We study Majorana devices featuring a competition between superconductivity and multichannel Kondo physics. Our proposal extends previous work on single-channel Kondo systems to a topologically nontrivial setting of a non-Fermi liquid type, where topological superconductor wires (with gap $\mathrm{\Delta }$) represent leads tunnel coupled to a Coulomb-blockaded Majorana box. On the box, a spin degree of freedom with Kondo temperature $T_K$ is nonlocally defined in terms of Majorana states. For $\mathrm{\Delta }\gg T_K$, the destruction of Kondo screening by superconductivity implies a $4\pi$-periodic Josephson current-phase relation. Using a strong-coupling analysis in the opposite regime $\mathrm{\Delta }\ll T_K$, we find a $6\pi$-periodic Josephson relation for three leads, with critical current $I_c\approx e{\mathrm{\Delta }}^2/\hslash T_K$, corresponding to the transfer of fractionalized charges $e^{*}=2e/3$.

We report time-resolved magneto-optic Kerr effect measurements of the longitudinal spin Seebeck effect in normal $\mathrm{metal}/{\mathrm{Y}}_3{\mathrm{Fe}}_5{\mathrm{O}}_{12}$ bilayers driven by an interfacial temperature difference between electrons and magnons. The measured time evolution of spin accumulation induced by laser excitation indicates transfer of angular momentum across normal $\mathrm{metal}/{\mathrm{Y}}_3{\mathrm{Fe}}_5{\mathrm{O}}_{12}$ interfaces on a picosecond time scale, too short for contributions from a bulk temperature gradient in an yttrium iron garnet. The product of spin-mixing conductance and the interfacial spin Seebeck coefficient determined is of the order of ${10}^8\mathrm{A}{\mathrm{m}}^{-2}{\mathrm{K}}^{-1}$.

Studying dynamical phenomena in finite populations often involves Markov processes of significant mathematical and/or computational complexity, which rapidly becomes prohibitive with increasing population size or an increasing number of individual configuration states. Here, we develop a framework that allows us to define a hierarchy of approximations to the stationary distribution of general systems that can be described as discrete Markov processes with time invariant transition probabilities and (possibly) a large number of states. This results in an efficient method for studying social and biological communities in the presence of stochastic effects—such as mutations in evolutionary dynamics and a random exploration of choices in social systems—including situations where the dynamics encompasses the existence of stable polymorphic configurations, thus overcoming the limitations of existing methods. The present formalism is shown to be general in scope, widely applicable, and of relevance to a variety of interdisciplinary problems.

We investigate the dynamics of Gaussian states of continuous variable systems under Gaussianity-preserving channels. We introduce a hierarchy of such evolutions encompassing Markovian and weakly and strongly non-Markovian processes and provide simple criteria to distinguish between the classes, based on the degree of positivity of intermediate Gaussian maps. We present an intuitive classification of all one-mode Gaussian channels according to their non-Markovianity degree and show that weak non-Markovianity has an operational significance, as it leads to a temporary phase-insensitive amplification of Gaussian inputs beyond the fundamental quantum limit. Explicit examples and applications are discussed.

Binary systems of two compact objects circularize and spiral toward each other via the emission of gravitational waves. The coupling of the spins of each object with the orbital angular momentum causes the orbital plane to precess, which leads to modulation of the gravitational wave signal. Until now, generating frequency-domain waveforms for fully precessing systems for use in gravitational wave data analysis meant numerically integrating the equations of motion, then Fourier transforming the result, which is very computationally intensive for systems that complete hundreds or thousands of cycles in the sensitive band of a detector. Previously, analytic solutions were only available for certain special cases or for simplified models. Here we describe the construction of closed-form, frequency-domain waveforms for fully precessing, quasicircular binary inspirals.

