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Joblin C, Pilleri P, Montillaud J, Fuente A, Gerin M, Berné O, et al. Gas morphology and energetics at the surface of PDRs: New insights with Herschel observations of NGC 7023. Astron. Astrophys.. 2010;521:L25.
Abstract: Context. We investigate the physics and chemistry of the gas and dust in dense photon-dominated regions (PDRs), along with their dependence on the illuminating UV field.
Aims. Using Herschel/HIFI observations, we study the gas energetics in NGC 7023 in relation to the morphology of this nebula. NGC 7023 is the prototype of a PDR illuminated by a B2V star and is one of the key targets of Herschel.
Methods. Our approach consists in determining the energetics of the region by combining the information carried by the mid-IR spectrum (extinction by classical grains, emission from very small dust particles) with that of the main gas coolant lines. In this letter, we discuss more specifically the intensity and line profile of the 158 μm (1901 GHz) [C ii] line measured by HIFI and provide information on the emitting gas.
Results. We show that both the [C ii] emission and the mid-IR emission from polycyclic aromatic hydrocarbons (PAHs) arise from the regions located in the transition zone between atomic and molecular gas. Using the Meudon PDR code and a simple transfer model, we find good agreement between the calculated and observed [C ii] intensities.
Conclusions. HIFI observations of NGC 7023 provide the opportunity to constrain the energetics at the surface of PDRs. Future work will include analysis of the main coolant line [O i] and use of a new PDR model that includes PAH-related species.
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Jang YR, Yoo K-H, Park SM. Rapid thermal annealing of ZnO thin films grown at room temperature. J. Vac. Sci. Technol. A. 2010;28(2):4.
Abstract: The authors successfully obtained high quality ZnO thin films by growing them at room temperature (RT) and postannealing by rapid thermal annealing (RTA). The thin films were grown by pulsed laser deposition on Si (100) substrates at RT, and RTA was performed under various temperatures and ambient conditions. Based on the UV emission to visible emission ratio in RT photoluminescence (PL) spectra, the optimum film was obtained at annealing temperature ~700 °C in an ambient of Ar, N2, or O2 at 0.1 Torr, while the optimum annealing temperature was above 1100 °C in the air ambient at atmospheric pressure. The morphology and structure of the films in different RTA conditions were investigated by using field emission scanning electron microscopy and grazing incidence x-ray diffraction, and were discussed in conjunction with the PL data.
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Home J. Quantum entanglement: Watching correlations disappear. Nat Phys. 2010;6(12):938–9.
Abstract: Engineered decoherence enables tracking of multipartite entanglement as a quantum state decays.
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Hoeffgen SK, Kuhnhenn J, Weinand U. High radiation sensitivity of chiral long period gratings. IEEE Trans. Nucl. Sci.. 2010;57(5):2915–22.
Abstract: The radiation sensitivity of chiral long period gratings was investigated for the first time. After a Co-60 gamma dose of 100 kGy they show radiation-induced changes of their transmission dip wavelength of up to 10 nm, which is 100 to 1000 times higher than the radiation-induced wavelength shift of different fiber Bragg grating types. They can therefore be used as radiation sensors down to doses of 10 Gy or even below, but not for accurate dose measurements since the size of the wavelength shift after a certain dose still depends on the radiation dose rate. Chiral gratings made of eight single mode fiber types with differences of their radiation-induced attenuation of several orders of magnitude were investigated in order to look for a correlation between dip wavelength shift and fiber attenuation. However, the dip wavelength curves do not show exactly the same order as the fiber attenuation curves. A theory that can exactly predict all properties of the chiral gratings might enable us to specify from our results an optimized fiber for the production of gratings that can also be used for radiation dosimetry.
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Heeres RW, Dorenbos SN, Koene B, Solomon GS, Kouwenhoven LP, Zwiller V. On-Chip Single Plasmon Detection. Nano Lett. 2010;10:661–4.
Abstract: Surface plasmon polaritons (plasmons) have the potential to interface electronic and optical devices. They could prove extremely useful for integrated quantum information processing. Here we demonstrate on-chip electrical detection of single plasmons propagating along gold waveguides. The plasmons are excited using the single-photon emission of an optically emitting quantum dot. After propagating for several micrometers, the plasmons are coupled to a superconducting detector in the near-field. Correlation measurements prove that single plasmons are being detected.
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Haviland D. Superconducting circuits: Quantum phase slips. Nat Phys. 2010;6:565–566.
Abstract: Coulomb interactions can cause a rapid change in the phase of the wavefunction along a very narrow superconducting system. Such a phase slip at the quantum level is now measured in a chain of Josephson junctions.
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Hartogh P, Jarchow C, Lellouch E, de Val-Borro M, Rengel M, Moreno R, et al. Herschel/HIFI observations of Mars: First detection of O2 at submillimetre wavelengths and upper limits on HCl and H2O2. Astron. Astrophys.. 2010;521:L49.
