In bilayers consisting of Pd and yttrium iron garnet (${\mathrm{Y}}_3{\mathrm{Fe}}_5{\mathrm{O}}_{12}$ or YIG), we observe vanishingly small room-temperature conventional anisotropic magnetoresistance but large new magnetoresistance that is similar to the spin Hall magnetoresistance previously reported in Pt-YIG bilayers. We report a temperature dependence study of the two magnetoresistance effects in Pt-YIG bilayers. As the temperature is decreased, the new magnetoresistance shows a peak, whereas the anisotropic magnetoresistance effect starts to appear and increases monotonically. We find that the magnetoresistance peak shifts to lower temperatures in thicker Pd samples, a feature characteristic of the spin current effect. The distinct temperature dependence reveals fundamentally different mechanisms responsible for the two effects in such hybrid structures.

We discuss multipulse magnetometry that exploits all three magnetic sublevels of the $S=1$ nitrogen-vacancy center in diamond to achieve enhanced magnetic field sensitivity. Based on dual frequency microwave pulsing, the scheme is twice as sensitive to ac magnetic fields as conventional two-level magnetometry. We derive the spin evolution operator for dual frequency microwave excitation and show its effectiveness for double-quantum state swaps. Using multipulse sequences of up to 128 pulses under optimized conditions, we show enhancement of the SNR by up to a factor of 2 in detecting NMR statistical signals, with a $4\times$ enhancement theoretically possible.

It is studied how the $\alpha$ cluster degrees of freedom, such as $\alpha$ clustering configurations close to the $\alpha$ decay threshold in ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$, including the linear chain, triangle, square, kite, and tetrahedron, affect nuclear collective vibrations with a microscopic dynamical approach, which can describe properties of nuclear ground states well across the nuclide chart and reproduce the standard giant dipole resonance (GDR) of ${}^{16}\mathrm{O}$ quite nicely. It is found that the GDR spectrum is highly fragmented into several apparent peaks due to the $\alpha$ structure. The different $\alpha$ cluster configurations in ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ have corresponding characteristic spectra of GDR. The number and centroid energies of peaks in the GDR spectra can be reasonably explained by the geometrical and dynamical symmetries of $\alpha$ clustering configurations. Therefore, the GDR can be regarded as a very effective probe to diagnose the different $\alpha$ cluster configurations in light nuclei.

The mass flux, $F$, carried by as-grown solid ${}^4\mathrm{He}$ in the range 25.6–26.3 bar rises with falling temperature, and at a concentration-dependent temperature, $T_d$, the flux decreases sharply within a few mK. We study $F$ as a function of ${}^3\mathrm{He}$ impurity concentration, $\chi$. We find that $T_d$ is an increasing function of increasing $\chi$. At temperatures above $T_d$ the flux has a universal temperature dependence and the flux terminates in a narrow window near a characteristic temperature $T_h\approx 625\mathrm{mK}$, which is independent of $\chi$.

We establish several relations between quantum error correction (QEC) and tensor network (TN) methods of quantum many-body physics. We exhibit correspondences between well-known families of QEC codes and TNs, and demonstrate a formal equivalence between decoding a QEC code and contracting a TN. We build on this equivalence to propose a new family of quantum codes and decoding algorithms that generalize and improve upon quantum polar codes and successive cancellation decoding in a natural way.

Privacy is a fundamental feature of quantum mechanics. A coherently transmitted quantum state is inherently private. Remarkably, coherent quantum communication is not a prerequisite for privacy: there are quantum channels that are too noisy to transmit any quantum information reliably that can nevertheless send private classical information. Here, we ask how much private classical information a channel can transmit if it has little quantum capacity. We present a class of channels ${\mathcal{N}}_d$ with input dimension $d^2$, quantum capacity $Q({\mathcal{N}}_d)\le 1$, and private capacity $P({\mathcal{N}}_d)=\log d$. These channels asymptotically saturate an interesting inequality $P(\mathcal{N})\le (1/2)[\log d_A+Q(\mathcal{N})]$ for any channel $\mathcal{N}$ with input dimension $d_A$ and capture the essence of privacy stripped of the confounding influence of coherence.

