Liquid foams are widely used in industry for their high effective viscosity, whose local origin is still unclear. This Letter presents new results on the extension of a suspended soap film, in a configuration mimicking the elementary deformation occurring during foam shearing. We evidence a surprising two-step evolution: the film first extends homogeneously, then its extension stops, and a new thicker film is extracted from the meniscus. The second step is independent of the nature of the surfactant solution, whereas the initial extension is only observed for surfactant solutions with negligible dilatational moduli. We predict this complex behavior using a model based on Frankel’s theory and on interface rigidification induced by confinement.

We investigate the temporal and spacial evolution of single bursts and their statistics emerging in heterogeneous materials under a constant external load. Based on a fiber bundle model we demonstrate that when the load redistribution is localized along a propagating crack front, the average temporal shape of pulses has a right-handed asymmetry; however, for long range interaction a symmetric shape with parabolic functional form is obtained. The pulse shape and spatial evolution of bursts proved to be correlated, which can be exploited in materials’ testing. The probability distribution of the size and duration of bursts have power law behavior with a crossover to higher exponents as the load is lowered. The crossover emerges due to the competition of the slow and fast modes of local breaking being dominant at low and high loads, respectively.

Even though synchronization in autonomous systems has been observed for over three centuries, reports of systematic experimental studies on synchronized oscillators are limited. Here, we report on observations of internal synchronization in coupled silicon micromechanical oscillators associated with a reduction in the relative phase random walk that is modulated by the magnitude of the reactive coupling force between the oscillators. Additionally, for the first time, a significant improvement in the frequency stability of synchronized micromechanical oscillators is reported. The concept presented here is scalable and could be suitably engineered to establish the basis for a new class of highly precise miniaturized clocks and frequency references.

A previously unknown instability creates space-filling lattices of 3D vortices in linearly stable, rotating, stratified shear flows. The instability starts from an easily excited critical layer. The layer intensifies by drawing energy from the background shear and rolls up into vortices that excite new critical layers and vortices. The vortices self-similarly replicate to create lattices of turbulent vortices. The vortices persist for all time. This self-replication occurs in stratified Couette flows and in the dead zones of protoplanetary disks where it can destabilize Keplerian flows.

The unusual features of quantum mechanics are enabling the development of technologies not possible with classical physics. These devices utilize nonclassical phenomena in the states of atoms, ions, and solid-state media as the basis for many prototypes. Here we investigate molecular states as a distinct alternative. We demonstrate a memory for light based on storing photons in the vibrations of hydrogen molecules. The THz-bandwidth molecular memory is used to store 100-fs pulses for durations up to $\sim 1\mathrm{ns}$, enabling $\sim {10}^4$ operational time bins. The results demonstrate the promise of molecules for constructing compact ultrafast quantum photonic technologies.

An atomic force microscope reveals that the sliding of a nanotip on a graphite surface occurs through a nanoscale stick-slip mechanism. The angle between the sliding direction and a stiff crystallographic axis determines the periodicity of the slip events defining domains of various friction properties. The experimental data are interpreted using the reaction rate theory, with the energy barrier driven by a local deformation of the surface and a thermally activated relaxation.

We demonstrate the time-reversed process of nondegenerate three-wave parametric amplification from three distinct sources in the fully nonlinear regime using a Josephson amplifier. In the reverse process, coherent attenuation, signal and idler beams destructively interfere in the presence of a pump to generate additional pump photons. This effect is observed through the symmetric phase-dependent amplification and attenuation of the signal and idler beams and, in the depleted pump regime, through the phase-dependent modulation of the amplifier gain, directly probing the enhancement of the pump. Results are found to be in good agreement with theory.

Lumped circuit elements (i.e., resistors, capacitors, and inductors) provide the basic building blocks of microelectronic devices ubiquitous in information processing, storage, and communications. The use of these modular quasistatic components can be extended to the nanoscale optical regime to achieve high-density, high-speed analogues of these traditional circuits. We reimagine these devices in the near-infrared (NIR) regime, making use of a simple nanorod geometry and plasmonic transparent conducting oxides (TCOs). We evaluate their equivalent impedance as lumped circuit elements and construct bandpass and band-stop filters operating at NIR wavelengths. Through variation in the TCO nanorod geometry and the addition of PbS nanocrystals in between and NiCr on top of the TCO nanorods, we present the first designable NIR lumped nanocircuits with tailorable response. The experimental results agree with both circuit models and full-wave simulations.

We study the wavelength scaling of high harmonic generation efficiency with visible driver wavelengths in the transition between the tunneling and the multiphoton ionization regimes where the Keldysh parameter is around unity. Our experiment shows a less dramatic wavelength scaling of efficiency than the conventional case for near- and mid-IR driver wavelengths, and it is well explained by a generalized three-step model for increased Keldysh parameters that employs complex ionization times in addition to the nonadiabatic ionization. The complex ionization time is critical to avoid the divergence when replacing the quasistatic ionization model by the more general nonadiabatic ionization model. Together, the two modifications present a consistent description of the influence of the atomic potential on the rescattering process in the intermediate Keldysh regime.

The exquisite procedure for imaging a molecular orbital with high-order harmonics proposed by Itatani et al. [Nature (London) 432, 867 (2004)] encounters difficulty when extended to an asymmetric molecule because the wave function there usually does not have a definite parity. With the observation that the wave function can be decomposed into a sum of odd and even functions and that the ionization process in harmonic generation is usually not sensitive to the asymmetry of the molecular potential, we predict that asymmetric molecular orbital imaging can be implemented through decoding odd-even high-order harmonics. A generalized tomography procedure is proposed, which has been certified by analytic deduction and numerical simulation. The above finding greatly extends the molecular tomography procedure and will further stimulate related experiments.

