Prospects for photon blockade in four level systems in the N configuration with more than one atom

We show that for appropriate choices of parameters it is possible to achieve photon blockade in idealised one, two and three atom systems. We also include realistic parameter ranges for rubidium as the atomic species. Our results circumvent the doubts cast by recent discussion in the literature (Grangier et al Phys. Rev Lett. 81, 2833 (1998), Imamoglu et al Phys. Rev. Lett. 81, 2836 (1998)) on the possibility of photon blockade in multi-atom systems.Comment: 8 page, revtex, 7 figures, gif. Submitted to Journal of Optics B: Quantum and Semiclassical Optic

Linear optical properties of one-dimensional Frenkel exciton systems with intersite energy correlations

We analyze the effects of intersite energy correlations on the linear optical properties of one-dimensional disordered Frenkel exciton systems. The absorption line width and the factor of radiative rate enhancement are studied as a function of the correlation length of the disorder. The absorption line width monotonously approaches the seeding degree of disorder on increasing the correlation length. On the contrary, the factor of radiative rate enhancement shows a non-monotonous trend, indicating a complicated scenario of the exciton localization in correlated systems. The concept of coherently bound molecules is exploited to explain the numerical results, showing good agreement with theory. Some recent experiments are discussed in the light of the present theory.Comment: 18 pages, 3 figues, REVTeX, to appear in Physical Review

Solar-Driven Reduction of Aqueous Protons Coupled to Selective Alcohol Oxidation with a Carbon Nitride-Molecular Ni Catalyst System.

Solar water-splitting represents an important strategy toward production of the storable and renewable fuel hydrogen. The water oxidation half-reaction typically proceeds with poor efficiency and produces the unprofitable and often damaging product, O2. Herein, we demonstrate an alternative approach and couple solar H2 generation with value-added organic substrate oxidation. Solar irradiation of a cyanamide surface-functionalized melon-type carbon nitride ((NCN)CNx) and a molecular nickel(II) bis(diphosphine) H2-evolution catalyst (NiP) enabled the production of H2 with concomitant selective oxidation of benzylic alcohols to aldehydes in high yield under purely aqueous conditions, at room temperature and ambient pressure. This one-pot system maintained its activity over 24 h, generating products in 1:1 stoichiometry, separated in the gas and solution phases. The (NCN)CNx-NiP system showed an activity of 763 μmol (g CNx)(-1) h(-1) toward H2 and aldehyde production, a Ni-based turnover frequency of 76 h(-1), and an external quantum efficiency of 15% (λ = 360 ± 10 nm). This precious metal-free and nontoxic photocatalytic system displays better performance than an analogous system containing platinum instead of NiP. Transient absorption spectroscopy revealed that the photoactivity of (NCN)CNx is due to efficient substrate oxidation of the material, which outweighs possible charge recombination compared to the nonfunctionalized melon-type carbon nitride. Photoexcited (NCN)CNx in the presence of an organic substrate can accumulate ultralong-lived "trapped electrons", which allow for fuel generation in the dark. The artificial photosynthetic system thereby catalyzes a closed redox cycle showing 100% atom economy and generates two value-added products, a solar chemical, and solar fuel.This work was supported by the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research, and Economy and the National Foundation for Research, Technology and Development) and the OMV Group (to E.R.), an Oppenheimer PhD scholarship (to B.C.M.M.), a Marie Curie Postdoctoral Fellowship (GAN 624997 to C.A.C.), a FRQNT Postdoctoral Fellowship (to R.G.), and an ERC Starting Grant (B. V. L., Grant No. 639233).This is the final version of the article. It first appeared from American Chemical Society via http://dx.doi.org/10.1021/jacs.6b0432

The role of timing and prototypical causality on how preschoolers fast-map novel verb meanings

In controlled contexts, young children find it more difficult to learn novel words for actions than words for objects: Imai et al. (2008) found that English-speaking three-year-olds mistakenly choose a novel object as a referent for a novel verb about 42% of the time despite hearing the verb in a transitive sentence. The current two studies investigated whether English three- and five-year-old children would find resultative actions easier (since they are prototypically causative) than the non-resultative, durative event types used in Imai et al.’s studies. The reverse was true. Furthermore, if the novel verbs were taught on completion of the action, this did not improve performance, which contrasts with previous findings (e.g. Tomasello & Kruger, 1992). Our resultative actions were punctual, change-of-location events which may be less visually salient than the non-resulative, durative actions. Visual salience may play a greater role than does degree of action causality in the relative ease of verb learning even at three years

