Competition between ordered phases, and their associated phase transitions, are significant in the study of strongly correlated systems. Here, we examine one aspect, the nonequilibrium dynamics of a photoexcited Mott-Peierls system, using an effective Peierls-Hubbard model and exact diagonalization. Near a transition where spin and charge become strongly intertwined, we observe antiphase dynamics and a coupling-strength-dependent suppression or enhancement in the static structure factors. The renormalized bosonic excitations coupled to a particular photoexcited electron can be extracted, which provides an approach for characterizing the underlying bosonic modes. The results from this analysis for different electronic momenta show an uneven softening due to a stronger coupling near $k_F$. This behavior reflects the strong link between the fermionic momenta, the coupling vertices, and ultimately, the bosonic susceptibilities when multiple phases compete for the ground state of the system.

We present single-crystal neutron scattering measurements of the spin-$1/2$ equilateral triangular-lattice antiferromagnet ${\mathrm{Ba}}_3{\mathrm{CoSb}}_2{\mathrm{O}}_9$. Besides confirming that the ${\mathrm{Co}}^{2+}$ magnetic moments lie in the $ab$ plane for zero magnetic field and then determining all the exchange parameters of the minimal quasi-2D spin Hamiltonian, we provide conclusive experimental evidence of magnon decay through observation of intrinsic line broadening. Through detailed comparisons with the linear and nonlinear spin-wave theories, we also point out that the large-$S$ approximation, which is conventionally employed to predict magnon decay in noncollinear magnets, is inadequate to explain our experimental observation. Thus, our results call for a new theoretical framework for describing excitation spectra in low-dimensional frustrated magnets under strong quantum effects.

In this work, we propose a novel computed tomography (CT) approach for three-dimensional (3D) object reconstruction, based on a generalized tomographic geometry with two-dimensional angular sampling (two angular degrees of freedom). The reconstruction is based on the 3D Radon transform and is compatible with anisotropic beam conditions. This allows isotropic 3D imaging with a source, which can be extended along one direction for increased flux, while high resolution is achieved by a small source size only in the orthogonal direction. This novel scheme for analytical CT is demonstrated by numerical simulations and proof-of-concept experiments. In this way high resolution and coherence along a single direction determines the reconstruction quality of the entire 3D data set, opening up, for example, new opportunities to achieve nanoscale resolution and/or phase contrast with low brilliance sources such as laboratory x-ray or neutron sources.

Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing, coherence) can be converted into entanglement. In this work, we present a general framework, based on superposition, for structurally connecting and converting nonclassicality to entanglement. In addition to capturing the previously known results, this framework also allows us to uncover new entanglement convertibility theorems in two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are “symmetric coherent states,” connected with symmetric representations of the group $SU(K)$. These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and nonlocal pictures of nonclassicality.

We present one-shot compression protocols that optimally encode ensembles of $N$ identically prepared mixed states into $O(\log N)$ qubits. In contrast to the case of pure-state ensembles, we find that the number of encoding qubits drops down discontinuously as soon as a nonzero error is tolerated and the spectrum of the states is known with sufficient precision. For qubit ensembles, this feature leads to a 25% saving of memory space. Our compression protocols can be implemented efficiently on a quantum computer.

Gamma-ray bursts (GRBs) are copious sources of gamma rays whose interaction with a planetary atmosphere can pose a threat to complex life. Using recent determinations of their rate and probability of causing massive extinction, we explore what types of universes are most likely to harbor advanced forms of life. We use cosmological $N$-body simulations to determine at what time and for what value of the cosmological constant ($\mathrm{\Lambda }$) the chances of life being unaffected by cosmic explosions are maximized. Life survival to GRBs favors Lambda-dominated universes. Within a cold dark matter model with a cosmological constant, the likelihood of life survival to GRBs is governed by the value of $\mathrm{\Lambda }$ and the age of the Universe. We find that we seem to live in a favorable point in this parameter space that minimizes the exposure to cosmic explosions, yet maximizes the number of main sequence (hydrogen-burning) stars around which advanced life forms can exist.

