Eleven-dimensional supergravity reveals large exceptional symmetries upon reduction, in accordance with the $U$-duality groups of $M$ theory, but their higher-dimensional geometric origin has remained a mystery. In this Letter, we show that $D=11$ supergravity can be extended to be fully covariant under the exceptional groups $E_{n(n)}$, $n=6$, 7, 8. Motivated by a similar formulation of double field theory we introduce an extended “exceptional spacetime.” We illustrate the construction by giving the explicit $E_{6(6)}$ covariant form: the full $D=11$ supergravity, in a $5+6$ splitting of coordinates but without truncation, embeds into an $E_{6(6)}$ covariant $5+27$ dimensional theory. We argue that this covariant form likewise comprises type IIB supergravity.

To describe theoretically the creation and evolution of the quark-gluon plasma, one typically employs three ingredients: a model for the initial state, nonhydrodynamic early time evolution, and hydrodynamics. In this Letter we study the nonhydrodynamic early time evolution using the AdS/CFT correspondence in the presence of inhomogeneities. We find that the AdS description of the early time evolution is well matched by free streaming. Near the end of the early time interval where our analytic computations are reliable, the stress tensor agrees with the second order hydrodynamic stress tensor computed from the local energy density and fluid velocity. Our techniques may also be useful for the study of far-from-equilibrium strongly coupled systems in other areas of physics.

We measure the time dependence of the ratio of decay rates for $D^0\to K^{+}{\pi }^{-}$ to the Cabibbo-favored decay $D^0\to K^{-}{\pi }^{+}$. The charge conjugate decays are included. A signal of $3.3\times {10}^4$ $D^{*+}\to {\pi }^{+}{D}^0$, $D^0\to K^{+}{\pi }^{-}$ decays is obtained with $D^0$ proper decay times between 0.75 and 10 mean $D^0$ lifetimes. The data were recorded with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of $9.6{\mathrm{fb}}^{-1}$ for $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$. Assuming $CP$ conservation, we search for $D^0$-${\overline{D}}^0$ mixing and measure the mixing parameters to be $R_D=(3.51\pm 0.35)\times {10}^{-3}$, $y^{\prime }=(4.3\pm 4.3)\times {10}^{-3}$, and $x^{\prime 2}=(0.08\pm 0.18)\times {10}^{-3}$. We report Bayesian probability intervals in the $x^{\prime 2}$-$y^{\prime }$ plane and find that the significance of excluding the no-mixing hypothesis is equivalent to 6.1 Gaussian standard deviations, providing the second observation of $D^0$-${\overline{D}}^0$ mixing from a single experiment.

The photoproduction of $\eta$ mesons off nucleons bound in ${}^2\mathrm{H}$ and ${}^3\mathrm{H}\mathrm{e}$ has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the $\eta \to 2\gamma$ and $\eta \to 3{\pi }^0$ decays and the recoil nucleons were detected with an almost $4\pi$ electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of $\gamma n\to n\eta$. The results from the two measurements are consistent, taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are $W=(1670\pm 5)\mathrm{MeV}$ and $\Gamma =(30\pm 15)\mathrm{MeV}$. For the first time precise results for the angular dependence of this structure have been extracted.

This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using $4.7{\mathrm{fb}}^{-1}$ of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at $\sqrt{s}=7\mathrm{TeV}$. Final states containing one or two isolated leptons (electrons or muons) and jets are considered. Two measurements of ${\alpha }_{\ell }P$, the product of the leptonic spin-analyzing power and the top quark polarization, are performed assuming that the polarization is introduced by either a $CP$ conserving or a maximally $CP$ violating production process. The measurements obtained, ${\alpha }_{\ell }{P}_{\mathrm{CPC}}=-0.035\pm 0.014(\mathrm{stat})\pm 0.037(\mathrm{syst})$ and ${\alpha }_{\ell }{P}_{\mathrm{CPV}}=0.020\pm 0.016(\mathrm{stat}{)}_{-0.017}^{+0.013}(\mathrm{syst})$, are in good agreement with the standard model prediction of negligible top quark polarization.

Classical novae are expected to contribute to the 1809-keV Galactic $\gamma$-ray emission by producing its precursor ${}^{26}\mathrm{Al}$, but the yield depends on the thermonuclear rate of the unmeasured ${}^{25}\mathrm{Al}(p,\gamma ){}^{26}\mathrm{Si}$ reaction. Using the $\beta$ decay of ${}^{26}\mathrm{P}$ to populate the key $J^{\pi }=3^{+}$ resonance in this reaction, we report the first evidence for the observation of its exit channel via a $1741.6\pm 0.6(\mathrm{stat})\pm 0.3(\mathrm{syst})\mathrm{keV}$ primary $\gamma$ ray, where the uncertainties are statistical and systematic, respectively. By combining the measured $\gamma$-ray energy and intensity with other experimental data on ${}^{26}\mathrm{Si}$, we find the center-of-mass energy and strength of the resonance to be $E_r=414.9\pm 0.6(\mathrm{stat})\pm 0.3(\mathrm{syst})\pm 0.6(\mathrm{lit}.)\mathrm{keV}$ and $\omega \gamma =23\pm 6(\mathrm{stat}{)}_{-10}^{+11}(\mathrm{lit}.)\mathrm{meV}$, respectively, where the last uncertainties are from adopted literature data. We use hydrodynamic nova simulations to model ${}^{26}\mathrm{Al}$ production showing that these measurements effectively eliminate the dominant experimental nuclear-physics uncertainty and we estimate that novae may contribute up to 30% of the Galactic ${}^{26}\mathrm{Al}$.