Motivated by recent experiments with ultracold matter, we derive a new bound on the propagation of information in $D$-dimensional lattice models exhibiting $1/r^{\alpha }$ interactions with $\alpha >D$. The bound contains two terms: One accounts for the short-ranged part of the interactions, giving rise to a bounded velocity and reflecting the persistence of locality out to intermediate distances, whereas the other contributes a power-law decay at longer distances. We demonstrate that these two contributions not only bound but, except at long times, qualitatively reproduce the short- and long-distance dynamical behavior following a local quench in an $XY$ chain and a transverse-field Ising chain. In addition to describing dynamics in numerous intractable long-range interacting lattice models, our results can be experimentally verified in a variety of ultracold-atomic and solid-state systems.

We consider a discrete model in which a tracer performs a random walk biased by an external force, in a dense bath of particles performing symmetric random walks constrained by hard-core interactions. We reveal the emergence of a striking velocity anomaly in confined geometries: in quasi-1D systems such as stripes or capillaries, the velocity of the tracer displays a long-lived plateau before ultimately dropping to a lower value. We develop an analytical solution that quantitatively accounts for this intriguing behavior. Our analysis suggests that such a velocity anomaly could be a generic feature of driven dynamics in quasi-1D crowded systems.

We propose 10 highly charged ions as candidates for the development of next generation atomic clocks, quantum information, and search for $\alpha$ variation. They have long-lived metastable states with transition wavelengths to the ground state between 170–3000 nm, relatively simple electronic structure, stable isotopes, and high sensitivity to $\alpha$ variation (e.g., ${\mathrm{Sm}}^{14+}$, ${\mathrm{Pr}}^{10+}$, ${\mathrm{Sm}}^{13+}$, ${\mathrm{Nd}}^{10+}$). We predict their properties crucial for the experimental exploration and highlight particularly attractive systems for these applications.

Recent in situ observations of interplanetary coronal mass ejections (ICMEs) found signatures of reconnection exhausts in their interior or trailing edge. Whereas reconnection on the leading edge of an ICME would indicate an interaction with the coronal or interplanetary environment, this result suggests that the internal magnetic field reconnects with itself. In light of this data, we consider the stability properties of flux ropes first developed in the context of astrophysics, then further elaborated upon in the context of reversed field pinches (RFPs). It was shown that the lowest energy state of a flux rope corresponds to $\mathbf{\nabla }\times \mathbf{B}=\lambda \mathbf{B}$ with $\lambda$ a constant, the so-called Taylor state. Variations from this state will result in the magnetic field trying to reorient itself into the Taylor state solution, subject to the constraints that the toroidal flux and magnetic helicity are invariant. In reversed field pinches, this relaxation is mediated by the reconnection of the magnetic field, resulting in a sawtooth crash. If we likewise treat the ICME as a flux rope, any deviation from the Taylor state will result in reconnection within the interior of the flux tube, in agreement with the observations by Gosling et al. Such a departure from the Taylor state takes place as the flux tube cross section expands in the latitudinal direction, as seen in magnetohydrodynamic (MHD) simulations of flux tubes propagating through the interplanetary medium. We show analytically that this elongation results in a state which is no longer in the minimum energy Taylor state. We then present magnetohydrodynamic simulations of an elongated flux tube which has evolved away from the Taylor state and show that reconnection at many surfaces produces a complex stochastic magnetic field as the system evolves back to a minimum energy state configuration.

The low-lying continuum spectrum of the ${}^6\mathrm{He}$ nucleus is investigated for the first time within an ab initio framework that encompasses the ${}^4\mathrm{He}+n+n$ three-cluster dynamics characterizing its lowest decay channel. This is achieved through an extension of the no-core shell model combined with the resonating-group method, in which energy-independent nonlocal interactions among three nuclear fragments can be calculated microscopically, starting from realistic nucleon-nucleon interactions and consistent ab initio many-body wave functions of the clusters. The three-cluster Schrödinger equation is solved with three-body scattering boundary conditions by means of the hyperspherical-harmonics method on a Lagrange mesh. Using a soft similarity-renormalization-group evolved chiral nucleon-nucleon potential, we find the known $J^{\pi }=2^{+}$ resonance as well as a result consistent with a new low-lying second $2^{+}$ resonance recently observed at GANIL at 2.6 MeV above the ${}^6\mathrm{He}$ ground state. We also find resonances in the $2^{-}$, $1^{+}$, and $0^{-}$ channels, while no low-lying resonances are present in the $0^{+}$ and $1^{-}$ channels.

