Spherically symmetric direct-drive-ignition designs driven by laser beams with a focal-spot size nearly equal to the target diameter suffer from energy losses due to crossed-beam energy transfer (CBET). Significant reduction of CBET and improvements in implosion hydrodynamic efficiency can be achieved by reducing the beam diameter. Narrow beams increase low-mode perturbations of the targets because of decreased illumination uniformity that degrades implosion performance. Initiating an implosion with nominal beams (equal in size to the target diameter) and reducing the beam diameter by $\sim 30\%–40\%$ after developing a sufficiently thick target corona, which smooths the perturbations, mitigate CBET while maintaining low-mode target uniformity in ignition designs with a fusion gain $\gg 1$.

We utilized microwave spectroscopy to study the magnetization oscillations locally induced in a Permalloy film by a pure spin current, which is generated due to the spin Hall effect in an adjacent Pt layer. The oscillation frequency is lower than the ferromagnetic resonance of Permalloy, indicating that the oscillation forms a self-localized nonpropagating spin-wave soliton. At cryogenic temperatures, the spectral characteristics are remarkably similar to the traditional spin-torque nano-oscillators driven by spin-polarized currents. However, the linewidth of the oscillation increases exponentially with temperature and an additional peak appears in the spectrum below the ferromagnetic resonance, suggesting that the spectral characteristics are determined by interplay between two localized dynamical states.

We have performed a search for muon neutrinos from dark matter annihilation in the center of the Sun with the 79-string configuration of the IceCube neutrino telescope. For the first time, the DeepCore subarray is included in the analysis, lowering the energy threshold and extending the search to the austral summer. The 317 days of data collected between June 2010 and May 2011 are consistent with the expected background from atmospheric muons and neutrinos. Upper limits are set on the dark matter annihilation rate, with conversions to limits on spin-dependent and spin-independent scattering cross sections of weakly interacting massive particles (WIMPs) on protons, for WIMP masses in the range $20–5000\mathrm{GeV}/c^2$. These are the most stringent spin-dependent WIMP-proton cross section limits to date above $35\mathrm{GeV}/c^2$ for most WIMP models.

Physical vapor deposition provides a controllable means of growing two-dimensional metallic thin films and one-dimensional metallic nanorods. While theories exist for the growth of metallic thin films, their counterpart for the growth of metallic nanorods is absent. Because of this absence, the lower limit of the nanorod diameter is theoretically unknown; consequently the experimental pursuit of the smallest nanorods has no clear target. This Letter reports a closed-form theory that defines the diameter of the smallest metallic nanorods using physical vapor deposition. Further, the authors verify the theory using lattice kinetic Monte Carlo simulations and validate the theory using published experimental data. Finally, the authors carry out a series of theory-guided experiments to grow well-separated metallic nanorods of $\sim 10\mathrm{nm}$ in diameter, which are the smallest ever reported using physical vapor deposition.

Some microalgae are sensitive to light intensity gradients. This property is known as phototaxis: The algae swim toward a light source (positive phototaxis). We use this property to control the motion of microalgae within a Poiseuille flow using light. The combination of flow vorticity and phototaxis results in a concentration of algae around the center of the flow. Intermittent light exposure allows analysis of the dynamics of this phenomenon and its reversibility. With this phenomenon, we hope to pave the way toward new algae concentration techniques (a bottleneck challenge in biofuel algal production) and toward the improvement of pollutant biodetector technology.

Giant tunability of ferroelectric polarization ($\Delta P=5000\mu \mathrm{C}/{\mathrm{m}}^2$) in the multiferroic ${\mathrm{GdMn}}_2{\mathrm{O}}_5$ with external magnetic fields is discovered. The detailed magnetic model from x-ray magnetic scattering results indicates that the Gd-Mn symmetric exchange striction plays a major role in the tunable ferroelectricity of ${\mathrm{GdMn}}_2{\mathrm{O}}_5$, which is in distinction from other compounds of the same family. Thus, the highly isotropic nature of Gd spins plays a key role in the giant magnetoelectric coupling in ${\mathrm{GdMn}}_2{\mathrm{O}}_5$. This finding provides a new handle in achieving enhanced magnetoelectric functionality.