We show that the dipole-dipole interaction between three identical Rydberg atoms can give rise to bound trimer states. The microscopic origin of these states is fundamentally different from Efimov physics. Two stable trimer configurations exist where the atoms form the vertices of an equilateral triangle in a plane perpendicular to a static electric field. The triangle edge length typically exceeds $R\approx 2\mu \mathrm{m}$, and each configuration is twofold degenerate due to Kramers degeneracy. The depth of the potential wells and the triangle edge length can be controlled by external parameters. We establish the Borromean nature of the trimer states, analyze the quantum dynamics in the potential wells, and describe methods for their production and detection.

We investigate the ionization of HeNe from below the He $1s3p$ excitation to the He ionization threshold. We observe ${\mathrm{HeNe}}^{+}$ ions with an enhancement by more than a factor of 60 when the He side couples resonantly to the radiation field. These ions are an experimental proof of a two-center resonant photoionization mechanism predicted by Najjari et al. [Phys. Rev. Lett. 105, 153002 (2010)]. Furthermore, our data provide electronic and vibrational state resolved decay widths of interatomic Coulombic decay in HeNe dimers. We find that the interatomic Coulombic decay lifetime strongly increases with increasing vibrational state.

Excitable localized states, spatial structures which possess both the features of temporal excitable pulses and of transverse cavity solitons, have been theoretically predicted in model systems as single pulses of light localized in space with a finite and deterministic duration. We study experimentally the nucleation of laser localized structures on a device defect and its motion along a spatial gradient. We demonstrate that in the reference frame of the drifting localized structure, the resulting dynamics presents the typical features of excitable systems. In particular, for specific parameter values, we observe that the nucleation of laser localized structures is triggered by noise, while the drift of the localized structure up to a spatial region where it vanishes provides the deterministic orbit which brings the system back to its initial rest state. The control of such structures may open the way to novel applications of localized structures beyond that of simple stationary bits.

The van der Pol oscillator is the prototypical self-sustained oscillator and has been used to model nonlinear behavior in biological and other classical processes. We investigate how quantum fluctuations affect phase locking of one or many van der Pol oscillators. We find that phase locking is much more robust in the quantum model than in the equivalent classical model. Trapped-ion experiments are ideally suited to simulate van der Pol oscillators in the quantum regime via sideband heating and cooling of motional modes. We provide realistic experimental parameters for ${}^{171}\mathrm{Yb}^{+}$ achievable with current technology.

We study the influence on steady turbulent states of the forcing in a von Karman flow, at constant impeller speed, or at constant torque. We find that the different forcing conditions change the nature of the stability of the steady states and reveal dynamical regimes that bear similarities to low-dimensional systems. We suggest that this forcing dependence may be applicable to other turbulent systems.

When using appropriate surfactants, oil and aqueous foam can be intimately mixed without the foam being destroyed. In this Letter, we show that a foam, initially free of oil, can draw an oil drop under the action of capillary forces and stretch it through the aqueous network. We focus on the suction of oil by a single horizontal foam channel, known as a Plateau border. In such confined channels, imbibition dynamics are governed by a balance between capillarity and viscosity. Yet, the scaling law for our system differs from that of classical imbibition in porous media such as aqueous foam. This is due to the particular geometry of the liquid channels: Plateau borders filled with foaming solution are always concave whereas they can be convex or flat when filled with oil. Finally, the oil slug, confined in the Plateau border, fragments into droplets following a film breakup.

We present the first measurements of the angular dependence of the betatron x-ray spectrum produced by electrons inside the cavity of a laser-wakefield accelerator. Electrons accelerated up to 300 MeV energies produce a beam of broadband, forward-directed betatron x-ray radiation extending up to 80 keV. The angular resolved spectrum from an image plate-based spectrometer with differential filtering provides data in a single laser shot. The simultaneous spectral and spatial x-ray analysis allows for a three-dimensional reconstruction of electron trajectories with micrometer resolution, and we find that the angular dependence of the x-ray spectrum is showing strong evidence of anisotropic electron trajectories.

