Tip-enhanced strong coupling spectroscopy, imaging, and control of a single quantum emitter

Optical cavities can enhance and control light-matter interactions. This level of control has recently been extended to the nanoscale with single emitter strong coupling even at room temperature using plasmonic nanostructures. However, emitters in static geometries, limit the ability to tune the coupling strength or to couple different emitters to the same cavity. Here, we present tip-enhanced strong coupling (TESC) with a nanocavity formed between a scanning plasmonic antenna tip and the substrate. By reversibly and dynamically addressing single quantum dots, we observe mode splitting up to 160 meV and anticrossing over a detuning range of ~100 meV, and with subnanometer precision over the deep subdiffraction-limited mode volume. Thus, TESC enables previously inaccessible control over emitter-nanocavity coupling and mode volume based on near-field microscopy. This opens pathways to induce, probe, and control single-emitter plasmon hybrid quantum states for applications from optoelectronics to quantum information science at room temperature

Black hole masses and enrichment of z ~ 6 SDSS quasars

We present sensitive near-infrared spectroscopic observations for a sample of five z ~ 6 quasars. These are amongst the most distant, currently known quasars in the universe. The spectra have been obtained using ISAAC at the VLT and include the CIV, MgII and FeII lines. We measure the FeII/MgII line ratio, as an observational proxy for the Fe/alpha element ratio. We derive a ratio of 2.7+/-0.8 for our sample, which is similar to that found for lower redshift quasars, i.e., we provide additional evidence for the lack of evolution in the FeII/MgII line ratio of quasars up to the highest redshifts. This result demonstrates that the sample quasars must have undergone a major episode of iron enrichment in less than one Gyr and star formation must have commenced at z > 8. The linewidths of the MgII and CIV lines give two estimates for the black hole masses. A third estimate is given by assuming that the quasars emit at their Eddington luminosity. The derived masses using these three methods agree well, implying that the quasars are not likely to be strongly lensed. We derive central black hole masses of 0.3-5.2 10^9 solar masses. We use the difference between the redshift of MgII (a proxy for the systemic redshift of the quasar) and the onset of the Gunn Peterson trough to derive the extent of the ionized Stromgren spheres around our target quasars. The derived physical radii are about five Mpc. Using a simple ionization model, the emission of the central quasars would need of order 10^6-10^8 year to create these cavities in a surrounding intergalactic medium with a neutral fraction between 0.1 and 1.0. As the e-folding time scale for the central accreting black hole is on the order of a few times 10^7 year, it can grow by one e-folding or less within this time span.Comment: Accepted by ApJ, 15 pages, 8 figure

Deformation of Crystals: Connections with Statistical Physics

We give a bird's-eye view of the plastic deformation of crystals aimed at the statistical physics community, as well as a broad introduction to the statistical theories of forced rigid systems aimed at the plasticity community. Memory effects in magnets, spin glasses, charge density waves, and dilute colloidal suspensions are discussed in relation to the onset of plastic yielding in crystals. Dislocation avalanches and complex dislocation tangles are discussed via a brief introduction to the renormalization group and scaling. Analogies to emergent scale invariance in fracture, jamming, coarsening, and a variety of depinning transitions are explored. Dislocation dynamics in crystals challenge nonequilibrium statistical physics. Statistical physics provides both cautionary tales of subtle memory effects in nonequilibrium systems and systematic tools designed to address complex scale-invariant behavior on multiple length scales and timescales

Visualizing probabilistic models in Minkowski space with intensive symmetrized Kullback-Leibler embedding

We show that the predicted probability distributions for any $N$-parameter statistical model taking the form of an exponential family can be explicitly and analytically embedded isometrically in a $N{+}N$-dimensional Minkowski space. That is, the model predictions can be visualized as control parameters are varied, preserving the natural distance between probability distributions. All pairwise distances between model instances are given by the symmetrized Kullback-Leibler divergence. We give formulas for these intensive symmetrized Kullback Leibler (isKL) coordinate embeddings, and illustrate the resulting visualizations with the Bernoulli (coin toss) problem, the ideal gas, $n$ sided die, the nonlinear least squares fit, and the Gaussian fit. We highlight how isKL can be used to determine the minimum number of parameters needed to describe probabilistic data, and conclude by visualizing the prediction space of the two-dimensional Ising model, where we examine the manifold behavior near its critical point.Comment: 18 pages, 9 figure

The stream–lake ecotone: potential habitat for juvenile endangered June suckers (\u3ci\u3eChasmistes liorus\u3c/i\u3e)