BABAR, Belle, and LHCb Collaborations report evidence for new physics in $B\to D\tau \nu$ and $B\to D^{*}\tau \nu$ of approximately $3.8\sigma$. There is also the long lasting discrepancy of about $3\sigma$ in the anomalous magnetic moment of the muon, and the branching ratio for $\tau \to \mu \nu \nu$ is $1.8\sigma$ ($2.4\sigma$) above the standard model expectation using the HFAG (PDG) values. Furthermore, CMS Collaboration finds hints for a nonzero decay rate of $h\to \mu \tau$. Interestingly, all these observations can be explained by introducing new scalars. In this Letter we consider these processes within a lepton-specific two-Higgs doublet model (i.e., of type X) with additional nonstandard Yukawa couplings. It is found that one can accommodate $\tau \to \mu \nu \nu$ with modified Higgs–$\tau$ couplings. The anomalous magnetic moment of the muon can be explained if the additional neutral $CP$-even Higgs boson $H$ is light (below 100 GeV). Also $\mathcal{R}(D)$ and $\mathcal{R}(D^{*})$ can be easily explained by additional $t$–$c$–Higgs couplings. Combining these $t$–$c$ couplings with a light $H$ the decay rate for $t\to Hc$ can be in a testable range for the LHC. Effects in $h\to \mu \tau$ are also possible, but in this case a simultaneous explanation of the anomalous magnetic moment of the muon is difficult due to the unavoidable $\tau \to \mu \gamma$ decay.

Based on $2.93{\mathrm{fb}}^{-1}$ $e^{+}{e}^{-}$ collision data taken at center-of-mass energy of 3.773 GeV by the BESIII detector, we report searches for the singly Cabibbo-suppressed decays $D^{+}\to \omega {\pi }^{+}$ and $D^0\to \omega {\pi }^0$. A double tag technique is used to measure the absolute branching fractions $\mathcal{B}(D^{+}\to \omega {\pi }^{+})=(2.79\pm 0.57\pm 0.16)\times {10}^{-4}$ and $\mathcal{B}(D^0\to \omega {\pi }^0)=(1.17\pm 0.34\pm 0.07)\times {10}^{-4}$, with statistical significances of $5.5\sigma$ and $4.1\sigma$, where the first and second uncertainties are statistical and systematic, respectively.

A near-field thermal Hall effect (i.e., Righi-Leduc effect) in networks of magneto-optical particles placed in a constant magnetic field is predicted. This many-body effect is related to a symmetry breaking in the system induced by the magnetic field, which gives rise to preferential channels for the heat transport by near-field interaction thanks to the particle’s anisotropy tuning.

Owing to complex geometry, gyrokinetic simulations in stellarator geometry produce large numbers of subdominant unstable and stable, near-orthogonal eigenmodes. Here, results based on the full eigenmode spectrum in stellarator geometry are presented for the first time. In the nonlinear state of a low-magnetic-shear ion-temperature-gradient-driven case, a multitude of these modes are active and imprint the system. Turbulent frequency spectra are broadband as a consequence, in addition to a nonlinear, narrow signature at electron frequencies. It is shown that successful quasilinear, mixing-length transport modeling is possible in stellarators, where it is essential to account for all subdominant unstable modes.

Amorphous solids yield at a critical value of the strain (in strain-controlled experiments); for larger strains, the average stress can no longer increase—the system displays an elastoplastic steady state. A long-standing riddle in the materials community is what the difference is between the microscopic states of the material before and after yield. Explanations in the literature are material specific, but the universality of the phenomenon begs a universal answer. We argue here that there is no fundamental difference in the states of matter before and after yield, but the yield is a bona fide first-order phase transition between a highly restricted set of possible configurations residing in a small region of phase space to a vastly rich set of configurations which include many marginally stable ones. To show this, we employ an order parameter of universal applicability, independent of the microscopic interactions, that is successful in quantifying the transition in an unambiguous manner.

The growth of Pb on $\mathrm{Si}(111)\text{−}(7\times 7)$ at temperatures from 72 to 201 K has been investigated using in situ electrical resistivity measurements and scanning tunneling microscopy. For temperatures $T>140\mathrm{K}$ the specific resistivity $\rho (\theta )$ versus coverage $\theta$ shows an unusual “hump,” instead of the expected monotonic decrease with $\theta$. This novel result correlates well with the formation of uniform height eight-layer Pb islands and the superdiffusive motion of the wetting layer, despite the low temperatures. A model of the film resistivity as two resistors in series, the amorphous wetting layer and the crystalline islands, explains quantitatively the resistivity dependence on $\theta$.

