Few-photon transport in low-dimensional systems: Interaction-induced radiation trapping

We present a detailed analysis of the dynamics of photon transport in waveguiding systems in the presence of a two-level system. In these systems, quantum interference effects generate a strong effective optical nonlinearity on the few-photon level. We clarify the relevant physical mechanisms through an appropriate quantum many-body approach. Based on this, we demonstrate that a single-particle photon-atom bound state with an energy outside the band can be excited via multi-particle scattering processes. We further show that these trapping effects are robust and, therefore, will be useful for the control of photon entanglement in solid-state based quantum optical systems

Green's Function Formalism for Waveguide QED Applications

We present a quantum-field-theoretical framework based on path integrals and Feynman diagrams for the investigation of the quantum-optical properties of one-dimensional waveguiding structures with embedded quantum impurities. In particular, we obtain the Green's functions for a waveguide with an embedded two-level system in the single- and two-excitation sector for arbitrary dispersion relations. In the single excitation sector, we show how to sum the diagrammatic perturbation series to all orders and thus obtain explicit expressions for physical quantities such as the spectral density and the scattering matrix. In the two-excitation sector, we show that strictly linear dispersion relations exhibit the special property that the corresponding diagrammatic perturbation series terminates after two terms, again allowing for closed-form expressions for physical quantities. In the case of general dispersion relations, notably those exhibiting a band edge or waveguide cut-off frequencies, the perturbation series cannot be summed explicitly. Instead, we derive a self-consistent T-matrix equation that reduces the computational effort to that of a single-excitation computation. This analysis allows us to identify a Fano resonance between the occupied quantum impurity and a free photon in the waveguide as a unique signature of the few-photon nonlinearity inherent in such systems. In addition, our diagrammatic approach allows for the classification of different physical processes such as the creation of photon-photon correlations and interaction-induced radiation trapping - the latter being absent for strictly linear dispersion relations. Our framework can serve as the basis for further studies that involve more complex scenarios such as several and many-level quantum impurities, networks of coupled waveguides, disordered systems, and non-equilibrium effects.Comment: 19 pages, 6 figure

3D modeling of indoor environments by a mobile platform with a laser scanner and panoramic camera

One major challenge of 3DTV is content acquisition. Here, we present a method to acquire a realistic, visually convincing D model of indoor environments based on a mobile platform that is equipped with a laser range scanner and a panoramic camera. The data of the 2D laser scans are used to solve the simultaneous lo- calization and mapping problem and to extract walls. Textures for walls and floor are built from the images of a calibrated panoramic camera. Multiresolution blending is used to hide seams in the gen- erated textures. The scene is further enriched by 3D-geometry cal- culated from a graph cut stereo technique. We present experimental results from a moderately large real environment.

Employee Qualification by Digital Learning Games

Global competition and individual customer requirements generate challenges for manufacturing companies. To cope with these challenges, companies require an increased level of flexibility. In the first place, this flexibility has to be provided by the employees, as they are one of the key success factors for mastering change. An essential prerequisite for this is a high level of employee qualification across all areas of the company. The learning factories approach has garnered particular attention in recent years as a playful and efficient way of learning the principles and methods of processes improvement. The drawbacks of this method include the limited, non-holistic perspective of each trainee as well as the non-recurring knowledge transfer. Moreover, this kind of qualification requires the trainees to be in the same place at the same time. These downsides can be successfully countered by supplementing learning factories with a digital learning component depicting the learning environment, as digital learning will enable individual learning routes for all trainees and is accessible at all times and all places. This paper serves to outline the idea of serious learning by using digital learning games along with the attendant benefits. Over and beyond this, it also presents a digital learning game for teaching specific lean production methods. © 2017 The Author

Designing industrial strategy for a low carbon transformation

The recent re-emergence of industrial policy as a legitimate pursuit of governments in Europe and the US has the potential to open up a new realm of policy action for climate change mitigation. This would aim to align efforts to secure national industrial opportunities with the development of low carbon industrial systems, so as to generate both socio-economic and environmental benefits. The paper discusses the role of low carbon industrial strategy in seeking to do this, thereby accelerating transitions to a low carbon economy. It sets out the elements of a more systemic low carbon industrial strategy, including providing a mission-oriented and learning-based approach, drawing on and combining insights from neo-Schumpeterian and ecological economics perspectives

