Generation of a wave packet tailored to efficient free space excitation of a single atom

We demonstrate the generation of an optical dipole wave suitable for the process of efficiently coupling single quanta of light and matter in free space. We employ a parabolic mirror for the conversion of a transverse beam mode to a focused dipole wave and show the required spatial and temporal shaping of the mode incident onto the mirror. The results include a proof of principle correction of the parabolic mirror's aberrations. For the application of exciting an atom with a single photon pulse we demonstrate the creation of a suitable temporal pulse envelope. We infer coupling strengths of 89% and success probabilities of up to 87% for the application of exciting a single atom for the current experimental parameters.Comment: to be published in Europ. Phys. J.

Stability of metallic stripes in the extended one-band Hubbard model

Based on an unrestricted Gutzwiller approximation (GA) we investigate the stripe orientation and periodicity in an extended one-band Hubbard model. A negative ratio between next-nearest and nearest neighbor hopping t'/t, as appropriate for cuprates, favors partially filled (metallic) stripes for both vertical and diagonal configurations. At around optimal doping diagonal stripes, site centered (SC) and bond centered (BC) vertical stripes become degenerate suggesting strong lateral and orientational fluctuations. We find that within the GA the resulting phase diagram is in agreement with experiment whereas it is not in the Hartree-Fock approximation due to a strong overestimation of the stripe filling. Results are in agreement with previous calculations within the three-band Hubbard model but with the role of SC and BC stripes interchanged.Comment: 10 pages, 8 figure

Hidden Order in the Cuprates

We propose that the enigmatic pseudogap phase of cuprate superconductors is characterized by a hidden broken symmetry of d(x^2-y^2)-type. The transition to this state is rounded by disorder, but in the limit that the disorder is made sufficiently small, the pseudogap crossover should reveal itself to be such a transition. The ordered state breaks time-reversal, translational, and rotational symmetries, but it is invariant under the combination of any two. We discuss these ideas in the context of ten specific experimental properties of the cuprates, and make several predictions, including the existence of an as-yet undetected metal-metal transition under the superconducting dome.Comment: 12 pages of RevTeX, 9 eps figure

Magnetic susceptibilities and the order parameters of some 4,4' -disubstituted biphenyl cyclohexanes

The diamagnetic susceptibilities of some 4,4'-disubstituted biphenyl cyclohexanes are reported as a function of temperature. The order parameters of the uniaxial nematic, smectic A and smectic B phases are calculated. The effect of the terminal substituents and the central groups on the magnetic anisotropy and the order parameter is discussed.Les susceptibilités diamagnétiques de quelques biphenyl cyclohexanes substitués 4,4' sont données en fonction de la température. Les paramètres d'ordre des phases uniaxial nématique, smectique A et smectique B sont calculés. Les influences des substituants terminaux et des groupements centraux sur l'anisotropie magnétique et sur le paramètre d'ordre sont discutées

Episomal vectors for gene therapy.

The increasing knowledge of the molecular and genetic background of many different human diseases has led to the vision that genetic engineering might be used one day for their phenotypic correction. The main goal of gene therapy is to treat loss-of-function genetic disorders by delivering correcting therapeutic DNA sequences into the nucleus of a cell, allowing its long-term expression at physiologically relevant levels. Manifold different vector systems for the therapeutic gene delivery have been described over the recent years. They all have their individual advantages but also their individual limitations and must be judged on a careful risk/benefit analysis. Integrating vector systems can deliver genetic material to a target cell with high efficiency enabling long-term expression of an encoded transgene. The main disadvantage of integrating vector systems, however, is their potential risk of causing insertional mutagenesis. Episomal vector systems have the potential to avoid these undesired side effects, since they behave as separate extrachromosomal elements in the nucleus of a target cell. Within this article we present a comprehensive survey of currently available episomal vector systems for the genetic modification of mammalian cells. We will discuss their advantages and disadvantages and their applications in the context of basic research, biotechnology and gene therapy

Leistungsgrenzen der Phasenkonjugation fuer Hochleistungs-Festkoerperlaser Abschlussbericht

In the frame of the present project oscillator and oscillator-amplifier systems with phase conjugating SBS (stimulated Brillouin scattering)-mirrors for better beam quality and higher output energy have been optimized. In designing Nd-solid state master oscillator double pass amplifier setups with almost diffraction limited beam quality, with 102 W average output power the world wide leading values could be reached. The developed systems with single laser rods instead of SLABs and the necessary additional devices for beam shaping and multipasses are much cheaper for the same performance than international competitors. The new systems with almost diffraction limited beam quality produced by the compensation of phase distortions via phase conjugating SBS-mirros allow for new applications as a consequence of their higher brightness compared to todays available commercial systems. (WEN)SIGLEAvailable from TIB Hannover: F94B1547+a+b / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Parametrization and validation of lithium ion battery cell models: Poster presented at 8. Internationale Fachtagung "Kraftwerk Batterie" 2016, Münster, 26. - 27. April 2016

Li‐Ion battery cells are basic components of the power train of Electric Vehicles. Their behaviour is controlled by battery management systems (BMS). As part of the IKEBA project [1], we create a prototype of a virtual simulation platform for BMS. This platform allows to verify the suitability and the interaction between selected hardware components (Li‐Ion batteries and semiconductor circuits for battery monitoring), and the software of a battery management system (BMS) by means of simulation. The electronic system level (ESL) behavioural languages SystemC and SystemC AMS were used for modelling. In this context, models of battery cells are essential. The cells were modelled by equivalent circuit models (ECM) that consist of a series connection of a voltage source, an internal resistance and two parallel connections of resistances (R) and capacitances (C). The components of the ECM cell model depend on temperature and state of charge (SOC). These dependencies can be described by one‐ and two‐dimensional lookup tables (LUT). Because of effort and uncertainties of material parameters, we resigned to determine ECM model parameter tables based on geometry and low level electrochemical behaviour simulations. Therefore, the data points that establish the tables were determined on the base of current interruption technique (CIT) measurements for a special battery cell type. For more details see [2]. The evaluation of cell voltages delivers the corresponding ECM parameter values. A special challenge is to derive the unique R und C values from observed time constants. For this purpose, only small changes from one CIT period to the next were accepted. We could approve the CIT measurement results by simulation with the parametrized cell model as expected. For better validation, we used a current profile that describes charging and discharging a battery based on the New European Drive Cycle (NEDC). Simulation and measurement results were in very good accordance. Only for a measurement with a SOC of 20% at the beginning, small deviations were detected. That means in our opinion, that the presented approach is a good choice for BMS simulations in the design process.References:[1] IKEBA - Integrierte Komponenten und integrierter Entwurf energie‐effizienter Batteriesysteme. Available: http://www.iam.kit.edu/awp/ikeba/[2] Boxia Lei et al., Comparison of calorimetric studies on 18650 lithium‐ion cells and equivalent circuit model‐based simulation applied to driving cycles (this conference)