An integrated cryogenic optical modulator

Integrated electrical and photonic circuits (PIC) operating at cryogenic temperatures are fundamental building blocks required to achieve scalable quantum computing, and cryogenic computing technologies. Optical interconnects offer better performance and thermal insulation than electrical wires and are imperative for true quantum communication. Silicon PICs have matured for room temperature applications but their cryogenic performance is limited by the absence of efficient low temperature electro-optic (EO) modulation. While detectors and lasers perform better at low temperature, cryogenic optical switching remains an unsolved challenge. Here we demonstrate EO switching and modulation from room temperature down to 4 K by using the Pockels effect in integrated barium titanate (BaTiO3)-based devices. We report the nonlinear optical (NLO) properties of BaTiO3 in a temperature range which has previously not been explored, showing an effective Pockels coefficient of 200 pm/V at 4 K. We demonstrate the largest EO bandwidth (30 GHz) of any cryogenic switch to date, ultra-low-power tuning which is 10^9 times more efficient than thermal tuning, and high-speed data modulation at 20 Gbps. Our results demonstrate a missing component for cryogenic PICs. It removes major roadblocks for the realisation of novel cryogenic-compatible systems in the field of quantum computing and supercomputing, and for interfacing those systems with the real world at room-temperature

Robot Navigation by Panoramic Vision and Attention Guided Features

In visual-based robot navigation, panoramic vision emerges as a very attractive candidate for solving the localization task. Unfortunately, current systems rely on specific feature selection processes that do not cover the requirements of general purpose robots. In order to fulfill new requirements of robot versatility and robustness to environmental changes, we propose in this paper to perform the feature selection of a panoramic vision system by means of the saliency-based model of visual attention, a model known for its universality. The first part of the paper describes a localization system combining panoramic vision and visual attention. The second part presents a series of indoor localization experiments using panoramic vision and attention guided feature detection. The results show the feasibility of the approach and illustrate some of its capabilities

A ferroelectric multilevel non-volatile photonic phase shifter

A novel class of programmable integrated photonic circuits has emerged over the past years, strongly driven by approaches to tackle unsolved computing problems in the optical domain. Photonic neuromorphic and quantum computing are examples of optical systems implemented in complex photonic circuits, which are reconfigured before and during operation. However, a key building block to enable efficient reconfigurable optical network architectures is still missing: a non-volatile optical phase shifter. Here we demonstrate such an element—compatible with silicon photonics—based on the monolithic integration of BaTiO3 thin films with silicon waveguides. By manipulating ferroelectric domains in BaTiO3 with electrical control signals, we achieve analogue and non-volatile optical phase tuning with no absorption changes. We demonstrate an eight-level long-term-stable photonic device with non-destructive optical readout and switching energy as low as 4.6 pJ. With our results, an analogue non-volatile photonic element is added to the integrated photonics toolbox, enabling a new generation of power-efficient programmable photonic circuits.ISSN:1749-4885ISSN:1749-489

Bildung und subjektives Wohlbefinden im Zeitverlauf, 1984–2002. Eine Mehrebenenanalyse

Diese Analyse des subjektiven Wohlbefindens verfolgt zwei Ziele. Zum einen wird die Entwicklung des subjektiven Wohlbefindens über die Periode zwischen 1984 und 2002 untersucht. Dabei werden Alters-, Perioden- und Kohorteneffekte simultan betrachtet. Als soziale Mechanismen hinter den Wandlungsprozessen, das heißt als Prädiktoren für das subjektive Wohlbefinden und die Variation im Zeitverlauf, werden Bildung und Bildungsexpansion thematisiert und in die Analysemodelle eingeführt. Um die Lebenszufriedenheit unabhängig von gesundheitlichen Aspekten zu untersuchen, wird die Gesundheitszufriedenheit kontrolliert. Methodisch folgt der Beitrag einem Mehrebenenansatz. Zur Datenanalyse werden Hierarchisch Lineare Modelle (HLM) herangezogen. Detailliert wird auf die benötigte Datenstruktur, die Anwendbarkeit und die Parameter-Schätzungen von HLM eingegangen. Die Datengrundlage bildet das Sozio-Ökonomische Panel (SOEP), wobei nur die Teil-Stichprobe der Westdeutschen in die Analyse einbezogen wird. In den Resultaten zeigen sich – neben einem starken Einfluss der Gesundheitszufriedenheit – u. a. robuste Bildungseffekte, ein substanzieller Alterseffekt und ein schwacher negativer Kohorteneffekt auf die Lebenszufriedenheit