The photon creation and annihilation operators are cornerstones of the quantum description of the electromagnetic field. They signify the isomorphism of the optical Hilbert space to that of the harmonic oscillator and the bosonic nature of photons. We perform complete experimental characterization (quantum process tomography) of these operators. By measuring their effect on coherent states by means of homodyne tomography, we obtain their process tensor in the Fock basis, which explicitly shows the “raising” and “lowering” properties of these operators with respect to photon number states. This is the first experimental demonstration of complete tomography of nondeterministic quantum processes.

For the first time a single trapped antiproton ($\overline{p}$) is used to measure the $\overline{p}$ magnetic moment ${\mathit{\mu }}_{\overline{p}}$. The moment ${\mathit{\mu }}_{\overline{p}}={\mu }_{\overline{p}}\mathit{S}/(\hslash /2)$ is given in terms of its spin $\mathit{S}$ and the nuclear magneton (${\mu }_N$) by ${\mu }_{\overline{p}}/{\mu }_N=-2.792845\pm 0.000012$. The 4.4 parts per million (ppm) uncertainty is 680 times smaller than previously realized. Comparing to the proton moment measured using the same method and trap electrodes gives ${\mu }_{\overline{p}}/{\mu }_p=-1.000000\pm 0.000005$ to 5 ppm, for a proton moment ${\mathit{\mu }}_p={\mu }_p\mathit{S}/(\hslash /2)$, consistent with the prediction of the $CPT$ theorem.

For a broad range of values of magnetic monopole mass and charge, the abundance of monopoles trapped inside Earth would be expected to be enhanced in the mantle beneath the geomagnetic poles. A search for magnetic monopoles was conducted using the signature of an induced persistent current following the passage of igneous rock samples through a SQUID-based magnetometer. A total of 24.6 kg of rocks from various selected sites, among which 23.4 kg are mantle-derived rocks from the Arctic and Antarctic areas, was analyzed. No monopoles were found, and a 90% confidence level upper limit of $9.8\times {10}^{-5}/\mathrm{g}$ is set on the monopole density in the search samples.

We consider measurement-based quantum computation (MBQC) on thermal states of the interacting cluster Hamiltonian containing interactions between the cluster stabilizers that undergoes thermal phase transitions. We show that the long-range order of the symmetry breaking thermal states below a critical temperature drastically enhances the robustness of MBQC against thermal excitations. Specifically, we show the enhancement in two-dimensional cases and prove that MBQC is topologically protected below the critical temperature in three-dimensional cases. The interacting cluster Hamiltonian allows us to perform MBQC even at a temperature 1 order of magnitude higher than that of the free cluster Hamiltonian.

We present the first ever observation of dark solitons on the surface of water. It takes the form of an amplitude drop of the carrier wave which does not change shape in propagation. The shape and width of the soliton depend on the water depth, carrier frequency, and the amplitude of the background wave. The experimental data taken in a water tank show an excellent agreement with the theory. These results may improve our understanding of the nonlinear dynamics of water waves at finite depths.

We report on transport measurements of an InAs nanowire coupled to niobium nitride leads at high magnetic fields. We observe a zero-bias anomaly (ZBA) in the differential conductance of the nanowire for certain ranges of magnetic field and chemical potential. The ZBA can oscillate in width with either the magnetic field or chemical potential; it can even split and re-form. We discuss how our results relate to recent predictions of hybridizing Majorana fermions in semiconducting nanowires, while considering more mundane explanations.

This Letter applies the concept of “jets,” as constructed from calorimeter cell four-vectors, to jets composed (primarily) of photons (or leptons). Thus jets become a superset of both traditional objects such as QCD jets, photons, and electrons, and more unconventional objects such as photon jets and electron jets, defined as collinear photons and electrons, respectively. Since standard objects such as single photons become a subset of jets in this approach, standard jet substructure techniques are incorporated into the photon finder toolbox. Using a (reasonably) realistic calorimeter model we demonstrate that, for a single photon identification efficiency of 80% or above, the use of jet substructure techniques reduces the number of QCD jets faking photons by factors of 2.5 to 4. Depending on the topology of the photon jets, the substructure variables reduce the number of photon jets faking single photons by factors of 10 to ${10}^3$ at a single photon identification efficiency of 80%.