The isoscalar monopole response has been measured in the unstable nucleus ${}^{68}\mathrm{Ni}$ using inelastic alpha scattering at $50A\mathrm{MeV}$ in inverse kinematics with the active target MAYA at GANIL. The isoscalar giant monopole resonance (ISGMR) centroid was determined to be $21.1\pm 1.9\mathrm{MeV}$ and indications for a soft monopole mode are provided for the first time at $12.9\pm 1.0\mathrm{MeV}$. Analysis of the corresponding angular distributions using distorted-wave-born approximation with random-phase approximation transition densities indicates that the $L=0$ multipolarity dominates the cross section for the ISGMR and significantly contributes to the low-energy mode. The $L=0$ part of this low-energy mode, the soft monopole mode, is dominated by neutron excitations. This demonstrates the relevance of inelastic alpha scattering in inverse kinematics in order to probe both the ISGMR and isoscalar soft modes in neutron-rich nuclei.

The half-lives of 20 neutron-rich nuclei with $Z=27–30$ have been measured at the RIBF, including five new half-lives of ${}^{76}\mathrm{Co}(21.7_{-4.9}^{+6.5}\mathrm{ms})$, ${}^{77}\mathrm{Co}(13.0_{-4.3}^{+7.2}\mathrm{ms})$, ${}^{79}\mathrm{Ni}({43.0}_{-7.5}^{+8.6}\mathrm{ms})$, ${}^{80}\mathrm{Ni}(23.9_{-17.2}^{+26.0}\mathrm{ms})$, and ${}^{81}\mathrm{Cu}(73.2\pm 6.8\mathrm{ms})$. In addition, the half-lives of ${}^{73–75}\mathrm{Co}$, ${}^{74–78}\mathrm{Ni}$, ${}^{78–80}\mathrm{Cu}$, and ${}^{80–82}\mathrm{Zn}$ were determined with higher precision than previous works. Based on these new results, a systematic study of the $\beta$-decay half-lives has been carried out, which suggests a sizable magicity for both the proton number $Z=28$ and the neutron number $N=50$ in ${}^{78}\mathrm{Ni}$.

We study the generic dipole interaction of a monochromatic free-space electromagnetic field with a bi-isotropic nanoparticle or a molecule. Contributions associated with the breaking of dual, $P$, and $T$ symmetries are responsible for electric-magnetic asymmetry, chirality, and the nonreciprocal magnetoelectric effect, respectively. We calculate absorption rates, radiation forces, and radiation torques for the nanoparticle and introduce novel field characteristics quantifying the transfer of energy, momentum, and angular momentum due to the three symmetry-breaking effects. In particular, we put forward a concept of “magnetoelectric energy density,” quantifying the local $PT$ symmetry of the field. Akin to the “superchiral” light suggested recently for local probing of molecular chirality, here we suggest employing complex fields for a sensitive probing of the nonreciprocal magnetoelectric effect in nanoparticles or molecules.

Nonlinear processes are often governed by selection rules imposed by the symmetries of the molecular configurations. The most well-known examples include the role of centrosymmetry breaking for the generation of even harmonics, and the selection rule related to the rotational symmetry in harmonic generation for fundamental beams with circular polarizations. While the role of centrosymmetry breaking in second harmonic generation has been extensively studied in plasmonic systems, the investigation of selection rules pertaining to circular polarization states of harmonic generation is limited to crystals, i.e., symmetries at the atomic level. In this Letter we demonstrate the rotational symmetry dependent third harmonic generation from nonlinear plasmonic metacrystals. We show that the selection rule can be imposed by the rotational symmetry of metacrystals embedded into an isotropic organic nonlinear thin film. The results presented here may open new avenues for designing symmetry-dependent nonlinear optical responses with tailored plasmonic nanostructures.

We report and discuss analytical solutions of the vector nonlinear Schrödinger equation that describe rogue waves in the defocusing regime. This family of solutions includes bright-dark and dark-dark rogue waves. The link between modulational instability (MI) and rogue waves is displayed by showing that only a peculiar kind of MI, namely baseband MI, can sustain rogue-wave formation. The existence of vector rogue waves in the defocusing regime is expected to be a crucial progress in explaining extreme waves in a variety of physical scenarios described by multicomponent systems, from oceanography to optics and plasma physics.