| 1. |
- Barnes, W. L., et al.
(författare)
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Solid-state single photon sources : light collection strategies
- 2002
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Ingår i: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 18:2, s. 197-210
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Tidskriftsartikel (refereegranskat)abstract
- We examine the problem of efficiently collecting the photons produced by solid-state single photon sources. The extent of the problem is first established with the aid of simple physical concepts. Several approaches to improving the collection efficiency are then examined and are broadly categorized into two types. First are those based on cavity quantum dynamics, in which the pathways by which the source may emit a photon are restricted, thus channeling emission into one desired mode. Second are those where we try to reshape the free space modes into a target mode in an optimal way, by means of refraction, without fundamentally altering the way in which the source emits. Respectively, we examine a variety of microcavities and solid immersion lenses. Whilst we find that the micropillar microcavities offer the highest collection efficiency (similar to70%), choosing this approach may not always be appropriate due to other constraints. Details of the different approaches, their merits and drawbacks are discussed in detail.
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| 2. |
- Bergström, I, et al.
(författare)
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High-precision Mass Measurements of Hydrogen-Like 24Mg11+ and 26Mg11+ ions in a Pening Trap
- 2002
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Ingår i: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 22:1, s. 41-45
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Tidskriftsartikel (refereegranskat)abstract
- For the determination of the bound-electron g factor in hydrogen-like heavy ions the mass of the ion is needed at a relative uncertainty of at least 1 ppb. With the SMILETRAP Penning trap mass spectrometer at the Manne Siegbahn Laboratory in Stockholm several mass measurements of ions with even-even nuclei at this level of precision have been performed so far, exploiting the fact that the mass precision increases linearly with the ion charge. Measurements of masses of the hydrogen-like ions of the two Mg-isotopes 24Mg and 26Mg are reported. The masses of the hydrogen-like ions are 23.979011054(14) u and 25.976562354(34) u, corresponding to the atomic masses 23.985041690(14) u and 25.982592986(34) u, respectively. The possibility to use these two isotopes for the first observation of an isotope effect in the bound-electron g factor in hydrogen-like heavy ions is discussed.
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| 3. |
- Biemont, E, et al.
(författare)
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Lifetime measurements and calculations in LaI
- 2004
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Ingår i: European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060. ; 30:2, s. 157-162
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Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetime measurements have been performed, with a time-resolved laser-induced fluorescence technique, for 20 odd-parity levels of La I belonging to the configurations 5d(2)6p, 5d6s6p and 4f5d6s. The new results are compared with the few experimental data available in the literature and with theoretical calculations including configuration interaction effects. The agreement theory-experiment is generally satisfying but discrepancies are observed for some levels emphasizing the difficulty to get a reliable theoretical model in such a heavy and complex neutral element.
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| 4. |
- Biemont, E, et al.
(författare)
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Radiative lifetime measurements and oscillator strength determination for transitions in singly ionized praseodymium (Pr II)
- 2003
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Ingår i: European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 27:1, s. 33-41
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Tidskriftsartikel (refereegranskat)abstract
- New radiative lifetimes for 20 levels of Pr II have been measured using the time-resolved laser-induced fluorescence (LIF) technique. The combination of these experimental values with theoretical branching fractions (BF) obtained with the pseudo-relativistic Hartree-Fock (HFR) approach has allowed us to determine oscillator strengths and transition probabilities for about 150 lines appearing in the spectral region between 369.9 and 741.2 nm. A detailed discussion of our new results and comparisons with previous data are also given in the present paper.
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| 5. |
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| 6. |
- Bylander, Jonas, 1978, et al.
(författare)
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Interference and correlation of two independent photons
- 2003
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Ingår i: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6079 .- 1434-6060. ; 22, s. 295-301
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Tidskriftsartikel (refereegranskat)abstract
- Two independent photons, produced through the spontaneous emission of two separate emitters subject to uncorrelated dephasing processes, can display two-photon interference (i.e. coalescence into a two-photon state) when they are incident simultaneously on a beamsplitter, in a manner analogous to that of twin photons produced through degenerate parametric fluorescence. The presence of dephasing processes, however, reduces the interference contrast (i.e. the probability of coalescence), by the ratio of the coherence time to the lifetime of the emitter.
