Topological quantum states with non-Abelian Fibonacci anyonic excitations are widely sought after for the exotic fundamental physics they would exhibit, and for universal quantum computing applications. The fractional quantum Hall (FQH) state at a filling factor of $\nu =12/5$ is a promising candidate; however, its precise nature is still under debate and no consensus has been achieved so far. Here, we investigate the nature of the FQH $\nu =13/5$ state and its particle-hole conjugate state at $12/5$ with the Coulomb interaction, and we address the issue of possible competing states. Based on a large-scale density-matrix renormalization group calculation in spherical geometry, we present evidence that the essential physics of the Coulomb ground state (GS) at $\nu =13/5$ and $12/5$ is captured by the $k=3$ parafermion Read-Rezayi state (${\mathrm{RR}}_3$), including a robust excitation gap and the topological fingerprint from the entanglement spectrum and topological entanglement entropy. Furthermore, by considering the infinite-cylinder geometry (topologically equivalent to torus geometry), we expose the non-Abelian GS sector corresponding to a Fibonacci anyonic quasiparticle, which serves as a signature of the ${\mathrm{RR}}_3$ state at $13/5$ and $12/5$ filling numbers.

Developing practical approaches to effectively reduce the amount of deep defect levels in semiconductors is critical for their use in electronic and optoelectronic devices, but this still remains a very challenging task. In this Letter, we propose that specific alloying can provide an effective means to suppress the deep defect levels in semiconductors while maintaining their basic electronic properties. Specifically, we demonstrate that for transition-metal dichalcogenides, such as ${\mathrm{MoSe}}_2$ and ${\mathrm{WSe}}_2$, where anion vacancies are the most abundant defects that can induce deep levels, the deep levels can be effectively suppressed in ${\mathrm{Mo}}_{1-x}{\mathrm{W}}_x{\mathrm{Se}}_2$ alloys at low W concentrations. This surprising phenomenon is associated with the fact that the band edge energies can be substantially tuned by the global alloy concentration, whereas the defect level is controlled locally by the preferred locations of Se vacancies around W atoms. Our findings illustrate a concept of alloy engineering and provide a promising approach to control the defect properties of semiconductors.

Recent experiments use Fabry-Perot (FP) interferometry to claim that the $\nu =5/2$ quantum Hall state exhibits non-Abelian topological order. We note that the experiments appear inconsistent with a model neglecting bulk-edge Coulomb coupling and Majorana tunneling, so we reexamine the theory of FP devices. Even a moderate Coulomb coupling may strongly affect some fractional plateaus, but very weakly affect others, allowing us to model the data over a wide range of plateaus. While experiments are consistent with the $\nu =5/2$ state harboring Moore-Read topological order, they may have measured Coulomb effects rather than an “even-odd effect” due to non-Abelian braiding.

We consider the problem of bound states in strongly anisotropic ferromagnetic impurities in a superconductor, motivated by recent experiments that claim to observe Majorana modes at the ends of ferromagnetic wires on a superconducting substrate [S. Nadj-Perge et al., Science 346, 602 (2014)]. Generalizing the successful theory of bound states of spherically symmetric impurities, we consider a wirelike potential using both analytical and numerical approaches. We find that away from the ends of the wire the bound states form bands with pronounced van Hove singularities, giving rise to subgap peaks in the local density of states. For sufficiently strong magnetization of the wire, we show that this process generically produces a sharp peak at zero energy in the local density of states near the ends of the wire. This zero-energy peak has qualitative similarities to the claimed signature of a Majorana mode observed in the aforementioned experiment.

We show that discrete synaptic weights can be efficiently used for learning in large scale neural systems, and lead to unanticipated computational performance. We focus on the representative case of learning random patterns with binary synapses in single layer networks. The standard statistical analysis shows that this problem is exponentially dominated by isolated solutions that are extremely hard to find algorithmically. Here, we introduce a novel method that allows us to find analytical evidence for the existence of subdominant and extremely dense regions of solutions. Numerical experiments confirm these findings. We also show that the dense regions are surprisingly accessible by simple learning protocols, and that these synaptic configurations are robust to perturbations and generalize better than typical solutions. These outcomes extend to synapses with multiple states and to deeper neural architectures. The large deviation measure also suggests how to design novel algorithmic schemes for optimization based on local entropy maximization.

