An iterated projection algorithm (N-Phaser) is developed that reconstructs a scattering potential from $N$-beam multiple Bragg scattered intensities. The method may be used to eliminate multiple scattering artifacts from electron diffraction data, solving the phase problem and increasing the thicknesses of samples used in materials science, solid-state chemistry, and small molecule crystallography. For high-energy transmission electron diffraction, we show that the algorithm recovers accurate complex structure factors from a wide range of thicknesses, orientations, and relativistic beam energies, and does not require known thickness or atomic-resolution data if sufficient multiple scattering occurs. Extensions to Cryo-electron microscopy and Micro-electron diffraction are suggested.

Glycerol pressurized to 2 kbar and hyperquenched from the bulk liquid at rates of about $-10000\mathrm{K}/\mathrm{s}$, has been frozen to an extreme out-of-equilibrium state. As compared to conventionally cooled melts, the resulting material exhibits lower orientational correlations, enabling the observation of a secondary relaxation peak in the ambient-pressure dielectric response. The hyperquenching rather than the pressurizing part of the preparation protocol induces the observed structural changes. These vanish entirely only well above the glass transition temperature of the equilibrium liquid and are evidence for strong similarities between hyperquenched and vapor-deposited glass formers.

We report a systematic elastoresistivity study on ${\mathrm{LaFe}}_{1-x}{\mathrm{Co}}_x\mathrm{AsO}$ single crystals, which have well separated structural and magnetic transition lines. All crystals show a Curie-Weiss–like nematic susceptibility in the tetragonal phase. The extracted nematic temperature is monotonically suppressed upon cobalt doping, and changes sign around the optimal doping level, indicating a possible nematic quantum critical point beneath the superconducting dome. The amplitude of the nematic susceptibility shows a peculiar double-peak feature. This could be explained by a combined effect of different contributions to the nematic susceptibility, which are amplified at separated doping levels of ${\mathrm{LaFe}}_{1-x}{\mathrm{Co}}_x\mathrm{AsO}$.

A set of electron-correlation energies as large as 10 eV have been measured for a magnetic 2 ML Fe film deposited on Ag(001). By exploiting the spin selectivity in angle-resolved Auger-photoelectron coincidence spectroscopy and the Cini-Sawatzky theory, the core-valence-valence Auger spectrum of a spin-polarized system have been resolved: correlation energies have been determined for each individual combination of the two holes created in the four subbands involved in the decay: majority and minority spin, as well as $e_g$ and $t_{2g}$. The energy difference between final states with parallel and antiparallel spin of the two emitted electrons is ascribed to the spin-flip energy for the final ion state, thus disentangling the contributions of Coulomb and exchange interactions.

Using pulsed ferroelectric measurements, we probe switching dynamics in multiferroic ${\mathrm{BiFeO}}_3$, revealing low-ns switching times and a clear pathway to sub-ns switching. Our data is well described by a nucleation and growth model, which accounts for the various timescales in the switching process, namely (1) the ferroelectric polarization switching (bound-charge) dynamics and (2) the RC-limited movement of free charge in the circuit. Our model shows good agreement with observed data and begins to bridge the gap between experiment and theory, indicating pathways to study ferroelectric switching on intrinsic timescales.

Shape, dynamics, and viscoelastic properties of eukaryotic cells are primarily governed by a thin, reversibly cross-linked actomyosin cortex located directly beneath the plasma membrane. We obtain time-dependent rheological responses of fibroblasts and MDCK II cells from deformation-relaxation curves using an atomic force microscope to access the dependence of cortex fluidity on prestress. We introduce a viscoelastic model that treats the cell as a composite shell and assumes that relaxation of the cortex follows a power law giving access to cortical prestress, area-compressibility modulus, and the power law exponent (fluidity). Cortex fluidity is modulated by interfering with myosin activity. We find that the power law exponent of the cell cortex decreases with increasing intrinsic prestress and area-compressibility modulus, in accordance with previous finding for isolated actin networks subject to external stress. Extrapolation to zero tension returns the theoretically predicted power law exponent for transiently cross-linked polymer networks. In contrast to the widely used Hertzian mechanics, our model provides viscoelastic parameters independent of indenter geometry and compression velocity.

Quantum coherence is a fundamental resource that quantum technologies exploit to achieve performance beyond that of classical devices. A necessary prerequisite to achieve this advantage is the ability of measurement devices to detect coherence from the measurement statistics. Based on a recently developed resource theory of quantum operations, here we quantify experimentally the ability of a typical quantum-optical detector, the weak-field homodyne detector, to detect coherence. We derive an improved algorithm for quantum detector tomography and apply it to reconstruct the positive-operator-valued measures of the detector in different configurations. The reconstructed positive-operator-valued measures are then employed to evaluate how well the detector can detect coherence using two computable measures. As the first experimental investigation of quantum measurements from a resource theoretical perspective, our work sheds new light on the rigorous evaluation of the performance of a quantum measurement apparatus.

