In the edge of an $L$-mode tokamak plasma, particle transport and ion energy transport are shown to follow a strong microturbulence (SMT) scaling, whereas in the plasma core the transport is shown to follow quasilinear turbulence scaling. The dependence of diffusivity on potential fluctuation amplitude is linear in the SMT regime, and quadratic in the quasilinear regime. The transition to strong microturbulence results from larger $E\times B$ drift velocities in the edge compared to the plasma core. At these larger velocities, ions traverse the spatially correlated range faster than the stochastic evolution of the electric potential. Hence, these particles do not experience a time-stochastic field as required by the quasilinear approximation. Instead, scattering of particles in the SMT regime is caused by spatial stochasticity. In contrast, electron energy transport remains quasilinear due to decorrelations caused by collisions and fast parallel motion. Improved understanding of transport beyond quasilinear theory opens the path to more accurate modeling of transport in the tokamak plasma edge.

We study the self-hybridization between Mie modes supported by water droplets with stretching and bending vibrations in water molecules. Droplets with radii $>2.7\mathrm{\mu }\mathrm{m}$ are found to be polaritonic on the onset of the ultrastrong light-matter coupling regime. Similarly, the effect is observed in larger deuterated water droplets at lower frequencies. Our results indicate that polaritonic states are ubiquitous and occur in water droplets in mists, fogs, and clouds. This finding may have implications not only for polaritonic physics but also for aerosol and atmospheric sciences.

Experiments were performed on laser wakefield acceleration in the highly nonlinear regime. With laser powers $P<250\mathrm{TW}$ and using an initial spot size larger than the matched spot size for guiding, we were able to accelerate electrons to energies ${\mathcal{E}}_{\max }>2.5\mathrm{GeV}$, in fields exceeding $500\mathrm{GV}{\mathrm{m}}^{-1}$, with more than 80 pC of charge at energies $\mathcal{E}>1\mathrm{GeV}$. Three-dimensional particle-in-cell simulations show that using an oversized spot delays injection, avoiding beam loss as the wakefield undergoes length oscillation. This enables injected electrons to remain in the regions of highest accelerating fields and leads to a doubling of energy gain as compared to results from using half the focal length with the same laser.

A quasicrystal is an ordered but nonperiodic structure understood as a projection from a higher-dimensional periodic structure. Some physical properties of quasicrystals are different from those of conventional solids. An anomalous increase in heat capacity at high temperatures has been discussed for over two decades as a manifestation of a hidden high dimensionality of quasicrystals. A plausible candidate for this origin has been the phason, which has excitation modes originating from the additional atomic rearrangements introduced by the quasiperiodic order, which can be understood in terms of shifting a higher-dimensional lattice. However, most theoretical studies of phasons have used toy models. A theoretical study of the heat capacity of realistic quasicrystals or their approximants has yet to be conducted because of the huge computational complexity. To bridge this gap between experiment and theory, we show experiments and molecular simulations on the same material, an Al-Pd-Ru quasicrystal, and its approximants. We show that at high temperatures, aluminum atoms diffuse with discontinuouslike jumps, and the diffusion paths of the aluminum can be understood in terms of jumps corresponding to hyperatomic-fluctuations-associated atomic rearrangements of the phason degrees of freedom. It is concluded that the anomaly in the heat capacity of quasicrystals arises from the hyperatomic fluctuations that play a role in diffusive Nambu-Goldstone modes.

We explore the relationship among the magnetic ordering in real space, the resulting spin texture on the Fermi surface, and the related superconducting gap structure in noncollinear antiferromagnetic metals without spin-orbit coupling. Via a perturbative approach, we show that noncollinear magnetic ordering in a metal can generate momentum-dependent spin texture on its Fermi surface, even in the absence of spin-orbit coupling, if the metal has more than three sublattices in its magnetic unit cell. Thus, our theory naturally extends the idea of altermagnetism to noncollinear spin structures. When superconductivity is developed in a magnetic metal, as the gap-opening condition is strongly constrained by the spin texture, the nodal structure of the superconducting state is also enforced by the magnetism-induced spin texture. Taking the noncollinear antiferromagnet on the kagome lattice as a representative example, we demonstrate how the Fermi surface spin texture induced by noncollinear antiferromagnetism naturally leads to odd-parity spin-triplet superconductivity with nontrivial topological properties.

