We show that generic pure states (states drawn according to the Haar measure) of four particles of equal internal dimension are uniquely determined among all other pure states by their two-body marginals. In fact, certain subsets of three of the two-body marginals suffice for the characterization. We also discuss generalizations of the statement to pure states of more particles, showing that these are almost always determined among pure states by three of their $(n\ensuremath{-}2)$-body marginals. Finally, we present special families of symmetric pure four-particle states that share the same two-body marginals and are therefore undetermined. These are four-qubit Dicke states in superposition with generalized GHZ states.
Abstract Contrail cirrus account for the major share of aviation’s climate impact. Yet, the links between jet fuel composition, contrail microphysics and climate impact remain unresolved. Here we present unique observations from two DLR-NASA aircraft campaigns that measured exhaust and contrail characteristics of an Airbus A320 burning either standard jet fuels or low aromatic sustainable aviation fuel blends. Our results show that soot particles can regulate the number of contrail cirrus ice crystals for current emission levels. We provide experimental evidence that burning low aromatic sustainable aviation fuel can result in a 50 to 70% reduction in soot and ice number concentrations and an increase in ice crystal size. Reduced contrail ice numbers cause less energy deposition in the atmosphere and less warming. Meaningful reductions in aviation’s climate impact could therefore be obtained from the widespread adoptation of low aromatic fuels, and from regulations to lower the maximum aromatic fuel content.
Das Ziel des Teilprojekts Integriertes Modell Ruhrgebiet war die Entwicklung und Anwendung eines integrierten Modellsystems, mit dem die Auswirkungen von Handlungsansatzen zur Reduzierung des Energieverbrauchs und von Treibhausgasemissionen in Stadtregionen bis zum Jahr 2050 abgeschatzt und bewertet werden konnen. In dem Teilprojekt wurde ein fur das ostliche Ruhrgebiet vorhandenes Flachennutzungs- und Verkehrsmodell auf das gesamte Ruhrgebiet erweitert und durch Teilmodelle des Energieverbrauchs von Gebauden und Verkehr erganzt. Die Ergebnisse sollen Zivilgesellschaft, Planung und Politik Hinweise darauf geben, welche Masnahmen auf europaischer, nationaler, regionaler und lokaler Ebene durchgefuhrt werden mussen, um die Ziele der Energiewende im Ruhrgebiet zu erreichen.
Im Fokus des Teilprojekts Regionaler Modal Shift stand der regionale Personenverkehr im Ruhrgebiet. Hier werden bislang 53 Prozent aller Wege mit dem motorisierten Individualverkehr zuruckgelegt gegenuber einem Ziel-Modal Split mit einem Pkw-Anteil von 25 Prozent und jeweils 25 weiteren Prozenten fur Fus- und Radverkehr sowie OPNV. Ein zentraler Ansatz zur Reduzierung des Energieverbrauchs und der Treibhausgasemissionen ist die Verlagerung (Modal Shift) von motorisiertem Individualverkehr auf den Umweltverbund (Fus, Rad, OPNV, Car-Sharing). Die polyzentrische Struktur des Verkehrsnetzes des Ruhrgebiets bietet gute Voraussetzungen fur eine klimafreundliche Mobilitat im Umweltverbund. Daruber hinaus kann Elektromobilitat einen weiteren Beitrag zur Reduzierung von Energieverbrauch und Treibhausgasemissionen leisten.
Dieser Bericht stellt die Ergebnisse aus den beiden Teilprojekten in integrierter Form dar.
Einstein’s Weak Equivalence Principle (WEP) states that gravitational mass is identical to inertial mass. This hypothesis has withstood experimental tests to an impressive accuracy of one part in one hundred billion. Various hypotheses based on theory and observations with matter suggest violations of WEP for antimatter may exist anywhere from the one part per million to the 200% level. An observed violation at any level would have a profound impact, e.g. it would offer an explanation of why matter and antimatter are so distinctly separated in the Cosmos. We propose a precise test of WEP for antiprotons in microgravity. We expect to test WEP for antimatter to about one part per million, and foresee that additional advancements of several orders of magnitude in precision could follow with further technical developments.
The separation of phases in a multiphase fluid mixture is significant in aerospace applications. The controlling of multiphase flows is therefore investigated numerically in this thesis. It is assumed that a gas bubble immersed in a liquid is subject to an acoustic field at different gravity levels. In the computation, the equations for radial oscillations and translational motion will be solved simultaneously with a numerical solver. While most of the numerical investigations of bubble phenomena deal with the radial bubble behavior and thus, the heat exchange, only a few studies were conducted on the translational motion. While the behavior of air bubbles immersed in water in an acoustic field parallel to gravity is well evaluated, the translational motion of vapor bubbles in liquid hydrogen has not been investigated so far, as well as the behavior of bubbles in different gravity environments. Here the rise of bubbles in micro and hypergravity conditions are discussed. Finally, the bubble motion is investigated in an acoustic field perpendicular to gravity. The results obtained in this thesis will be the first steps towards a numerical code with the capability of fully controlling the vertical and horizontal position of a bubble within an acoustic field.
We present new bounds on the existence of general quantum maximum distance separable codes (QMDS): the length n of all QMDS codes with local dimension D and distance d≥3 is bounded by n≤D2+d−2. We obtain their weight distribution and present additional bounds that arise from Rains' shadow inequalities. Our main result can be seen as a generalization of bounds that are known for the two special cases of stabilizer QMDS codes and absolutely maximally entangled states, and confirms the quantum MDS conjecture in the special case of distance-three codes. As the existence of QMDS codes is linked to that of highly entangled subspaces (in which every vector has uniform r-body marginals) of maximal dimension, our methods directly carry over to address questions in multipartite entanglement.
