Creation and localization of entanglement in a simple configuration of coupled harmonic oscillators

We investigate a simple arrangement of coupled harmonic oscillators which brings out some interesting effects concerning creation of entanglement. It is well known that if each member in a linear chain of coupled harmonic oscillators is prepared in a ``classical state'', such as a pure coherent state or a mixed thermal state, no entanglement is created in the rotating wave approximation. On the other hand, if one of the oscillators is prepared in a nonclassical state (pure squeezed state, for instance), entanglement may be created between members of the chain. In the setup considered here, we found that a great family of nonclassical (squeezed) states can localize entanglement in such a way that distant oscillators never become entangled. We present a detailed study of this particular localization phenomenon. Our results may find application in future solid state implementations of quantum computers, and we suggest an electromechanical system consisting of an array of coupled micromechanical oscillators as a possible implementation.Comment: 7 pages, 8 figures, minor typos fixe

Imidazopyrrolone/imide copolymers Patent

Synthesis and chemical properties of imidazopyrrolone/imide copolymer

Dosimeter for high levels of absorbed radiation Patent

Development of dosimeter for measuring absorbed dose of high energy ionizing radiatio

Two destructive effects of decoherence on Bell inequality violation

We consider a system of two spin-1/2 particles, initially in an entangled Bell state. If one of the particles is interacting with an environment (e.g. a collection of N independent spins), the two-particle system undergoes decoherence. Using a simple model of decoherence, we show that this process has two consequences. First, the maximal amount by which the CHSH inequality is violated decays to zero. Second, the set of directions of measurement for which the inequality is violated is reduced in the course of decoherence. The volume of that set is bounded above by C|r|^2, where r is the decoherence factor. We obtain similar results for the case when each of the two particles is in interaction with a separate environment.Comment: v2: added results for decoherence due to interactions of both particles + minor changes; v3: minor change

Orbiter/payload proximity operations: Lateral approach technique

The lateral approach is presented for proximity operations associated with the retrieval of free flying payloads. An out of plane final approach emphasizing onboard software support is recommended for all except the latter segment of the final approach in which manual control is considered mandatory. An overall assessment of various candidate proximity operations techniques are made

Development of advanced fuel cell system, phase 3

A multiple task research and development program was performed to improve the weight, life, and performance characteristics of hydrogen-oxygen alkaline fuel cells for advanced power systems. Gradual wetting of the anode structure and subsequent long-term performance loss was determined to be caused by deposition of a silicon-containing material on the anode. This deposit was attributed to degradation of the asbestos matrix, and attention was therefore placed on development of a substitute matrix of potassium titanate. An 80 percent gold 20 percent platinum catalyst cathode was developed which has the same performance and stability as the standard 90 percent gold - 10 percent platinum cathode but at half the loading. A hybrid polysulfone/epoxy-glass fiber frame was developed which combines the resistance to the cell environment of pure polysulfone with the fabricating ease of epoxy-glass fiber laminate. These cell components were evaluated in various configurations of full-size cells. The ways in which the baseline engineering model system would be modified to accommodate the requirements of the space tug application are identified

Development of advanced fuel cell system, phase 2

A multiple task research and development program was performed to improve the weight, life, and performance characteristics of hydrogen-oxygen alkaline fuel cells for advanced power systems. Development and characterization of a very stable gold alloy catalyst was continued from Phase I of the program. A polymer material for fabrication of cell structural components was identified and its long term compatibility with the fuel cell environment was demonstrated in cell tests. Full scale partial cell stacks, with advanced design closed cycle evaporative coolers, were tested. The characteristics demonstrated in these tests verified the feasibility of developing the engineering model system concept into an advanced lightweight long life powerplant

Fathers and substance misuse: a literature review

Purpose To review the following research questions from the available literature: • What evidence is there to suggest that substance misuse specifically by fathers (including alcohol and other drugs) causes wider harms, including child welfare concerns? • How do professionals respond specifically to substance misuse by fathers? • Do interventions aimed at parental substance misuse (particularly in the UK) include both mothers and fathers and if so how? Design/methodology/approach Scoping literature review, identifying 34 papers, (including scoping reviews published in 2006 and 2008 and six cited papers, covering the period 1990 – 2005), and 26 additional studies published between 2002 and 2020. Findings The review is organized into six themes: 1) Negative impact of men’s substance misuse problems on their parenting behaviours 2) Quality of the relationship between parents is affected by substance misuse of the fathers, in turn affecting the parenting behaviour and outcomes for child/ren 3) Importance to fathers of their fathering role (for example as financial provider) 4) Difficulties fathers may face in developing their fathering role 5) Sidelining of the fathering role in substance misuse services 6) Professionals tending to focus on the mother’s role in parenting inventions and services Originality The review focuses on fathers and substance misuse, an under-researched field within the wider contexts of fathering research and research into parental substance misus

Bell's Theorem and Nonlinear Systems

For all Einstein-Podolsky-Rosen-type experiments on deterministic systems the Bell inequality holds, unless non-local interactions exist between certain parts of the setup. Here we show that in nonlinear systems the Bell inequality can be violated by non-local effects that are arbitrarily weak. Then we show that the quantum result of the existing Einstein-Podolsky-Rosen-type experiments can be reproduced within deterministic models that include arbitrarily weak non-local effects.Comment: Accepted for publication in Europhysics Letters. 14 pages, no figures. In the Appendix (not included in the EPL version) the author says what he really thinks about the subjec