The interpenetration and interaction of supersonic, magnetized tungsten plasma flows has been directly observed via spatially and temporally resolved measurements of the Thomson scattering ion feature. A novel scattering geometry allows independent measurements of the axial and radial velocity components of the ions. The plasma flows are produced via the pulsed power driven ablation of fine tungsten wires in a cylindrical wire array $z$ pinch. Fits of the data reveal the variations in radial velocity, axial velocity, and temperature of the ion streams as they interpenetrate and interact. A previously unobserved increase in axial velocity is measured near the array axis. This may be the result of $\overrightarrow{v}\times \overrightarrow{B}$ bending of the ion streams by a toroidal magnetic field, advected to and accumulated about the axis by the streams.

We present a microscopic explanation of the controversially discussed transient negative differential transmission observed in degenerate optical pump-probe measurements in graphene. Our approach is based on the density matrix formalism allowing a time- and momentum-resolved study of carrier-light, carrier-carrier, and carrier-phonon interaction on microscopic footing. We show that phonon-assisted optical intraband transitions give rise to transient absorption in the optically excited hot carrier system counteracting pure absorption bleaching of interband transitions. While interband transition bleaching is relevant in the first hundreds of fs after the excitation, intraband absorption sets in at later times. In particular, in the low excitation regime, these intraband absorption processes prevail over the absorption bleaching resulting in a zero crossing of the differential transmission. Our findings are in good qualitative agreement with recent experimental pump-probe studies.

Tribological shearing of polycrystalline metals typically leads to grain refinement at the sliding interface. This study, however, shows that nanocrystalline metals exhibit qualitatively different behavior. Using large-scale atomistic simulations, we demonstrate that during sliding, contact interface nanocrystalline grains self-organize through extensive grain coarsening and lattice rotation until the optimal plastic slip orientation is established. Subsequently, plastic deformation is frequently confined to localized nanoshear bands aligned with the shearing direction and emanating from voids and other defects in the vicinity of the sliding interface.

We argue that, because of quantum entanglement, the local physics of strongly correlated materials at zero temperature is described in a very good approximation by a simple generalized Gibbs distribution, which depends on a relatively small number of local quantum thermodynamical potentials. We demonstrate that our statement is exact in certain limits and present numerical calculations of the iron compounds FeSe and FeTe and of the elemental cerium by employing the Gutzwiller approximation that strongly support our theory in general.

We investigate the spin dynamics of half-solitons in quantum fluids of interacting photons (exciton polaritons). Half-solitons, which behave as emergent monopoles, can be accelerated by the presence of effective magnetic fields. We study the generation of dc magnetic currents in a gas of half-solitons. At low densities, the current is suppressed due to the dipolar oscillations. At moderate densities, a magnetic current is recovered as a consequence of the collisions between the carriers. We show a deviation from Ohm’s law due to the competition between dipoles and monopoles.

We show that dry active nematics, e.g., collections of shaken elongated granular particles, exhibit large-scale spatiotemporal chaos made of interacting dense, ordered, bandlike structures in a parameter region including the linear onset of nematic order. These results are obtained from the study of both the well-known (deterministic) hydrodynamic equations describing these systems and of the self-propelled particle model they were derived from. We prove, in particular, that the chaos stems from the generic instability of the band solution of the hydrodynamic equations. Revisiting the status of the strong fluctuations and long-range correlations in the particle model, we show that the giant number fluctuations observed in the chaotic phase are a trivial consequence of density segregation. However anomalous, curvature-driven number fluctuations are present in the homogeneous quasiordered nematic phase and characterized by a nontrivial scaling exponent.

Large weak values have been used to amplify the sensitivity of a linear response signal for detecting changes in a small parameter, which has also enabled a simple method for precise parameter estimation. However, producing a large weak value requires a low postselection probability for an ancilla degree of freedom, which limits the utility of the technique. We propose an improvement to this method that uses entanglement to increase the efficiency. We show that by entangling and postselecting $n$ ancillas, the postselection probability can be increased by a factor of $n$ while keeping the weak value fixed (compared to $n$ uncorrelated attempts with one ancilla), which is the optimal scaling with $n$ that is expected from quantum metrology. Furthermore, we show the surprising result that the quantum Fisher information about the detected parameter can be almost entirely preserved in the postselected state, which allows the sensitive estimation to approximately saturate the relevant quantum Cramér-Rao bound. To illustrate this protocol we provide simple quantum circuits that can be implemented using current experimental realizations of three entangled qubits.