The first observation of the $t\overline{t}H$ process in a single Higgs boson decay channel with the full reconstruction of the final state ($H\to \gamma \gamma$) is presented, with a significance of 6.6 standard deviations ($\sigma$). The $CP$ structure of Higgs boson couplings to fermions is measured, resulting in an exclusion of the pure $CP$-odd structure of the top Yukawa coupling at $3.2\sigma$. The measurements are based on a sample of proton-proton collisions at a center-of-mass energy $\sqrt{s}=13\mathrm{TeV}$ collected by the CMS detector at the LHC, corresponding to an integrated luminosity of $137{\mathrm{fb}}^{-1}$. The cross section times branching fraction of the $t\overline{t}H$ process is measured to be ${\sigma }_{t\overline{t}H}{\mathcal{B}}_{\gamma \gamma }={1.56}_{-0.32}^{+0.34}\mathrm{fb}$, which is compatible with the standard model prediction of ${1.13}_{-0.11}^{+0.08}\mathrm{fb}$. The fractional contribution of the $CP$-odd component is measured to be $f_{CP}^{Htt}=0.00\pm 0.33$.

A study of the charge conjugation and parity ($CP$) properties of the interaction between the Higgs boson and top quarks is presented. Higgs bosons are identified via the diphoton decay channel ($H\to \gamma \gamma$), and their production in association with a top quark pair ($t\overline{t}H$) or single top quark ($tH$) is studied. The analysis uses $139{\mathrm{fb}}^{-1}$ of proton–proton collision data recorded at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$ with the ATLAS detector at the Large Hadron Collider. Assuming a $CP$-even coupling, the $t\overline{t}H$ process is observed with a significance of 5.2 standard deviations. The measured cross section times $H\to \gamma \gamma$ branching ratio is ${1.64}_{-0.36}^{+0.38}(\text{stat}{)}_{-0.14}^{+0.17}(\text{sys})\mathrm{fb}$, and the measured rate for $t\overline{t}H$ is ${1.43}_{-0.31}^{+0.33}(\text{stat}{)}_{-0.15}^{+0.21}(\text{sys})$ times the Standard Model expectation. The $tH$ production process is not observed and an upper limit on its rate of 12 times the Standard Model expectation is set. A $CP$-mixing angle greater (less) than 43 $(-43)°$ is excluded at 95% confidence level.

The double-polarization observable $E$ and helicity-dependent cross sections ${\sigma }_{1/2}$, ${\sigma }_{3/2}$ have been measured for the photoproduction of ${\pi }^0$ pairs off quasifree protons and neutrons at the Mainz MAMI accelerator with the Crystal Ball/TAPS setup. A circularly polarized photon beam was produced by bremsstrahlung from longitudinally polarized electrons and impinged on a longitudinally polarized deuterated butanol target. The reaction products were detected with an almost $4\pi$ covering calorimeter. The results reveal for the first time the helicity- and isospin-dependent structure of the $\gamma N\to N{\pi }^0{\pi }^0$ reaction. They are compared to predictions from reaction models in view of nucleon resonance contributions and also to a refit of one model that predicted results for the proton and for the neutron target. The comparison of the prediction and the refit demonstrates the large impact of the new data.

In laboratory studies and numerical simulations, we observe clear signatures of unstable time-periodic solutions in a moderately turbulent quasi-two-dimensional flow. We validate the dynamical relevance of such solutions by demonstrating that turbulent flows in both experiment and numerics transiently display time-periodic dynamics when they shadow unstable periodic orbits (UPOs). We show that UPOs we computed are also statistically significant, with turbulent flows spending a sizable fraction of the total time near these solutions. As a result, the average rates of energy input and dissipation for the turbulent flow and frequently visited UPOs differ only by a few percent.

A new class of ignition designs is proposed for inertial confinement fusion experiments. These designs are based on the hot-spot ignition approach, but instead of a conventional target that is comprised of a spherical shell with a thin frozen deuterium-tritium (DT) layer, a liquid DT sphere inside a wetted-foam shell is used, and the lower-density central region and higher-density shell are created dynamically by appropriately shaping the laser pulse. These offer several advantages, including simplicity in target production (suitable for mass production for inertial fusion energy), absence of the fill tube (leading to a more-symmetric implosion), and lower sensitivity to both laser imprint and physics uncertainty in shock interaction with the ice-vapor interface. The design evolution starts by launching an $\sim 1$-Mbar shock into a DT sphere. After bouncing from the center, the reflected shock reaches the outer surface of the sphere and the shocked material starts to expand outward. Supporting ablation pressure ultimately stops such expansion and subsequently launches a shock toward the target center, compressing the ablator and fuel, and forming a shell. The shell is then accelerated and fuel is compressed by appropriately shaping the drive laser pulse, forming a hot spot using the conventional or shock ignition approaches. This Letter demonstrates the feasibility of the new concept using hydrodynamic simulations and discusses the advantages and disadvantages of the concept compared with more-traditional inertial confinement fusion designs.

