The precipitation of a glass forming solute from solution is modeled using a lattice model previously introduced to study dissolution kinetics of amorphous materials. The model includes the enhancement of kinetics at the surface of a glass in contact with a plasticizing solvent. We demonstrate that precipitation can produce a glass substantially more stable than that produced by very long time annealing of the bulk glass former. The energy of these ultrastable amorphous precipitates is found to be dominated by residual solvent rather than high energy glass configurations.

The hydrodynamic theory of polar liquid crystals is widely used to describe biological active fluids as well as passive molecular materials. Depending on the “shear-alignment parameter”, in passive or weakly active polar fluids under external shear, the polar order parameter $\mathbf{p}$ is either inclined to the flow at a fixed (Leslie) angle, or rotates continuously. Here, we study the role of an additional “shear-elongation parameter” that has been neglected in the recent literature and causes $|\mathbf{p}|$ to change under flow. We show that this effect can give rise to a shear-induced first-order phase transition from isotropic to polar, and significantly change the rheological properties of both active and passive polar fluids.

We introduce a new distance-based measure for the nonclassicality of the states of a bosonic field, which outperforms the existing such measures in several ways. We define for that purpose the operator ordering sensitivity of the state which evaluates the sensitivity to operator ordering of the Renyi entropy of its quasiprobabilities and which measures the oscillations in its Wigner function. Through a sharp control on the operator ordering sensitivity of classical states we obtain a precise geometric image of their location in the density matrix space allowing us to introduce a distance-based measure of nonclassicality. We analyze the link between this nonclassicality measure and a recently introduced quantum macroscopicity measure, showing how the two notions are distinct.

The classical cubic-lattice dimer model undergoes an unconventional transition between a columnar crystal and a dimer liquid, in the same universality class as the deconfined quantum critical point in spin-$1/2$ antiferromagnets but with very different microscopic physics and microscopic symmetries. Using Monte Carlo simulations, we show that this transition has emergent SO(5) symmetry relating quantities characterizing the two phases. While the low-temperature phase has a conventional order parameter, the defining property of the Coulomb liquid on the high-temperature side is deconfinement of monomers, and so SO(5) relates fundamentally different types of objects. Studying linear system sizes up to $L=96$, we find that this symmetry applies with an excellent precision, consistently improving with system size over this range. It is remarkable that SO(5) emerges in a system as basic as the cubic dimer model, with only simple discrete degrees of freedom. Our results are important evidence for the generality of the SO(5) symmetry that has been proposed for the noncompact ${\mathrm{CP}}^1$ field theory. We describe an interpretation for these results in terms of a consistent hypothesis for the renormalization-group flow structure, allowing for the possibility that SO(5) may ultimately be a near-symmetry rather than exact.

I apply recently proposed “swampland” conjectures to eternal inflation in single-scalar field theories. Eternal inflation is a phase of infinite self-reproduction of a quasi–de Sitter universe which has been argued to be a generic consequence of cosmological inflation. The originally proposed de Sitter swampland conjectures were shown by Matsui and Takahashi, and by Dimopoulos, to be generically incompatible with eternal inflation. However, the more recently proposed “refined” swampland conjecture imposes a slightly weaker criterion on the scalar field potential in inflation, and is consistent with the existence of a tachyonic instability. In this Letter, I show that eternal inflation is marginally consistent with the refined de Sitter swampland conjecture. Thus, if the refined conjecture is correct, the existence of a landscape-based “multiverse” in string theory is not incompatible with a self-consistent ultraviolet completion, with significant consequences for model building in string theory.

We apply the recently developed notion of complexity for field theory to a quantum quench through a critical point in $1+1$ dimensions. We begin with a toy model consisting of a quantum harmonic oscillator, and show that complexity exhibits universal scalings in both the slow and fast quench regimes. We then generalize our results to a one-dimensional harmonic chain, and show that preservation of these scaling behaviors in free field theory depends on the choice of norm. Applying our setup to the case of two oscillators, we quantify the complexity of purification associated with a subregion, and demonstrate that complexity is capable of probing features to which the entanglement entropy is insensitive. We find that the complexity of subregions is subadditive, and comment on potential implications for holography.

