We find that the recently introduced model of self-trapping supported by a spatially growing strength of a repulsive nonlinearity gives rise to robust vortex-soliton tori, i.e., three-dimensional vortex solitons, with topological charges $S\ge 1$. The family with $S=1$ is completely stable, while the one with $S=2$ has alternating regions of stability and instability. The families are nearly exactly reproduced in an analytical form by the Thomas-Fermi approximation. Unstable states with $S=2$ and 3 split into persistently rotating pairs or triangles of unitary vortices. Application of a moderate torque to the vortex torus initiates a persistent precession mode, with the torus’ axle moving along a conical surface. A strong torque heavily deforms the vortex solitons, but, nonetheless, they restore themselves with the axle oriented according to the vectorial addition of angular momenta.

We propose a novel four-coloring model which describes “frustrated superfluidity” of $p$-band bosons in the diamond optical lattice. The superfluid phases of the condensate wave functions on the diamond-lattice bonds are mapped to four distinct colors at low temperatures. The fact that a macroscopic number of states satisfy the constraints that four differently colored bonds meet at the same site leads to an extensive degeneracy in the superfluid ground state at the classical level. We demonstrate that the phase of the superfluid wave function as well as the orbital angular momentum correlations exhibit a power-law decay in the degenerate manifold that is described by an emergent magnetostatic theory with three independent flux fields. Our results thus provide a novel example of critical superfluid phase with algebraic order in three dimensions. We further show that quantum fluctuations favor a Néel ordering of orbital angular moments with broken sublattice symmetry through the order-by-disorder mechanism.

The physics of air-water interfaces plays a central role in modern theories of the hydrophobic effect. Implementing these theories, however, has been hampered by the difficulty of addressing fluctuations in the shape of such soft interfaces. We show that this challenge is a fundamental consequence of mapping long wavelength density variations onto discrete degrees of freedom. Drawing from studies of surface roughness in lattice models, we account for the resulting nonlinearities simply but accurately. Simulations show that this approach captures complex solvation behaviors quantitatively.

The propagation of cosmic rays (CRs) in turbulent interstellar magnetic fields is typically described as a spatial diffusion process. This formalism predicts only a small deviation from an isotropic CR distribution in the form of a dipole in the direction of the CR density gradient or relative background flow. We show that the existence of a global CR dipole moment necessarily generates a spectrum of higher multipole moments in the local CR distribution. These anomalous anisotropies are a direct consequence of Liouville’s theorem in the presence of a local turbulent magnetic field. We show that the predictions of this model are in excellent agreement with the observed power spectrum of multi-TeV CRs.

We explain the physical role of nonperturbative saddle points of path integrals in theories without instantons, using the example of the asymptotically free two-dimensional principal chiral model (PCM). Standard topological arguments based on homotopy considerations suggest no role for nonperturbative saddles in such theories. However, the resurgence theory, which unifies perturbative and nonperturbative physics, predicts the existence of several types of nonperturbative saddles associated with features of the large-order structure of the perturbation theory. These points are illustrated in the PCM, where we find new nonperturbative “fracton” saddle point field configurations, and suggest a quantum interpretation of previously discovered “uniton” unstable classical solutions. The fractons lead to a semiclassical realization of IR renormalons in the circle-compactified theory and yield the microscopic mechanism of the mass gap of the PCM.

We report on a study of the process $e^{+}{e}^{-}\to {\pi }^{\pm }{(D{\overline{D}}^{*})}^{\mp }$ at $\sqrt{s}=4.26\mathrm{GeV}$ using a $525\mathrm{pb}{}^{-1}$ data sample collected with the BESIII detector at the BEPCII storage ring. A distinct charged structure is observed in the ${(D{\overline{D}}^{*})}^{\mp }$ invariant mass distribution. When fitted to a mass-dependent-width Breit-Wigner line shape, the pole mass and width are determined to be $M_{\mathrm{pole}}=\mathbf{(}3883.9\pm 1.5(\mathrm{stat})\pm 4.2(\mathrm{syst})\mathbf{)}\mathrm{MeV}/c^2$ and ${\mathrm{\Gamma }}_{\mathrm{pole}}=\mathbf{(}24.8\pm 3.3(\mathrm{stat})\pm 11.0(\mathrm{syst})\mathbf{)}\mathrm{MeV}$. The mass and width of the structure, which we refer to as $Z_c(3885)$, are $2\sigma$ and $1\sigma$, respectively, below those of the $Z_c(3900)\to {\pi }^{\pm }J/\psi$ peak observed by BESIII and Belle in ${\pi }^{+}{\pi }^{-}J/\psi$ final states produced at the same center-of-mass energy. The angular distribution of the $\pi Z_c(3885)$ system favors a $J^P=1^{+}$ quantum number assignment for the structure and disfavors $1^{-}$ or $0^{-}$. The Born cross section times the $D{\overline{D}}^{*}$ branching fraction of the $Z_c(3885)$ is measured to be ${\sigma \mathbf{(}{e}^{+}{e}^{-}\to {\pi }^{\pm }{Z}_c(3885)}^{\mp }\mathbf{)}\times {\mathcal{B}\mathbf{(}{Z}_c(3885)}^{\mp }\to {(D{\overline{D}}^{*})}^{\mp }\mathbf{)}=\mathbf{(}83.5\pm 6.6(\mathrm{stat})\pm 22.0(\mathrm{syst})\mathbf{)}\mathrm{pb}$. Assuming the $Z_c(3885)\to D{\overline{D}}^{*}$ signal reported here and the $Z_c(3900)\to \pi J/\psi$ signal are from the same source, the partial width ratio $(\mathrm{\Gamma }(Z_c(3885)\to D{\overline{D}}^{*})/\mathrm{\Gamma }(Z_c(3900)\to \pi J/\psi ))=6.2\pm 1.1(\mathrm{stat})\pm 2.7(\mathrm{syst})$ is determined.

