic field increases, the local conductivity at the edge drops to zero more slowly than in the bulk. This behavior is consistent with the calculated spatial profile of the charge gap in the canted antiferromagnetic phase. For comparison, we also perform microwave imaging of integer quantum Hall states away from neutrality, which host dissipationless chiral edge channels. The evolution of the edge signal as a function of the bulk gap is fundamentally different between the Landau level filling factor $\nu =0$ and $|\nu |\ge 1$ integer quantum Hall states, which can be qualitatively explained by numerical simulations and theoretical analysis. Our results provide a comprehensive microscopic picture of the edge and bulk states as the Fermi level moves across the unique Landau-level spectrum of graphene.

The Fermilab E906/SeaQuest collaboration performed measurements of the Drell-Yan process using 120 GeV proton beams bombarding liquid hydrogen and liquid deuterium targets. A combined analysis of all collected data was performed to obtain the final results for the ${\sigma }_{pd}/2{\sigma }_{pp}$ Drell-Yan cross section ratio covering the kinematic region of $0.13<x<0.45$. The $x$ dependencies of $\overline{d}(x)/\overline{u}(x)$ and $\overline{d}(x)-\overline{u}(x)$ are extracted from these cross section ratios. It is found that $\overline{d}(x)$ is greater than $\overline{u}(x)$ over the entire measured $x$ range, with improved statistical accuracy compared to previous measurements. The new results on $\overline{d}(x)/\overline{u}(x)$ and $\overline{d}(x)-\overline{u}(x)$ are compared to various parton distribution functions and theoretical calculations.

The absence of a well-defined Fermi surface in flat-band systems challenges the conventional understanding of instabilities toward Landau order based on nesting. We investigate the existence of an intrinsic nesting structure encoded in the band geometry [i.e., the wave functions of the flat band(s)], which leads to a maximal susceptibility at the mean-field level and, thus, determines the instability toward ordered phases. More generally, we show that, for a given band structure and observable, we can define two vector fields: one which corresponds to the Bloch vector of the projection operator onto the manifold of flat bands and another which is “dressed” by the observable. The overlap between the two vector fields, possibly shifted by a momentum vector $\mathit{Q}$, fully determines the mean-field susceptibility of the corresponding order parameter. When the overlap is maximized, so is the susceptibility, and this geometrically corresponds to “perfect nesting” of the band structure. In that case, we show that the correlation length of this order parameter, even for $\mathit{Q}\ne \mathbf{0}$, is entirely characterized by a generalized quantum metric in an intuitive manner and is, therefore, lower bounded in topologically nontrivial bands. As an example, we demonstrate hidden nesting for staggered antiferromagnetic spin order in an exactly flat-band model, which is notably different from the general intuition that flat bands are closely associated with ferromagnetism. We check the actual emergence of this long-range order using the determinantal quantum Monte Carlo algorithm. Additionally, we demonstrate that a Fulde-Ferrell-Larkin-Ovchinnikov-like state (pairing with nonzero center of mass momentum) can arise in flat bands upon breaking time-reversal symmetry, even if Zeeman splitting is absent.

We present a first joint extraction of the Collins-Soper kernel (CSK) combining experimental and lattice QCD data in the context of an analysis of transverse-momentum-dependent distributions (TMDs). Based on a neural-network parametrization, we perform a Bayesian reweighting of an existing fit of TMDs using lattice data, as well as a joint TMD fit to lattice and experimental data. We consistently find that the inclusion of lattice information shifts the central value of the CSK by approximately 10% and reduces its uncertainty by 40%–50%, highlighting the potential of lattice inputs to improve TMD extractions.

Parton distribution functions (PDFs) are central to precision QCD phenomenology. Their Mellin moments can be computed on the lattice, but direct determinations using local operators, besides $⟨x⟩$, face severe challenges from reduced hypercubic symmetry, limiting results to the lowest moments. A recently proposed method resolves these issues using gradient flow. We demonstrate the efficacy of this method by computing ratios of flavor nonsinglet pion PDF moments up to $⟨x^5⟩$ on four lattice spacings at $m_{\pi }\simeq 411\mathrm{MeV}$. The moments and reconstructed PDF agree quantitatively with recent phenomenological extractions.