Resonant nonlinear magneto-optical effects in atoms

In this article, we review the history, current status, physical mechanisms, experimental methods, and applications of nonlinear magneto-optical effects in atomic vapors. We begin by describing the pioneering work of Macaluso and Corbino over a century ago on linear magneto-optical effects (in which the properties of the medium do not depend on the light power) in the vicinity of atomic resonances, and contrast these effects with various nonlinear magneto-optical phenomena that have been studied both theoretically and experimentally since the late 1960s. In recent years, the field of nonlinear magneto-optics has experienced a revival of interest that has led to a number of developments, including the observation of ultra-narrow (1-Hz) magneto-optical resonances, applications in sensitive magnetometry, nonlinear magneto-optical tomography, and the possibility of a search for parity- and time-reversal-invariance violation in atoms.Comment: 51 pages, 23 figures, to appear in Rev. Mod. Phys. in Oct. 2002, Figure added, typos corrected, text edited for clarit

Challenging notions of gendered game play: teenagers playing `The Sims`

This paper challenges notions of gendered game playing practice implicit in much research into young women\u27s involvement with the computer gaming culture. It draws on a study of Australian teenagers playing The Sims Deluxe as part of an English curriculum unit and insights from feminist media studies to explore relationships between gender and game playing practices. Departing from a reliance on predetermined notions of &ldquo;gender&rdquo;, &ldquo;domestic space&rdquo;, and &ldquo;successful game play&rdquo;, it conceptualizes The Sims as a game in which the boundaries between gender and domestic space are disturbed. It argues that observing students\u27 constructions of gender and domestic space through the act of game play itself provides a more productive insight into the gendered dimensions of game play for educators wishing to work computer games such as The Sims into curriculum development.<br /

Fabrication Of Smooth Diamond Films On Sio2 By The Addition Of Nitrogen To The Gas Feed In Hot-filament Chemical Vapor Deposition

The morphology of small roughness diamond films deposited onto thermally oxidized silicon substrates by a process of anisotropic crystalline growth induced by nitrogen in a hot-filament chemical vapor deposition (CVD) reactor was investigated. Square plates of low roughness were obtained on the top surface of the diamond films. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy indicated films made up of good quality. The films possessed a large number of defects due to substitutional nitrogen. Planar defects were created due to large amount of nitrogen introduced in the CVD process. Substitutional nitrogen provoked lateral vacancies that have a catalytic effect on the lateral rate of diamond growth.19410521056Angus, J.C., Hayman, C.C., (1988) Science, 241, p. 913Yarborough, W.A., Messier, R., (1990) Science, 241, p. 688Derjaguin, B.V., Fedoseev, D., (1977) Izd., , Nauka, Moscow, Chap. 4Tankala, K., DebRoy, T., (1992) J. Appl. Phys., 72, p. 712Okano, K., Koizumi, S., Silva, S.R.P., Amaratunga, G.A.J., (1996) Nature (London), 381, p. 140Liao, X.Z., Zhang, R.J., Lee, C.S., Tong Lee, S., Lam, Y.W., (1997) Diamond Relat. Mater., 6, p. 521Dos Santos Filho, S.G., Hasenack, C.M., Lopes, M.C.V., Baranauskas, V., (1995) Semicond. Sci. Technol., 10, p. 990Jin, S., Moustakas, T.D., (1994) Appl. Phys. Lett., 65, p. 403Locher, R., Wild, C., Herres, N., Behr, D., Koidl, P., (1996) Appl. Phys. Lett., 65, p. 759Walker, J.E., (1979) Rep. Prog. Phys., 42, p. 42Evans, T., Rainey, P., (1975) Proc. R. Soc. London, Ser. A, 344, p. 111Baranauskas, V., Li, B.B., Peterlevitz, A., Tosin, M.C., Durrant, S.F., (1999) J. Appl. Phys., 85, p. 7455Baranauskas, V., Peled, A., Trava-Airoldi, V.J., Lima, C.A.S., Doi, I., Corat, E.J., (1994) Appl. Surf. Sci., 79-80, p. 129Barros, R.C.M., Corat, E.J., Ferreira, N.G., Souza, T.M., Trava-Airoldi, V.J., Leite, N.F., Iha, K., (1996) Diamond Relat. Mater., 5, p. 1323Lang, A.R., (1964) Proc. Phys. Soc., 84, p. 871Sumida, N., Lang, A.R., (1988) Proc. R. Soc. London, Ser. A, 419, p. 235Bridon, P.R., Jones, R., (1993) Physica B, 185, p. 17