We theoretically predict an exotic topological superfluid state with a spatially modulated pairing gap in one-dimensional spin-orbit-coupled Fermi gases. This inhomogeneous topological superfluidity is induced by applying simultaneously a perpendicular Zeeman magnetic field and an equally weighted Rashba and Dresselhaus spin-orbit coupling in one-dimensional optical lattices. Based on the self-consistent Bogoliubov–de Gennes theory, we confirm that this novel topological phase is a unique condensation of Cooper pairs, which manifests the interplay between the inhomogeneity of a superfluid and its nontrivial topological structure. The properties of the emergent Majorana bound states are investigated in detail by examining the associated ${\mathbb{Z}}_2$ topological number, the eigenenergy and density of states spectra, as well as the wave functions of the localized Majorana end modes. The experimental feasibility of observing this new topological state of matter is also discussed.

Carbon monoxide and nitrogen are among the potentially interesting high-energy density materials. However, in spite of the physical similarities of the molecules, they behave very differently at high pressures. Using density functional theory and structural prediction methods, we examine the ability of these systems to combine their respective properties and form novel mixed crystalline phases under pressures of up to 100 GPa. Interestingly, we find that CO catalyzes the molecular dissociation of ${\mathrm{N}}_2$, which means mixed structures are favored at a relatively low pressure (below 18 GPa), and that a three-dimensional framework with $Pbam$ symmetry becomes the most stable phase above 52 GPa, i.e., at much milder conditions than in pure solid nitrogen. This structure is dynamically stable at ambient pressure and has an energy density of approximately $2.2\mathrm{kJ}{\mathrm{g}}^{-1}$, making it a candidate for a high-energy density material, and one that could be achieved at less prohibitive experimental conditions.

For carbon nanotube transistors, as for graphene, the electrical contacts are a key factor limiting device performance. We calculate the device characteristics as a function of nanotube diameter and metal work function. Although the on-state current varies continuously, the transfer characteristics reveal a relatively abrupt crossover from Schottky to Ohmic contacts. We find that typical high-performance devices fall surprisingly close to the crossover. Therefore, tunneling plays an important role even in this regime, so that current fails to saturate with gate voltage as was expected due to “source exhaustion.”

A theoretical development of prior analyses, together with our solenoid scan measurements on eight planar metal photocathodes (Ag, Be, Cr, Cu, Mo, Sn, Ta, and W) and previous data on Mg [X. J. Wang, M. Babzien, R. Malone, and Z. Wu, in Proceedings of LINAC2002, Gyeongju, Korea, 2002 (Pohang Accelerator Laboratory, Pohang, Korea, 2002), pp. 142–144.] indicate that the transverse momentum (and hence intrinsic emittance) of an electron beam is fundamentally dependent on the electron effective mass in the metal.

This Letter reports all-optically tunable and highly indistinguishable single Raman photons from a driven single quantum dot spin. The frequency, linewidth, and lifetime of the Raman photons are tunable by varying the driving field power and detuning. Under continuous-wave excitation, subnatural linewidth single photons from off-resonant Raman scattering show an indistinguishability of 0.98(3). Under $\pi$ pulse excitation, spin- and time-tagged Raman fluorescence photons show an almost vanishing multiphoton emission probability of 0.01(2) and a two-photon quantum interference visibility of 0.95(3). Lastly, Hong-Ou-Mandel interference is demonstrated between two single photons emitted from remote, independent quantum dots with an unprecedented visibility of 0.87(4).

The rheology of dense granular flows is studied numerically in a shear cell controlled at constant pressure and shear stress, confined between two granular shear flows. We show that a liquid state can be achieved even far below the yield stress, whose flow can be described with the same rheology as above the yield stress. A nonlocal constitutive relation is derived from dimensional analysis through a gradient expansion and calibrated using the spatial relaxation of velocity profiles observed under homogeneous stresses. Both for frictional and frictionless grains, the relaxation length is found to diverge as the inverse square root of the distance to the yield point, on both sides of that point.

Uncertainty relations are a distinctive characteristic of quantum theory that impose intrinsic limitations on the precision with which physical properties can be simultaneously determined. The modern work on uncertainty relations employs entropic measures to quantify the lack of knowledge associated with measuring noncommuting observables. However, there is no fundamental reason for using entropies as quantifiers; any functional relation that characterizes the uncertainty of the measurement outcomes defines an uncertainty relation. Starting from a very reasonable assumption of invariance under mere relabeling of the measurement outcomes, we show that Schur-concave functions are the most general uncertainty quantifiers. We then discover a fine-grained uncertainty relation that is given in terms of the majorization order between two probability vectors, significantly extending a majorization-based uncertainty relation first introduced in M. H. Partovi, Phys. Rev. A 84, 052117 (2011). Such a vector-type uncertainty relation generates an infinite family of distinct scalar uncertainty relations via the application of arbitrary uncertainty quantifiers. Our relation is therefore universal and captures the essence of uncertainty in quantum theory.