External magnetic fields reduce diffusion of carbon in BCC iron, but the physical mechanism is not understood. Using DFT calculations with magnetic moments sampled from a Heisenberg model, we calculate diffusivities of carbon in iron at high temperatures and with field. Our model reproduces the measured suppression of diffusivity from field. We find that increasing magnetic disorder flattens the electron density of states compared with the ferromagnetic case, which distorts the octahedral cages around carbon, lowering the activation barrier to diffusion; an applied field reverses these trends.

Quantum technologies have been widely recognized as unprecedented opportunities for ultrahigh precision metrology. As a celebrated example in modern quantum optics, the Hong-Ou-Mandel (HOM) interferometer is well known for enabling temporal resolutions on the attosecond scale. However, the relatively low Fisher information per trial in ordinary HOM measurements typically necessitates tens of thousands of repetitions to achieve such precision. Here, we propose and demonstrate a sample-half-inserted HOM (SHOM) interferometer, which enhances the Fisher information by 5 orders of magnitude in a single interference event. By introducing an asymmetric photon-sample interaction, the SHOM configuration produces a distinctive dip-bump-dip interference structure, converting what was previously viewed as an artifact into a helpful metrological resource. Experimentally, we measured the optical path difference with an average precision of 4.09 nm (13.63 as) and an average accuracy of 1.22 nm (4.07 as) using $O({10}^7)$ photons. Our results establish SHOM interferometry as an efficient phase-insensitive approach, not only paving the way toward practical quantum-enhanced thickness measurement for transparent materials, but also serving as an elegant strategy to improve the performance of various quantum devices.

We discuss a universal nonequilibrium enhancement of long-wavelength Goldstone bosons induced by quenches to the broken phase in Model G—the dynamical universality class of an $O(4)$ antiferromagnet and the chiral phase transition in QCD. Scaling arguments for the coarsening dynamics describing the formation of the chiral condensate predict a parametric enhancement in the infrared spectra of Goldstone bosons, a prediction confirmed by stochastic simulations of the transition. The details of the enhancement are determined by the nonlinear dynamics of a superfluid effective theory, which is a limit of Model G reflecting the broken $O(4)$ symmetry. Our results translate to a parametric enhancement of low-momentum pions in heavy-ion collisions at the LHC, which are underpredicted in current hydrodynamic models without critical dynamics.

Recent studies have completed the $A=16$ isospin quintets for states with $J^{\pi }=0^{+}$ and $2^{+}$. The dependence of their masses as a function of isospin projection shows evidence for deviations from quadratic behavior indicating isospin violation beyond the expectation from two-body forces. The deviation is most pronounced for the $2^{+}$ states. Predictions from the shell model embedded in the continuum allow us to explain that this isospin violation is associated with a modification of the nuclear structure due to the open-quantum-system nature of the proton-rich members of the quintet. In particular, the $0^{+}$ and $2^{+}$ states in ${}^{16}\mathrm{Ne}$ and the $2^{+}$ state in ${}^{16}\mathrm{F}$ are threshold resonances located just above a proton-decay threshold where $s$-wave coupling to the continuum is expected. The measured deviations of these threshold states from the quadratic behavior of the remaining members of the multiplets makes it possible to obtain information on the magnitude and the energy dependence of the continuum-coupling energy correction. Continuum coupling is also indicated for the ground state of ${}^8\mathrm{C}$, but this time through $p$-wave coupling.

Electron quantum optics explores coherent single-electron charge pulse propagation in electronic nanoscale circuits akin to tabletop photon setups. While past experiments focused on normal-state conductors, incorporating superconductors holds promise for exploiting the electron-hole degree of freedom in quantum sensing applications and quantum information processing. Here, we propose and analyze an on-demand and tunable mechanism for converting single-electron pulses into holes through Andreev processes on a superconductor. We develop a Floquet-Nambu scattering formalism to demonstrate the dynamic conversion of charge pulses and the controllable generation of coherent electron-hole superpositions through interferometric magnetic flux control based on the chiral edge states of a quantum Hall sample. Our discussion covers optimal conditions in realistic scenarios, affirming the feasibility of our proposal with current technology.