We study the magnetotransport properties of high-mobility holes in monolayer and bilayer ${\mathrm{WSe}}_2$, which display well defined Shubnikov–de Haas (SdH) oscillations, and quantum Hall states in high magnetic fields. In both mono- and bilayer ${\mathrm{WSe}}_2$, the SdH oscillations and the quantum Hall states occur predominantly at even filling factors, evincing a twofold Landau level degeneracy. The Fourier transform analysis of the SdH oscillations in bilayer ${\mathrm{WSe}}_2$ reveals the presence of two subbands localized in the top or the bottom layer, as well as negative compressibility. From the temperature dependence of the SdH oscillations we determine a hole effective mass of $0.45m_0$ for both mono- and bilayer ${\mathrm{WSe}}_2$.

We theoretically investigate spin dynamics in spin-orbit-coupled materials. In the ballistic limit, the spin lifetime is dictated by dephasing that arises from energy broadening plus a nonuniform spin precession. For the case of clean graphene, we find a strong anisotropy with spin lifetimes that can be short even for modest energy scales, on the order of a few ns. These results offer deeper insight into the nature of spin dynamics in graphene, and are also applicable to the investigation of other systems where spin-orbit coupling plays an important role.

We report the temperature $T$ and magnetic field $H$ dependence of the thermopower $S$ of an itinerant triangular antiferromagnet ${\mathrm{PdCrO}}_2$ in high magnetic fields up to 32 T. In the paramagnetic phase, the zero-field thermopower is positive with a value typical of good metals with a high carrier density. In marked contrast to typical metals, however, $S$ decreases rapidly with increasing magnetic field, approaching zero at the maximum field scale for $T>70\mathrm{K}$. We argue here that this profound change in the thermoelectric response derives from the strong interaction of the $4d$ correlated electrons of the Pd ions with the short-range spin correlations of the ${\mathrm{Cr}}^{3+}$ spins that persist beyond the Néel ordering temperature due to the combined effects of geometrical frustration and low dimensionality.

Diffusion nuclear magnetic resonance (NMR) is a powerful technique for studying porous media, but yields ambiguous results when the sample comprises multiple regions with different pore sizes, shapes, and orientations. Inspired by solid-state NMR techniques for correlating isotropic and anisotropic chemical shifts, we propose a diffusion NMR method to resolve said ambiguity. Numerical data inversion relies on sparse representation of the data in a basis of radial and axial diffusivities. Experiments are performed on a composite sample with a cell suspension and a liquid crystal.

Characterizing structural inhomogeneity is an essential step in understanding the mechanical response of amorphous materials. We introduce a threshold-free measure based on the field of vectors pointing from the center of each particle to the centroid of the Voronoi cell in which the particle resides. These vectors tend to point in toward regions of high free volume and away from regions of low free volume, reminiscent of sinks and sources in a vector field. We compute the local divergence of these vectors, where positive values correspond to overpacked regions and negative values identify underpacked regions within the material. Distributions of this divergence are nearly Gaussian with zero mean, allowing for structural characterization using only the moments of the distribution. We explore how the standard deviation and skewness vary with the packing fraction for simulations of bidisperse systems and find a kink in these moments that coincides with the jamming transition.

We compare the high velocity dewetting behavior, at elevated temperatures, of atactic polystyrene (aPS) and isotactic polystyrene (iPS) films, with the zero shear bulk viscosity (${\eta }_{\text{bulk}}$) of aPS being approximately ten times larger than iPS. As expected, for aPS the apparent viscosity of the films (${\eta }_f$) derived from high-shear dewetting is less than ${\eta }_{\text{bulk}}$, displaying a shear thinning behavior. Surprisingly, for iPS films, ${\eta }_f$ is always larger than ${\eta }_{\text{bulk}}$, even at about $50°\mathrm{C}$ above the melting point, with ${\eta }_f/{\eta }_{\text{bulk}}$ following an Arrhenius behavior. The corresponding activation energy of $\sim 160\pm 10\mathrm{kJ}/\mathrm{mol}$ for iPS films suggests a cooperative motion of segments which are aligned and agglomerated by fast dewetting.