Potamodromous fish are poorly studied even though they are threatened often by human activities. The June sucker (Chasmistes liorus) is an endangered potamodromous species endemic to Utah Lake. Larval June suckers have not been collected from Utah Lake for at least 3 decades. Recruitment appears to be limited by low temperatures and scarce food, resulting in mass starvation of larval June suckers in the stream environment. We compared water temperature, zooplankton food availability, and small fish abundance in the stream and in 3 habitats along the stream–lake ecotone (dense emergent vegetation, sparse emergent vegetation, and open lake) to test the hypothesis that all 3 factors would reach a maximum in the dense emergent vegetation of the stream–lake ecotone. We used the abundance of fathead minnows in each habitat type as a surrogate for small fish like juvenile June suckers. We found that temperature, food, and fathead minnows reached their maximums in the open lake rather than in vegetated habitats of the stream–lake ecotone. The stream had the lowest average temperatures (15.1 °C) and the lowest zooplankton concentrations (61 ∙ L–1) over the growing season. Contrary to expectations, low temperatures (16.9 °C) and low food abundance (505 ∙ L–1) also characterized the densely vegetated habitat, whereas the open lake had the highest temperatures (20.4° C) and highest concentrations of zooplankton (2353 ∙ L–1). Restoration should include a mechanism to transport larval fish through the densely vegetated portion of the stream–lake ecotone, which can be hundreds of meters wide, to the warm productive waters of the open lake. The braided planform of the terminal reaches of Hobble Creek should be replaced with shallow riffles to increase mean stream velocity and decrease the transport time of larval June suckers.Los peces potamodromos se han estudiado poco a pesar de que a menudo los amenazan las actividades humanas. El matalote junio (Chasmistes liorus) es una especie potamodroma en peligro de extinción que es endémica del Lago Utah. Hace al menos tres décadas que no se colectan matalotes larvales del Lago Utah. El reclutamiento parece estar limitado tanto por las temperaturas bajas como por la escasez de alimento, la cual causa una inanición masiva de matalotes junio larvales en el hábitat fluvial. Comparamos la temperatura del agua, disponibilidad de zooplancton y abundancia de peces pequeños en el arroyo y en tres hábitats a lo largo del ecotono arroyo–lago (vegetación semisumergida tupida, vegetación semisumergida escasa y el lago abierto) para comprobar la hipótesis de que los tres factores alcanzarían su máximo en la vegetación semisumergida tupida del ecotono arroyo–lago. Utilizamos la abundancia de la carpita cabezona en cada clase de hábitat como indicador indirecto de peces pequeños como los matalotes junio juveniles. Descubrimos que la temperatura, el alimento y las carpitas cabezonas alcanzaron sus niveles máximos en el lago abierto y no en los hábitats con vegetación del ecotono arroyo–lago. El arroyo tuvo las temperaturas promedio más bajas durante la temporada de crecimiento (15.1 °C) y concentraciones bajas de zooplancton (61 ∙ L–1). Al contrario de lo esperado, el hábitat de vegetación tupida tuvo temperaturas bajas (16.9 °C) y concentraciones bajas de alimento (505 ∙ L–1), mientras que el lago abierto tuvo la temperatura más alta (20.4 °C) y la mayor concentración de zooplancton (2353 ∙ L–1). La restauración de esta especie debe incluir algún mecanismo para transportar los peces larvales a través de la parte de vegetación tupida del ecotono arroyo–lago, la cual puede tener cientos de metros de ancho, a las aguas cálidas y más productivas del lago abierto. Se debe reemplazar la forma trenzada de los tramos terminales de Hobble Creek con encalladeros para aumentar la velocidad promedio del arroyo y agilizar la travesía de los matalotes junio larvales

Recent evolution of a maternally-acting sex-determining supergene in a fly with single-sex broods

Sex determination is a key developmental process, yet it is remarkably variable across the tree of life. The dipteran family Sciaridae exhibits one of the most unusual sex determination systems in which mothers control offspring sex through selective elimination of paternal X chromosomes. Whereas in some members of the family females produce mixed-sex broods, others such as the dark-winged fungus gnat Bradysia coprophila are monogenic, with females producing single-sex broods. Female-producing females were previously found to be heterozygous for a large X-linked paracentric inversion (X'), which is maternally inherited and absent from male-producing females. Here, we assembled and characterized the X' sequence. As close sequence homology between the X and X' made identification of the inversion challenging, we developed a k-mer-based approach to bin genomic reads before assembly. We confirmed that the inversion spans most of the X' chromosome (∼55 Mb) and encodes ∼3,500 genes. Analysis of the divergence between the inversion and the homologous region of the X revealed that it originated very recently (&lt;0.5 Ma). Surprisingly, we found that the X' is more complex than previously thought and is likely to have undergone multiple rearrangements that have produced regions of varying ages, resembling a supergene composed of evolutionary strata. We found functional degradation of ∼7.3% of genes within the region of recombination suppression, but no evidence of accumulation of repetitive elements. Our findings provide an indication that sex-linked inversions are driving turnover of the strange sex determination system in this family of flies.</p