We report the first observation of the radiative charm decay $D^0\to {\rho }^0\gamma$ and the first search for $CP$ violation in decays $D^0\to {\rho }^0\gamma$, $\varphi \gamma$, and ${\overline{K}}^{*0}(892)\gamma$, using a data sample of $943{\mathrm{fb}}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The branching fraction is measured to be $\mathcal{B}(D^0\to {\rho }^0\gamma )=(1.77\pm 0.30\pm 0.07)\times {10}^{-5}$, where the first uncertainty is statistical and the second is systematic. The obtained $CP$ asymmetries ${\mathcal{A}}_{CP}(D^0\to {\rho }^0\gamma )=+0.056\pm 0.152\pm 0.006$, ${\mathcal{A}}_{CP}(D^0\to \varphi \gamma )=-0.094\pm 0.066\pm 0.001$, and ${\mathcal{A}}_{CP}(D^0\to {\overline{K}}^{*0}\gamma )=-0.003\pm 0.020\pm 0.000$ are consistent with no $CP$ violation. We also present an improved measurement of the branching fractions $\mathcal{B}(D^0\to \varphi \gamma )=(2.76\pm 0.19\pm 0.10)\times {10}^{-5}$ and $\mathcal{B}(D^0\to {\overline{K}}^{*0}\gamma )=(4.66\pm 0.21\pm 0.21)\times {10}^{-4}$.

Previous experiments observed a $4^{+}$ state in the $N=28$ nucleus ${}^{44}\mathrm{S}$ and suggested that this state may exhibit a hindered $E2$-decay rate, inconsistent with being a member of the collective ground state band. We populate this state via two-proton knockout from a beam of exotic ${}^{46}\mathrm{Ar}$ projectiles and measure its lifetime using the recoil distance method with the GRETINA $\gamma$-ray spectrometer. The result, $76(14{)}_{\mathrm{stat}}(20{)}_{\mathrm{syst}}\mathrm{ps}$, implies a hindered transition of $B(E2;4^{+}\to 2_1^{+})=0.61(19)$ single-particle or Weisskopf units strength and supports the interpretation of the $4^{+}$ state as a $K=4$ isomer, the first example of a high-$K$ isomer in a nucleus of such low mass.

We describe a mechanism by which nonlinear phononics allows ultrafast coherent and directional control of transient structural distortions. With ${\text{ErFeO}}_3$ as a model system, we use density functional theory to calculate the structural properties as input into an anharmonic phonon model that describes the response of the system to a pulsed optical excitation. We find that the trilinear coupling of two orthogonal infrared-active phonons to a Raman-active phonon causes a transient distortion of the lattice. In contrast to the quadratic-linear coupling that has been previously explored, the direction of the distortion is determined by the polarization of the exciting light, introducing a novel mechanism for nonlinear phononic switching. Since the occurrence of the coupling is determined by the symmetry of the system we propose that it is a universal feature of orthorhombic and tetragonal perovskites.

Many of the remarkable properties of surface nanobubbles, such as unusually small contact angles and long lifetimes, are related to the force that pins them onto their substrates. This pinning force is yet to be quantified experimentally. Here, surface-attached nanobubbles are pulled with an atomic force microscope tip while their mechanical responses are observed with total internal reflection fluorescence microscopy. We estimate that a pinning force on the order of $0.1\mu \mathrm{N}$ is required to unpin a nanobubble from its substrate. The maximum force that the tip can exert on the nanobubble is limited by the stability of the neck pulled from the bubble and is enhanced by the hydrophobicity of the tip.

Would a raindrop impacting on a coarse beach behave differently from that impacting on a desert of fine sand? We study this question by a series of model experiments, where the packing density of the granular target, the wettability of individual grains, the grain size, the impacting liquid, and the impact speed are varied. We find that by increasing the grain size and/or the wettability of individual grains the maximum droplet spreading undergoes a transition from a capillary regime towards a viscous regime, and splashing is suppressed. The liquid-grain mixing is discovered to be the underlying mechanism. An effective viscosity is defined accordingly to quantitatively explain the observations.

