In this Letter, we present an upper limit of ${\mathrm{\Omega }}_{\mathrm{GW}}<1.2\times {10}^8$ on an isotropic stochastic gravitational-wave (GW) background integrated over a year in the frequency range 0.05–1 Hz, which improves current upper limits from high-precision laboratory experiments by about 9 orders of magnitude. The limit is obtained using the response of Earth itself to GWs via a free-surface effect described more than 40 years ago by Dyson. The response was measured by a global network of broadband seismometers selected to maximize the sensitivity.

Indirect drive experiments at the National Ignition Facility are designed to achieve fusion by imploding a fuel capsule with x rays from a laser-driven hohlraum. Previous experiments have been unable to determine whether a deficit in measured ablator implosion velocity relative to simulations is due to inadequate models of the hohlraum or ablator physics. ViewFactor experiments allow for the first time a direct measure of the x-ray drive from the capsule point of view. The experiments show a 15%–25% deficit relative to simulations and thus explain nearly all of the disagreement with the velocity data. In addition, the data from this open geometry provide much greater constraints on a predictive model of laser-driven hohlraum performance than the nominal ignition target.

We find that the hierarchical organization of the potential energy landscape in a model supercooled liquid can be related to a change in the spatial distribution of soft normal modes. For groups of nearby minima, between which fast relaxation processes typically occur, the localization of the soft modes is very similar. The spatial distribution of soft regions changes, instead, for minima between which transitions relevant to structural relaxation occur. This may be the reason why the soft modes are able to predict spatial heterogeneities in the dynamics. Nevertheless, the very softest modes are only weakly correlated with dynamical heterogeneities and instead show higher statistical overlap with regions in the local minima that would undergo nonaffine rearrangements if subjected to a shear deformation. This feature of the supercooled liquid is reminiscent of the behavior of nonaffine deformations in amorphous solids, where the very softest modes identify the loci of plastic instabilities.

We show that the heavy-fermion compound ${\mathrm{CeCu}}_2{\mathrm{Si}}_2$ undergoes a transition between two regimes dominated by different crystal-field states. At low pressure $P$ and low temperature $T$ the Ce $4f$ electron resides in the atomic crystal-field ground state, while at high $P$ or $T$, the electron occupancy and spectral weight is transferred to an excited crystal-field level that hybridizes more strongly with itinerant states. These findings result from first-principles dynamical-mean-field-theory calculations. We predict experimental signatures of this orbital transition in x-ray spectroscopy. The corresponding fluctuations may be responsible for the second high-pressure superconducting dome observed in this and similar materials.

We have investigated the superconducting state of the noncentrosymmetric compound ${\mathrm{Re}}_6\mathrm{Zr}$ using magnetization, heat capacity, and muon-spin relaxation or rotation ($\mu \mathrm{SR}$) measurements. ${\mathrm{Re}}_6\mathrm{Zr}$ has a superconducting transition temperature, $T_c=6.75\pm 0.05\mathrm{K}$. Transverse-field $\mu \mathrm{SR}$ experiments, used to probe the superfluid density, suggest an $s$-wave character for the superconducting gap. However, zero and longitudinal-field $\mu \mathrm{SR}$ data reveal the presence of spontaneous static magnetic fields below $T_c$ indicating that time-reversal symmetry is broken in the superconducting state and an unconventional pairing mechanism. An analysis of the pairing symmetries identifies the ground states compatible with time-reversal symmetry breaking.

We present a theory of topological edge states in one-dimensional resonant photonic crystals with a compound unit cell. Contrary to the conventional electronic topological states, the modes under consideration are radiative; i.e., they decay in time due to the light escape through the structure boundaries. We demonstrate that the edge states survive despite their radiative decay and can be detected both in time- and frequency-dependent light reflection.

We study a flow of ultracold bosonic atoms through a one-dimensional channel that connects two macroscopic three-dimensional reservoirs of Bose-condensed atoms via weak links implemented as potential barriers between each of the reservoirs and the channel. We consider reservoirs at equal chemical potentials so that a superflow of the quasicondensate through the channel is driven purely by a phase difference $2\mathrm{\Phi }$ imprinted between the reservoirs. We find that the superflow never has the standard Josephson form $\sim \sin 2\mathrm{\Phi }$. Instead, the superflow discontinuously flips direction at $2\mathrm{\Phi }=\pm \mathrm{\pi }$ and has metastable branches. We show that these features are robust and not smeared by fluctuations or phase slips. We describe a possible experimental setup for observing these phenomena.

We report the first branching-ratio measurement of the superallowed $0^{+}\to 0^{+}\beta$ transition from ${}^{38}\mathrm{Ca}$. The result, 0.7728(16), leads to an $ft$ value of 3062.3(68) s with a relative precision of $\pm 0.2\%$. This makes possible a high-precision comparison of the $ft$ values for the mirror superallowed transitions, ${}^{38}\mathrm{Ca}{\to }^{38m}\mathrm{K}$ and ${}^{38m}\mathrm{K}\to {}^{38}\mathrm{Ar}$, which sensitively tests the isospin symmetry-breaking corrections required to extract $V_{ud}$, the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, from superallowed $\beta$ decay. The result supports the corrections currently used and points the way to even tighter constraints on CKM unitarity.