Theoretical analysis and experimental quantification on the ellipsoidal relaxation of vesicles are presented. The current work reveals the simplicity and universal aspects of this process. The Helfrich formula is shown to apply to the dynamic relaxation of moderate-to-high tension membranes, and a closed-form solution is derived which predicts the vesicle aspect ratio as a function of time. Scattered data are unified by a time scale, which leads to a similarity behavior, governed by a distinctive solution for each vesicle type. Two separate regimes in the relaxation are identified, namely, the “entropic” and the “constant-tension” regimes. The bending rigidity and the initial membrane tension can be simultaneously extracted from the data analysis, posing the current approach as an effective means for the mechanical analysis of biomembranes.

We consider single-particle quantum transport on parametrized complex networks. Based on general arguments regarding the spectrum of the corresponding Hamiltonian, we derive bounds for a measure of the global transport efficiency defined by the time-averaged return probability. For treelike networks, we show analytically that a transition from efficient to inefficient transport occurs depending on the (average) functionality of the nodes of the network. In the infinite system size limit, this transition can be characterized by an exponent which is universal for all treelike networks. Our findings are corroborated by analytic results for specific deterministic networks, dendrimers and Vicsek fractals, and by Monte Carlo simulations of iteratively built scale-free trees.

We present a nucleon-nucleon potential at fifth order in chiral effective field theory. We find a substantial improvement in the description of nucleon-nucleon phase shifts as compared to the fourth-order results utilizing a coordinate-space regularization. This provides clear evidence of the corresponding two-pion exchange contributions with all low-energy constants being determined from pion-nucleon scattering. The fifth-order corrections to nucleon-nucleon observables appear to be of a natural size, which confirms the good convergence of the chiral expansion for nuclear forces. Furthermore, the obtained results provide strong support for the novel way of quantifying the theoretical uncertainty due to the truncation of the chiral expansion proposed by the authors. Our work opens up new perspectives for precision ab initio calculations in few- and many-nucleon systems and is especially relevant for ongoing efforts towards a quantitative understanding of the structure of the three-nucleon force in the framework of chiral effective field theory.

Particles suspended in turbulent flows are affected by the turbulence and at the same time act back on the flow. The resulting coupling can give rise to rich variability in their dynamics. Here we report experimental results from an investigation of finite-sized buoyant spheres in turbulence. We find that even a marginal reduction in the particle’s density from that of the fluid can result in strong modification of its dynamics. In contrast to classical spatial filtering arguments and predictions of particle models, we find that the particle acceleration variance increases with size. We trace this reversed trend back to the growing contribution from wake-induced forces, unaccounted for in current particle models in turbulence. Our findings highlight the need for improved multiphysics based models that account for particle wake effects for a faithful representation of buoyant-sphere dynamics in turbulence.

We use an on-chip superconducting resonator as a sensitive meter to probe the properties of graphene double quantum dots at microwave frequencies. Specifically, we investigate the charge dephasing rates in a circuit quantum electrodynamics architecture. The dephasing rates strongly depend on the number of charges in the dots, and the variation has a period of four charges, over an extended range of charge numbers. Although the exact mechanism of this fourfold periodicity in dephasing rates is an open problem, our observations hint at the fourfold degeneracy expected in graphene from its spin and valley degrees of freedom.

We report the direct observation of a localized magnetic soliton in a spin-transfer nanocontact using scanning transmission x-ray microscopy. Experiments are conducted on a lithographically defined 150 nm diameter nanocontact to an ultrathin ferromagnetic multilayer with perpendicular magnetic anisotropy. Element-resolved x-ray magnetic circular dichroism images show an abrupt onset of a magnetic soliton excitation localized beneath the nanocontact at a threshold current. However, the amplitude of the excitation $\simeq 25°$ at the contact center is far less than that predicted ($⪅180°$), showing that the spin dynamics is not described by existing models.

We investigate the link between information and thermodynamics embodied by Landauer’s principle in the open dynamics of a multipartite quantum system. Such irreversible dynamics is described in terms of a collisional model with a finite temperature reservoir. We demonstrate that Landauer’s principle holds, for such a configuration, in a form that involves the flow of heat dissipated into the environment and the rate of change of the entropy of the system. Quite remarkably, such a principle for heat and entropy power can be explicitly linked to the rate of creation of correlations among the elements of the multipartite system and, in turn, the non-Markovian nature of their reduced evolution. Such features are illustrated in two exemplary cases.

