We show that the orbital angular momentum (OAM) of electrons is dynamically induced by circularly polarized phonons. The induced OAM originates from the adiabatic evolution in which electrons acquire Berry phase formulated in terms of the Berry curvature encoded in phonon displacement space. By introducing a tight-binding model with $p$ orbitals on a honeycomb lattice, we show a microscopic picture that ionic rotations modulate orbital overlaps of electrons, and calculate the generated OAM, whose sign depends on phonon chirality. We then construct an effective model for valley phonons with different phonon pseudoangular momenta and identity their distinct intervalley-scattering channels. Our model obeys the selection rule between phonons and electrons with the orbital degree of freedom. Extending this framework to $d$-orbital electrons, our model is applied to describe the induced OAM in monolayer transition metal dichalcogenides. Our results reveal a direct orbital generation mechanism that emerges even in materials with weak spin-orbital coupling, opening a new promising way for orbitronics applications.

We theoretically investigate orbital accumulation driven by chiral phonons via orbital-dependent electron-lattice coupling. We derive a formula for the orbital accumulation induced by classical lattice dynamics or nonequilibrium phonons, emphasizing the rectified second-order response of the orbital moment to lattice displacement. We show that chiral phonons primarily couple to orbital quadrupole moments and that static orbital dipole accumulation can be generated at second order in the lattice displacement. Our Letter provides a useful method for generating orbital accumulation without using spin-orbit interactions and suggests a strategy to boost its magnitude by harnessing band structure hot spots associated with orbital degeneracy.

The primordial power spectrum of matter density perturbations contains highly valuable information about new fundamental physics, in particular cosmological inflation, but is only very weakly constrained observationally for small cosmological scales $k\gtrsim 3{\mathrm{Mpc}}^{-1}$. We derive novel constraints, ${\mathcal{P}}_{\mathcal{R}}(k)\lesssim 5\times {10}^{-6}$ over a large range of such scales, from the formation of ultracompact minihalos in the early universe. Unlike most existing constraints of this type, our results do not rest on the assumption that dark matter can annihilate into ordinary matter.

The first search for the lepton-flavor violating decays $B^{+}\to {\pi }^{+}{\mu }^{\pm }{e}^{\mp }$ in proton-proton collisions is presented, using data collected by the LHCb experiment between 2011 and 2018, corresponding to an integrated luminosity of $9{\mathrm{fb}}^{-1}$. No significant signal is observed and an upper limit on the branching fraction is set at $\mathcal{B}(B^{+}\to {\pi }^{+}{\mu }^{\pm }{e}^{\mp })<1.8\times {10}^{-9}$ at the 90% confidence level, 2 orders of magnitude more restrictive than the most stringent upper limit to date. This is the first constraint on lepton-flavor violating $b\to d$ quark transitions at the LHC and also sets the most stringent upper limits to date on $b\to d{\mu }^{\pm }{e}^{\mp }$ transitions. Limits on left-handed and scalar scenarios beyond the standard model are also reported.

The precise quantification of fusion suppression in heavy-projectile induced reactions is obscured by dominant noncompound processes, limited data, and uncertain models. Mass-total kinetic energy (MTKE) distributions for the reaction ${}^{54}\mathrm{Cr}+{}^{209}\mathrm{Bi}$ were measured at three beam energies, $E_{\mathrm{beam}}=261$, 271, and 278 MeV. The fission fragments were detected using the newly developed TOSCA spectrometer setup. This Letter reveals, for the first time, two asymmetric mass modes at $\sim 80\mathrm{u}$ (complementary $\sim 183\mathrm{u}$), and $\sim 105$ u (complementary $\sim 158\mathrm{u}$), likely associated with the spherical $N=50$ shell and the deformed $Z\approx 42/N\approx 94$ shells, respectively. At the lowest energy, the symmetric mode exhibits a narrow, super-short-like width and high correlated TKE caused likely by $Z=50$, $N=82$ shells. The fusion probability (${\mathrm{P}}_{\mathrm{CN}}$) from multi-Gaussian fits to gated mass (and TKE) distributions using a refined tail-subtraction approach to remove the quasifission background remains robust despite model dependence. $P_{\mathrm{CN}}$ peaks near the barrier and decreases on either side, with a slower decrease at the above-barrier energy, differing from the sub-barrier fusion enhancement reported in [Phys. Rev. Lett. 122, 232503 (2019)] and indicating an open question for further study.

