Quantized flag manifolds and irreducible *-representations

We study irreducible *-representations of a certain quantization of the algebra of polynomial functions on a generalized flag manifold regarded as a real manifold. All irreducible *-representations are classified for a subclass of flag manifolds containing in particular the irreducible compact Hermitian symmetric spaces. For this subclass it is shown that the irreducible *-representations are parametrized by the symplectic leaves of the underlying Poisson bracket. We also discuss the relation between the quantized flag manifolds studied in this paper and the quantum flag manifolds studied by Soibelman, Lakshimibai and Reshetikhin, Jurco and Stovicek, and Korogodsky.Comment: AMS-LaTeX v1.2, 27 pages, no figure

Tailoring optical response of a hybrid comprising a quantum dimer emitter strongly coupled to a metal nanoparticle

We study theoretically the optical response of a nanohybrid comprising a symmetric quantum dimer emitter coupled to a metal nanoparticle (MNP). The interactions between the exitonic transitions in the dimer and the plasmons in the MNP lead to novel effects in the composite's input-output characteristics for the light intensity and the absorption spectrum, which we study in the linear and nonlinear regimes. We fnd that the exciton-plasmon hybridization leads to optical bistability and hysteresis for the one-exciton transition and enhancement of excitation for the two-exciton transition. The latter leads to a signifcant decrease of the field strength needed to saturate the system. In the linear regime, the absortion spectrum has a dispersive (Fano-like) line shape. The spectral position and shape of this spectrum depend on the detuning of the dimer's one-exciton resonance relative to the plasmon resonance. Upon increasing the applied field intensity to the nonlinear regime, the Fano-like singularities in the absorption spectra are smeared and they disappear due to the saturation of the dimer, which leads to the MNP dominating the spectrum. The above effects, for which we provide physical explanations, allow one to tailor the Fano-like shape of the absorption spectrum, by changing either the detuning or the input power

Sonic refugia: Nature, noise abatement and landscape design in West Berlin

This paper extends the history of landscape design and urban green planning by discussing the work of landscape designers in West Berlin, who attempted to create ‘sonic refugia’ using trees, bushes and other plants for noise abatement purposes. It expands the narrow conceptions of landscape as a solely visual experience also to include the acoustic realm. Motivated by increasing concerns over the physiological and psychological effects of noise pollution, and drawing on late nineteenth and early twentieth century ideas of nature as a remedy for the negative effects of modern urban life, this paper places the work of landscape designers in the context of ongoing discourses on the intersections of urban nature and public health. Sonic experiments with plants of the 1960s not only draw our attention to the acoustic qualities of urban nature, but also open reflections on the wider historical, political and cultural contexts in which urban landscapes were experienced. Hereby, West Berlin’s marginal spaces or terrains vagues, which emerged as accidental by-products of the island city’s spatial confinement, were exemplary sites in their attempts to foreground the sensory experience of space.ERC Advanced Grant Rethinking Urban Natur

Atmospheric environment for space shuttle (STS-1) launch

Atmospheric conditions near space shuttle STS-1 launch time on April, 12, 1981, at Kennedy Space Center, Florida, are reported. Values of ambient pressure, temperature, moisture, ground winds, visual observations (cloud), and winds aloft are included. The sequence of prelaunch Jimsphere measured vertical wind profiles is presented. Also presented are the wind and thermodynamic parameters measured at the surface and aloft in the SRB descent/impact ocean area. Final meteorological data tapes for STS-1 vehicle ascent, and SRB descent have been constructed which consist of wind and thermodynamic parameters versus altitude

Plasmon-assisted two-photon Rabi oscillations in a semiconductor quantum dot -- metal nanoparticle heterodimer

Tho-photon Rabi oscillations hold potential for quantum computing and quantum information processing, because during a Rabi cycle a pair of entangled photons may be created. We theoretically investigate the onset of this phenomenon in a heterodimer comprising a semiconductor quantum dot strongly coupled to a metal nanoparticle. Two-photon Rabi oscillations in this system occur due to a coherent two-photon process involving the ground-to-biexciton transition in the quantum dot. The presence of a metal nanoparticle nearby the quantum dot results in a self-action of the quantum dot via the metal nanoparticle, because the polatization state of the latter depends on the quantum state of the former. The interparticle interaction gives rise to two principal effects: (i) - enhancement of the external field amplitude and (ii) - renormalization of the quantum dot's resonance frequencies and relaxation rates of the off-diagonal density matrix elements, both depending on the populations of the quantum dot's levels. Here, we focus on the first effect, which results in interesting new features, in particular, in an increased number of Rabi cycles per pulse as compared to an isolated quantum dot and subsequent growth of the number of entangled photon pairs per pulse. We also discuss the destructive role of radiative decay of the excitonic states on two-photon Rabi oscillations for both an isolated quantum dot and a heterodimer.Comment: 11 pages, 19 figure

Global and regional importance of the direct dust-climate feedback.

Feedbacks between the global dust cycle and the climate system might have amplified past climate changes. Yet, it remains unclear what role the dust-climate feedback will play in future anthropogenic climate change. Here, we estimate the direct dust-climate feedback, arising from changes in the dust direct radiative effect (DRE), using a simple theoretical framework that combines constraints on the dust DRE with a series of climate model results. We find that the direct dust-climate feedback is likely in the range of -0.04 to +0.02 Wm -2 K-1, such that it could account for a substantial fraction of the total aerosol feedbacks in the climate system. On a regional scale, the direct dust-climate feedback is enhanced by approximately an order of magnitude close to major source regions. This suggests that it could play an important role in shaping the future climates of Northern Africa, the Sahel, the Mediterranean region, the Middle East, and Central Asia