The transmission of information can couple two entities of very different nature, one of them serving as a memory for the other. Here we study the situation in which information is stored in a wave field and serves as a memory that pilots the dynamics of a particle. Such a system can be implemented by a bouncing drop generating surface waves sustained by a parametric forcing. The motion of the resulting “walker” when confined in a harmonic potential well is generally disordered. Here we show that these trajectories correspond to chaotic regimes characterized by intermittent transitions between a discrete set of states. At any given time, the system is in one of these states characterized by a double quantization of size and angular momentum. A low dimensional intermittency determines their respective probabilities. They thus form an eigenstate basis of decomposition for what would be observed as a superposition of states if all measurements were intrusive.

A robust method for producing half-cycle–few-cycle attosecond pulses in the extreme ultraviolet spectral range is proposed. It is based on coherent undulator radiation of relativistic ultrathin electron layers (nanobunches), which are produced by nanobunching of ultrashort electron bunches by a 10-TW power laser in a modulator undulator. Our numerical calculations predict the generation of nanobunches shorter than 10 nm. By using these electron nanobunches the production of carrier-envelope-phase stable attosecond pulses with up to a few tens of nJ energy and down to 10 nm wavelength and 35 as duration is predicted.

A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales $\sim 10^4{\omega }_{pe}^{-1}$. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well confined to the downstream region of the electrostatic shock. The shock formation process is not modified, and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock.

The quantitative structure determination of adsorbed species on quasicrystal surfaces has so far appeared to present insurmountable problems. The normal incidence standing x-ray wave field technique offers a simple solution, without extensive data sets or large computations. Its application to quasicrystals raises several conceptual difficulties that are related to the phase problem in x-ray diffraction. We demonstrate their solution for the case of Si atoms adsorbed on the decagonal Co-rich modification of the Al-Co-Ni quasicrystal to determine the local structure, comprising 6-atom clusters in particular hollow sites.

We report on in situ chemical reactions between an organic trimesic acid (TMA) ligand and a Co atom center. By varying the substrate temperature, we are able to explore the Co–TMA interactions and create novel magnetic complexes that preserve the chemical structure of the ligands. Using scanning tunneling microscopy and spectroscopy combined with density functional theory calculations, we elucidate the structure and the properties of the newly synthesized complex at atomic or molecular size level. Hybridization between the atomic orbitals of the Co and the $\pi$ orbitals of the ligand results in a delocalized spin distribution onto the TMA. The here demonstrated possibility to conveniently magnetize such versatile molecules opens up new potential applications for TMAs in molecular spintronics.

We study a problem of interconvertibility of two supraquantum resources: one is the so-called Popescu-Rohrlich (PR) box, which violates Clauser-Horne-Shimony-Holt inequality up to the maximal algebraic bound, and the second is the so-called random access code (RAC). The latter is a functionality that enables Bob (receiver) to choose one of two bits of Alice. It is known that a PR box supplemented with one bit of communication can be used to simulate a RAC. We ask the converse question: to what extent can a RAC can simulate a PR box? To this end, we introduce a “racbox”: a box such that when it is supplemented with one bit of communication it offers a RAC. As said, a PR box can simulate a racbox. The question we raise is whether any racbox can simulate a PR box. We show that a nonsignaling racbox, indeed, can simulate a PR box; hence, these two resources are equivalent. We also provide an example of a signaling racbox that cannot simulate a PR box. We give a resource inequality between racboxes and PR boxes and show that it is saturated.

We derive a general framework that lifts any set of bipartite to multipartite entanglement witnesses and we show how positive maps can naturally be incorporated into this framework. We show that some previous approaches for multipartite entanglement detection are intimately connected to the witnesses derived from partial transposition and that such criteria can easily be outperformed in higher dimensions by nondecomposable maps. As an exemplary case we present a witness that is capable of detecting genuine multipartite entanglement in bound entangled states.

