We study Gutzwiller-projected wave functions for triangular-lattice U(1) Dirac spin liquids in a Zeeman field, where we allow the U(1) gauge field to develop a gauge flux, resulting in (spin-split) spinon Landau levels. We find that at a given magnetization, the optimal candidate state has a finite flux chosen such that the spinon filling lies in a $|C|=1$ Landau-level gap: it gives the lowest variational energy and the smallest energy variance within our correlation-matrix reconstruction for local Heisenberg-type models. By symmetry, we argue that the finite gauge flux results in a nonzero (staggered) scalar spin chirality, as also numerically observed, and further find that the $|C|=1$ state exhibits dominant quasi-long-ranged 120° magnetic correlations. Studying the next-to-optimal wave function with a $|C|=2$ Landau-level gap, we observe unusual spin-nematic correlations. Our results may provide guidance for analyzing the magnetic-field response of Dirac spin liquid candidate materials and offer numerical diagnostics that can connect to the underlying theory of spinons coupled to an emergent U(1) gauge field.

The center of mass and helicity are two dynamic degrees of freedom of skyrmions. In this Letter, we study the current-driven skyrmion motion in frustrated $d$-wave altermagnets. Contrary to conventional wisdom, we find that the skyrmion helicity is not locked with the skyrmion Hall angle, but unidirectionally rotates with a global angular velocity proportional to the square of the current density. In addition, we find that the helicity rotation velocity is highly anisotropic, depending on the direction of current flows. We also observe helicity oscillation in the terahertz regime, where the nonlinear mixing between the fast and slow modes generates a comblike spectrum. Full atomistic spin dynamics simulations verify our theoretical predictions. Our results establish frustrated altermagnets as a promising platform for skyrmionics, terahertz technology, and magnon frequency comb.

Infrared (IR) and Raman vibrational spectra of materials and surfaces can be rather complex and are often interpreted in combination with simulations based on the double-harmonic approximation. A variety of anharmonic spectral features (band shifts, combination bands, overtones, hot bands, resonances) affect the spectra both quantitatively and qualitatively. We introduce a general method for the efficient description of these anharmonic features—including Fermi and Darling-Dennison resonances—in IR and Raman spectra of materials from first principles. Nuclear quantum effects are explicitly taken into account, and phonon couplings are treated nonperturbatively within a new subspace iterative vibrational configuration interaction (SI-VCI) approach. We apply the SI-VCI method to solid thiourea and solid ${\mathrm{CO}}_2$ (dry ice): two molecular crystals with distinct characteristics. Thiourea is a hydrogen-containing system for which we identify a strong three-mode Fermi-like resonance $SS:b+b^{\prime }$ between the fundamental of a symmetric stretching and the combination of two distinct bending modes of ${\mathrm{NH}}_2$ groups in the solid phase, which is not observed in the isolated gas-phase molecule. Our results, supported by group theoretical arguments, exclude the presence of bending overtones in the resonant mechanism. Dry ice exhibits four known resonances appearing in the form of dyads and triads (two in the IR spectrum and two in the Raman spectrum), which are also observed in the gas-phase isolated molecule. Our simulations predict an additional Fermi resonance in the IR spectrum of ${\mathrm{CO}}_2$ around $2000{\mathrm{cm}}^{-1}$ in the form of a dyad with a splitting $\delta \simeq 150{\mathrm{cm}}^{-1}$. We perform IR transmission experiments where the new resonant spectral feature is observed, assessing the predictiveness of the proposed theoretical approach.

We present a framework for mechanochemical self-organization in active solids where elasticity is reciprocally coupled to Hopf oscillators. Our model reveals a rich landscape of symmetry-protected phases identified through amplitude equations and group-theoretic analysis. We uncover a universal transition to compression-driven oscillation death, providing a physical basis for localized signaling dampening in biological tissues that resolves inconsistencies in previous models. Our work demonstrates that complex self-organization in active solids can be classified purely through symmetry arguments.

For centuries, the human distinction between consonant and dissonant dyadic sounds (“c-d perception phenomenon”) has remained an unresolved puzzle, igniting novel directions in physics research. Here, we demonstrate that nonlinear sound processing by the network of activated cochlear amplifiers reveals a close correlate of the psychoacoustic perception that matches the behavioral data to the level of the best phenomenological approach, suggesting that combination-tone avalanches triggered from coupled nonlinear oscillators, paired with biological information parsimony, may be the essential elements underlying this phenomenon. The observed correlate highlights the potential of a physics-driven explanation of behavioral phenomena that are commonly attributed to “the cortex” but may have their origins in the nonlinear properties of the involved sensors.

