We present initial-state selective fully differential cross sections for ionization of lithium by 24 MeV ${\mathrm{O}}^{8+}$ impact. The data for ionization from the $2s$ and $2p$ states look qualitatively different from each other and from $1s$ ionization of He. For ionization from the $2p$ state, to which in our study the $m_L=-1$ substate predominantly contributes, we observe orientational dichroism and for $2s$ ionization pronounced interference which we trace back to the nodal structure of the initial-state wave function.

We demonstrate a novel method to measure $N$th-order ($N=1,2,3,4$) interferometric autocorrelation with high sensitivity and temporal resolution. It is based on the combination of linear absorption and nonlinear detection in a superconducting nanodetector, providing much higher efficiency than methods based on all-optical nonlinearities. Its temporal resolution is only limited by the quasiparticle energy relaxation time, which is directly measured to be in the 20 ps range for the NbN films used in this work. We present a general model of interferometric autocorrelation with these nonlinear detectors and discuss the comparison with other approaches and possible improvements.

We present a structurally and conceptually simple acoustic double negative metamaterial comprising two coupled membranes. Owing to its symmetry, the system can generate both monopolar and dipolar resonances that are separately tunable, thereby making broadband double negativity possible. A homogenization scheme is implemented that enables the exact characterization of our metamaterial by the effective mass density and bulk modulus even beyond the usual long-wavelength regime, with the measured displacement fields on the sample’s surfaces as inputs. Double negativity is achieved in the frequency range of 520–830 Hz. Transmission and reflection predictions using effective parameters are shown to agree remarkably well with the experiment.

We have investigated the influence of thin films of a dielectric material on the near-field mediated heat transfer at the fundamental limit of single monolayer islands on a metallic substrate. We present spatially resolved measurements by near-field scanning thermal microscopy showing a distinct enhancement in heat transfer above NaCl islands compared to the bare Au(111) film. Experiments at this subnanometer scale call for a microscopic theory beyond the macroscopic fluctuational electrodynamics used to describe near-field heat transfer today. The method facilitates the possibility of developing designs of nanostructured surfaces with respect to specific requirements in heat transfer down to a single atomic layer.

Using ion carbon beams generated by high intensity short pulse lasers we perform measurements of single shot mean charge equilibration in cold or isochorically heated solid density aluminum matter. We demonstrate that plasma effects in such matter heated up to 1 eV do not significantly impact the equilibration of carbon ions with energies $0.045–0.5\mathrm{MeV}/\mathrm{nucleon}$. Furthermore, these measurements allow for a first evaluation of semiempirical formulas or ab initio models that are being used to predict the mean of the equilibrium charge state distribution for light ions passing through warm dense matter.

The electron diffusion region during magnetic reconnection lies in different regimes depending on the pressure anisotropy, which is regulated by the properties of thermal electron orbits. In kinetic simulations at the weakest guide fields, pitch angle mixing in velocity space causes the outflow electron pressure to become nearly isotropic. Above a threshold guide field that depends on a range of parameters, including the normalized electron pressure and the ion-to-electron mass ratio, electron pressure anisotropy develops in the exhaust and supports extended current layers. This new regime with electron current sheets extending to the system size is also reproduced by fluid simulations with an anisotropic closure for the electron pressure. It offers an explanation for recent spacecraft observations.

We study the response of ultracold atoms to a weak force in the presence of a temporally strongly modulated optical lattice potential. It is experimentally demonstrated that the strong ac driving allows for a tailoring of the mobility of a dilute atomic Bose-Einstein condensate with the atoms moving ballistically either along or against the direction of the applied force. Our results are in agreement with a theoretical analysis of the Floquet spectrum of a model system, thus revealing the existence of diabatic Floquet bands in the atoms’ band spectra and highlighting their role in the nonequilibrium transport of the atoms.

A phase transition indicates a sudden change in the properties of a large system. For temperature-driven phase transitions this is related to nonanalytic behavior of the free energy density at the critical temperature: The knowledge of the free energy density in one phase is insufficient to predict the properties of the other phase. In this Letter we show that a close analogue of this behavior can occur in the real time evolution of quantum systems, namely nonanalytic behavior at a critical time. We denote such behavior a dynamical phase transition and explore its properties in the transverse-field Ising model. Specifically, we show that the equilibrium quantum phase transition and the dynamical phase transition in this model are intimately related.