The scaling exponent $g$ of the quasiparticle propagator for incompressible fractional quantum Hall states in the Laughlin sequence is expected to be robust against perturbations that do not close the gap. Utilizing a novel AlGaAs/GaAs heterostructure designed to produce sharp edge confinement, we probe the robustness of the chiral Luttinger liquid at the boundary of the $\nu =1/3$ state by measuring the tunneling conductance between counterpropagating edge modes. We demonstrate that for transmission $t\ge 0.7$ the tunneling conductance is well-described by the first two terms of a perturbative series expansion corresponding to $g=1/3$. We demonstrate that the measured scaling exponent is robustly pinned to $g=1/3$ across the plateau, only deviating as the bulk state becomes compressible. We examine the impact of weak disorder on the scaling exponent, finding it insensitive. These measurements establish the topological robustness of anyon tunneling at $\nu =1/3$ and substantiate the chiral Luttinger liquid description of the edge mode.

Nuclear-spin conversion in molecular hydrogen is governed by strict symmetry rules that typically require magnetic fields or catalytic surfaces to break. Here we demonstrate that the intrinsic tensor composition of a nonmagnetic molecular crystal field can impose and relax these rules without external fields. High-resolution infrared spectra of ${\mathrm{H}}_2$ in crystalline ${\mathrm{CO}}_2$ reveal large rank-2 (quadrupolar) crystal-field splittings of the $m$ sublevels, while nuclear-spin conversion occurs only through $\mathrm{\Delta }m=0$ channels. Replacing ${\mathrm{CO}}_2$ with polar ${\mathrm{N}}_2\mathrm{O}$ introduces rank-1 (dipole) components that partially open $\mathrm{\Delta }m\ne 0$ pathways, while incorporation of paramagnetic ${\mathrm{NO}}_2$ fully lifts the restriction. These results establish a direct correspondence between crystal-field tensor rank and nuclear-spin dynamics, introducing a general symmetry-based framework for designing and controlling spin-isomer populations and quantum-state connectivity in molecular solids.

We demonstrate that superconductivity driven by strong quantum-critical fluctuations can emerge near relativistic Mott transitions in twisted two-dimensional materials. In twisted double-bilayer ${\mathrm{WSe}}_2$, all time-reversal-even, gap-opening collective modes promote pairing, whereas time-reversal-odd modes do not. In twisted bilayer graphene, all transitions into intervalley-coherent insulators give rise to superconductivity. Hence, the two separate superconducting domes of insulating or semimetallic undoped systems are expected to merge near the Gross-Neveu transition angle. A crucial ingredient of the theory is that critical fluctuations render the electronic states strongly incoherent, allowing attractive pairing channels to overcome the bare Dirac semimetal behavior. The richer the Dirac structure, the more readily pairs can form. Finally, we demonstrate a direct relation between boson-mediated pairing and the formation of charge-carrying skyrmions in the proximate insulating state.

The advent of wurtzite ferroelectrics is enabling new ferroelectric devices for computer memory that have the potential to bypass the von Neumann bottleneck due to their robust polarization and silicon compatibility. However, the atomistic switching mechanism of wurtzites is still undetermined due to the limitations of density functional theory simulation size and experimental temporal and spatial resolution. Thus, physics-informed materials engineering to reduce coercive field and breakdown in these devices has been limited. Here, the atomistic mechanism of domain wall migration and domain growth in aluminum nitride-based wurtzites is uncovered using molecular dynamics and Monte Carlo simulations. We reveal the anomalous switching mechanism of fast 1D single columns of atoms propagating from a slow-moving 2D fractallike domain wall. We find that the critical nucleus is a single aluminum ion that breaks its bond with one nitrogen and bonds to another nitrogen; this creates a cascade that flips atoms directly only in the same column, due to the extreme locality (sharpness) of the domain walls in wurtzites. We further show how the fractallike shape of the domain wall in the 2D plane breaks assumptions in the Kolmogorov, Avrami, and Ishibashi (KAI) model and leads to the anomalously fast switching in wurtzite structured ferroelectrics.