Bound states in the continuum (BICs) have been extensively exploited to enhance light-matter interactions in metamaterials, yet their emergence and utility in multiatom waveguide platforms remain far less explored. Here we study atom-waveguide-dressed BICs in a one-dimensional coupled-resonator waveguide, where two spatially separated atomic arrays couple to distinct resonators with time-dependent strengths. We show that these BICs host standing-wave photonic components and enable the transfer of unknown atomic quantum states encoded in the single-excitation subspace between the two arrays, with fidelities exceeding 99%. Going beyond traditional cascaded-quantum-network protocols, our scheme leverages BIC-assisted interference to remain robust against both disorder and intrinsic dissipation. Our results establish BICs as long-lived resources for high-fidelity quantum information processing in waveguide-QED architectures.

We demonstrate single-spin spectroscopy of a fluorescent tumbling defect in silicon called the “G center,” behaving as a pseudomolecule randomly reorienting itself in the crystalline matrix. Using high-resolution spin spectroscopy, we reveal a fine magnetic structure resulting from the spin principal axes jumping between discrete orientations in the crystal. Modeling the atomic reorientation of the defect shows that spin tumbling induces variations in the coupling to the microwave magnetic field, enabling position-dependent Rabi frequencies to be detected in coherent spin control experiments. By virtue of its pseudomolecule configuration, the G center in silicon is a unique quantum system to investigate the mutual interaction between optical, spin, and rotation properties in a highly versatile material.

Open systems feature a variety of phenomena that arise from non-Hermitian physics. Recent theoretical studies have offered many insights into these phenomena through the non-Bloch band theory, though many of the theory’s key features are experimentally elusive. In particular, the correspondence between complex momenta and non-Hermitian bands, while central to non-Bloch band theory, has so far defied direct experimental observation. Here we experimentally study the non-Hermitian spectral deformation in complex-momentum space, by implementing a non-Hermitian lattice with long-range couplings in the synthetic orbital-angular-momentum (OAM) dimension of photons inside a degenerate cavity. Encoding the complex momenta in the phase and amplitude modulations of the OAM modes, and devising a complex-momentum-resolved projective detection, we reconstruct the spectral deformation in complex-momentum space, where the eigenspectrum on the complex plane morphs through distinct geometries. This enables us to experimentally extract key information of the system under the non-Bloch band theory, including exceptional points in the complex-momentum space, the open-boundary spectra, and the generalized Brillouin zone. Our work demonstrates a versatile platform for exploring non-Hermitian physics and non-Bloch band theory, and opens the avenue for direct experimental investigation of non-Bloch features in the complex-momentum space.

Self-generated magnetic fields in laser-solid interactions are experimentally characterized to reveal the 3D location and local field strength, rather than path-integrated quantities, using multiview proton radiography and tomographic inversion. We infer magnetic fields that extend several millimeters off the target into the hot, rarefied corona, sufficient to strongly magnetize the plasma (${\mathrm{\Omega }}_e{\tau }_e\gg 1$). The data are compared to magnetohydrodynamic simulations incorporating recent improvements in modeling magnetic field generation and transport; the volume-averaged coronal field strength and magnetic flux agree to within 25% using a model with magnetic relocalization of transport, although the near-target morphology is not reproduced. This Letter demonstrates tomographic proton radiography as a valuable tool for investigating magnetic fields in laser-produced plasmas.

Geometric frustration lies at the heart of many unconventional quantum phases in strongly interacting electron systems. Here, we analytically determine the ground state magnetization of the half-filled Hubbard model on frustrated geometries where superstable states—eigenstates which are robust against frustration—are manifest. Our results apply to a broad class of lattices, including those where altermagnetic and superconducting states are known to emerge. Furthermore, they provide evidence for phase transitions involving a geometric rearrangement of magnetic correlations in the thermodynamic limit.

Recent works reveal a simplicity in equal-time correlators absent from wave functions. We show that it follows from the fact that correlators are full spacetime integrals rather than half-spacetime integrals as for the wave function. This makes striking properties manifest: some wave function singularities are absent, factorization simplifies, and around every pole the Laurent expansion has a vanishing first subleading term. Near the total-energy pole, the expansion to second order is generated by a differential operator on scattering amplitudes.