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of ${}^{1}H(\mathrm{\gamma ⃗},\mathrm{p⃗}){\pi }^0$ in the range $0.4<E_{\gamma }<1.4\mathrm{GeV}$ validates the technique and provides essential new data to constrain the excitation spectrum of the nucleon.

In quantum mechanics the Young-type double-slit experiment can be performed with electrons either traveling through a double slit or being coherently emitted from two inversion symmetric molecular sites. In the latter one the valence photoionization cross sections of homonuclear diatomic molecules were predicted to oscillate over kinetic energy almost 50 years ago. Beyond the direct proof of the oscillatory behavior of these photoionization cross sections $\sigma$, we show that the angular distribution of the emitted electrons reveals hitherto unexplored information on the relative phase shift between the corresponding partial waves through two-center interference patterns.

A set of parameters describing electron-impact ionization from laser-aligned atoms are reported, which define the “length”, “width”, and “direction” of the quadruple differential cross section (QDCS) as a function of target alignment ${\mathbf{k}}_{\mathit{B}}$ for fixed ingoing electron momentum ${\mathbf{k}}_0$ and outgoing momenta ${\mathbf{k}}_1$, ${\mathbf{k}}_2$. ${}^{24}\mathrm{Mg}$ was used, with ${\mathbf{k}}_0$, ${\mathbf{k}}_1$, ${\mathbf{k}}_2$, and ${\mathbf{k}}_{\mathit{B}}$ in the same plane. The parameters are derived for a range of ${\mathbf{k}}_2$ angles, with ${\mathbf{k}}_1$ set at 30° to ${\mathbf{k}}_0$. The QDCS is then determined for all ${\mathbf{k}}_{\mathit{B}}$. The parameters are very angle sensitive, the QDCS direction varying more than 90° as the length to width ratio varied more than an order of magnitude.

We report the confinement of an optomechanical micro-oscillator in a squeezed thermal state, obtained by parametric modulation of the optical spring. We propose and implement an experimental scheme based on parametric feedback control of the oscillator, which stabilizes the amplified quadrature while leaving the orthogonal one unaffected. This technique allows us to surpass the $-3\mathrm{dB}$ limit in the noise reduction, associated with parametric resonance, with a best experimental result of $-7.4\mathrm{dB}$. While the present experiment is in the classical regime, in a moderately cooled system our technique may allow squeezing of a macroscopic mechanical oscillator below the zero-point motion.

We explore trapped ions as a setting to investigate nonequilibrium phases in a generalized Dicke model of dissipative spins coupled to phonon modes. We find a rich dynamical phase diagram including superradiantlike regimes, dynamical phase coexistence, and phonon-lasing behavior. A particular advantage of trapped ions is that these phases and transitions among them can be probed in situ through fluorescence. We demonstrate that the main physical insights are captured by a minimal model and consider an experimental realization with $\mathrm{Ca}{}^{+}$ ions trapped in a linear Paul trap with a dressing scheme to create effective two-level systems with a tunable dissipation rate.

We demonstrate the generation of self-accelerating surface plasmon beams along arbitrary caustic curvatures. These plasmonic beams are excited by free-space beams through a two-dimensional binary plasmonic phase mask, which provides the missing momentum between the two beams in the direction of propagation and sets the required phase for the plasmonic beam in the transverse direction. We examine the cases of paraxial and nonparaxial curvatures and show that this highly versatile scheme can be designed to produce arbitrary plasmonic self-accelerating beams. Several different plasmonic beams, which accelerate along polynomial and exponential trajectories, are demonstrated both numerically and experimentally, with a direct measurement of the plasmonic light intensity using a near-field scanning optical microscope.

We present direct experimental evidence for position-dependent diffusion in open random media. The interference of light in time-reversed paths results in renormalization of the diffusion coefficient, which varies spatially. To probe the wave transport inside the system, we fabricate two-dimensional disordered waveguides and monitor the light intensity from the third dimension. Change the geometry of the system or dissipation limits the size of the loop trajectories, allowing us to control the renormalization of the diffusion coefficient. This work shows the possibility of manipulating wave diffusion via the interplay of localization and dissipation.