Lagrangian measurements of tracer particle dispersion in stratified turbulence are presented from a large-scale experiment achieving both high buoyancy Reynolds numbers and low Froude numbers—a regime characteristic of oceanic conditions. Stratification has a pronounced effect on the vertical particle dispersion, which is observed to be constrained to distances on the order of the buoyancy scale $w_{\mathrm{std}}/N$, where $w_{\mathrm{std}}$ is the standard deviation of the vertical velocity and $N$ is the Brunt-Väisälä frequency. As expected in strongly nonlinear, stratified turbulence, the frequency spectrum of the Lagrangian velocity becomes isotropic at frequencies higher than $N$. The spectral decay follows a $1/f^3$ scaling, which contrasts with the $1/f^2$ behavior typical of homogeneous isotropic turbulence. At time scales corresponding to internal waves, the statistics of velocity increments remain Gaussian, consistent with the weakly nonlinear regime of wave turbulence. At smaller scales, however, the flow exhibits strongly non-Gaussian statistics, indicative of fully nonlinear turbulent dynamics driven by wave breaking.

Elemental superconductors serve as essential model systems because their compositional simplicity enables fundamental mechanisms to be probed with minimal extrinsic complexity. Their superconducting transition temperatures ($T_{\mathrm{c}}$), however, are generally low, with the notable exception of scandium, which reaches 36 K at 260 GPa—the highest $T_{\mathrm{c}}$ reported for any elemental material. Although bulk boron is semiconducting at ambient pressure, two-dimensional boron monolayers (borophenes) exhibit rich structural polymorphism, and several phases are predicted to be superconducting with $T_{\mathrm{c}}$ values of 3.7–27.6 K, limited by relatively weak electron-phonon coupling. Here, we show that borophene bilayers, stabilized by interlayer B-B bonds, unexpectedly enhance the electronic density of states near the Fermi level and promote cooperative electron-phonon interactions, in which $p_{\text{x},\text{y}}$ states couple to in-plane phonons and $p_{\text{z}}$ states to out-of-plane modes. A high-throughput search of more than 9000 bilayer configurations identifies an $AA$-stacked, low-energy $v_{1/7}$ structure with $T_{\mathrm{c}}\approx 68\mathrm{K}$, setting a new record for elemental superconductivity.

We investigate Bloch oscillations in a lattice system featuring a momentum gap ($k$ gap), where in-gap modes exhibit exponential growth or decay. We demonstrate that the interplay of $k$-gap amplification, attenuation, and interband interference gives rise to a critical regime, where the wave packet alternates between the growing and decaying channels, forming a period-doubled oscillation with globally stable intensity under critical driving—a phenomenon we term self-balanced Bloch oscillations. This self-balance arises from phase-accumulation-dependent selection of the $k$-gap channels during band traversal, as confirmed by numerical simulations and spectral analysis. This mechanism, broadly applicable to $k$-gap-engineered systems, not only enables intrinsic stabilization beyond mere amplification but also offers a powerful route for controlling wave propagation in time-varying media and non-Hermitian physics.

Altermagnetic materials, especially ${\mathrm{RuO}}_2$, have recently attracted considerable attention for their unique magnetic properties and energy-efficient spintronic applications. However, recent experimental studies have reported highly conflicting signatures regarding altermagnetic spin splitting and charge-spin interconversion (CSI) in ${\mathrm{RuO}}_2$. While some experiments link efficient CSI to nonrelativistic altermagnetic spin-splitting effects, others observe large CSI signals in non-spin-splitting ${\mathrm{RuO}}_2$, which are instead explained by relativistic inverse spin Hall effects. In this Letter, based on first-principles calculations, we reveal that these controversial experimental results originate from a phase-dependent coexistence and relative dominance of the orbital Hall effect (OHE) and spin Hall effect (SHE) in ${\mathrm{RuO}}_2$. We systematically investigate the OHE and SHE in both altermagnetic and nonmagnetic phases of ${\mathrm{RuO}}_2$. Our results show that the altermagnetic state hosts a giant OHE that exceeds the SHE by 2 orders of magnitude and carries an opposite sign. This dominant OHE can generate experimentally observed “SHE-like” voltages through orbital-to-spin conversion, explaining previously reported altermagnetic CSI signals. In contrast, OHE of nonmagnetic ${\mathrm{RuO}}_2$ is suppressed and a large relativistic SHE emerges, in agreement with recent angle-resolved photoemission and spin-pumping experiments. Finally, we demonstrate that the coexistence of OHE and SHE is tunable via chemical doping, enabling on-demand modulation of CSI in ${\mathrm{RuO}}_2$. Our work provides a new physical mechanism for understanding CSI in ${\mathrm{RuO}}_2$ and highlights the central role of orbital transport.