The higher-order topological phases have attracted intense attention in the past years, which reveals various intriguing topological properties. Meanwhile, the enrichment of group symmetries with projective symmetry algebras redefines the fundamentals of topological matter and makes Stiefel-Whitney (SW) classes in classical wave systems possible. Here, we report the experimental realization of higher-order topological nodal loop semimetal in an acoustic system and obtain the inherent SW topological invariants. In stark contrast to higher-order topological semimetals relating to complex vector bundles, the hinge and surface states in the SW topological phase are protected by two distinctive SW topological charges relevant to real vector bundles. Our findings push forward the studies of SW class topology in classical wave systems, which also show possibilities in robust high-$Q$-resonance-based sensing and energy harvesting.

Fidelity estimation is an important technique for evaluating prepared quantum states in noisy quantum devices. A recent theoretical work proposed a frugal approach called neural quantum fidelity estimation (NQFE) [X. Zhang et al., Phys. Rev. Lett. 127, 130503 (2021).]. While this requires a much smaller number of measurement operators than full quantum state tomography, it uses a weight-based floating measurement strategy that predetermines the top global Pauli operators that contribute the most to the fidelity and uses discrete fidelity intervals as predictions. In this Letter, we develop a measurement-fixed NQFE based on a transformer model which requires less measurement cost and can output continuous estimates of fidelity. Here we further experimentally apply the NQFE in a realistic situation using a nuclear spin quantum processor. We prepare the ground states of local Hamiltonians and arbitrary states and investigate how to estimate their fidelity with reference states, and we compare the fidelity estimation strategy with our and the original NQFE to conventional tomography. It is shown that NQFE can estimate the fidelity with comparable accuracy to the tomography approach. In the future, NQFE will become an important tool for benchmarking quantum states ahead of the advent of well-trusted fault-tolerant quantum computers.

The disagreement in the Hubble constant measured by different cosmological probes highlights the need for a better understanding of the observations or new physics. The standard siren method, a novel approach using gravitational-wave observations to determine the distance to binary mergers, has great potential to provide an independent measurement of the Hubble constant and shed light on the tension in the next few years. To realize this goal, we must thoroughly understand the sources of potential systematic bias of standard sirens. Among the known sources of systematic uncertainties, selection effects originating from electromagnetic counterpart observations of gravitational-wave sources may dominate the measurements with percent-level bias and no method to mitigate this effect is currently established. In this Letter, we develop a new formalism to mitigate the counterpart selection effect. We show that our formalism can reduce the systematic uncertainty of standard siren Hubble constant measurement to less than the statistical uncertainty with a simulated population of 200 observations ($\lesssim 1\%$) for a realistic electromagnetic emission model. We conclude with how to apply our formalism to different electromagnetic emissions and observing scenarios.

The recently reported observation of VFTS 243 is the first example of a massive black-hole binary system with negligible binary interaction following black-hole formation. The black-hole mass ($\approx 10M_{\odot }$) and near-circular orbit ($e\approx 0.02$) of VFTS 243 suggest that the progenitor star experienced complete collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence level, the natal kick velocity (mass decrement) is $\lesssim 10\mathrm{km}/\mathrm{s}$ ($\lesssim 1.0M_{\odot }$), with a full probability distribution that peaks when $\approx 0.3M_{\odot }$ were ejected, presumably in neutrinos, and the black hole experienced a natal kick of $4\mathrm{km}/\mathrm{s}$. The neutrino-emission asymmetry is $\lesssim 4\%$, with best fit values of $\sim 0–0.2\%$. Such a small neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.

We discuss relations between closed and open string amplitudes at one loop. While at tree level these relations are known as Kawai-Lewellen-Tye (KLT) and/or double copy relations, here we investigate how such relations are manifested at one loop. Although, we find examples of one-loop closed string amplitudes that can strikingly be written as sum over squares of one-loop open string amplitudes, generically the one-loop closed string amplitudes assume a form reminiscent of the one-loop double copy structure of gravitational amplitudes involving a loop momentum. This double copy structure represents the one-loop generalization of the KLT relations.