We present the experimental demonstration and theoretical framework of an acoustophoretic concept enabling contactless, controlled orbital motion or spinning of droplets and particles in air. The orbital plane is parallel to gravity, requiring acoustophoretic lifting and elevation. The motion (spinning, smooth, or turnstile) is shown to have its origin in the spatiotemporal modulation of the acoustic field and the acoustic potential nodes. We describe the basic principle in terms of a superposition of harmonic acoustic potential sources and the intrinsic tendency of the particle to locate itself at the bottom of the total potential well.

We derive a scaling relationship for the mean square rotation rate of rods with lengths in the inertial range in turbulence: $⟨{\stackrel{.}{p}}_i{\stackrel{.}{p}}_i⟩\propto l^{-4/3}$. We present experimental measurements of the rotational statistics of neutrally buoyant rods with lengths $2.8<l/\eta <72.9$, and find that the measurements approach the predicted scaling. The approach to inertial range scaling is shown to be more complex than anticipated with an overshoot and approach to the scaling from above. For all rod lengths, the correlation time of the Lagrangian autocorrelation of the rotation rate scales as the turnover time of the eddies of the size of the rod. Measuring rotational dynamics of single long rods provides a new way to access the spatial structure of the flow at different length scales.

We show through experiments and supporting simulations that propagation of a highly relativistic and dense electron bunch through a plasma can lead to distributed injection of electrons, which depletes the accelerating field, i.e., beam loads the wake. The source of the injected electrons is ionization of the second electron of rubidium (Rb II) within the wake. This injection of excess charge is large enough to severely beam load the wake, and thereby reduce the transformer ratio $T$. The reduction of the average $T$ with increasing beam loading is quantified for the first time by measuring the ratio of peak energy gain and loss of electrons while changing the beam emittance. Simulations show that beam loading by Rb II electrons contributes to the reduction of the peak accelerating field from its weakly loaded value of $43\mathrm{GV}/\mathrm{m}$ to a strongly loaded value of $26\mathrm{GV}/\mathrm{m}$.

We measured the density of vibrational states (DOS) and the specific heat of various glassy and crystalline polymorphs of ${\mathrm{SiO}}_2$. The typical (ambient) glass shows a well-known excess of specific heat relative to the typical crystal ($\alpha$-quartz). This, however, holds when comparing a lower-density glass to a higher-density crystal. For glassy and crystalline polymorphs with matched densities, the DOS of the glass appears as the smoothed counterpart of the DOS of the corresponding crystal; it reveals the same number of the excess states relative to the Debye model, the same number of all states in the low-energy region, and it provides the same specific heat. This shows that glasses have higher specific heat than crystals not due to disorder, but because the typical glass has lower density than the typical crystal.

We show that memory can be encoded in a model amorphous solid subjected to athermal oscillatory shear deformations, and in an analogous spin model with disordered interactions, sharing the feature of a deformable energy landscape. When these systems are subjected to oscillatory shear deformation, they retain memory of the deformation amplitude imposed in the training phase, when the amplitude is below a “localization” threshold. Remarkably, multiple persistent memories can be stored using such an athermal, noise-free, protocol. The possibility of such memory is shown to be linked to the presence of plastic deformations and associated limit cycles traversed by the system, which exhibit avalanche statistics also seen in related contexts.

The resonant x-ray scattering (magnetic elastic, RXMS, and inelastic, RIXS) of ${\mathrm{Ir}}^{4+}$ at the $L_{2,3}$ edges relevant to spin-orbit Mott insulators $A_{n+1}{\mathrm{Ir}}_n{\mathrm{O}}_{3n+1}$ ($A=\mathrm{Sr}$, Ba, etc.) are calculated using a single-ion model which treats the spin-orbit and tetragonal crystal-field terms on an equal footing. Both RXMS and RIXS in the spin-flip channel are found to display a nontrivial dependence on the direction of the magnetic moment, $\mathit{\mu }$. Crucially, we show that for $\mathit{\mu }$ in the $ab$ plane, RXMS in the cross-polarized channel at the $L_2$ edge is zero irrespective of the tetragonal crystal field; spin-flip RIXS, relevant to measurements of magnons, behaves reciprocally, being zero at $L_2$ when $\mathit{\mu }$ is perpendicular to the $ab$ plane. Our results have important implications for the assignment of a $j_{\mathrm{eff}}=1/2$ ground state on the basis of resonant x-ray experiments.

We observe edge transport in the topologically insulating $\mathrm{InAs}/\mathrm{GaSb}$ system in the disordered regime. Using asymmetric current paths we show that conduction occurs exclusively along the device edge, exhibiting a large Hall signal at zero magnetic fields, while for symmetric current paths, the conductance between the two mesoscopicly separated probes is quantized to $2e^2/h$. Both quantized and self-averaged transport show resilience to magnetic fields, and are temperature independent for temperatures between 20 mK and 1 K.