Guiding electromagnetic waves far below the diffraction limit usually produce severe propagation loss because the field is forced into dissipative material boundaries. We discover that a metal-Epsilon-near-zero (ENZ) interface can support an optical antiskin effect, significantly reducing propagation loss by orders of magnitude while preserving subdiffraction confinement. In the proposed metal-ENZ-high-index-air (MEHA) line, a nanoscale ENZ shell suppresses the lossy surface-bound mode and pushes it above a dielectric-confined mode in the modal hierarchy, allowing the low-loss volume mode to serve as the fundamental guided state. Realistic $\mathrm{Ag}/\mathrm{GaAs}/\mathrm{Si}$ MEHA lines support a mode-reordered terahertz band with robust bend transmission. This boundary-engineering mechanism establishes a compact, bend-tolerant, low-loss metallic-waveguide platform for high-density terahertz and midinfrared integration and localized wave delivery.

Stretched exponential distributions of nonequilibrium steady-state fluctuations are ubiquitous in living and nonliving systems alike, yet their microscopic origins have remained elusive. In this Letter, we track the motion of three types of vesicles across different cell types and find that their trajectories undergo random transitions between directed runs (on state) and diffusionlike jiggling (off state) in the highly dynamic, heterogeneous cytoplasm. The dwell times in these two states follow a stretched exponential distribution, which arises from a continuous weighted sum of simple exponential distributions that align with the unbinding kinetics of motor proteins traversing the cytoskeletal filaments in vitro. Our findings illuminate the profound connection between stretched exponential statistics and dynamic heterogeneity, shedding new light on the complex spatiotemporal landscape of cargo transport within cells.

We argue that the presence of any exact U(1) higher-form symmetry, under mild assumptions, presents a fundamental obstruction to ergodicity under unitary dynamics in lattice systems with local interactions and finite on-site Hilbert space dimension. Focusing on the two-dimensional case, we show that such systems necessarily exhibit Hilbert space fragmentation and explicitly construct Krylov sectors whose number scales exponentially with system size. While these sectors cannot be distinguished by symmetry quantum numbers, we identify the emergent integrals of motion that characterize them. Our symmetry-based approach is insensitive to details of the Hamiltonian and the lattice, providing a systematic explanation for ergodicity breaking in a range of systems, including quantum link models.

The evolution of an isolated quantum system inevitably exhibits recurrence: the state returns to the vicinity of its initial condition after finite time. Despite its fundamental nature, a rigorous quantitative understanding of recurrence has been lacking. We establish upper bounds on the recurrence time, $t_{\mathrm{rec}}\lesssim t_{\mathrm{exit}}(\epsilon )(1/\epsilon {)}^d$, where $d$ is the Hilbert-space dimension, $\epsilon$ the neighborhood size, and $t_{\mathrm{exit}}(\epsilon )$ the escape time from this neighborhood. For pure states evolving under a Hamiltonian $H$, estimating $t_{\mathrm{exit}}$ is equivalent to an inverse quantum speed limit problem: finding upper bounds on the time a time-evolved state ${\psi }_t$ needs to depart from the $\epsilon$ vicinity of the initial state ${\psi }_0$. We provide a partial solution, showing that under mild assumptions $t_{\mathrm{exit}}(\epsilon )\approx \epsilon /\sqrt{\mathrm{\Delta }(H^2)}$, with $\mathrm{\Delta }(H^2)$ the Hamiltonian variance in ${\psi }_0$. We show that our upper bound on $t_{\mathrm{rec}}$ is generically saturated for random Hamiltonians. Finally, we analyze the impact of coherence of the initial state in the eigenbasis of $H$ on recurrence behavior.

The performance of quantum annealing for combinatorial optimization is fundamentally limited by the minimum energy gap $\mathrm{\Delta }$ encountered at quantum phase transitions. We investigate the scaling of $\mathrm{\Delta }$ with system size $N$ for two paradigmatic quantum spin-glass models: the two-dimensional Edwards-Anderson (2D-EA) and the all-to-all Sherrington-Kirkpatrick (SK) models. Utilizing a newly proposed unbiased energy-gap estimator for continuous-time projection quantum Monte Carlo simulations, complemented by high-performance sparse eigenvalue solvers, we characterize the gap distributions across disorder realizations. It is found that, in the 2D-EA case, the inverse-gap distribution develops a fat tail with infinite variance as $N$ increases. This indicates that the unfavorable superalgebraic scaling of $\mathrm{\Delta }$, recently reported for binary couplings [M. Bernaschi et al., The quantum transition of the two-dimensional Ising spin glass, Nature (London) 631, 749 (2024)], persists for the Gaussian disorder considered here, pointing to a universal feature of 2D spin glasses. Conversely, the SK model retains a finite-variance distribution, with the disorder-averaged gap following a rather slow power law, close to $\mathrm{\Delta }\propto N^{-1/3}$. This finding provides a promising outlook for the potential efficiency of quantum annealers for optimization problems with dense connectivity.