The collisionality scaling of density and potential coupling together with zonal flow energy transfer and spectral power is investigated at the stellarator experiment TJ-K. With a poloidal probe array, consisting of 128 Langmuir probes, density and potential fluctuations are measured on four neighboring flux surfaces simultaneously over the complete poloidal circumference. By analyzing Reynolds stress and pseudo-Reynolds stress, it is found that, for increasing collisionality, the coupling between density and potential decreases which hinders the zonal flow drive. Also, as a consequence, the nonlinear energy transfer, as well as the zonal flow contribution to the complete turbulent spectrum, decreases the same way. This is in line with theoretical expectations and is a first experimental verification of the importance of collisionality for large-scale structure formation in magnetically confined toroidal plasmas.

In this Letter we report high-resolution synchrotron x-ray powder diffraction and transmission electron microscope analysis of Mn-substituted LaFeAsO samples, demonstrating that a static incommensurate modulated structure develops across the low-temperature orthorhombic phase, whose modulation wave vector depends on the Mn content. The incommensurate structural distortion is likely originating from a charge-density-wave instability, a periodic modulation of the density of conduction electrons associated with a modulation of the atomic positions. Our results add a new component in the physics of Fe-based superconductors, indicating that the density wave ordering is charge driven.

We study the crystal growth in binary Lennard-Jones mixtures by molecular dynamics simulations. Growth dynamics, the structure of the liquid-solid interfaces as well as droplet incorporation into the crystal vary with solution properties. For demixed systems we observe a strongly enhanced crystal growth at the cost of enclosed impurities. Furthermore, we find different interface morphologies depending on solubility. We relate our observations to growth mechanisms based on the Gibbs-Thomson effect as well as to predictions of the Kardar-Parisi-Zhang theory in $2+1$ dimensions.

The magnetic order in antiferromagnetic materials is hard to control with external magnetic fields. Using x-ray magnetic linear dichroism microscopy, we show that staggered effective fields generated by electrical current can induce modification of the antiferromagnetic domain structure in microdevices fabricated from a tetragonal CuMnAs thin film. A clear correlation between the average domain orientation and the anisotropy of the electrical resistance is demonstrated, with both showing reproducible switching in response to orthogonally applied current pulses. However, the behavior is inhomogeneous at the submicron level, highlighting the complex nature of the switching process in multidomain antiferromagnetic films.

A recent granular rheology based on an implicit “granular fluidity” field has been shown to quantitatively predict many nonlocal phenomena. However, the physical nature of the field has not been identified. Here, the granular fluidity is found to be a kinematic variable given by the velocity fluctuation and packing fraction. This is verified with many discrete element simulations, which show that the operational fluidity definition, solutions of the fluidity model, and the proposed microscopic formula all agree. Kinetic theoretical and Eyring-like explanations shed insight into the obtained form.

We analyze the effect of gravitational backreaction on cosmic string loops with kinks, which is an important determinant of the shape, and thus the potential observability, of string loops which may exist in the Universe today. Kinks are not rounded off, but may be straightened out. This means that backreaction will only cause loops with kinks to develop cusps after some potentially large fraction of their lifetimes. In some loops, symmetries prevent even this process, so that the loop evaporates in a self-similar fashion and the kinks are unchanged. As an example, we discuss backreaction on the rectangular Garfinkle-Vachaspati loop.

We construct a numerical solution of the small-$x$ evolution equations derived in our recent work [J. High Energy Phys. 01 (2016) 072.] for the (anti)quark transverse momentum dependent helicity TMDs and parton distribution functions (PDFs) as well as the $g_1$ structure function. We focus on the case of large $N_c$, where one finds a closed set of equations. Employing the extracted intercept, we are able to predict directly from theory the behavior of the quark helicity PDFs at small $x$, which should have important phenomenological consequences. We also give an estimate of how much of the proton’s spin carried by the quarks may be at small $x$ and what impact this has on the spin puzzle.