We report the observation of the rare charm decay $D^0\to K^{-}{\pi }^{+}{e}^{+}{e}^{-}$, based on $468{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected at or close to the center-of-mass energy of the $\mathrm{\Upsilon }(4\mathrm{S})$ resonance with the BABAR detector at the SLAC National Accelerator Laboratory. We find the branching fraction in the invariant mass range $0.675<m(e^{+}{e}^{-})<0.875\mathrm{GeV}/c^2$ of the electron-positron pair to be $\mathcal{B}(D^0\to K^{-}{\pi }^{+}{e}^{+}{e}^{-})=(4.0\pm 0.5\pm 0.2\pm 0.1)\times 10^{-6}$, where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty in the branching fraction of the decay $D^0\to K^{-}{\pi }^{+}{\pi }^{+}{\pi }^{-}$ used as a normalization mode. The significance of the observation corresponds to 9.7 standard deviations including systematic uncertainties. This result is consistent with the recently reported $D^0\to K^{-}{\pi }^{+}{\mu }^{+}{\mu }^{-}$ branching fraction, measured in the same invariant mass range, and with the value expected in the standard model. In a set of regions of $m(e^{+}{e}^{-})$, where long-distance effects are potentially small, we determine a 90% confidence level upper limit on the branching fraction $\mathcal{B}(D^0\to K^{-}{\pi }^{+}{e}^{+}{e}^{-})<3.1\times 10^{-6}$.

We consider an extension of the standard model by right-handed neutrinos and we argue that, under plausible assumptions, a neutrino mass of $\mathcal{O}(0.1)\mathrm{eV}$ is naturally generated by the breaking of the lepton number at the Planck scale, possibly by gravitational effects, without the necessity of introducing new mass scales in the model. Some implications of this framework are also briefly discussed.

We present both a theoretical description and experimental observation of the nonlinear mutual interactions between a pair of copropagative breathers in the framework of the focusing one-dimensional nonlinear Schrödinger equation. As a general case, we show that the resulting bound state of breathers exhibits moleculelike behavior with quasiperiodic oscillatory dynamics (i.e., internal coherent interactions and pulsations), while for commensurate conditions the molecule oscillations become exactly periodic. Our theoretical model is confirmed by an experimental observation of shaped moleculelike breather light waves propagating in a nearly conservative optical fiber system. Our work sheds new light on the existence of localized wave structures and recurrence dynamics beyond the multisoliton complexes.

We are reporting the observation of the breakdown of electrons’ degeneracy and emergence of classical statistics in the simplest element: metallic deuterium. We have studied the optical reflectance, shock velocity, and temperature of dynamically compressed liquid deuterium up to its Fermi temperature $T_F$. Above the insulator-metal transition, the optical reflectance shows the distinctive temperature-independent resistivity saturation, which is prescribed by Mott’s minimum metallic limit, in agreement with previous experiments. At $T>0.4T_F$, however, the reflectance of metallic deuterium starts to rise with a temperature-dependent slope, consistent with the breakdown of the Fermi surface. The experimentally inferred electron-ion collisional time in this region exhibits the characteristic temperature dependence expected for a classical Landau-Spitzer plasma. Our observation of electron degeneracy lifting extends studies of degeneracy to new fermionic species—electron Fermi systems—and offers an invaluable benchmark for quantum statistical models of Coulomb systems over a wide range of temperatures relevant to dense astrophysical objects and ignition physics.

The Mohr-Coulomb criterion is widely used in geosciences and solid mechanics to relate the state of stress at failure to the observed orientation of the resulting faults. This relation is based on the assumption that macroscopic failure takes place along the plane that maximizes the Coulomb stress. Here, this hypothesis is assessed by simulating compressive tests on an elastodamageable material that follows the Mohr-Coulomb criterion at the mesoscopic scale. We find that the macroscopic fault orientation is not given by the Mohr-Coulomb criterion. Instead, for a weakly disordered material, it corresponds to the most unstable mode of damage growth, which we determine through a linear stability analysis of its homogeneously damaged state. Our study reveals that compressive failure emerges from the coalescence of damaged clusters within the material and that this collective process is suitably described at the continuum scale by introducing an elastic kernel that describes the interactions between these clusters.

