Chiral emission into nanophotonic resonators

Chiral emission, where the handedness of a transition dipole determines the direction in which a photon is emitted, has recently been observed from atoms and quantum dots coupled to nanophotonic waveguides. Here, we consider the case of chiral light-matter interactions in resonant nanophotonic structures, deriving closed-form expressions for the fundamental quantum electrodynamic quantities that describe these interactions. We show how parameters such as the position dependent, directional Purcell factors and mode volume can be calculated using computationally efficient two dimensional eigenmode simulations. As an example, we calculate these quantities for a prototypical ring resonator with a geometric footprint of only 4.5~$\mu$m$^2$, showing that perfect directionality with a simultaneous Purcell enhancement upwards of 400 are possible. The ability to determine these fundamental properties of nanophotonic chiral interfaces is crucial if they are to form elements of quantum circuits and networks

The early childhood generalized trust belief scale

The study was designed to develop and evaluate the Early Childhood Generalized Trust Belief Scale (ECGTBS) as a method of assessing 5-to-8-year-olds’ generalized trust. Two hundred and eleven (103 male and 108 female) children (mean age 6 years and 2 months at Time 1) completed the ECGTBS twice over a year. A subsample of participants completed the ECGTBS after two weeks to assess the scale’s test-retest reliability. Exploratory and confirmatory factor analyses confirmed that the ECGTBS assessed the expected three factors: reliability, emotional trust, and honesty with item-pairs loading most strongly on their corresponding factor. However, the ECGTBS demonstrated low to modest internal consistency and test-retest reliability which indicates a need for further development of this instrument. As evidence for the convergent validity of the ECGTBS, the reliability and emotional trust items were associated with the children’s trust in classmates at Time 2. Concurrent asymmetric quadratic relationships indicated the importance of midrange generalized trust. Specifically, children with very high generalized trust experienced greater loneliness and children with very low generalized trust had fewer friendships than children with midrange trust

Young children's interpersonal trust consistency as a predictor of future school adjustment

Young children’s interpersonal trust consistency was examined as a predictor of future school adjustment. One hundred and ninety two (95 male and 97 female, M age = 6 years 2 months, SD age = 6 months) children from school years 1 and 2 in the United Kingdom were tested twice over one-year. Children completed measures of peer trust and school adjustment and teachers completed the Short-Form Teacher Rating Scale of School Adjustment. Longitudinal quadratic relationships emerged between consistency of children’s peer trust beliefs and peer-reported trustworthiness and school adjustment and these varied according to social group, facet of trust, and indictor of school adjustment. The findings support the conclusion that interpersonal trust consistency, especially for secret-keeping, predicts aspects of young children’s school adjustment

Molecular hydrodynamics from memory kernels

The memory kernel for a tagged particle in a fluid, computed from molecular dynamics simulations, decays algebraically as t−3/2. We show how the hydrodynamic Basset-Boussinesq force naturally emerges from this long-time tail and generalize the concept of hydrodynamic added mass. This mass term is negative in the present case of a molecular solute, which is at odds with incompressible hydrodynamics predictions. Lastly, we discuss the various contributions to the friction, the associated time scales, and the crossover between the molecular and hydrodynamic regimes upon increasing the solute radius

Cluster sum rules for three-body systems with angular-momentum dependent interactions

We derive general expressions for non-energy weighted and energy-weighted cluster sum rules for systems of three charged particles. The interferences between pairs of particles are found to play a substantial role. The energy-weighted sum rule is usually determined by the kinetic energy operator, but we demonstrate that it has similar additional contributions from the angular momentum and parity dependence of two- and three-body potentials frequently used in three-body calculations. The importance of the different contributions is illustrated with the dipole excitations in $^6$He. The results are compared with the available experimental data.Comment: 11 pages, 3 figures, 2 table

Semi-relativistic description of quasielastic neutrino reactions and superscaling in a continuum shell model

The so-called semi-relativistic expansion of the weak charged current in powers of the initial nucleon momentum is performed to describe charge-changing, quasielastic neutrino reactions $(\nu_\mu,\mu^-)$ at intermediate energies. The quality of the expansion is tested by comparing with the relativistic Fermi gas model using several choices of kinematics of interest for ongoing neutrino oscillation experiments. The new current is then implemented in a continuum shell model together with relativistic kinematics to investigate the scaling properties of $(e,e')$ and $(\nu_\mu,\mu^-)$ cross sections.Comment: 33 pages, 10 figures, to appear in PR

Strictly One-Dimensional Electron System in Au Chains on Ge(001) Revealed By Photoelectron K-Space Mapping

Atomic nanowires formed by Au on Ge(001) are scrutinized for the band topology of the conduction electron system by k-resolved photoemission. Two metallic electron pockets are observed. Their Fermi surface sheets form straight lines without undulations perpendicular to the chains within experimental uncertainty. The electrons hence emerge as strictly confined to one dimension. Moreover, the system is stable against a Peierls distortion down to 10 K, lending itself for studies of the spectral function. Indications for unusually low spectral weight at the chemical potential are discussed.Comment: 4 pages, 4 figures - revised version with added Fig. 2e) and additional reference

Massive Dirac fermions in a ferromagnetic kagome metal

The kagome lattice is a two-dimensional network of corner-sharing triangles known as a platform for exotic quantum magnetic states. Theoretical work has predicted that the kagome lattice may also host Dirac electronic states that could lead to topological and Chern insulating phases, but these have evaded experimental detection to date. Here we study the d-electron kagome metal Fe$_3$Sn$_2$ designed to support bulk massive Dirac fermions in the presence of ferromagnetic order. We observe a temperature independent intrinsic anomalous Hall conductivity persisting above room temperature suggestive of prominent Berry curvature from the time-reversal breaking electronic bands of the kagome plane. Using angle-resolved photoemission, we discover a pair of quasi-2D Dirac cones near the Fermi level with a 30 meV mass gap that accounts for the Berry curvature-induced Hall conductivity. We show this behavior is a consequence of the underlying symmetry properties of the bilayer kagome lattice in the ferromagnetic state with atomic spin-orbit coupling. This report provides the first evidence for a ferromagnetic kagome metal and an example of emergent topological electronic properties in a correlated electron system. This offers insight into recent discoveries of exotic electronic behavior in kagome lattice antiferromagnets and may provide a stepping stone toward lattice model realizations of fractional topological quantum states.Comment: 19 pages, 4 figure