A plasma transport theory that spans weak to strong coupling is developed from a binary collision picture, but where the interaction potential is taken to be an effective potential that includes correlation effects and screening self-consistently. This physically motivated approach provides a practical model for evaluating transport coefficients across coupling regimes. The theory is shown to compare well with classical molecular dynamics simulations of temperature relaxation in electron-ion plasmas as well as simulations and experiments of self-diffusion in one-component plasmas. The approach is versatile and can be applied to other transport coefficients as well.

Strong mitigation of edge-localized modes has been observed on Experimental Advanced Superconducting Tokamak, when lower hybrid waves (LHWs) are applied to $H$-mode plasmas with ion cyclotron resonant heating. This has been demonstrated to be due to the formation of helical current filaments flowing along field lines in the scrape-off layer induced by LHW. This leads to the splitting of the outer divertor strike points during LHWs similar to previous observations with resonant magnetic perturbations. The change in the magnetic topology has been qualitatively modeled by considering helical current filaments in a field-line-tracing code.

We study a system of spinless fermions in two dimensions with a short-range interaction fine-tuned to a $p$-wave resonance. We show that three such fermions form an infinite tower of bound states of orbital angular momentum $\ell =\pm 1$ and their binding energies obey a universal doubly exponential scaling $E_3^{(n)}\propto \exp (-2e^{3\pi n/4+\theta })$ at large $n$. This “super Efimov effect” is found by a renormalization group analysis and confirmed by solving the bound state problem. We also provide an indication that there are $\ell =\pm 2$ four-body resonances associated with every three-body bound state at $E_4^{(n)}\propto \exp (-2e^{3\pi n/4+\theta -0.188})$. These universal few-body states may be observed in ultracold atom experiments and should be taken into account in future many-body studies of the system.

The recently discovered high pressure phase VII of calcium [M. Sakata et al., Phys. Rev. B 83, 220512(R) (2011)] has the highest superconducting transition temperature ($T_c$) of 29 K among all the elements. Understanding the cause for such a high $T_c$ state is necessary to clarify its crystal structure. The structure of this phase was determined by an x-ray powder diffraction experiment and a density functional theory calculation and was not found to be the usual host-guest type but consisted of a $2\times 2$ supercell in the tetragonal $ab$ plane with a commensurate host-guest ratio of $4/3$ along the $c$ axis containing 128 atoms.

We analyzed the size effect on a first-order spin transition governed by elastic interactions. This study was performed in the framework of a nonextensive thermodynamic core-shell model. When decreasing the particle size, differences in surface energies between the two phases lead to the shrinking of the thermal hysteresis width, the lowering of the transition temperature, and the increase of residual fractions at low temperature, in good agreement with recent experimental observations on spin transition nanomaterials. On the other hand, a modification of the particle-matrix interface may allow for the existence of the hysteresis loop even at very low sizes. In addition, an unexpected reopening of the hysteresis, when the size decreases, is also possible due to the hardening of the nanoparticles at very small sizes, which we deduced from the size dependence of the Debye temperature of a series of coordination nanoparticles.

It is well known in experimental studies that Cu is usually a fast diffuser in semiconductors. In some semiconductors (e.g., CdTe), Ag is also a fast diffuser. The diffusion plays an important role in many applications when Cu (Ag) is employed to tune the semiconductor’s electrical or optical properties. However, the origin of why Cu (Ag) shows different diffusion behavior compared to group-IA elements is still unclear. Using first-principles method, we compare the diffusion behaviors between Cu (Ag) and group-IA elements in CdTe, and find that the novel diffusion is due to the strong coupling between Cu (Ag) $d$ levels and unoccupied host $s$ levels. This coupling alters the stable doping site, diffusion pathway, and diffusion energy curve from those of group-IA elements, which have no active $d$ levels, thus making the Cu (Ag) diffusion faster in many semiconductors.

We report a comprehensive study of the paradigmatic quasi-1D compound $({\mathrm{TaSe}}_4{)}_2\mathrm{I}$ performed by means of angle-resolved photoemission spectroscopy (ARPES) and first-principles electronic structure calculations. We find it to be a zero-gap semiconductor in the nondistorted structure, with non-negligible interchain coupling. Theory and experiment support a Peierls-like scenario for the charge-density wave formation below $T_{\mathrm{CDW}}=263\mathrm{K}$, where the incommensurability is a direct consequence of the finite interchain coupling. The formation of small polarons, strongly suggested by the ARPES data, explains the puzzling semiconductor-to-semiconductor transition observed in transport at $T_{\mathrm{CDW}}$.