The scattering equations on the Riemann sphere give rise to remarkable formulas for tree-level gauge theory and gravity amplitudes. Adamo, Casali, and Skinner conjectured a one-loop formula for supergravity amplitudes based on scattering equations on a torus. We use a residue theorem to transform this into a formula on the Riemann sphere. What emerges is a framework for loop integrands on the Riemann sphere that promises to have a wide application, based on off-shell scattering equations that depend on the loop momentum. We present new formulas, checked explicitly at low points, for supergravity and super-Yang-Mills amplitudes and for $n$-gon integrands at one loop. Finally, we show that the off-shell scattering equations naturally extend to arbitrary loop order, and we give a proposal for the all-loop integrands for supergravity and planar super-Yang-Mills theory.

We report a measurement of the time-dependent $CP$ asymmetry of ${\overline{B}}^0\to D_{CP}^{(*)}{h}^0$ decays, where the light neutral hadron $h^0$ is a ${\pi }^0$, $\eta$, or $\omega$ meson, and the neutral $D$ meson is reconstructed in the $CP$ eigenstates $K^{+}{K}^{-}$, $K_S^0{\pi }^0$, or $K_S^0\omega$. The measurement is performed combining the final data samples collected at the $\mathrm{\Upsilon }(4S)$ resonance by the BABAR and Belle experiments at the asymmetric-energy $B$ factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain $(471\pm 3)\times {10}^6\hspace{0.17em}B\overline{B}$ pairs recorded by the BABAR detector and $(772\pm 11)\times {10}^6\hspace{0.17em}B\overline{B}$ pairs recorded by the Belle detector. We measure the $CP$ asymmetry parameters $-{\eta }_f\mathcal{S}=+0.66\pm 0.10(\text{stat})\pm 0.06(\text{syst})$ and $\mathcal{C}=-0.02\pm 0.07(\text{stat})\pm 0.03(\text{syst})$. These results correspond to the first observation of $CP$ violation in ${\overline{B}}^0\to D_{CP}^{(*)}{h}^0$ decays. The hypothesis of no mixing-induced $CP$ violation is excluded in these decays at the level of 5.4 standard deviations.

We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged $SU(3{)}^{\prime }\times SU(2{)}^{\prime }$, a twin Higgs doublet, and only third-generation twin fermions. Naturalness requires the ${\mathrm{QCD}}^{\prime }$ scale ${\mathrm{\Lambda }}_{\mathrm{QCD}}^{\prime }\simeq 0.5–20\mathrm{GeV}$, and that $t^{\prime }$ is heavy. We focus on the light $b^{\prime }$ quark regime, $m_{b^{\prime }}\lesssim {\mathrm{\Lambda }}_{\mathrm{QCD}}^{\prime }$, where ${\mathrm{QCD}}^{\prime }$ is characterized by a single scale ${\mathrm{\Lambda }}_{\mathrm{QCD}}^{\prime }$ with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-$3/2$ twin baryon, ${\mathrm{\Delta }}^{\prime }\sim b^{\prime }{b}^{\prime }{b}^{\prime }$, with a dynamically determined mass ($\sim 5{\mathrm{\Lambda }}_{\mathrm{QCD}}^{\prime }$) in the preferred range for the DM-to-baryon ratio ${\mathrm{\Omega }}_{\mathrm{DM}}/{\mathrm{\Omega }}_{\text{baryon}}\simeq 5$. Gauging the $U(1{)}^{\prime }$ group leads to twin atoms (${\mathrm{\Delta }}^{\prime }\text{−}\overline{{\tau }^{\prime }}$ bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors.

The light-dressing effect in Xe atoms was identified in laser-assisted elastic electron scattering (LAES) signals. In the angular distribution of LAES signals with energy shifts of $\pm \hslash \omega$ recorded by the scattering of 1 keV electrons by Xe in an intense nonresonant laser field, a peak profile appeared at small scattering angles ($<0.5°$). This peak was interpreted as evidence of the light dressing of Xe atoms induced by an intense laser field on the basis of a numerical simulation in which the light-dressing effect is included.