The possibility of the conversion of intense continuous microwave radiation into a periodic train of short pulses by means of resonant interaction with a beam of unexcited cyclotron electron oscillators moving backward is shown. In such a system there is a certain range of parameters where the incident stationary signal splits into a train of short pulses and each of them can be interpreted as a soliton. It is proposed to use this effect for amplitude modulation of radiation of short wavelength gyrotrons.

This Letter describes the theoretical structure of the plasma diffusion layer that develops from an initially sharp gas-metal interface. The layer dynamics under isothermal and isobaric conditions is considered so that only mass diffusion (mixing) processes can occur. The layer develops a distinctive structure with asymmetric and highly nonlinear features. On the gas side of the layer the diffusion coefficient goes nearly to zero, causing a sharp “front,” or well defined boundary between mix layer and clean gas with similarities to the Marshak thermal waves. Similarity solutions for the nonlinear profiles are found and verified with full ion kinetic code simulations. A criterion for plasma diffusion to significantly affect burn is given.

Magnetic field ($B$) variation of the electrical polarization $P_c$ ($\parallel c$) of the perfect triangular lattice antiferromagnet $\mathrm{RbFe}{({\mathrm{MoO}}_4)}_2$ is examined up to the saturation point of the magnetization for $B\perp c$. $P_c$ is observed only in phases for which chirality is predicted in the in-plane magnetic structures. No strong anomaly is observed in $P_c$ at the field at which the spin modulation along the $c$ axis, and hence the spin helicity, exhibits a discontinuity to the commensurate state. These results indicate that the ferroelectricity in this compound originates predominantly from the spin chirality, the explanation of which would require a new mechanism for magnetoferroelectricity. The obtained field-temperature phase diagram of ferroelectricity agree well with those theoretically predicted for the spin chirality of a Heisenberg spin triangular lattice antiferromagnet.

We study grain-scale mechanical and geometrical features of partially crystallized packings of frictional spheres, produced experimentally by a vibrational protocol. By combining x-ray computed tomography, 3D image analysis, and discrete element method simulations, we have access to the 3D structure of internal forces. We investigate how the network of mechanical contacts and intergranular forces change when the packing structure evolves from amorphous to near perfect crystalline arrangements. We compare the behavior of the geometrical neighbors (quasicontracts) of a grain to the evolution of the mechanical contacts. The mechanical coordination number $Z_m$ is a key parameter characterizing the crystallization onset. The high fluctuation level of $Z_m$ and of the force distribution in highly crystallized packings reveals that a geometrically ordered structure still possesses a highly random mechanical backbone similar to that of amorphous packings.

Single and collective cellular oscillations driven by the actomyosin cytoskeleton have been observed in numerous biological systems. Here, we propose that these oscillations can be accounted for by a generic oscillator model of a material turning over and contracting against an elastic element. As an example, we show that during dorsal closure of the Drosophila embryo, experimentally observed changes in actomyosin concentration and oscillatory cell shape changes can, indeed, be captured by the dynamic equations studied here. We also investigate the collective dynamics of an ensemble of such contractile elements and show that the relative contribution of viscous and friction losses yields different regimes of collective oscillations. Taking into account the diffusion of force-producing molecules between contractile elements, our theoretical framework predicts the appearance of traveling waves, resembling the propagation of actomyosin waves observed during morphogenesis.

Einstein-Podolsky-Rosen (EPR) steering, a generalization of the original concept of “steering” proposed by Schrödinger, describes the ability of one system to nonlocally affect another system’s states through local measurements. Some experimental efforts to test EPR steering in terms of inequalities have been made, which usually require many measurement settings. Analogy to the “all-versus-nothing” (AVN) proof of Bell’s theorem without inequalities, testing steerability without inequalities would be more strong and require less resources. Moreover, the practical meaning of steering implies that it should also be possible to store the state information on the side to be steered, a result that has not yet been experimentally demonstrated. Using a recent AVN criterion for two-qubit entangled states, we experimentally implement a practical steering game using quantum memory. Furthermore, we develop a theoretical method to deal with the noise and finite measurement statistics within the AVN framework and apply it to analyze the experimental data. Our results clearly show the facilitation of the AVN criterion for testing steerability and provide a particularly strong perspective for understanding EPR steering.