We show how to numerically calculate several quantities that characterize topological order starting from a microscopic fractional quantum Hall Hamiltonian. To find the set of degenerate ground states, we employ the infinite density matrix renormalization group method based on the matrix-product state representation of fractional quantum Hall states on an infinite cylinder. To study localized quasiparticles of a chosen topological charge, we use pairs of degenerate ground states as boundary conditions for the infinite density matrix renormalization group. We then show that the wave function obtained on the infinite cylinder geometry can be adapted to a torus of arbitrary modular parameter, which allows us to explicitly calculate the non-Abelian Berry connection associated with the modular $\mathcal{T}$ transformation. As a result, the quantum dimensions, topological spins, quasiparticle charges, chiral central charge, and Hall viscosity of the phase can be obtained using data contained entirely in the entanglement spectrum of an infinite cylinder.

Under mesoscopic conditions, the transport potential on a thin film carrying a current is theoretically expected to bear spatial variation due to quantum interference. Scanning tunneling potentiometry is the ideal tool to investigate such variation, by virtue of its high spatial resolution. We report in this Letter the first detailed measurement of transport potential under mesoscopic conditions. Epitaxial graphene at a temperature of 17 K was chosen as the initial system for study because the characteristic transport length scales in this material are relatively large. Tip jumping artifacts are a major possible contribution to systematic errors; and we mitigate such problems by using custom-made slender and sharp tips manufactured by focused ion beam. In our data, we observe residual resistivity dipoles associated with topographical defects, and local peaks and dips in the potential that are not associated with topographical defects.

In situ micro-four-point-probe conductivity measurements in ultrahigh vacuum revealed that the Si(111)-striped incommensurate-Pb surface showed the superconductivity transition at 1.1 K. Both of the hexagonal and rectangular phases of $\mathrm{Si}(111)\sqrt{7}\times \sqrt{3}$-In surface showed superconductivity at 2.4 and 2.8 K, respectively. By applying magnetic field perpendicular to the surface, the upper critical field was deduced to be 0.1–1 T. The derived Ginzburg-Landau coherence length of the Cooper pairs was several tens of nm, which was much smaller than the Pippard’s coherence length estimated from the band structures. The short coherence length is determined by the carrier mean free path.

We report the spin structure of an exchange-biased ferromagnetic oxide heterostructure, ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_3/{\mathrm{SrRuO}}_3$, through magnetization and polarized neutron reflectometry measurements. We reveal that the magnetization reversal process of the ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_3$ biased layer critically depends on the frozen-in spin structure of the ${\mathrm{SrRuO}}_3$ biasing layer during the cooling process. Furthermore, we observe unexpected double-shifted hysteresis loops of the biased layer that originates from the formation of lateral 180° magnetic domains within the biasing layer, a new mechanism not found in conventional exchange-bias systems.

The crystal and magnetic structures of single-crystalline hexagonal ${\mathrm{LuFeO}}_3$ films have been studied using x-ray, electron, and neutron diffraction methods. The polar structure of these films are found to persist up to 1050 K; and the switchability of the polar behavior is observed at room temperature, indicating ferroelectricity. An antiferromagnetic order was shown to occur below 440 K, followed by a spin reorientation resulting in a weak ferromagnetic order below 130 K. This observation of coexisting multiple ferroic orders demonstrates that hexagonal ${\mathrm{LuFeO}}_3$ films are room-temperature multiferroics.

Stochastic fluctuations of ion current through one chitoporin (ChiP) channel within a bilayer lipid membrane in sugar solution are analyzed. These reflect single-molecule dynamics, which indicate that ChiP has multiple binding sites for sugar and exploits interactions between bound molecules to direct sugar passage. Since ChiP is used by marine bacteria, this is likely an adaptive strategy to enhance sugar translocation from rough water.