The specific heat $C$ of $e$-beam evaporated amorphous silicon ($a$-Si) thin films prepared at various growth temperatures $T_S$ and thicknesses $t$ was measured from 2 to 300 K, along with sound velocity $v$, shear modulus $G$, density $n_{\mathrm{Si}}$, and Raman spectra. Increasing $T_S$ results in a more ordered amorphous network with increases in $n_{\mathrm{Si}}$, $v$, $G$, and a decrease in bond angle disorder. Below 20 K, an excess $C$ is seen in films with less than full density where it is typical of an amorphous solid, with both a linear term characteristic of two-level systems (TLS) and an additional (non-Debye) $T^3$ contribution. The excess $C$ is found to be independent of the elastic properties but to depend strongly on density. The density dependence suggests that low energy glassy excitations can form in $a$-Si but only in microvoids or low density regions and are not intrinsic to the amorphous silicon network. A correlation is found between the density of TLS $n_0$ and the excess $T^3$ specific heat $c_{\mathrm{ex}}$ suggesting that they have a common origin.

Physical vapor deposition provides a controllable means of growing two-dimensional metallic thin films and one-dimensional metallic nanorods. While theories exist for the growth of metallic thin films, their counterpart for the growth of metallic nanorods is absent. Because of this absence, the lower limit of the nanorod diameter is theoretically unknown; consequently the experimental pursuit of the smallest nanorods has no clear target. This Letter reports a closed-form theory that defines the diameter of the smallest metallic nanorods using physical vapor deposition. Further, the authors verify the theory using lattice kinetic Monte Carlo simulations and validate the theory using published experimental data. Finally, the authors carry out a series of theory-guided experiments to grow well-separated metallic nanorods of $\sim 10\mathrm{nm}$ in diameter, which are the smallest ever reported using physical vapor deposition.

We study dynamical phase transitions from antiferromagnetic to paramagnetic states driven by an interaction quench in the fermionic Hubbard model using the nonequilibrium dynamical mean-field theory. We identify two dynamical transition points where the relaxation behavior qualitatively changes: one corresponds to the thermal phase transition at which the order parameter decays critically slowly in a power law $\propto t^{-1/2}$, and the other is connected to the existence of nonthermal antiferromagnetic order in systems with effective temperature above the thermal critical temperature. The frequency of the amplitude mode extrapolates to zero as one approaches the nonthermal (quasi)critical point, and thermalization is significantly delayed by the trapping in the nonthermal state. A slow relaxation of the nonthermal order is followed by a faster thermalization process.

We study electronic transport in a Luttinger liquid with an embedded impurity, which is either a weak scatterer (WS) or a weak link (WL), when interacting electrons are coupled to one-dimensional massless bosons (e.g., acoustic phonons). We find that the duality relation, ${\Delta }_{\mathrm{WS}}{\Delta }_{\mathrm{WL}}=1$, between scaling dimensions of the electron backscattering in the WS and WL limits, established for the standard Luttinger liquid, holds in the presence of the additional coupling for an arbitrary fixed strength of boson scattering from the impurity. This means that at low temperatures such a system remains either an ideal insulator or an ideal metal, regardless of the scattering strength. On the other hand, when fermion and boson scattering from the impurity are correlated, the system has a rich phase diagram that includes a metal-insulator transition at some intermediate values of the scattering.

We present time-resolved photoemission experiments from a peculiar bismuth surface, Bi(114). The strong one-dimensional character of this surface is reflected in the Fermi surface, which consists of spin-polarized straight lines. Our results show that the depletion of the surface state and the population of the bulk conduction band after the initial optical excitation persist for very long times. The disequilibrium within the hot electron gas along with strong electron-phonon coupling cause a displacive excitation of coherent phonons, which in turn are reflected in coherent modulations of the electronic states. Beside the well-known $A_{1g}$ bulk phonon mode at 2.76 THz, the time-resolved photoelectron spectra reveal a second mode at 0.72 THz which can be attributed to an optical surface phonon mode along the atomic rows of the Bi(114) surface.