We determine the transverse system size of the initial nonequilibrium Glasma state and of the hydrodynamically evolving fireball as a function of produced charged particles in $p+p$, $p+\mathrm{Pb}$, and $\mathrm{Pb}+\mathrm{Pb}$ collisions at the Large Hadron Collider. Our results show features similar to those of recent measurements of Hanbury Brown–Twiss (HBT) radii by the ALICE Collaboration. Azimuthal anisotropy coefficients $v_n$ generated by combining the early time Glasma dynamics with viscous fluid dynamics in $\mathrm{Pb}+\mathrm{Pb}$ collisions are in excellent agreement with experimental data for a wide range of centralities. In particular, event-by-event distributions of the $v_n$ values agree with the experimental data out to fairly peripheral centrality bins. In striking contrast, our results for $p+\mathrm{Pb}$ collisions significantly underestimate the magnitude and do not reproduce the centrality dependence of data for $v_2$ and $v_3$ coefficients. We argue that the measured $v_n$ data and HBT radii strongly constrain the shapes of initial parton distributions across system sizes that would be compatible with a flow interpretation in $p+\mathrm{Pb}$ collisions. Alternately, additional sources of correlations may be required to describe the systematics of long-range rapidity correlations in $p+p$ and $p+\mathrm{Pb}$ collisions.

The direct $3\alpha$ decay branch from the $0_2^{+}$ state at $E_x=7.65\mathrm{MeV}$ in ${}^{12}\mathrm{C}$, which is known as the Hoyle state, is considered to affect the triple-$\alpha$ reaction rate strongly and to give crucial information on its structure. We have performed a high-precision measurement of the $3\alpha$ decay from this state using the ${}^{12}\mathrm{C}({}^{12}\mathrm{C},3\alpha ){}^{12}\mathrm{C}$ reaction at $E_{{}^{12}\mathrm{C}}=110\mathrm{MeV}$. The branching ratio of the direct $3\alpha$ decay was under the detection limit in the present experiment. By comparing with Monte Carlo simulations for three decay mechanisms as the sequential decay through the ground state of ${}^8\mathrm{Be}$, the direct decay with equal energies of three $\alpha$ particles, and the direct decay to the phase space uniformly, we have obtained the upper limit of 0.2% on the direct $3\alpha$ decay.

The linear stability of multiple coherent laser beams with respect to two-plasmon-decay instability in an inhomogeneous plasma in three dimensions has been determined. Cooperation between beams leads to absolute instability of long-wavelength decays, while shorter-wavelength shared waves are shown to saturate convectively. The multibeam, in its absolutely unstable form, has the lowest threshold for most cases considered. Nonlinear calculations using a three-dimensional extended Zakharov model show that Langmuir turbulence created by the absolute instability modifies the convective saturation of the shorter-wavelength modes, which are seen to dominate at late times.

Here we introduce a new approach to compute the finite temperature lattice dynamics from first principles via the newly developed slave mode expansion. We study PbTe where inelastic neutron scattering reveals strong signatures of nonlinearity as evidenced by anomalous features which emerge in the phonon spectra at finite temperature. Using our slave mode expansion in the classical limit, we compute the vibrational spectra and show remarkable agreement with temperature dependent inelastic neutron scattering measurements. Furthermore, we resolve an experimental controversy by showing that there are no appreciable local nor global spontaneously broken symmetries at finite temperature and that the anomalous spectral features simply arise from two anharmonic interactions. Our approach should be broadly applicable across the periodic table.