It is well known that an unambiguous discrimination of the four optically encoded Bell states is possible with a probability of 50% at best, when using static, passive linear optics and arbitrarily many vacuum-mode ancillae. By adding unentangled single-photon ancillae, we are able to surpass this limit and reach a success probability of at least 75%. We discuss the error robustness of the proposed scheme and a generalization to reach a success probability arbitrarily close to 100%.

The $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^0{\chi }_{bJ}$ ($J=0,1,2$) processes are studied using a $118{\mathrm{fb}}^{-1}$ data sample acquired with the Belle detector at a center-of-mass energy of 10.867 GeV. Unambiguous ${\pi }^{+}{\pi }^{-}{\pi }^0{\chi }_{bJ}$ ($J=1,2$), $\omega {\chi }_{b1}$ signals are observed, and indication for $\omega {\chi }_{b2}$ is seen, both for the first time, and the corresponding cross section measurements are presented. No significant ${\pi }^{+}{\pi }^{-}{\pi }^0{\chi }_{b0}$ or $\omega {\chi }_{b0}$ signals are observed, and 90% confidence level upper limits on the cross sections for these two processes are obtained. In the ${\pi }^{+}{\pi }^{-}{\pi }^0$ invariant mass spectrum, significant non-$\omega$ signals are also observed. We search for the $X(3872)$-like state (named $X_b$) decaying into $\omega \mathrm{\Upsilon }(1S)$; no significant signal is observed with a mass between 10.55 and $10.65\mathrm{GeV}/c^2$.

We report the first measurement of charmed-hadron ($D^0$) production via the hadronic decay channel ($D^0\to K^{-}+{\pi }^{+}$) in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$ with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, $N_{\mathrm{bin}}$, from $p+p$ to central $\mathrm{Au}+\mathrm{Au}$ collisions. The $D^0$ meson yields in central $\mathrm{Au}+\mathrm{Au}$ collisions are strongly suppressed compared to those in $p+p$ scaled by $N_{\mathrm{bin}}$, for transverse momenta $p_T>3\mathrm{GeV}/c$, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate $p_{\mathrm{T}}$ is also observed. Model calculations including strong charm-medium interactions and coalescence hadronization describe our measurements.

We experimentally demonstrate quantum enhanced resolution in confocal fluorescence microscopy exploiting the nonclassical photon statistics of single nitrogen-vacancy color centers in diamond. By developing a general model of superresolution based on the direct sampling of the $k$th-order autocorrelation function of the photoluminescence signal, we show the possibility to resolve, in principle, arbitrarily close emitting centers.

We propose a realistic protocol for the preparation and readout of mechanical Bell states in an optomechanical system. The proposal relies on parameters characterizing a photonic crystal cavity mode, coupled to two localized flexural modes of the structure, but equally applies to other optomechanical systems in the same parameter range. The nonclassical states are heralded via optical postselection and revealed in specific interference patterns characterizing the emission at the cavity frequency.

We study optimal synchronization in networks of heterogeneous phase oscillators. Our main result is the derivation of a synchrony alignment function that encodes the interplay between network structure and oscillators’ frequencies and that can be readily optimized. We highlight its utility in two general problems: constrained frequency allocation and network design. In general, we find that synchronization is promoted by strong alignments between frequencies and the dominant Laplacian eigenvectors, as well as a matching between the heterogeneity of frequencies and network structure.