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| 7. |
- Ellmann, H., et al.
(författare)
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Investigation and characterization of a 3D double optical lattice
- 2003
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Ingår i: European Physical Journal D. - : EDP Sciences. - 1434-6060 .- 1434-6079. ; 22:3, s. 355-364
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Tidskriftsartikel (refereegranskat)abstract
- We present a detailed description of measurements performed with a novel double optical lattice setup. In this we trap two different cesium hyperfine ground states in separate periodic potentials. A detailed account of the technical solutions and its foundations are given. We demonstrate the possibility to modulate the relative spatial position of the lattices and perform a series of systematic measurements in order to investigate the static and dynamic properties of the double optical lattice system.
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| 8. |
- Ellmann, Harald, et al.
(författare)
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Temperatures in 3D optical lattices influenced by neighbouring transitions
- 2001
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Ingår i: European Physical Journal D. - 1434-6060 .- 1434-6079. ; 13:3, s. 379-384
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Tidskriftsartikel (refereegranskat)abstract
- A detailed experimental study of the steady-state temperature in a 3D optical lattice for cesium has been performed for a wide range of detunings. Specifically, we have investigated the situation with the cooling and trapping light detuned far red of a (J(g) --> J(e) = J(g) + 1)-transition, where the blue detuned interaction with a (J(g) --> J(e) = J(g))-transition can not be neglected. We find that the temperature scales with the optical potential due to the interaction with just the (J(g) --> J(e) = J(g) + 1)-transition. This indicates that blue Sisyphus cooling has essentially no effect on the dynamics of the system, when there exists a neighbouring red detuned transition.
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| 9. |
- Feifel, Raimund, et al.
(författare)
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From localised to delocalised electronic states in free Ar, Kr and Xe clusters
- 2004
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Ingår i: European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 30:3, s. 343-351
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Tidskriftsartikel (refereegranskat)abstract
- We present new results for the inner valence levels of clusters of the three inert gases Ar, Kr and Xe based on photoelectron spectroscopy studies. The inner valence levels are compared to the localised core levels and to the delocalised outer valence levels. This comparison shows a gradual change from a relatively localised behaviour for Ar inner valence 3s, over the intermediate case of Kr inner valence 4s, to a more delocalised behaviour for Xe inner valence 5s. This change correlates well with the ratio between the orbital sizes and the interatomic distances. The Kr4s intermediate case is found to exhibit characteristics of both localised and delocalised behaviour.
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| 10. |
- Gorbach, A.V., et al.
(författare)
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Gap and out-gap breathers in a binary modulated discrete nonlinear Schrödinger model
- 2004
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Ingår i: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 29:1, s. 77-93
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Tidskriftsartikel (refereegranskat)abstract
- We consider a modulated discrete nonlinear Schrödinger (DNLS) model with alternating on-site potential, having a linear spectrum with two branches separated by a 'forbidden' gap. Nonlinear localized time-periodic solutions with frequencies in the gap and near the gap - discrete gap and out-gap breathers (DGBs and DOGBs) - are investigated. Their linear stability is studied varying the system parameters from the continuous to the anti-continuous limit, and different types of oscillatory and real instabilities are revealed. It is shown, that generally DGBs in infinite modulated DNLS chains with hard (soft) non-linearity do not possess any oscillatory instabilities for breather frequencies in the lower (upper) half of the gap. Regimes of 'exchange of stability' between symmetric and antisymmetric DGBs are observed, where an increased breather mobility is expected. The transformation from DGBs to DOGBs when the breather frequency enters the linear spectrum is studied, and the general bifurcation picture for DOGBs with tails of different wave numbers is described. Close to the anti-continuous limit, the localized linear eigenmodes and their corresponding eigenfrequencies are calculated analytically for several gap/out-gap breather configurations, yielding explicit proof of their linear stability or instability close to this limit.
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