We study the THz-driven spin dynamics of the canted antiferromagnet ${\mathrm{ErFeO}}_3$ across the spin reorientation temperatures 80–90 K. The amplitudes of the soft antiferromagnetic resonance mode are drastically enhanced by an order of magnitude in the middle of the spin reorientation temperature interval in ${\mathrm{ErFeO}}_3$. Conversely, in the phenomenologically similar magnetic system of ${\mathrm{TmFeO}}_3$, exhibiting the same phase transitions at very similar temperatures, this enhancement is not observed. We attribute this enhancement in ${\mathrm{ErFeO}}_3$ to the dynamic interaction of the iron $3d$ spins with the rare-earth $4f$-electronic transitions of the Kramers ${\mathrm{Er}}^{3+}$ ions. We confirm this interpretation by comparing measurements on ${\mathrm{TmFeO}}_3$, where the non-Kramers ${\mathrm{Tm}}^{3+}$ electronic states do not strongly couple to the antiferromagnetic mode. Thus, our results indicate that the character of the microscopic electronic $4f$ states may drastically alter the ultrafast magnetic response in the materials with otherwise very similar static magnetic properties and phase diagrams.

We study the gyrotropic magnetic effect (GME), the low-frequency limit of optical gyrotropy, in metals and semimetals coupled to chiral spin textures. In these systems, the chiral spin texture which lacks inversion symmetry can imprint itself upon the electronic structure through Hund’s coupling, leading to novel low-frequency optical activity. Using perturbation theory and numerical diagonalization of both relativistic and nonrelativistic models of conduction electrons coupled to spin textures, we analyze how the GME manifests in both single-$q$ and multi-$q$ textures. Analytical expressions for the rotatory power are derived in terms of universal scaling functions. Estimates based on realistic material parameters reveal an experimentally viable range of values for the rotatory power. The GME arises from the orbital and spin magnetic moments of conduction electrons, with the orbital part closely tied to Berry curvature and playing a significant role in relativistic metals but not so in nonrelativistic metals where there is no inherent Berry curvature. The spin contribution to the GME can be significant in nonrelativistic metals with a large Fermi energy. Our Letter shows that the GME can be a sensitive probe of magnetic chirality and symmetry breaking in metallic chiral magnets.

The spontaneous formation of knots in semiflexible filaments is not only a fundamental aspect of polymer physics but also plays a crucial role in biological systems, where DNA, proteins, and other macromolecules exhibit complex knotting behavior. From Brownian dynamics simulations, we examine the sedimentation of semiflexible filaments under strong fields. We show how hydrodynamics induce knotting dynamics and stabilization into tight knotted configurations. Controlling the knotting of semiflexible filaments presents opportunities to create materials with unique structural properties.

We observe entanglement between collective excitations of a Bose-Einstein condensate in a configuration analogous to particle production during the preheating phase of the early Universe. In our setup, the oscillation of the inflaton field is mimicked by the transverse breathing mode of a cigar-shaped condensate, which parametrically excites longitudinal quasiparticles with opposite momenta. After a short modulation period, we observe entanglement of these pairs that reveals the role played by vacuum fluctuations in seeding the parametric growth, confirming the quantum origin of the excitations. As the system continues to evolve, we observe a decrease in correlations and a disappearance of nonclassical features. These point toward future experimental probes of the late-time nonlinear regime where further analogies can be drawn with reheating, i.e., the thermalization of the postinflationary Universe.

We investigate whether collider experiments can reach the quantum limit of precision, defined by the quantum Fisher information (QFI), using only classical observables such as particle momenta. As a case study, we focus on the ${\tau }^{+}{\tau }^{-}$ system and the decay channel $\tau \to \pi \nu$, which offers maximal spin-analyzing power and renders the decay a projective measurement. We develop a general framework to determine when collider measurements can, in principle, saturate the QFI in an entangled biparticle system, and this framework extends naturally to other such systems. Within this framework, QFI saturation occurs if and only if the symmetric logarithmic derivative (SLD) commutes with a complete set of orthonormal separable projectors associated with collider-accessible measurements. This separability condition, reflecting the independence of decay amplitudes, is highly nontrivial. To meet this condition, a key requirement is that the spin density matrix be rank deficient, allowing the SLD sufficient freedom. We show that the classical Fisher information asymptotically saturates the QFI for magnetic dipole moments and $CP$-violating Higgs interactions in selected phase-space regions, but not for electric dipole moments. These results bridge quantum metrology and collider physics, providing a systematic method to identify quantum-optimal sensitivity in collider experiments.

We report a systematic procedure to engineer the van der Waals force between levitated nanoparticles in high vacuum by setting them into a fast rotation. By tuning the rotation frequency close to a polaritonic resonance, we can significantly enhance the van der Waals attraction. In addition, for frequencies slightly beyond resonance, rotation can change the nature of the interaction from attraction to repulsion. Rotational Doppler shifts effectively modify the frequency-dependent polarizability of the nanoparticles, thereby reshaping their mutual interaction. As a concrete and realistic example, we consider spinning barium strontium titanate nanoparticles at state-of-the-art rotation frequencies and demonstrate a modification of the force within the sensitivity of current experimental techniques.