We report the low-temperature electronic and magnetic properties of the alkali metal-organic solvent intercalated iron selenide superconductor $\mathrm{Li}({\mathrm{C}}_5{\mathrm{H}}_5\mathrm{N}{)}_{0.2}{\mathrm{Fe}}_2{\mathrm{Se}}_2$ using muon-spin-spectroscopy measurements. The zero-field muon spin relaxation ($\mu \mathrm{SR}$) results indicate that nearly half of the sample is magnetically ordered and spatially phase separated from the superconducting region. The transverse-field $\mu \mathrm{SR}$ results reveal that the superfluid density of $\mathrm{Li}({\mathrm{C}}_5{\mathrm{H}}_5\mathrm{N}{)}_{0.2}{\mathrm{Fe}}_2{\mathrm{Se}}_2$ is two dimensional in nature. The temperature dependence of the penetration depth $\lambda (T)$ can be explained using a two-gap $s$-wave model. This implies that, despite the 2D nature of the superfluid density, the symmetry of the superconducting gap remains unaltered to the parent compound FeSe.

X-ray diffraction measurements show that the high-temperature superconductor ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6.54}$, with ortho-II oxygen order, has charge-density-wave order in the absence of an applied magnetic field. The dominant wave vector of the charge density wave is ${\mathbf{q}}_{\mathrm{CDW}}=\mathbf{(}0,0.328(2),0.5\mathbf{)}$, with the in-plane component parallel to the $\mathbf{b}$ axis (chain direction). It has a similar incommensurability to that observed in ortho-VIII and ortho-III samples, which have different dopings and oxygen orderings. Our results for ortho-II contrast with recent high-field NMR measurements, which suggest a commensurate wave vector along the $\mathbf{a}$ axis. We discuss the relationship between spin and charge correlations in ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_y$ and recent high-field quantum oscillation, NMR, and ultrasound experiments.

Vaso-occlusion, the stoppage of blood flow in sickle-cell disease, is a complex dynamical process spanning multiple time and length scales. Motivated by recent ex vivo microfluidic measurements of hemostasis using blood from sickle-cell patients, we develop a multiphase model that couples the kinetics and hydrodynamics of a flowing suspension of normal and sickled cells in a fluid. We use the model to derive expressions for the cell velocities and concentrations that quantify the hydrodynamics of hemostasis, and provide simple criteria as well as a phase diagram for occlusion, consistent with our simulations and earlier observations.

We present a new quantitative x-ray phase-contrast imaging method based on the edge illumination principle, which allows achieving unprecedented nanoradian sensitivity. The extremely high angular resolution is demonstrated theoretically and through experimental images obtained at two different synchrotron radiation facilities. The results, achieved at both very high and very low x-ray energies, show that this highly sensitive technique can be efficiently exploited over a very broad range of experimental conditions. This method can open the way to new, previously inaccessible scientific applications in various fields including biology, medicine and materials science.

Some microalgae are sensitive to light intensity gradients. This property is known as phototaxis: The algae swim toward a light source (positive phototaxis). We use this property to control the motion of microalgae within a Poiseuille flow using light. The combination of flow vorticity and phototaxis results in a concentration of algae around the center of the flow. Intermittent light exposure allows analysis of the dynamics of this phenomenon and its reversibility. With this phenomenon, we hope to pave the way toward new algae concentration techniques (a bottleneck challenge in biofuel algal production) and toward the improvement of pollutant biodetector technology.

We utilize the wormlike chain model in the framework of the self-consistent field theory to investigate the influence of chain rigidity on the phase diagram of $AB$ diblock copolymers in the full three-dimensional space. We develop an efficient numerical scheme that can be used to calculate the physical properties of ordered microstructures self-assembled from semiflexible block copolymers. The calculation describes the entire physical picture of the phase diagram, crossing from the flexible over to rodlike polymer behavior.

In this Letter, we derive an entropic Einstein-Podolsky-Rosen (EPR) steering inequality for continuous-variable systems using only experimentally measured discrete probability distributions and details of the measurement apparatus. We use this inequality to witness EPR steering between the positions and momenta of photon pairs generated in spontaneous parametric down-conversion. We examine the asymmetry between parties in this inequality, and show that this asymmetry can be used to reduce the technical requirements of experimental setups intended to demonstrate the EPR paradox. Furthermore, we develop a more stringent steering inequality that is symmetric between parties, and use it to show that the down-converted photon pairs also exhibit symmetric EPR steering.