We present a calculation of the complete set of QED corrections of order $m{\alpha }^7$ for one-electron two-center systems. Leading corrections of order $m{\alpha }^8$ are also considered, which allows us to estimate the magnitude of yet uncalculated contributions. The theoretical uncertainty on the frequencies of rovibrational transitions in the hydrogen molecular ions ${\mathrm{H}}_2^{+}$ and ${\mathrm{HD}}^{+}$, and of two-photon transition in antiprotonic helium is reduced by about 1 order of magnitude, down to $(3–4)\times 10^{-11}$ and ${10}^{-10}$, respectively. These results open new perspectives for improved determination of the proton- and antiproton-to-electron mass ratios by precision spectroscopy experiments.

We consider correlated transfer ionization in relativistic collisions between a highly charged ion and a light atom. In this process two quasifree electrons of the atom interact with each other during the short collision time that results in the capture of one of them by the ion and emission of the other. We show that this process is strongly influenced by the generalized Breit interaction already at modest relativistic impact energies.

We study the dynamics of a laser-trapped nanoparticle in high vacuum. Using parametric coupling to an external excitation source, the linewidth of the nanoparticle’s oscillation can be reduced by three orders of magnitude. We show that the oscillation of the nanoparticle and the excitation source are synchronized, exhibiting a well-defined phase relationship. Furthermore, the external source can be used to controllably drive the nanoparticle into the nonlinear regime, thereby generating strong coupling between the different translational modes of the nanoparticle. Our work contributes to the understanding of the nonlinear dynamics of levitated nanoparticles in high vacuum and paves the way for studies of pattern formation, chaos, and stochastic resonance.

A quantum polarized light microscope using entangled NOON states with $N=2$ and $N=3$ is shown to provide phase supersensitivity beyond the standard quantum limit. We constructed such a microscope and imaged birefringent objects at a very low light level of 50 photons per pixel, where shot noise seriously hampers classical imaging. The NOON light source is formed by combining a coherent state with parametric down-converted light. We were able to show improved phase images with sensitivity close to the Heisenberg limit.

We report new measurements of single particle dispersion in turbulent two-dimensional (2D) flows. Laboratory experiments in electromagnetically driven and Faraday wave driven turbulence reveal a transition from weakly dispersing superdiffusive regime to strongly dispersing Brownian diffusion as the flow energy is increased in a broad range. The transition to fully developed 2D turbulence is characterized by the topological changes in the fluid particle trajectories and the development of self-similar diffusion. The degree of 2D turbulence development can be quantified by a parameter describing the deviation of single particle dispersion from the Taylor dispersion.

Complicated wave behavior observed in the cylindrical pair-ion (fullerene) experiments by Oohara and co-workers are now identified to be low harmonic ion cyclotron waves combined with ion plasma oscillations inherent to kinetic theory. The electrostatic dispersion equation derived is based on an approximation for the current from the exact solutions of the characteristic cylindrical geometry form of the Vlasov plasma equation in a uniform magnetized plasma cylinder surrounded by a larger metal boundary outside a vacuum gap, which thus differs from that in unbounded plasmas. Positive and negative ions, differing only in the sign of their charge, respond to a potential in the same time scale and cooperate to reflect the enhanced kinetic orbital behaviors to the macroscopic propagation characteristics. In addition, the experimental value of the Larmor radius (comparable to the discharge radius but small enough to make the analytic approximation useful) makes higher harmonic ion cyclotron effects both observable and calculable with the appropriate approximation for the kinetic theory.

We report on the dynamics of ultrafast heating in cryogenic hydrogen initiated by a $\lesssim 300\mathrm{fs}$, 92 eV free electron laser x-ray burst. The rise of the x-ray scattering amplitude from a second x-ray pulse probes the transition from dense cryogenic molecular hydrogen to a nearly uncorrelated plasmalike structure, indicating an electron-ion equilibration time of $\sim 0.9\mathrm{ps}$. The rise time agrees with radiation hydrodynamics simulations based on a conductivity model for partially ionized plasma that is validated by two-temperature density-functional theory.

We report on the formation and growth of nanobubbles around laser-heated gold nanoparticles in water. Using a hydrodynamic free-energy model, we show that the temporal evolution of the nanobubble radius is asymmetrical: the expansion is found to be adiabatic, while the collapse is best described by an isothermal evolution. We unveil the critical role of the thermal boundary resistance in the kinetics of formation of the nanobubbles: close to the vapor production threshold, nanobubble generation is very long, yielding optimal conditions for laser-energy conversion. Furthermore, the long appearance times allow nanoparticle melting before the onset of vaporization.

We demonstrate in a simple model the surprising result that turning on an on-site Coulomb interaction $U$ in a doped band insulator leads to the formation of a half-metallic state. In the undoped system, we show that increasing $U$ leads to a first order transition at a finite value $U_{\mathrm{AF}}$ between a paramagnetic band insulator and an antiferomagnetic Mott insulator. Upon doping, the system exhibits half-metallic ferrimagnetism over a wide range of doping and interaction strengths on either side of $U_{\mathrm{AF}}$. Our results, based on dynamical mean field theory, suggest a new route to half metallicity, and will hopefully motivate searches for new materials for spintronics.