Propagating phonons coupled to an artificial atom

Quantum information can be stored in micromechanical resonators, encoded as quanta of vibration known as phonons. The vibrational motion is then restricted to the stationary eigenmodes of the resonator, which thus serves as local storage for phonons. In contrast, we couple propagating phonons to an artificial atom in the quantum regime, and reproduce findings from quantum optics with sound taking over the role of light. Our results highlight the similarities between phonons and photons, but also point to new opportunities arising from the unique features of quantum mechanical sound. The low propagation speed of phonons should enable new dynamic schemes for processing quantum information, and the short wavelength allows regimes of atomic physics to be explored which cannot be reached in photonic systems.Comment: 30 pages, 6 figures, 1 tabl

Dynkin games with heterogeneous beliefs

Copyright © 2017 Applied Probability Trust. We study zero-sum optimal stopping games (Dynkin games) between two players who disagree about the underlying model. In a Markovian setting, a verification result is established showing that if a pair of functions can be found that satisfies some natural conditions then a Nash equilibrium of stopping times is obtained, with the given functions as the corresponding value functions. In general, however, there is no uniqueness of Nash equilibria, and different equilibria give rise to different value functions. As an example, we provide a thorough study of the game version of the American call option under heterogeneous beliefs. Finally, we also study equilibria in randomized stopping times

Effects of three-nucleon forces and two-body currents on Gamow-Teller strengths

We optimize chiral interactions at next-to-next-to leading order to observables in two- and three-nucleon systems, and compute Gamow-Teller transitions in carbon-14, oxygen-22 and oxygen-24 using consistent two-body currents. We compute spectra of the daughter nuclei nitrogen-14, fluorine-22 and fluorine-24 via an isospin-breaking coupled-cluster technique, with several predictions. The two-body currents reduce the Ikeda sum rule, corresponding to a quenching factor q^2 ~ 0.84-0.92 of the axial-vector coupling. The half life of carbon-14 depends on the energy of the first excited 1+ state, the three-nucleon force, and the two-body current

Global observation of vertical-CLVD earthquakes at active volcanoes

Some of the largest and most anomalous volcanic earthquakes have non-double-couple focal mechanisms. Here, we investigate the link between volcanic unrest and the occurrence of non-double-couple earthquakes with dominant vertical tension or pressure axes, known as vertical compensated-linear-vector-dipole (vertical-CLVD) earthquakes. We determine focal mechanisms for 313 target earthquakes from the standard and surface wave catalogs of the Global Centroid Moment Tensor Project and identify 86 shallow 4.3 ≤ MW ≤ 5.8 vertical-CLVD earthquakes located near volcanoes that have erupted in the last ~100 years. The majority of vertical-CLVD earthquakes occur in subduction zones in association with basaltic-to-andesitic stratovolcanoes or submarine volcanoes, although vertical-CLVD earthquakes are also located in continental rifts and in regions of hot spot volcanism. Vertical-CLVD earthquakes are associated with many types of confirmed or suspected eruptive activity at nearby volcanoes, including volcanic earthquake swarms as well as effusive and explosive eruptions and caldera collapse. Approximately 70% of all vertical-CLVD earthquakes studied occur during episodes of documented volcanic unrest at a nearby volcano. Given that volcanic unrest is underreported, most shallow vertical-CLVD earthquakes near active volcanoes are likely related to magma migration or eruption processes. Vertical-CLVD earthquakes with dominant vertical pressure axes generally occur after volcanic eruptions, whereas vertical-CLVD earthquakes with dominant vertical tension axes generally occur before the start of volcanic unrest. The occurrence of these events may be useful for identifying volcanoes that have recently erupted and those that are likely to erupt in the future

Severe breastfeeding difficulties: Existential lostness as a mother—Women's lived experiences of initiating breastfeeding under severe difficulties

A majority of women in Sweden initiate breastfeeding but almost a quarter stop or wean the infant in the first few weeks after birth because of difficulties. In order to develop care that facilitates initiation of breastfeeding and enables mothers to realize their expectations concerning breastfeeding, it is necessary to understand what having severe breastfeeding difficulties means for women who experience them. The aim of this study is to describe the lived experiences of initiating breastfeeding under severe difficulties. A reflective lifeworld research design was used. Eight women, seven primiparous and one multipara, were interviewed within 2 months of giving birth. The essential meaning of the phenomenon is described as “Existential lostness as a mother forcing oneself into a constant fight”. This pattern is further explicated through its constituents; shattered expectations, a lost time for closeness, being of no use to the infant, being forced to expose oneself, and gaining strength through sharing. The results show that mothers with severe breastfeeding difficulties feel alone and exposed because of their suffering and are lost in motherhood. Thus, adequate care for mothers should enhance the forming of a caring relationship through sharing rather than exposing

Boron depletion in 9 to 15 M(circle dot) stars with rotation

The treatment of mixing is still one of the major uncertainties in stellar evolution models. One open question is how well the prescriptions for rotational mixing describe the real effects. We tested the mixing prescriptions included in the Geneva stellar evolution code (GENEC) by following the evolution of surface abundances of light isotopes in massive stars, such as boron and nitrogen. We followed 9, 12 and 15 M(O) models with rotation from the zero age main sequence up to the end of He burning. The calculations show the expected behaviour with faster depletion of boton for faster rotating stars and more massive stars. The mixing at the surface is more efficient, than predicted by prescriptions used in other codes and reproduces the majority of observations very well However two observed stars with strong boron depletion but, no nitrogen enhancement still can not be explained and let the question open whether additional mixing processes are acting in these massive star

On the behavior of micro-spheres in a hydrogen pellet target

A pellet target produces micro-spheres of different materials, which are used as an internal target for nuclear and particle physics studies. We will describe the pellet hydrogen behavior by means of fluid dynamics and thermodynamics. In particular one aim is to theoretically understand the cooling effect in order to find an effective method to optimize the working conditions of a pellet target. During the droplet formation the evaporative cooling is best described by a multi-droplet diffusion-controlled model, while in vacuum, the evaporation follows the (revised) Hertz-Knudsen formula. Experimental observations compared with calculations clearly indicated the presence of supercooling, the effect of which is discussed as well.Comment: 22 pages, 8 figures (of which two are significantly compressed for easier download