Quantum coherence, correlated noise and Parrondo games

We discuss the effect of correlated noise on the robustness of quantum coherent phenomena. First we consider a simple, toy model to illustrate the effect of such correlations on the decoherence process. Then we show how decoherence rates can be suppressed using a Parrondo-like effect. Finally, we report the results of many-body calculations in which an experimentally-measurable quantum coherence phenomenon is significantly enhanced by non-Markovian dynamics arising from the noise source.Comment: 8 page

Naval Surface Warfare Center Dahlgren Division Engagement Systems (G) Department Development of a Plan to Maintain, Expand, and Create Corporate Knowledge

This dissertation presents the implementation of an organizational study in a technical organization that provides basic information for proper decision making to establish, continue, nurture, modify, transfer or terminate a Knowledge Management (KM) practice. Different aspects of an organization influence the capability to create and retain knowledge. Understanding the factors and the environment of the KM problem in an organization is essential for a successful plan and execution of knowledge creation, transfer and retention. The study purpose was to describe the contextual situation of the organization in terms of Human, Structural and Relational Capital; identify critical knowledge for the organization and knowledge at risk; and identify barriers for knowledge transfer and knowledge retention. The method presented in this project can partially fulfill the development of solutions per the objectives of this project. The actions recommended as a result of this study will help modify the organizational culture to support an environment of knowledge sharing. The study results also provide a baseline for KM metrics in areas that were not previously tracked by the organization. Limitations to the methodology were identified. Not enough participants answered the survey to identify knowledge at risk. The execution of this project and the study results support that KM can provide a structured approach for the development of solutions to the selected goals. Furthermore, it helps changing strategic objectives into specific actions supported by empirical data that can be executed at the working level of the organization. The study identifies what KM efforts are needed to continue to be used, modified, disregarded or implemented to meet the organization\u27s KM objectives

Crossover between the Dense Electron-Hole Phase and the BCS Excitonic Phase in Quantum Dots

Second order perturbation theory and a Lipkin-Nogami scheme combined with an exact Monte Carlo projection after variation are applied to compute the ground-state energy of $6\le N\le 210$ electron-hole pairs confined in a parabolic two-dimensional quantum dot. The energy shows nice scaling properties as N or the confinement strength is varied. A crossover from the high-density electron-hole phase to the BCS excitonic phase is found at a density which is roughly four times the close-packing density of excitons.Comment: Improved variational and projection calculations. 17 pages, 3 ps figures. Accepted for publication in Int. J. Mod. Phys.

High Angular Resolution Observations of the Collimated Jet Source Associated with a Massive Protostar in IRAS 16547-4247

A triple radio source recently detected in association with the luminous infrared source IRAS 16547-4247 has been studied with high angular resolution and high sensitivity with the Very Large Array at 3.6 and 2 cm. Our observations confirm the interpretation that the central object is a thermal radio jet, while the two outer lobes are most probably heavily obscured HH objects. The thermal radio jet is resolved angularly for the first time and found to align closely with the outer lobes. The opening angle of the thermal jet is estimated to be $\sim 25^\circ$, confirming that collimated outflows can also be present in massive protostars. The proper motions of the outer lobes should be measurable over timescales of a few years. Several fainter sources detected in the region are most probably associated with other stars in a young cluster.Comment: 9 pages, 2 figure