The calculations presented here reveal that an electron probe carrying orbital angular momentum is just a particular case of a wider class of electron beams that can be used to measure electron magnetic circular dichroism (EMCD) with atomic resolution. It is possible to obtain an EMCD signal with atomic resolution by simply breaking the symmetry of the electron probe phase distribution using the aberration-corrected optics of a scanning transmission electron microscope. The required phase distribution of the probe depends on the magnetic symmetry and crystal structure of the sample. The calculations indicate that EMCD signals utilizing the phase of the electron probe are as strong as those obtained by nanodiffraction methods.

We consider the phase equilibria of a fluid confined in a deep capillary groove of width $L$ with identical side walls and a bottom made of a different material. All walls are completely wet by the liquid. Using density functional theory and interfacial models, we show that the meniscus separating liquid and gas phases at two phase capillary coexistence meets the bottom capped end of the groove at a capillary contact angle ${\theta }^{\text{cap}}(L)$ which depends on the difference between the Hamaker constants. If the bottom wall has a weaker wall-fluid attraction than the side walls, then ${\theta }^{\text{cap}}>0$ even though all the isolated walls are themselves completely wet. This alters the capillary condensation transition which is now first order; this would be continuous in a capped capillary made wholly of either type of material. We show that the capillary contact angle ${\theta }^{\text{cap}}(L)$ vanishes in two limits, corresponding to different capillary wetting transitions. These occur as the width (i) becomes macroscopically large, and (ii) is reduced to a microscopic value determined by the difference in Hamaker constants. This second wetting transition is characterized by large scale fluctuations and essential critical singularities arising from marginal interfacial interactions.

We consider ultracold bosonic atoms in a single trap in the Thomas-Fermi regime, forming many-body states corresponding to stable macroscopically fragmented two-mode condensates. It is demonstrated that upon free expansion of the gas, the spatial dependence of the density-density correlations at late times provides a unique signature of fragmentation. This hallmark of fragmented condensate many-body states in a single trap is due to the fact that the time of flight modifies the correlation signal such that two opposite points in the expanding cloud become uncorrelated, in distinction to a nonfragmented Bose-Einstein condensate, where they remain correlated.

We present the gravity dual of large $N$ supersymmetric gauge theories on a squashed five-sphere. The one-parameter family of solutions is constructed in Euclidean Romans $F(4)$ gauged supergravity in six dimensions, and uplifts to massive type IIA supergravity. By renormalizing the theory with appropriate counterterms we evaluate the renormalized on-shell action for the solutions. We also evaluate the large $N$ limit of the gauge theory partition function, and find precise agreement.

Three-body $B^{+}\to p\overline{p}{K}^{+}$ and $B^{+}\to p\overline{p}{\pi }^{+}$ decays are studied using a data sample corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$ collected by the LHCb experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV. Evidence of $CP$ violation in the $B^{+}\to p\overline{p}{K}^{+}$ decay is found in regions of the phase space, representing the first measurement of this kind for a final state containing baryons. Measurements of the forward-backward asymmetry of the light meson in the $p\overline{p}$ rest frame yield $A_{\mathrm{FB}}(p\overline{p}{K}^{+},m_{p\overline{p}}<2.85\mathrm{GeV}/c^2)=0.495\pm 0.012(\text{stat})\pm 0.007(\text{syst})$ and $A_{\mathrm{FB}}(p\overline{p}{\pi }^{+},m_{p\overline{p}}<2.85\mathrm{GeV}/c^2)=-0.409\pm 0.033(\text{stat})\pm 0.006(\text{syst})$. In addition, the branching fraction of the decay $B^{+}\to \overline{\mathrm{\Lambda }}(1520)p$ is measured to be $\mathcal{B}\mathbf{(}{B}^{+}\to \overline{\mathrm{\Lambda }}(1520)p\mathbf{)}=\mathbf{(}3.15\pm 0.48(\text{stat})\pm 0.07(\text{syst})\pm 0.26(\mathrm{BF})\mathbf{)}\times 10^{-7}$, where BF denotes the uncertainty on secondary branching fractions.