When two jets of fluid collide, they can “bounce” off each other, due to a thin film of air which keeps them separated. We describe the phenomenon of stable noncoalescence between two jets of the same fluid, colliding obliquely with each other. Using a simple experimental setup, we carry out a parametric study of the bouncing jets by varying the jet diameter, velocity, angle of inclination, and fluid viscosity, which suggests that the contact time of bouncing jets scales as the square root of the normal Weber number We. A dimensionless parameter $K=(\mathrm{We}\sqrt{\mathrm{Re}}/\sin \alpha {)}^{1/2}$, where Re is the normal Reynolds number and $\alpha$ the angle of inclination of the jets, quantitatively captures the transition of colliding jets from bouncing to coalescence. This parameter draws parallels between jet coalescence and droplet splashing and indicates that the transition is governed by a surface instability. Stable and continuous noncoalescence between fluid jets makes it a good platform for experimental studies of the interaction between fluid interfaces and the properties of the interfacial air films.

We report noninvasive single-charge detection of the full probability distribution $P_n$ of the initialization of a quantum dot with $n$ electrons for rapid decoupling from an electron reservoir. We analyze the data in the context of a model for sequential tunneling pinch-off, which has generic solutions corresponding to two opposing mechanisms. One limit considers sequential “freeze-out” of an adiabatically evolving grand canonical distribution, the other one is an athermal limit equivalent to the solution of a generalized decay cascade model. We identify the athermal capturing mechanism in our sample, testifying to the high precision of our combined theoretical and experimental methods. The distinction between the capturing mechanisms allows us to derive efficient experimental strategies for improving the initialization.

It is shown that the tension between recent neutrino oscillation experiments, favoring sterile neutrinos with masses of the order of 1 eV, and cosmological data which impose stringent constraints on neutrino masses from the free streaming suppression of density fluctuations, can be resolved in models of the present accelerated expansion of the Universe based on $f(R)$ gravity.

We present evidence for Rydberg-Rydberg interaction in a gas of rubidium atoms above room temperature. Rabi oscillations on the nanosecond time scale to different Rydberg states are investigated in a vapor cell experiment. Analyzing the atomic time evolution and comparing to a dephasing model, we find a scaling with the Rydberg quantum number $n$ that is consistent with van der Waals interaction. Our results show that the interaction strength can be larger than the kinetic energy scale (Doppler width), which is the requirement for realization of thermal quantum devices in the GHz regime.

In high-spectral resolution experiments with the petawatt Vulcan laser, strong x-ray radiation of $KK$ hollow atoms (atoms without $n=1$ electrons) from thin Al foils was observed at pulse intensities of $3\times {10}^{20}\mathrm{W}/{\mathrm{cm}}^2$. The observations of spectra from these exotic states of matter are supported by detailed kinetics calculations, and are consistent with a picture in which an intense polychromatic x-ray field, formed from Thomson scattering and bremsstrahlung in the electrostatic fields at the target surface, drives the $KK$ hollow atom production. We estimate that this x-ray field has an intensity of $>5\times {10}^{18}\mathrm{W}/{\mathrm{cm}}^2$ and is in the 3 keV range.

A spin battery concept is applied for the dynamical generation of pure spin current and spin transport in $p$-type silicon ($p$-Si). Ferromagnetic resonance and effective $s\mathrm{\text{−}}d$ coupling in ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$ results in spin accumulation at the ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}/p$-Si interface, inducing spin injection and the generation of spin current in the $p$-Si. The pure spin current is converted to a charge current by the inverse spin Hall effect of Pd evaporated onto the $p$-Si. This approach demonstrates the generation and transport of pure spin current in $p$-Si at room temperature.

An electromechanical resonator harboring an atomlike spectrum of discrete mechanical vibrations, namely, phonon modes, has been developed. A purely mechanical three-mode system becomes available in the electromechanical atom in which the energy difference of the two higher modes is resonant with a long-lived lower mode. Our measurements reveal that even an incoherent input into the higher mode results in coherent emission in the lower mode that exhibits all the hallmarks of phonon lasing in a process that is reminiscent of Brillouin lasing.