We present results of single-shot resonant magnetic scattering experiments of $\mathrm{Co}/\mathrm{Pt}$ multilayer systems using 100 fs long ultraintense pulses from an extreme ultraviolet (XUV) free-electron laser. An x-ray-induced breakdown of the resonant magnetic scattering channel during the pulse duration is observed at fluences of $5\mathrm{J}/{\mathrm{cm}}^2$. Simultaneously, the speckle contrast of the high-fluence scattering pattern is significantly reduced. We performed simulations of the nonequilibrium evolution of the $\mathrm{Co}/\mathrm{Pt}$ multilayer system during the XUV pulse duration. We find that the electronic state of the sample is strongly perturbed during the first few femtoseconds of exposure leading to an ultrafast quenching of the resonant magnetic scattering mechanism.

Current sheet configurations in natural and laboratory plasmas are often accompanied by a finite normal magnetic component that is known to stabilize the two-dimensional resistive tearing instability in the high Lundquist number regime. Recent magnetohydrodynamic simulations indicate that the nonlinear development of ballooning instability is able to induce the formation of $X$ lines and plasmoids in a generalized Harris sheet with a finite normal magnetic component in the high Lundquist number regime where the linear two-dimensional resistive tearing mode is stable.

Using Bogoliubov theory we calculate the excitation spectrum of a spinor Bose-Einstein condensed gas with an equal Rashba and Dresselhaus spin-orbit coupling in the stripe phase. The emergence of a double gapless band structure is pointed out as a key signature of Bose-Einstein condensation and of the spontaneous breaking of translational invariance symmetry. In the long wavelength limit the lower and upper branches exhibit, respectively, a clear spin and density nature. For wave vectors close to the first Brillouin zone, the lower branch acquires an important density character responsible for the divergent behavior of the structure factor and of the static response function, reflecting the occurrence of crystalline order. The sound velocities are calculated as functions of the Raman coupling for excitations propagating orthogonal and parallel to the stripes. Our predictions provide new perspectives for the identification of supersolid phenomena in ultracold atomic gases.

In this Letter, we consider the fluctuation-induced force exerted between two plates separated by a distance $L$ in a fluid with a temperature gradient. We predict that for a range of distances $L$, this nonequilibrium force is anomalously large compared to other Casimir forces. The physical reason is that correlations in a nonequilibrium fluid are generally of longer range than other correlations, even than those near an equilibrium critical point. This giant Casimir force is related to a divergent Burnett coefficient that characterizes an Onsager cross effect between the pressure and the temperature gradient. The predicted Casimir force should be detectable with currently available experimental techniques.

We report on the experimental observation of waves at a liquid foam surface propagating faster than the bulk shear waves. The existence of such waves has long been debated, but the recent observation of supershear events in a geophysical context has inspired us to search for their existence in a model viscoelastic system. An optimized fast profilometry technique allows us to observe on a liquid foam surface the waves triggered by the impact of a projectile. At high impact velocity, we show that the expected subshear Rayleigh waves are accompanied by faster surface waves that can be identified as supershear Rayleigh waves.

Quasielastic neutron scattering of ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$ in the same nanoporous carbon at 10–40 K demonstrates extreme quantum sieving, with ${\mathrm{D}}_2$ diffusing up to 76 times faster. ${\mathrm{D}}_2$ also shows liquidlike diffusion while ${\mathrm{H}}_2$ exhibits Chudley-Elliott jump diffusion, evidence of their different relationships with the local lattice of adsorption sites due to quantum effects on intermolecular interactions. The onset of diffusion occurs at 22–25 K for ${\mathrm{H}}_2$ and 10–13 K for ${\mathrm{D}}_2$. At these temperatures, ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$ have identical thermal de Broglie wavelengths that correlate with the dominant pore size.

The thermal conductivity measurements are performed on the heavy-fermion compound ${\mathrm{YbRh}}_2{\mathrm{Si}}_2$ down to 0.04 K and under magnetic fields through a quantum critical point (QCP) at $B_c=0.66\mathrm{T}\parallel c$ axis. In the limit as $T\to 0$, we find that the Wiedemann-Franz law is satisfied within experimental error at the QCP despite the destruction of the standard signature of Fermi liquid. Our results place strong constraints on models that attempt to describe the nature of the unconventional quantum criticality of ${\mathrm{YbRh}}_2{\mathrm{Si}}_2$.