Bound states in the continuum (BICs), exotic resonances with infinite lifetimes embedded in radiation continua, have long been studied for their topological robustness. Meanwhile, nodal lines—degenerate momentum-space manifolds in photonic and electronic band structures—represent another cornerstone of topological physics. Here, we unveil a profound connection between these phenomena by demonstrating that BICs act as topological chain points pinning together nodal lines within scattering-matrix eigenvalue space. Through scattering-matrix eigenphase analysis, we show that BICs enforce robust nodal chain formation in frequency-momentum space, even when system symmetries are broken. Experimentally, we validate this mechanism using a metasurface platform, where angle-resolved phase measurements reveal nodal lines intersecting at a symmetry-protected BIC. Strikingly, breaking mirror symmetry preserves the BIC-pinned nodal chain, highlighting its origin in the intrinsic singular scattering nature of BICs rather than conventional symmetry protection. This Letter establishes scattering matrices as a natural framework to unify BICs and nodal topology, offering new pathways to engineer topologically robust photonic systems resilient to perturbations. Our findings bridge fundamental concepts in topological photonics and open avenues for applications in metasurfaces and light-matter interaction control.

Recent advances in materials informatics have expanded the number of synthesizable materials. However, screening promising candidates, such as semiconductors, based on defect properties remains challenging. This is primarily due to the lack of a general framework for predicting defect formation energies in multiple charge states from structural data. In this Letter, we present a protocol, namely data normalization, Fermi level alignment, and treatment of perturbed host states, and validate it by accurately predicting oxygen vacancy formation energies in three charge states using a single model. We also introduce a joint machine-learning model that integrates defect formation energies and band-edge predictions for virtual screening. Using this framework, we identify 89 hole-dopable oxides, including BaGaSbO, a potential ambipolar photovoltaic material. Our protocol is expected to become a standard approach for machine-learning studies on point defect formation energies.

Field theories of the composite-fermion (CF) metal model it as a Fermi sea of composite fermions coupled to an emergent gauge field. Within a random phase approximation, these theories predict that the Landau damping of the gauge field resulting from its coupling to the low-energy, long-wavelength CF particle-hole excitations modifies the electrons’ density-density correlation function related to the static structure factor $S(q)$ at wave vector $q$. This produces a nonanalytic correction $\propto q^3\ln q$ to $S(q)$ (with the magnetic length ${\ell }_B=1$). Thanks to the recently developed quaternion formulation for Jain-Kamilla projection of CF wave functions, the evaluation of $S(q)$ from the accurate microscopic theory of composite fermions has now become possible for systems containing as many as $N=900$ CFs, which enables a reliable determination of the small-$q$ behavior of $S(q)$. We study CF metals corresponding to electrons at Landau level filling factors $\nu =1/2$ and $1/4$, and for completeness, also of bosons at $\nu =1$ and $1/3$. In the $q\to 0$ limit, our microscopic calculation reveals a $q^3$ term in $S(q)$ of the CF metals rather than $q^3\ln q$. This behavior is well predicted by a model of a noninteracting Fermi sea of dipolar CFs, which also obtains its coefficient accurately.

The recent realization of Hofstadter spectra and fractional Chern insulators in moiré materials has introduced a new ingredient, a periodic lattice potential, to the study of quantum Hall phases. While the fractionalized states in moiré systems are expected to be in the same universality class as their counterparts in Landau levels, the periodic potential can have qualitative and quantitative effects on physical observables. Here, we examine how the magnetoroton collective modes of fractional quantum Hall (FQH) states are altered by external periodic potentials. Employing a single-mode approximation, we derive an effective Hamiltonian for the low-energy neutral excitations expressed in terms of three-point density correlation functions, which are computed using Monte Carlo. Our analysis is applicable to FQH states in graphene with a hexagonal boron nitride (hBN) substrate and also to fractional Chern insulator (FCI) states in twisted ${\mathrm{MoTe}}_2$ bilayers. We predict experimentally testable trends in the THz absorption characteristics of FCI and FQH states and estimate the external potential strength at which a soft-mode phase transition occurs between FQH and charge density wave states.

Synchronization of activity among myocytes constituting vital organs, e.g., the heart, is crucial for physiological functions. Self-organized coordination in such heterogeneous ensemble of excitable and oscillatory cells is therefore of clinical importance. We show by varying the strength of intercellular coupling and the electrophysiological diversity, a wide range of collective behavior emerges including clusters of synchronized activity. Strikingly, stretch-activated currents allow waves of mechanical deformation to alter the activity of neighboring cells, promoting robust global coherence.