We argue that a three-dimensional electronic system with the Fermi level at the quadratic band touching point such as HgTe could be unstable with respect to the spontaneous formation of the (topological) Mott insulator at arbitrary weak long-range Coulomb interaction. The mechanism of the instability can be understood as the collision of Abrikosov’s non-Fermi liquid fixed point with another, quantum critical, fixed point, which approaches it in the coupling space as the system’s dimensionality $d\to d_{\text{low}}+$, with the “lower critical dimension” $2<d_{\text{low}}<4$. Arguments for the existence of the quantum critical point based on considerations in the large-$N$ limit in $d=3$, as well as close to $d=2$, are given. In the one-loop calculation we find that $d_{\text{low}}=3.26$, and thus above, but not far from three dimensions. This translates into a temperature or energy window ($T_{\mathrm{c}}$, $T_{*}$) over which the non-Fermi liquid scaling should still be observable, before the Mott transition finally takes place at the critical temperature $T_{\mathrm{c}}\sim T_{*}\exp [-zC/(d_{\text{low}}-d{)}^{1/2}]$. We estimate $C=\pi /1.1$, dynamical critical exponent $z\approx 1.8$, and the temperature scale $k_B{T}_{*}\approx (4m/m_{\text{el}}{ϵ}^2)13.6\mathrm{eV}$, with $m$ as the band mass and $ϵ$ as the dielectric constant.

An effective low-energy Hamiltonian of itinerant electrons for iridium oxide ${\mathrm{Na}}_2{\mathrm{IrO}}_3$ is derived by an ab initio downfolding scheme. The model is then reduced to an effective spin model on a honeycomb lattice by the strong coupling expansion. Here we show that the ab initio model contains spin-spin anisotropic exchange terms in addition to the extensively studied Kitaev and Heisenberg exchange interactions, and allows us to describe the experimentally observed zigzag magnetic order, interpreted as the state stabilized by the antiferromagnetic coupling of the ferromagnetic chains. We clarify possible routes to realize quantum spin liquids from existing ${\mathrm{Na}}_2{\mathrm{IrO}}_3$.

We measure biexciton Auger recombination (AR) in colloidal graphene quantum dots (GQDs) by transient absorption spectroscopy. AR is reflected in GQDs with 132 and 168 ${sp}^2$-hybridized C atoms as a decay with a $\sim 0.3\mathrm{ps}$ time constant and an amplitude depending superlinearly on pump fluence. Despite the orders-of-magnitude difference in size between GQDs and carbon nanotubes, their biexciton AR rates are similar. This similarity is a result of strong carrier interactions in $s{p}^2$-hybridized carbon nanostructures and suggests that GQDs may hold promise in the context of carrier multiplication.

We propose a new mechanism to generate the electroweak scale within the framework of QCD, which is extended to include conformally invariant scalar degrees of freedom belonging to a larger irreducible representation of $\mathrm{SU}(3{)}_c$. The electroweak symmetry breaking is triggered dynamically via the Higgs portal by the condensation of the colored scalar field around 1 TeV. The mass of the colored boson is restricted to be $350\mathrm{GeV}\lesssim m_S\lesssim 3\mathrm{TeV}$, with the upper bound obtained from perturbative renormalization group evolution. This implies that the colored boson can be produced at the LHC. If the colored boson is electrically charged, the branching fraction of the Higgs boson decaying into two photons can slightly increase, and moreover, it can be produced at future linear colliders. Our idea of nonperturbative electroweak scale generation can serve as a new starting point for more realistic model building in solving the hierarchy problem.

A quantum emitter efficiently coupled to a nanophotonic waveguide constitutes a promising system for the realization of single-photon transistors, quantum-logic gates based on giant single-photon nonlinearities, and high bit-rate deterministic single-photon sources. The key figure of merit for such devices is the $\beta$ factor, which is the probability for an emitted single photon to be channeled into a desired waveguide mode. We report on the experimental achievement of $\beta =98.43\%\pm 0.04\%$ for a quantum dot coupled to a photonic crystal waveguide, corresponding to a single-emitter cooperativity of $\eta =62.7\pm 1.5$. This constitutes a nearly ideal photon-matter interface where the quantum dot acts effectively as a 1D “artificial” atom, since it interacts almost exclusively with just a single propagating optical mode. The $\beta$ factor is found to be remarkably robust to variations in position and emission wavelength of the quantum dots. Our work demonstrates the extraordinary potential of photonic crystal waveguides for highly efficient single-photon generation and on-chip photon-photon interaction.