Rydberg excitation of a single trapped ion

We demonstrate excitation of a single trapped cold $^{40}$Ca$^+$ ion to Rydberg levels by laser radiation in the vacuum-ultraviolet at 122 nm wavelength. Observed resonances are identified as 3d$^2$D$_{3/2}$ to 51 F, 52 F and 3d$^2$D$_{5/2}$ to 64F. We model the lineshape and our results imply a large state-dependent coupling to the trapping potential. Rydberg ions are of great interest for future applications in quantum computing and simulation, in which large dipolar interactions are combined with the superb experimental control offered by Paul traps.Comment: 4 pages, 3 figure

Continuous Lyman-alpha generation by four-wave mixing in mercury for laser-cooling of antihydrogen

Cooling antihydrogen atoms is important for future experiments both to test the fundamental CPT symmetry by high-resolution laser spectroscopy and also to measure the gravitational acceleration of antimatter. Laser-cooling of antihydrogen can be done on the strong 1S-2P transition at the wavelength of Lyman-alpha (121.6nm). A continuous-wave laser at the Lyman-alpha wavelength based on solid-state fundamental lasers is described. By using a two-photon and a near one photon resonance a scan across the whole phasematching curve of the four-wave mixing process is possible. Furthermore the influence of the beam profile of one fundamental beam on the four-wave mixing process is studied.Comment: 4 pages, 4 figure

High power, continuous-wave, single frequency fiber amplifier at 1091 nm and frequency doubling to 545.5 nm

We present a high power single-frequency ytterbium fiber amplifier system with an output power of 30 W at 1091 nm. The amplifier system consists of two stages, a preamplifier stage in which amplified spontaneous emission is efficiently suppressed (>40 dB) and a high power amplifier with an efficiency of 52 %. Two different approaches of frequency doubling are compared. We achieve 8.6 W at 545.5 nm by single-pass frequency doubling in a MgO-doped periodically poled stoichiometric LiTaO3 and up to 19.3 W at 545.5 nm by frequency doubling with a lithium-triborate (LBO) crystal in an external enhancement cavity

A semiconductor laser system for the production of antihydrogen

Laser-controlled charge exchange is a promising method for producing cold antihydrogen. Caesium atoms in Rydberg states collide with positrons and create positronium. These positronium atoms then interact with antiprotons, forming antihydrogen. Laser excitation of the caesium atoms is essential to increase the cross section of the charge-exchange collisions. This method was demonstrated in 2004 by the ATRAP collaboration by using an available copper vapour laser. For a second generation of charge-exchange experiments we have designed a new semiconductor laser system that features several improvements compared to the copper vapour laser. We describe this new laser system and show the results from the excitation of caesium atoms to Rydberg states within the strong magnetic fields in the ATRAP apparatus

A semiconductor laser system for the production of antihydrogen

Laser-controlled charge exchange is a promising method for producing cold antihydrogen. Caesium atoms in Rydberg states collide with positrons and create positronium. These positronium atoms then interact with antiprotons, forming antihydrogen. Las er excitation of the caesium atoms is essential to increase the cross section of the charge-exchange collisions. This method was demonstrated in 2004 by the ATRAP collaboration by using an available copper vapour laser. For a second generation of charge-e xchange experiments we have designed a new semiconductor laser system that features several improvements compared to the copper vapour laser. We describe this new laser system and show the results from the excitation of caesium atoms to Rydberg states wit hin the strong magnetic fields in the ATRAP apparatus

A reliable cw Lyman-α\alpha laser source for future cooling of antihydrogen

We demonstrate a reliable continuous-wave (cw) laser source at the 1\,$S$--2\,$P$ transition in (anti)hydrogen at 121.56\,nm (Lyman-$\alpha$) based on four-wave sum-frequency mixing in mercury. A two-photon resonance in the four-wave mixing scheme is essential for a powerful cw Lyman-$\alpha$ source and is well investigated.Comment: 8 pages, 3 figures, Proceedings of LEAP 201

North Seas Offshore Network (NSON): Machbarkeit und Implikationen verschiedener Offshore-Netzkonzepte in der Nordseeregion. Schlussbericht des Verbundprojekts

In diesem Bericht werden Ergebnisse aus dem Verbundvorhaben North Seas O˙shore Network (NSON) – Machbarkeit und Implikationen verschiedener O˙shore-Netzkonzepte in der Nordseeregion vorgestellt. Dieser wurde gemeinsam durch die drei Verbundpartner, das Fraunhofer-Institut für Energiewirtschaft und Energiesystemtechnik IEE (FKZ 0325734A), die Universität Kassel (FKZ 0325734B) und die Leib-niz Universität Hannover (FKZ 0325734C), erstellt. Für die Förderung des Verbundprojekts wird dem Bundesministerium für Wirtschaft und Energie BMWi ausdrücklich gedankt. Der Schlussbericht umfasst die Beschreibung der neu- und weiterentwickelten Modelle und Optimierungsverfahren sowie die Simulationsergebnisse zukünftiger O˙shore-Netzkonzepte im Nordseeraum. Hierbei liegt der Fokus auf der markt- und technologiebasierten O˙shore-Netzplanung sowie der anschließenden Validierung und Rückwirkungsanalyse der Netzplanungsergebnisse durch Leistungsflussberechnungen. Um die Entwicklung des zukünftige deutschlandweiten und europäischen Energieversorgungs-systems adäquat zu berücksichtigen, wird als Basis der eigentlichen Untersuchungsschritte zunächst die Ermittlung projektspezifischer Energieszenarien mit langfristig ambitionierten Dekarbonisierungszielen und einem hohen Grad an Sektorintegration vorangestellt. Die für jeden Modell- und Untersuchungs-schritt dargestellten Simulationsergebnisse umfassen Bewertungen der O˙shore-Netzinvestitionen, der Koste-Nutzen-Allokation, Engpasssituationen und Erweiterungen im Versorgungsnetz am Festland