Crumpled paper or drapery patterns are everyday examples of how elastic sheets can respond to external forcing. In this Letter, we study experimentally a different sort of forcing. We consider a circular flexible plate clamped at its center and subject to a uniform flow normal to its initial surface. As the flow velocity is gradually increased, the plate exhibits a rich variety of bending deformations: from a cylindrical shape, to isometric developable cones with azimuthal periodicity two or three, to eventually a rolled-up period-three cone. We show that this sequence of flow-induced deformations can be qualitatively predicted by a linear analysis based on the balance between elastic energy and pressure force work.

Do nonlinear waves destroy Anderson localization? Computational and experimental studies yield subdiffusive nonequilibrium wave packet spreading. Chaotic dynamics and phase decoherence assumptions are used for explaining the data. We perform a quantitative analysis of the nonequilibrium chaos assumption and compute the time dependence of main chaos indicators—Lyapunov exponents and deviation vector distributions. We find a slowing down of chaotic dynamics, which does not cross over into regular dynamics up to the largest observed time scales, still being fast enough to allow for a thermalization of the spreading wave packet. Strongly localized chaotic spots meander through the system as time evolves. Our findings confirm for the first time that nonequilibrium chaos and phase decoherence persist, fueling the prediction of a complete delocalization.

We use confocal microscopy to directly visualize the spatial fluctuations in fluid flow through a three-dimensional porous medium. We find that the velocity magnitudes and the velocity components both along and transverse to the imposed flow direction are exponentially distributed, even with residual trapping of a second immiscible fluid. Moreover, we find pore-scale correlations in the flow that are determined by the geometry of the medium. Our results suggest that despite the considerable complexity of the pore space, fluid flow through it is not completely random.

We present an analytic random matrix theory for the effect of incomplete channel control on the measured statistical properties of the scattering matrix of a disordered multiple-scattering medium. When the fraction of the controlled input channels, $m_1$, and output channels, $m_2$, is decreased from unity, the density of the transmission eigenvalues is shown to evolve from the bimodal distribution describing coherent diffusion, to the distribution characteristic of uncorrelated Gaussian random matrices, with a rapid loss of access to the open eigenchannels. The loss of correlation is also reflected in an increase in the information capacity per channel of the medium. Our results have strong implications for optical and microwave experiments on diffusive scattering media.

We show experimentally that a resolution far beyond that of conventional far-field optical profilometers can be reached with optical diffraction tomography. This result is obtained in the presence of multiple scattering when using an adapted inverse scattering algorithm for profile reconstruction. This new profilometry technique, whose resolution can be compared to that of atomic microscopes, also gives access to the permittivity of the surface.

We report the experimental observation of multi-bound-soliton solutions of the nonlinear Schrödinger equation (NLS) in the context of hydrodynamic surface gravity waves. Higher-order $N$-soliton solutions with $N=2$, 3 are studied in detail and shown to be associated with self-focusing in the wave group dynamics and the generation of a steep localized carrier wave underneath the group envelope. We also show that for larger input soliton numbers, the wave group experiences irreversible spectral broadening, which we refer to as a hydrodynamic supercontinuum by analogy with optics. This process is shown to be associated with the fission of the initial multisoliton into individual fundamental solitons due to higher-order nonlinear perturbations to the NLS. Numerical simulations using an extended NLS model described by the modified nonlinear Schrödinger equation, show excellent agreement with experiment and highlight the universal role that higher-order nonlinear perturbations to the NLS play in supercontinuum generation.

We study the dynamical regime of wave turbulence of a vibrated thin elastic plate based on experimental and numerical observations. We focus our study on the strongly nonlinear regime described in a previous Letter by Yokoyama and Takaoka. At small forcing, a weakly nonlinear regime is compatible with the weak turbulence theory when the dissipation is localized at high wave number. When the forcing intensity is increased, a strongly nonlinear regime emerges: singular structures dominate the dynamics at large scales whereas at small scales the weak turbulence is still present. A turbulence of singular structures with folds and $D$ cones develops that alters significantly the energy spectra and causes the emergence of intermittency.

In pattern-forming systems, localized patterns are states of intermediate complexity between fully extended ordered patterns and completely irregular patterns. They are formed by stationary fronts enclosing an ordered pattern inside an homogeneous background. In two dimensions, the ordered pattern is most often hexagonal and the conditions for fronts to stabilize are still unknown. In this Letter, we show how the locking of these fronts depends on their orientation relative to the pattern. The theory rests on general asymptotic arguments valid when the spatial scale of the front is slow compared to that of the hexagonal pattern. Our analytical results are confirmed by numerical simulations with the Swift-Hohenberg equation, relevant to hydrodynamical and buckling instabilities, and a nonlinear optical cavity model.

Time-delayed systems are found to display remarkable temporal patterns the dynamics of which split into regular and chaotic components repeating at the interval of a delay. This novel long-term behavior for delay dynamics results from strongly asymmetric nonlinear delayed feedback driving a highly damped harmonic oscillator dynamics. In the corresponding virtual space-time representation, the behavior is found to develop as a chimeralike state, a new paradigmatic object from the network theory characterized by the coexistence of synchronous and incoherent oscillations. Numerous virtual chimera states are obtained and analyzed, through experiment, theory, and simulations.

We use a scattering formalism to derive a condition of strong coupling between a resonant scatterer and an Anderson localized mode for electromagnetic waves in two dimensions. The strong coupling regime is demonstrated based on exact numerical simulations, in perfect agreement with theory. The strong coupling threshold can be expressed in terms of the Thouless conductance and the Purcell factor. This connects key concepts in transport theory and cavity quantum electrodynamics, and provides a practical tool for the design or analysis of experiments.