We theoretically study spin current through ferromagnet ($F$) in a Josephson junction composed of $s$-wave superconductors and two layers of ferromagnets. Using quasiclassical theory, we show that the long-range spin current can be driven by the superconducting phase difference without a voltage drop. The origin of this spin current is due to spin-triplet Cooper pairs (STCs) formed by electrons of equal spin, which are induced by the proximity effect inside the $F$. We find that the spin current carried by the STCs exhibits long-range propagation in the $F$ even where the Josephson charge current is practically zero. We also show that this spin current persists over a remarkably longer distance than the ordinary spin current carried by spin polarized conduction electrons in the $F$. Our results thus indicate the promising potential of Josephson junctions based on multilayer ferromagnets for spintronics applications with long-range propagating spin current.

We present a model for the dynamics of fluid vesicles in linear flow which consistently includes thermal fluctuations and nonlinear coupling between different modes. At the transition between tank treading and tumbling, we predict a trembling motion which is at odds with the known deterministic motions and for which thermal noise is strongly amplified. In particular, highly asymmetric shapes are observed even though the deterministic flow only allows for axisymmetric ones. Our results explain quantitatively recent experimental observations [Levant and Steinberg, Phys. Rev. Lett. 109, 268103 (2012)].

Solving linear systems of equations is ubiquitous in all areas of science and engineering. With rapidly growing data sets, such a task can be intractable for classical computers, as the best known classical algorithms require a time proportional to the number of variables $N$. A recently proposed quantum algorithm shows that quantum computers could solve linear systems in a time scale of order $\log (N)$, giving an exponential speedup over classical computers. Here we realize the simplest instance of this algorithm, solving $2\times 2$ linear equations for various input vectors on a quantum computer. We use four quantum bits and four controlled logic gates to implement every subroutine required, demonstrating the working principle of this algorithm.

We have measured the frequency of the extremely narrow $1S\mathrm{\text{−}}2S$ two-photon transition in atomic hydrogen using a remote cesium fountain clock with the help of a 920 km stabilized optical fiber. With an improved detection method we obtain $f_{1S\mathrm{\text{−}}2S}=2466061413187018(11)\mathrm{Hz}$ with a relative uncertainty of $4.5\times {10}^{-15}$, confirming our previous measurement obtained with a local cesium clock [C. G. Parthey et al., Phys. Rev. Lett. 107, 203001 (2011)]. Combining these results with older measurements, we constrain the linear combinations of Lorentz boost symmetry violation parameters $c_{(TX)}=(3.1\pm 1.9)\times {10}^{-11}$ and $0.92c_{(TY)}+0.40c_{(TZ)}=(2.6\pm 5.3)\times {10}^{-11}$ in the standard model extension framework [D. Colladay, V. A. Kostelecký, Phys. Rev. D. 58, 116002 (1998)].

We study a relativistic plasma containing charged chiral fermions in an external electric field. We show that with the presence of both vector and axial charge densities, the electric field can induce an axial current along its direction and thus cause chirality separation. We call it the chiral electric separation effect (CESE). On a very general basis, we argue that the strength of CESE is proportional to ${\mu }_V{\mu }_A$ with ${\mu }_V$ and ${\mu }_A$ the chemical potentials for vector charge and axial charge. We then explicitly calculate this CESE conductivity coefficient in thermal QED at leading-log order. The CESE can manifest a new gapless wave mode propagating along the electric field. Potential observable effects of CESE in heavy-ion collisions are also discussed.

The transformation of a system from one state to another is often mediated by a bottleneck in the system’s phase space. In chemistry, these bottlenecks are known as transition states through which the system has to pass in order to evolve from reactants to products. The chemical reactions are usually associated with configurational changes where the reactants and products states correspond, e.g., to two different isomers or the undissociated and dissociated state of a molecule or cluster. In this Letter, we report on a new type of bottleneck which mediates kinetic rather than configurational changes. The phase space structures associated with such kinetic transition states and their dynamical implications are discussed for the rotational vibrational motion of a triatomic molecule. An outline of more general related phase space structures with important dynamical implications is given.