Fluorescence enhancement by dark plasmon modes

We investigate the fluorescence properties of colloidal quantum dots attached to gold rod nanoantennas. These structures are fabricated by a two step electron beam lithography process in combination with a chemical linking method. By varying the nanoantenna length, the plasmon modes of the nanoantennas are successively tuned through the emission band of the quantum dots. We observe a pronounced fluorescence enhancement both for short and long nanoantennas. These findings can be attributed to the coupling of the quantum dots to bright and dark plasmon modes, respectively

A relativistic variant of the Wigner function

The conventional Wigner function is inappropriate in a quantum field theory setting because, as a quasiprobability density over phase space, it is not manifestly Lorentz covariant. A manifestly relativistic variant is constructed as a quasiprobability density over trajectories instead of over phase space.Comment: v3: as accepted by Phys. Lett.

Binding between two-component bosons in one dimension

We investigate the ground state of one-dimensional few-atom Bose-Bose mixtures under harmonic confinement throughout the crossover from weak to strong inter-species attraction. The calculations are based on the numerically exact multi-configurational time-dependent Hartree method. For repulsive components we detail the condition for the formation of a molecular Tonks-Girardeau gas in the regime of intermediate inter-species interactions, and the formation of a molecular condensate for stronger coupling. Beyond a critical inter-species attraction, the system collapses to an overall bound state. Different pathways emerge for unequal particle numbers and intra-species interactions. In particular, for mixtures with one attractive component, this species can be viewed as an effective potential dimple in the trap center for the other, repulsive component.Comment: 10 pages, 10 figure

Keimlinge als neuartige multifunktionelle Zutat in ökologischen Backwaren - Optimierung der Herstellung und Verwendung

Im Rahmen des Projektes „Keimlinge als neuartige multifunktionelle Zutat in ökologischen Backwaren - Optimierung der Herstellung und Verwendung“ wurde die sichere betriebseigene Herstellung von Keimlingen, der Einsatz von Keimlingen in Sprossenbroten und der Einsatz zu technologischen Zwecken entwickelt und optimiert. Diese allgemeinen Handlungsempfehlungen wurden in einem Leitfaden für handwerkliche Bäckereien festgehalten. Um gleichmäßige Backergebnisse zu erhalten, werden Keimlinge mit konstanter Qualität benötigt. Qualitätsbestimmende Faktoren sind die mikrobiologische Belastung, die wertgebenden Inhaltsstoffe und die Enzymatik. Das Keimergebnis lässt sich im Keimprozess durch die Keimtemperatur, die Schichthöhe und die Keimdauer beeinflussen und steuern. Die Einflüsse dieser Faktoren auf die qualitätsbestimmenden Eigenschaften wurden im Projekt untersucht. Aus den Ergebnissen konnte die Faustzahl „15:15:30“ abgeleitet werden. Bei einer Schichthöhe von 15 cm, einer Keimtemperatur von maximal 15 °C und einer Keimdauer von 30 Stunden lassen sich gute Keimlingsergebnisse erzielen. Die Herstellung von Essener Broten stellt besondere Anforderungen an die Teigführung. Durch die Keimung kommt es zu einer deutlichen Vermehrung der Enzymaktivität im Keimgut. Diese Enzymaktivität ist insbesondere für Roggenteige technologisch hoch relevant. Es empfiehlt sich, die Keimlinge möglichst spät und eher grob zerkleinert dem gut gesäuerten Teig hinzu zu geben. Unter Einhaltung der im Leitfaden beschriebenen Bedingungen gelingt es, ein Essener Brot ausschließlich aus Keimlingen herzustellen. Je niedriger die Keimtemperatur, desto fester die Krumenbeschaffenheit und desto weniger klebrig ist die Krume. Die Backergebnisse sind durch die Temperatur bei der Keimung beeinflussbar und die Krumenfestigkeit bzw. die Krumenklebrigkeit kann gesteuert werden. Das so genannte Essener Brot wird typischerweise eher bei niedrigeren Temperaturen über eine verlängerte Backzeit gebacken. Die Keimlinge oder auch das so gewonnene aktive Malz kann zu Steuerung der Enzymatik bei der Teigführung eingesetzt werden. Der Einsatz von Roggenkeimlingen als Zutat bei Weizenbrot kann sehr positive Ergebnisse zeigen. Der Zerkleinerungsgrad der Keimlinge hat entscheidenden Einfluss auf die Qualität der hergestellten Weizengebäcke. Insgesamt konnten das Volumen, die Krumenelastizität und die Krumenfestigkeit verbessert werden