Using a proton-proton collision data sample corresponding to an integrated luminosity of $3{\mathrm{fb}}^{-1}$ collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 ${\mathrm{\Xi }}_b^0\to {\mathrm{\Xi }}_c^{+}{\pi }^{-}$, ${\mathrm{\Xi }}_c^{+}\to p{K}^{-}{\pi }^{+}$ signal decays are reconstructed. From this sample, the first measurement of the ${\mathrm{\Xi }}_b^0$ baryon lifetime is made, relative to that of the ${\mathrm{\Lambda }}_b^0$ baryon. The mass differences $M({\mathrm{\Xi }}_b^0)-M({\mathrm{\Lambda }}_b^0)$ and $M({\mathrm{\Xi }}_c^{+})-M({\mathrm{\Lambda }}_c^{+})$ are also measured with precision more than 4 times better than the current world averages. The resulting values are $$\begin{gathered} \frac{{\tau }_{{\mathrm{\Xi }}_b^0}}{{\tau }_{{\mathrm{\Lambda }}_b^0}}=1.006\pm 0.018\pm 0.010, \\ M({\mathrm{\Xi }}_b^0)-M({\mathrm{\Lambda }}_b^0)=172.44\pm 0.39\pm 0.17\mathrm{MeV}/c^2, \\ M({\mathrm{\Xi }}_c^{+})-M({\mathrm{\Lambda }}_c^{+})=181.51\pm 0.14\pm 0.10\mathrm{MeV}/c^2, \end{gathered}$$where the first uncertainty is statistical and the second is systematic. The relative rate of ${\mathrm{\Xi }}_b^0$ to ${\mathrm{\Lambda }}_b^0$ baryon production is measured to be $$\frac{f_{{\mathrm{\Xi }}_b^0}}{f_{{\mathrm{\Lambda }}_b^0}}\frac{\mathcal{B}({\mathrm{\Xi }}_b^0\to {\mathrm{\Xi }}_c^{+}{\pi }^{-})}{\mathcal{B}({\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^{+}{\pi }^{-})}\frac{\mathcal{B}({\mathrm{\Xi }}_c^{+}\to p{K}^{-}{\pi }^{+})}{\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+})}=(1.88\pm 0.04\pm 0.03)\times 10^{-2},$$where the first factor is the ratio of fragmentation fractions, $b\to {\mathrm{\Xi }}_b^0$ relative to $b\to {\mathrm{\Lambda }}_b^0$. Relative production rates as functions of transverse momentum and pseudorapidity are also presented.

We show that a returning electron wave packet in high-order harmonic generation (HHG) with midinfrared laser pulses converges to a universal limit for a laser wavelength above about $3\mu \mathrm{m}$. The results are consistent among the different methods: a numerical solution of the time-dependent Schrödinger equation, the strong-field approximation, and the quantum orbits theory. We further analyze how the contribution from different electron “trajectories” survives the macroscopic propagation in the medium. Our result thus provides a new framework for investigating the wavelength scaling law for the HHG yields.

Dust particulates immersed in a quasineutral plasma can emit electrons in several important applications. Once electron emission becomes strong enough, the dust enters the positively charged regime where the conventional orbital-motion-limited (OML) theory can break down due to potential-well effects on trapped electrons. A minimal modification of the trapped-passing boundary approximation in the so-called ${\mathrm{OML}}^{+}$ approach is shown to accurately predict the dust charge and heat collection flux for a wide range of dust size and temperature.

We measure the position- and momentum-space breathing dynamics of trapped one-dimensional Bose gases at finite temperature. The profile in real space reveals sinusoidal width oscillations whose frequency varies continuously through the quasicondensate to ideal Bose gas crossover. A comparison with theoretical models taking temperature into account is provided. In momentum space, we report the first observation of a frequency doubling in the quasicondensate regime, corresponding to a self-reflection mechanism due to the repulsive interactions. Such a mechanism is predicted for a fermionized system, and has not been observed to date. The disappearance of the frequency doubling through the crossover is mapped out experimentally, giving insights into the dynamics of the breathing evolution.

Deformation of ductile crystalline-amorphous nanolaminates is not well understood due to the complex interplay of interface mechanics, shear banding, and deformation-driven chemical mixing. Here we present indentation experiments on 10 nm nanocrystalline Cu–100 nm amorphous CuZr model multilayers to study these mechanisms down to the atomic scale. By using correlative atom probe tomography and transmission electron microscopy we find that crystallographic slip bands in the Cu layers coincide with noncrystallographic shear bands in the amorphous CuZr layers. Dislocations from the crystalline layers drag Cu atoms across the interface into the CuZr layers. Also, crystalline Cu blocks are sheared into the CuZr layers. In these sheared and thus Cu enriched zones the initially amorphous CuZr layer is rendered into an amorphous plus crystalline nanocomposite.

We investigate the formation of photonic bound states in the continuum (BICs) in photonic crystal slabs from an analytical perspective. Unlike the stationary at-$\mathrm{\Gamma }$ BICs which originate from the geometric symmetry, the tunable off-$\mathrm{\Gamma }$ BICs are due to the weighted destructive via the continuum interference in the vicinity of accidental symmetry when the majority of the radiation is precanceled. The symmetric compatible nature of the off-$\mathrm{\Gamma }$ BICs leads to a trapping of light that can be tuned through continuously varying the wave vector. With the analytical approach, we explain a reported experiment and predict the existence of a new BIC at an unrevealed symmetry.

Biomaterials such as protein or polysaccharide gels are known to behave qualitatively as soft solids and to rupture under an external load. Combining optical and ultrasonic imaging to shear rheology we show that the failure scenario of a protein gel is reminiscent of brittle solids: after a primary creep regime characterized by a power-law behavior whose exponent is fully accounted for by linear viscoelasticity, fractures nucleate and grow logarithmically perpendicularly to shear, up to the sudden rupture of the gel. A single equation accounting for those two successive processes nicely captures the full rheological response. The failure time follows a decreasing power law with the applied shear stress, similar to the Basquin law of fatigue for solids. These results are in excellent agreement with recent fiber-bundle models that include damage accumulation on elastic fibers and exemplify protein gels as model, brittlelike soft solids.

We validate experimentally a fluctuation relation known as generalized Jarzynski equality governing the work distribution in a feedback-controlled system. The feedback control is performed on a single electron box analogously to the original Szilard engine. In the generalized Jarzynski equality, mutual information is treated on an equal footing with the thermodynamic work. Our measurements provide the first evidence of the role of mutual information in the fluctuation theorem and thermodynamics of irreversible processes.