Entanglement is a key element in quantum information processing. Here, we present schemes to generate robust photon entanglement via optomechanical quantum interfaces in the strong coupling regime. The schemes explore the excitation of the Bogoliubov dark mode and the destructive quantum interference between the bright modes of the interface, similar to electromagnetically induced transparency, to eliminate leading-order effects of the mechanical noise. Both continuous-variable and discrete-state entanglements that are robust against the mechanical noise can be achieved. The schemes can be used to generate entanglement in hybrid quantum systems between, e.g., microwave photon and optical photon.

We report on the observation of self-induced precession of an optical vortex as a result of the nonlinear interaction between light and liquid crystals. The phenomenon corresponds to an instability for the spin-orbit interaction of light that manifests as a spontaneous axial symmetry breaking, which leads to the orbital motion of the optical vortex around the beam propagation. A nonlinear spin Hall effect of light is experimentally identified, thereby unveiling an original demonstration of spin to extrinsic orbital light angular momentum self-conversion.

We show that supersymmetry can provide a versatile platform in synthesizing a new class of optical structures with desired properties and functionalities. By exploiting the intimate relationship between superpatners, one can systematically construct index potentials capable of exhibiting the same scattering and guided wave characteristics. In particular, in the Helmholtz regime, we demonstrate that one-dimensional supersymmetric pairs display identical reflectivities and transmittivities for any angle of incidence. Optical supersymmetry is then extended to two-dimensional systems where a link between specific azimuthal mode subsets is established. Finally, we explore supersymmetric photonic lattices where discreteness can be utilized to design lossless integrated mode filtering arrangements.

A nonlinear parallel force can be exerted through the inhomogeneity of rf resonant absorption in a magnetized plasma. While providing no integrated force over a plasma volume, this force can redistribute momentum parallel to the magnetic field. Because flows and currents parallel to the magnetic field encounter different resistances, this redistribution can play a large role, in addition to the role played by the direct absorption of parallel momentum. For nearly perpendicular propagating waves in a tokamak plasma, this additional force is expected to affect significantly the toroidal rf-driven current and the toroidal flow drive.

The geometry of oxygen atoms in hollow sites of Fe nanoislands ($\oslash \approx 1–2\mathrm{nm}$) on Fe(001) is modified by mesoscopic misfit-induced relaxations of the island atoms. Surface x-ray diffraction, scanning tunneling microscopy, and ab initio calculations indicate a 0.3 Å increased adsorption height [0.7 Å versus 0.4 Å in $\mathrm{O}/\mathrm{Fe}(001)\mathrm{\text{−}}p(1\times 1)$] of O atoms going in parallel with a reduced Fe-Fe layer spacing inducing a reduction of the surface magnetic moment ($2.85{\mu }_B$ versus $3.2{\mu }_B$). Our results demonstrate the importance of the mesoscopic misfit for surface physical properties in general.

We propose the initial single chiral particle emission mechanism, with which the hidden-charm dikaon decays of higher charmonia and charmoniumlike states are studied. Calculating the distributions of differential decay width, we obtain the line shape of the $J/\psi K^{+}$ invariant mass spectrum of ${\psi }_i\to J/\psi K^{+}{K}^{-}$, where ${\psi }_i=\psi (4415)$, $Y(4660)$, and $\psi (4790)$. Our numerical results show that there exist enhancement structures with both hidden-charm and open-strange channels, which are near the $D{\overline{D}}_s^{*}/D^{*}{\overline{D}}_s$ and $D^{*}{\overline{D}}_s^{*}/{\overline{D}}^{*}{D}_s^{*}$ thresholds. These charged charmoniumlike structures predicted in this Letter can be accessible in future experiments, especially BESIII, BelleII, and SuperB.

In top-pair events where at least one of the tops decays semileptonically, the identification of the lepton charge allows us to tag not only the top quark charge but also that of the subsequent $b$ quark. In cases where the $b$ also decays semileptonically, the charge of the two leptons can be used to probe $CP$ violation in heavy flavor mixing and decays. This strategy to measure $CP$ violation is independent of those adopted so far in experiments, and can already constrain non standard model sources of $CP$ violation with current and near future LHC data. To demonstrate the potential of this method we construct two $CP$ asymmetries based on same-sign and opposite-sign leptons and estimate their sensitivities. This proposal opens a new window for doing precision measurements of $CP$ violation in $b$ and $c$ quark physics via high $p_T$ processes at ATLAS and CMS.