Understanding mechanisms of rare but important events in complex molecular systems, such as protein folding or ligand (un)binding, requires accurately mapping transition paths from an initial to a final state. The committor is the ideal reaction coordinate for this purpose, but calculating it for high-dimensional, nonlinear systems has long been considered intractable. Here, we introduce an iterative path-sampling strategy for computing the committor function for systems with high free-energy barriers. We start with an initial guess to define isocommittor interfaces for transition interface sampling. The resulting path ensemble is then reweighted and used to train a neural network, yielding a more accurate committor model. This process is repeated until convergence, effectively solving the long-standing circular problem in enhanced sampling where a good reaction coordinate is needed to generate efficient sampling, and vice versa. The final, converged committor model can be interrogated to extract mechanistic insights. We demonstrate the power of the method on a benchmark 2D potential and a host-guest (un)binding process in an explicit solvent.

Supernova remnants (SNRs) have been considered as the primary contributors to cosmic rays (CRs) in our Galaxy. However, the maximum energy of particles that can be accelerated by shocks of SNRs is uncertain, and SNRs’ contribution to CRs around PeV energies is unclear. In this Letter, we present observations of high-energy $\gamma$-ray emission from the SNR IC 443 using the Large High Altitude Air Shower Observatory (LHAASO). The morphological analysis reveals a pointlike source whose location and spectrum are consistent with those of the Fermi-LAT-detected compact source with ${\pi }^0$-decay signature, and a more extended source that is associated with a newly discovered Fermi source. The spectrum of the point source can be described by a power-law function with an index of $\sim 3.0$, extending beyond $\sim 30\mathrm{TeV}$ without apparent cutoff. Assuming a hadronic origin of the $\gamma$-ray emission, the 95% lower limit of accelerated protons reaches about 300 TeV. The extended source might be associated with IC 443, SNR $\mathrm{G}189.6+3.3$, or the putative pulsar wind nebula CXOU $\mathrm{J}061705.3+222127$, and can be explained by either a hadronic or a leptonic model with particles reaching hundreds of TeV. These LHAASO results provide compelling evidence that sub-PeV CRs can be accelerated efficiently by shocks of SNRs.

The spontaneous emergence of chirality in crystalline solids has profound implications for electronic, optical, and topological properties, making the control of chiral phases a central challenge in materials design. Here, we investigate the structural and electronic properties of a new family of layered compounds, ${\mathrm{NbOX}}_2$, and explore the connection between their achiral $Immm$ phase and chiral $C2$ phase. Through first-principles calculations, we identify an intermediate achiral $C2/m$ phase that bridges the high- and low-symmetry phases within a three-dimensional order parameter space. By analyzing the Born-Oppenheimer energy surfaces, we find that the shallow energy minima of the $C2/m$ phase suggest it may be stabilized either by external factors such as pressure, as demonstrated here, or by ionic quantum or thermal fluctuations and the resulting lattice anharmonicity. Additionally, we show how an external electric field, by breaking the necessary symmetries, biases the system toward a preferred chirality by lifting the energy degeneracy between the two enantiomers. This, combined with the small energy barrier between the enantiomers in the $C2$ phase, enables handedness control and allows us to propose a mechanism for selective handedness stabilization by leveraging electric fields and pressure or temperature-dependent anharmonic effects. Our findings establish a framework for understanding chirality emergence in layered materials and offer a pathway for designing systems with tunable enantiomeric populations.

Recent observations of quantum anomalous Hall effects in moiré systems have revealed the emergence of interaction-driven ferromagnetism with significant orbital contributions. To capture this physics, we extend the modern theory of orbital magnetization to Hartree–Fock states and show that the standard expression remains valid with Hartree–Fock orbitals and Hamiltonians. Then, we benchmark our theory against the extended Kane-Mele-Hubbard model in a weak field, which yields excellent agreement with direct numerical calculations. Applying our theory to twisted ${\mathrm{MoTe}}_2$ bilayers, we find orbital magnetization of order one Bohr magneton per moiré cell with a nonmonotonic twist-angle dependence. Our work establishes a general theory of orbital magnetization in interacting moiré systems and provides quantitative guidance for interpreting recent experiments.