We present the first lattice-QCD validation of multiple sum rules associated with quark-gluon decomposition of hadron mass by computing all relevant tensor components of the quark and gluon energy-momentum tensor matrix elements from first principles. We achieve this through nonperturbative renormalization of the QCD energy-momentum tensor, including its trace, in a gradient-flow scheme, followed by continuum extrapolations, two-loop matching to the $\overline{\mathrm{MS}}$ scheme, and zero-flow-time extrapolations. These ingredients enable a direct and simultaneous verification, in a common renormalization scheme and scale, of multiple energy-density-based and trace-based mass decomposition sum rules proposed in the literature. We demonstrate the framework for the ${\eta }_c$ and $J/\psi$ charmonia using three fine lattice spacings with a physical strange-quark and near-physical up- and down-quark masses. We present the first lattice-QCD results for the gravitational form factor $\overline{C}$. We find sizable gluonic contributions to charmonia masses at the hadronic scale, $\sim 15\%$ in the Lorcé and Metz-Pasquini-Rodini decompositions. The trace-anomaly contribution in the Ji sum rule is $\sim 6\%$, while the gluonic component of the trace anomaly in the Hatta-Rajan-Tanaka sum rule is $\sim 35\%$. The method is general and can be straightforwardly adopted for lattice-QCD calculations of mass and spin decompositions as well as gravitational form factors of other hadrons and nuclei.

Dense nucleonic matter is of vital importance for understanding compact stars and inferring the transition into deconfined quark phase. We present ab initio exact calculations of infinite nucleonic matter with the state-of-the-art full configuration-interaction quantum Monte Carlo method, enabling us to rigorously benchmark many-body methods and assess the degree to which the nucleonic matter is correlated. Our method has been numerically validated against exact diagonalization within a small model space. Calculations of nucleonic matter using chiral nuclear forces reveal that symmetric nuclear matter is strikingly strongly correlated, raising questions on previous ab initio calculations of nuclear matter with many-body expansion truncations and offering insights into simultaneous descriptions of finite nuclei and infinite nucleonic matter from first principles.

The Stark effect in autoionizing high-$n$ Rydberg states decouples the Rydberg electron from the ion core through $\ell$ mixing with core-nonpenetrating high-$\ell$ states. The Rydberg states become long-lived, which is ideal for precision spectroscopy, and their structures reflect the fine and hyperfine structures of the ion-core levels. We report on precision measurements, in weak electric fields, of the fine and hyperfine structures of two distinct categories of high autoionizing molecular Rydberg-Stark states differing by the nature of the ion-core angular momentum: Rydberg states of para-${\mathrm{H}}_2$ (total nuclear spin $I=0\mathrm{,}2$) with a rotationally excited ($N^{+}=2$) ${\mathrm{H}}_2^{+}$ ion core and Rydberg states of ortho-${\mathrm{D}}_2$ ($I=0,2$) with a rotationless ($N^{+}=0$) ion core. The spectra reveal striking differences which are interpreted as arising from the dominance of anisotropic charge-quadrupole interactions between the rotating quadrupolar ion core and the Rydberg electron in para-${\mathrm{H}}_2$ and the absence of such interactions in rotationless ortho-${\mathrm{D}}_2$ Rydberg states. In ortho-${\mathrm{D}}_2$, the dominant interaction, the magnetic Fermi-contact hyperfine interaction in the ion core, does not significantly affect the motion of the Rydberg electron. By analyzing these spectra based on a treatment combining multichannel quantum-defect theory and matrix diagonalization, we derive new experimental values of the hyperfine coupling constant $b_F=139.84(5)\mathrm{MHz}$ of ${\mathrm{D}}_2^{+}(v^{+}=1,N^{+}=0)$, the spin-rotation coupling constant $c_e=39.62(11)\mathrm{MHz}$ of ${\mathrm{H}}_2^{+}(v^{+}=1,N^{+}=2)$ and the fundamental vibrational interval of ortho-${{\mathrm{D}}_2}^{+}$ [47 279 980.8(1.9) MHz]. The approach followed here in the study of molecular Rydberg-Stark states is general and broadly applicable to measurements of the fine and hyperfine structures of molecular cations.