Large coupling strengths in exciton-photon interactions are important for the quantum photonic network, while strong cavity–quantum dot interactions have been focused on $s$-shell excitons with small coupling strengths. Here we demonstrate strong interactions between cavities and $p$-shell excitons with a great enhancement by the in situ wave-function control. The $p$-shell excitons are demonstrated with much larger wave-function extents and nonlocal interactions beyond the dipole approximation. Then the interaction is tuned from the nonlocal to the local regime by the wave function shrinking, during which the enhancement is obtained. A large coupling strength of $210\mu \mathrm{eV}$ has been achieved, indicating the great potential of $p$-shell excitons for coherent information exchange. Furthermore, we propose a distributed delay model to quantitatively explain the coupling strength variation, revealing the intertwining of excitons and photons beyond the dipole approximation.

While coalescence is ultimately the most drastic destabilization process in foams, its underlying processes are still unclear. To better understand them, we track individual coalescence events in two-dimensional foams at controlled capillary pressure. We obtain statistical information revealing the influence of the different parameters which have been previously proposed to explain coalescence. Our main conclusion is that coalescence probability is simply proportional to the area of the thin film separating two bubbles, suggesting that coalescence is mostly stochastic.

Contextuality is considered as an intrinsic signature of nonclassicality and a crucial resource for achieving unique advantages of quantum information processing. However, recently, there have been debates on whether classical fields may also demonstrate contextuality. Here, we experimentally configure a contextuality test for optical fields, adopting various definitions of measurement events, and analyze how the definitions affect the emergence of nonclassical correlations. The heralded single-photon state, which is a typical nonclassical light field, manifests contextuality in our setup; whereas contextuality for classical coherent fields strongly depends on the specific definition of measurement events, which is equivalent to filtering the nonclassical component of the input state. Our results highlight the importance of the definition of measurement events to demonstrate contextuality, and they link the contextual correlations to nonclassicality defined by quasiprobabilities in phase space.

Quantum computers will require encoding of quantum information to protect them from noise. Fault-tolerant quantum computing architectures illustrate how this might be done but have not yet shown a conclusive practical advantage. Here we demonstrate that a small but useful error detecting code improves the fidelity of the fault-tolerant gates implemented in the code space as compared to the fidelity of physically equivalent gates implemented on physical qubits. By running a randomized benchmarking protocol in the logical code space of the [4,2,2] code, we observe an order of magnitude improvement in the infidelity of the gates, with the two-qubit infidelity dropping from 5.8(2)% to 0.60(3)%. Our results are consistent with fault-tolerance theory and conclusively demonstrate the benefit of carrying out computation in a code space that can detect errors. Although the fault-tolerant gates offer an impressive improvement in fidelity, the computation as a whole is not below the fault-tolerance threshold because of noise associated with state preparation and measurement on this device.

We present the analytic form of the planar two-loop five-gluon scattering amplitudes in QCD for a complete set of independent helicity configurations of external gluons. These include the first analytic results for five-point two-loop amplitudes relevant for the computation of next-to-next-to-leading-order QCD corrections at hadron colliders. The results were obtained by reconstructing analytic expressions from numerical evaluations. The complexity of the computation is reduced by exploiting physical and analytical properties of the amplitudes, employing a minimal basis of so-called pentagon functions that have recently been classified.

The interaction of electromagnetic waves with condensed matter and the resultant force is fundamental in the physical sciences. The maximum pressure on a planar surface is understood to be twice the incident wave power density normalized by the background velocity. We demonstrate for the first time that this pressure can be exceeded by a substantial factor by structuring a surface. Experimental results for direct optomechanical deflection of a nanostructured gold film on a silicon nitride membrane illuminated by a laser beam are shown to significantly exceed those for the planar surface. This enhanced pressure can be understood as being associated with an asymmetric optical cavity array realized in the membrane film. The possible enhancement depends on the material properties and the geometrical parameters of the structured material. Such control and increase of optical pressure with nanostructured material should impact applications across the physical sciences.