We develop a novel amplitude bootstrap technique manifestly free of unphysical poles for classically spinning particles interacting with gravitons utilizing only the double-copy and physical factorization limits. Combined with nonfactorization polynomial contact contributions from physical data for Kerr black holes, we can address high-spin-order covariant gravitational Compton amplitudes, identifying a pattern for the amplitude that we believe could extend to all orders in spin. Finally, we outline applications and outstanding questions.

We report the measurement of the inclusive cross sections for $e^{+}{e}^{-}\to \mathrm{nOCH}$ (where nOCH denotes non-open charm hadrons) with improved precision at center-of-mass (c.m.) energies from 3.645 to 3.871 GeV. We observe three resonances: $\mathcal{R}(3760)$, $\mathcal{R}(3780)$, and $\mathcal{R}(3810)$ with significances of $8.1\sigma$, $13.7\sigma$, and $8.8\sigma$, respectively. The $\mathcal{R}(3810)$ state is observed for the first time, while the $\mathcal{R}(3760)$ and $\mathcal{R}(3780)$ states are observed for the first time in the nOCH cross sections. Two sets of resonance parameters describe the energy-dependent line shape of the cross sections well. In set I [set II], the $\mathcal{R}(3810)$ state has mass ($3805.7\pm 1.1\pm 2.7$) $[(3805.7\pm 1.1\pm 2.7)]\mathrm{MeV}/c^2$, total width ($11.6\pm 2.9\pm 1.9$) $[(11.5\pm 2.8\pm 1.9)]\mathrm{MeV}$, and an electronic width multiplied by the nOCH decay branching fraction of ($10.9\pm 3.8\pm 2.5$) $[(11.0\pm 3.4\pm 2.5)]\mathrm{eV}$. In addition, we measure the branching fractions $\mathcal{B}[\mathcal{R}(3760)\to \mathrm{nOCH}]=(25.2\pm 16.1\pm 30.4)\%[(6.4\pm 4.8\pm 7.7)\%]$ and $\mathcal{B}[\mathcal{R}(3780)\to \mathrm{nOCH}]=(12.3\pm 6.6\pm 8.3)\%[(10.4\pm 4.8\pm 7.0)\%]$ for the first time. The $\mathcal{R}(3760)$ state can be interpreted as an open-charm (OC) molecular state, but containing a simple four-quark state component. The $\mathcal{R}(3810)$ state can be interpreted as a hadrocharmonium state.

We investigate the transmission of vector beams, correlated in their polarization and spatial degrees of freedom, through cold atoms in the presence of a transverse magnetic coupling field. The resulting phase-dependent dynamics allow us to imprint the spatially varying polarization of a vector beam onto atomic spin polarizations, thereby establishing a direct link between optical space-polarization correlations and atomic-state interference. We find that the resulting absorption profiles show interference fringes whose modulation strength is given by the squared concurrence of the vector beam, letting us identify optical concurrence from a single absorption image. We expect impact across a diverse range of applications, including spintronics, quantum memories, metrology, and clocks.

The gapped symmetric phase of the Affleck-Kennedy-Lieb-Tasaki model exhibits fractionalized spins at the ends of an open chain. We show that breaking SU(2) symmetry and applying a global spin-lowering dissipator achieves synchronization of these fractionalized spins. Additional local dissipators ensure convergence to the ground state manifold. In order to understand which aspects of this synchronization are robust within the entire Haldane-gap phase, we reduce the biquadratic term, which eliminates the need for an external field but destabilizes synchronization. Within the ground state subspace, stability is regained using only the global lowering dissipator. These results demonstrate that fractionalized degrees of freedom can be synchronized in extended systems with a significant degree of robustness arising from topological protection. A direct consequence is that permutation symmetries are not required for the dynamics to be synchronized, representing a clear advantage of topological synchronization compared to synchronization induced by permutation symmetries.

We study a family of higher-twist Regge trajectories in $\mathcal{N}=4$ supersymmetric Yang-Mills theory using the quantum spectral curve. We explore the many-sheeted Riemann surface connecting the different trajectories and show the interplay between the degenerate nonlocal operators known as (near-)horizontal trajectories. We resolve their degeneracy analytically by computing the first nontrivial order of the Regge intercept at weak coupling, which exhibits new behavior: It depends linearly on the coupling. This is consistent with our numerics, which interpolate all the way to strong coupling.