We report on the realization of a double-barrier resonant tunneling diode for cavity polaritons, by lateral patterning of a one-dimensional cavity. Sharp transmission resonances are demonstrated when sending a polariton flow onto the device. We show that a nonresonant beam can be used as an optical gate and can control the device transmission. Finally, we evidence distortion of the transmission profile when going to the high-density regime, signature of polariton-polariton interactions.

The Hopf fibration is an example of a texture: a topologically stable, smooth, global configuration of a field. Here we demonstrate the controlled sculpting of the Hopf fibration in nematic liquid crystals through the control of point defects. We demonstrate how these are related to torons by use of a topological visualization technique derived from the Pontryagin-Thom construction.

We report the results of a high-statistics search for $H$ dibaryon production in inclusive ${\rm Y}(1S)$ and ${\rm Y}(2S)$ decays. No indication of an $H$ dibaryon with a mass near the $M_H=2m_{\Lambda }$ threshold is seen in either the $H\to \Lambda p{\pi }^{-}$ or $\Lambda \Lambda$ decay channels and 90% confidence level branching-fraction upper limits are set that are between one and two orders of magnitude below the measured branching fractions for inclusive ${\rm Y}(1S)$ and ${\rm Y}(2S)$ decays to antideuterons. Since ${\rm Y}(1S,2S)$ decays produce flavor-$SU(3)$-symmetric final states, these results put stringent constraints on $H$ dibaryon properties. The results are based on analyses of 102 million ${\rm Y}(1S)$ and 158 million ${\rm Y}(2S)$ events collected with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider.

We present the first lattice QCD calculation of the decay constants $f_B$ and $f_{B_s}$ with physical light quark masses. We use configurations generated by the MILC Collaboration including the effect of $u$, $d$, $s$, and $c$ highly improved staggered quarks in the sea at three lattice spacings and with three $u/d$ quark mass values going down to the physical value. We use improved nonrelativistic QCD (NRQCD) for the valence $b$ quarks. Our results are $f_B=0.186(4)\mathrm{GeV}$, $f_{B_s}=0.224(4)\mathrm{GeV}$, $f_{B_s}/f_B=1.205(7)$, and $M_{B_s}-M_B=85(2)\mathrm{MeV}$, superseding earlier results with NRQCD $b$ quarks. We discuss the implications of our results for the standard model rates for $B_{(s)}\to {\mu }^{+}{\mu }^{-}$ and $B\to \tau \nu$.

We demonstrate optomechanically mediated electromagnetically induced transparency and wavelength conversion in silicon nitride (${\mathrm{Si}}_3{\mathrm{N}}_4$) microdisk resonators. Fabricated devices support whispering gallery optical modes with a quality factor ($Q$) of ${10}^6$, and radial breathing mechanical modes with a $Q={10}^4$ and a resonance frequency of 625 MHz, so that the system is in the resolved sideband regime. Placing a strong optical control field on the red (blue) detuned sideband of the optical mode produces coherent interference with a resonant probe beam, inducing a transparency (absorption) window for the probe. This is observed for multiple optical modes of the device, all of which couple to the same mechanical mode, and which can be widely separated in wavelength due to the large band gap of ${\mathrm{Si}}_3{\mathrm{N}}_4$. These properties are exploited to demonstrate frequency up-conversion and down-conversion of optical signals between the 1300 and 980 nm bands with a frequency span of 69.4 THz.

A compact high repetition rate attosecond light source based on a standard laser oscillator combined with plasmonic enhancement is analyzed. At repetition rates of tens of MHz, we predict focusable pulses with durations of $\lesssim 300$ as and a spherical wave front at collimation angles $\lesssim 5°$. Plasmonic mode and guiding of the attosecond radiation determine the beam parameters. The beam is robust with respect to variations of driver pulse focus and duration.

The partition of energy flux in magnetic reconnection is examined experimentally using Cluster satellite observations of collisionless reconnection in Earth’s magnetotail. In this plasma regime, the dominant component of the energy flux is ion enthalpy flux, with smaller contributions from the electron enthalpy and heat flux and the ion kinetic energy flux. However, the Poynting flux is not negligible, and in certain parts of the ion diffusion region the Poynting flux in fact dominates. Evidence for earthward-tailward asymmetry is ascribed to the presence of Earth’s dipole fields.