Abstract: We report on an initial analysis of Herschel/HIFI observations of hydrogen chloride (HCl), hydrogen peroxide (H2O2), and molecular oxygen (O2) in the Martian atmosphere performed on 13 and 16 April 2010 (Ls ~ 77°). We derived a constant volume mixing ratio of 1400 ± 120 ppm for O2 and determined upper limits of 200 ppt for HCl and 2 ppb for H2O2. Radiative transfer model calculations indicate that the vertical profile of O2 may not be constant. Photochemical models determine the lowest values of H2O2 to be around Ls ~ 75° but overestimate the volume mixing ratio compared to our measurements.
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Hartogh P, Crovisier J, de Val-Borro M, Bockelée-Morvan D, Biver N, Lis DC, et al. HIFI observations of water in the atmosphere of comet C/2008 Q3 (Garradd). Astron. Astrophys.. 2010;518:L150 (1 to 5).
Abstract: High-resolution far-infrared and sub-millimetre spectroscopy of water lines is an important tool to understand the physical and chemical properties of cometary atmospheres. We present observations of several rotational ortho- and para-water transitions in comet C/2008 Q3 (Garradd) performed with HIFI on Herschel. These observations have provided the first detection of the 212–101 (1669 GHz) ortho and 111–000 (1113 GHz) para transitions of water in a cometary spectrum. In addition, the ground-state transition 110–101 at 557 GHz is detected and mapped. By detecting several water lines quasi-simultaneously and mapping their emission we can constrain the excitation parameters in the coma. Synthetic line profiles are computed using excitation models which include excitation by collisions, solar infrared radiation, and radiation trapping. We obtain the gas kinetic temperature, constrain the electron density profile, and estimate the coma expansion velocity by analyzing the map and line shapes. We derive water production rates of 1.7–2.8 × 1028 s-1 over the range rh = 1.83–1.85 AU.
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Hanneke D, Home JP, Jost JD, Amini JM, Leibfried D, Wineland DJ. Realization of a programmable two-qubit quantum processor. Nat Phys. 2010;6(1):13–6.
Abstract: The universal quantum computer is a device capable of simulating any physical system and represents a major goal for the field of quantum information science. In the context of quantum information, `universal' refers to the ability to carry out arbitrary unitary transformations in the system's computational space. Combining arbitrary single-quantum-bit (qubit) gates with an entangling two-qubit gate provides a set of gates capable of achieving universal control of any number of qubits, provided that these gates can be carried out repeatedly and between arbitrary pairs of qubits. Although gate sets have been demonstrated in several technologies, they have so far been tailored towards specific tasks, forming a small subset of all unitary operators. Here we demonstrate a quantum processor that can be programmed with 15 classical inputs to realize arbitrary unitary transformations on two qubits, which are stored in trapped atomic ions. Using quantum state and process tomography, we characterize the fidelity of our implementation for 160 randomly chosen operations. This universal control is equivalent to simulating any pairwise interaction between spin-1/2 systems. A programmable multiqubit register could form a core component of a large-scale quantum processor, and the methods used here are suitable for such a device.
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Griffin MJ, Abergel A, Abreu A, Ade PAR, André P, Augueres J-L, et al. The Herschel-SPIRE instrument and its in-flight performance. A&A. 2010;518:7.
Abstract: The Spectral and Photometric Imaging REceiver (SPIRE), is the Herschel Space Observatory`s submillimetre camera and spectrometer. It contains a three-band imaging photometer operating at 250, 350 and 500 μm, and an imaging Fourier-transform spectrometer (FTS) which covers simultaneously its whole operating range of 194-671 μm (447-1550 GHz). The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 0.3 K. The photometer has a field of view of 4Â´× 8´, observed simultaneously in the three spectral bands. Its main operating mode is scan-mapping, whereby the field of view is scanned across the sky to achieve full spatial sampling and to cover large areas if desired. The spectrometer has an approximately circular field of view with a diameter of 2.6´. The spectral resolution can be adjusted between 1.2 and 25 GHz by changing the stroke length of the FTS scan mirror. Its main operating mode involves a fixed telescope pointing with multiple scans of the FTS mirror to acquire spectral data. For extended source measurements, multiple position offsets are implemented by means of an internal beam steering mirror to achieve the desired spatial sampling and by rastering of the telescope pointing to map areas larger than the field of view. The SPIRE instrument consists of a cold focal plane unit located inside the Herschel cryostat and warm electronics units, located on the spacecraft Service Module, for instrument control and data handling. Science data are transmitted to Earth with no on-board data compression, and processed by automatic pipelines to produce calibrated science products. The in-flight performance of the instrument matches or exceeds predictions based on pre-launch testing and modelling: the photometer sensitivity is comparable to or slightly better than estimated pre-launch, and the spectrometer sensitivity is also better by a factor of 1.5-2.
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