We investigate the radio-frequency spectroscopy of impurities interacting with a quantum gas at finite temperature. In the limit of a single impurity, we show using Fermi’s golden rule that introducing (or injecting) an impurity into the medium is equivalent to ejecting an impurity that is initially interacting with the medium, since the “injection” and “ejection” spectral responses are simply related to each other by an exponential function of frequency. Thus, the full spectral information for the quantum impurity is contained in the injection spectral response, which can be determined using a range of theoretical methods, including variational approaches. We use this property to compute the finite-temperature equation of state and Tan contact of the Fermi polaron. Our results for the contact of a mobile impurity are in excellent agreement with recent experiments and we find that the finite-temperature behavior is qualitatively different compared to the case of infinite impurity mass.

The understanding of thermodynamic glass transition has been hindered by the lack of proper models beyond mean-field theories. Here, we propose a three-dimensional lattice glass model on a simple cubic lattice that exhibits the typical dynamics observed in fragile supercooled liquids such as two-step relaxation, super-Arrhenius growth in the relaxation time, and dynamical heterogeneity. Using advanced Monte Carlo methods, we compute the thermodynamic properties deep inside the glassy temperature regime, well below the onset temperature of the slow dynamics. The specific heat has a finite jump towards the thermodynamic limit with critical exponents close to those expected from the hyperscaling and the random first-order transition theory for the glass transition. We also study an effective free energy of glasses, the Franz-Parisi potential, as a function of the overlap between equilibrium and quenched configurations. The effective free energy indicates the existence of a first-order phase transition, consistent with the random first-order transition theory. These findings strongly suggest that the glassy dynamics of the model has its origin in thermodynamics.

We propose a new current-driven mechanism for achieving significant plasmon dispersion nonreciprocity in systems with narrow, strongly hybridized electron bands. The magnitude of the effect is controlled by the strength of electron-electron interactions $\alpha$, which leads to its particular prominence in moiré materials, characterized by $\alpha \gg 1$. Moreover, this phenomenon is most evident in the regime where Landau damping is quenched and plasmon lifetime is increased. The synergy of these two effects holds great promise for novel optoelectronic applications of moiré materials.

We provide an exact study of dynamical correlations for the quantum spin-orbital liquid phases of an SU(2)-symmetric Kitaev honeycomb lattice model. We show that the spin dynamics in this Kugel-Khomskii type model is exactly the density-density correlation function of $S=1$ fermionic magnons, which could be probed in resonant inelastic x-ray scattering experiments. We predict the characteristic signatures of spin-orbital fractionalization in inelastic scattering experiments and compare them to the ones of the spin-anisotropic Kitaev honeycomb spin liquid. In particular, the resonant inelastic x-ray scattering response shows a characteristic momentum dependence directly related to the dispersion of fermionic excitations. The neutron scattering cross section displays a mixed response of fermionic magnons as well as spin-orbital excitations. The latter has a bandwidth of broad excitations and a vison gap that is three times larger than that of the spin-$1=2$ Kitaev model.

Photon recycling has received increased attention in recent years following its observation in halide perovskites. It has been shown to lower the effective bimolecular recombination rate and thus increase excitation densities within a material. Here we introduce a general framework to quantify photon recycling which can be applied to any material. We apply our model to idealized solar cells and light-emitting diodes based on halide perovskites. By varying controllable parameters which affect photon recycling, namely, thickness, charge trapping rate, nonideal transmission at interfaces, and absorptance, we quantify the effect of each on photon recycling. In both device types, we demonstrate that maximizing absorption and emission processes remains paramount for optimizing devices, even if this is at the expense of photon recycling. Our results provide new insight into quantifying photon recycling in optoelectronic devices and demonstrate that photon recycling cannot always be seen as a beneficial process.

We experimentally demonstrate a dipolar polariton based electric-field sensor. We tune and optimize the sensitivity of the sensor by varying the dipole moment of polaritons. We show polariton interactions play an important role in determining the conditions for optimal electric-field sensing, and achieve a sensitivity of $0.12\mathrm{V}{\mathrm{m}}^{-1}{\mathrm{Hz}}^{-0.5}$. Finally, we apply the sensor to illustrate that excitation of polaritons modifies the electric field in a spatial region much larger than the optical excitation spot.