Mixed state geometric phases, entangled systems, and local unitary transformations

The geometric phase for a pure quantal state undergoing an arbitrary evolution is a ``memory'' of the geometry of the path in the projective Hilbert space of the system. We find that Uhlmann's geometric phase for a mixed quantal state undergoing unitary evolution not only depends on the geometry of the path of the system alone but also on a constrained bi-local unitary evolution of the purified entangled state. We analyze this in general, illustrate it for the qubit case, and propose an experiment to test this effect. We also show that the mixed state geometric phase proposed recently in the context of interferometry requires uni-local transformations and is therefore essentially a property of the system alone.Comment: minor changes, journal reference adde

Generalization of geometric phase to completely positive maps

We generalize the notion of relative phase to completely positive maps with known unitary representation, based on interferometry. Parallel transport conditions that define the geometric phase for such maps are introduced. The interference effect is embodied in a set of interference patterns defined by flipping the environment state in one of the two paths. We show for the qubit that this structure gives rise to interesting additional information about the geometry of the evolution defined by the CP map.Comment: Minor revision. 2 authors added. 4 pages, 2 figures, RevTex

Geometric Phases for Mixed States during Cyclic Evolutions

The geometric phases of cyclic evolutions for mixed states are discussed in the framework of unitary evolution. A canonical one-form is defined whose line integral gives the geometric phase which is gauge invariant. It reduces to the Aharonov and Anandan phase in the pure state case. Our definition is consistent with the phase shift in the proposed experiment [Phys. Rev. Lett. \textbf{85}, 2845 (2000)] for a cyclic evolution if the unitary transformation satisfies the parallel transport condition. A comprehensive geometric interpretation is also given. It shows that the geometric phases for mixed states share the same geometric sense with the pure states.Comment: 9 pages, 1 figur

A case study on how design theory can be used to create guidelines to use when designing user friendly surveillance systems

Designprinciper används av interaktionsdesigners för att underlätta skapandet av användarvänlig design genom att få dessa att tänka på olika aspekter av designen. Dessa principer har vidareutvecklats sedan uppkomsten på 1990-talet och idag används de ofta inom interaktionsdesign. Genom att använda sig av dessa designprinciper kan dålig design undvikas och därmed minska frustration hos användaren. Designmönster beskrivs som strukturella och beteendemässiga egenskaper som förbättrar miljön för exempelvis användargränssnitt. Dessa egenskaper kan bidra till att göra saker lättare att förstå eller förbättra dess utseende, de gör verktyg mer användbara. Syftet med denna uppsats är att ta fram ett antal designriktlinjer vid utformning av övervakningssystem. Det leder fram till frågeställningen: Vilka riktlinjer med fokus på interaktionsdesign bör användas vid utformning av användarvänliga övervakningssystem? För att ta reda på hur interaktion med övervakningssystem fungerar så har vi samarbetat med Saab Electronic Defence Systems där vi undersökt interaktionen med deras radarövervakningssystem ”Giraffe AMB”. Undersökningen bestod av observationer och intervjuer av personal på Saab. Detta för att få en bred bild av den insamlade datan att analysera. Resultatet av undersökningen analyserades och vi kom fram till en del riktlinjer som baseras på tre teman och i vår slutsats presenteras tydlighet och konsekvens som två återkommande begrepp och ses som uppsatsen bidrag till den akademiska världen. Anledningen till detta är att begreppen tror vi är viktiga för att kunna tackla övervakningssystemens komplexitet och stora mängd information som presenteras.Design principles are usually used by interaction designers to help creating a user friendly design by making the designer think about the different aspects of the design. These design principles has been further developed since they emerged in the 1990s, and today they're often used in the field of interaction design. By using the design principles, bad design can be avoided and the frustration of the user reduced. Design patterns is described as structural and behavioral characteristics to improve the environment in user interface amongst other areas. These characteristics could make things easier to understand or improve their appearance, they make tools more usable. The purpose with this essay is to identify design guidelinesto be used by developers when designing surveillance systems. The research question is: Which guidelines in the aspect of interaction design used as guidelines when designing user friendly surveillance systems? To examine the use of the system we observed Saab employees taking the roll as a radar operator. In addition to observing them we also interviewed the employees with hope of gathering data with wide range and depth. The result of our survey was analyzed and we determined some guidelines based on three themes, in the conclusion we identified two concepts that was a part of every guideline. Theese concepts are clarity and concistency and is our contribution to the field of research. This is to tackle the complexity of the surveillance system and large amount of information to interpret Resultatet av undersökningen analyserades och vi kom fram till en del riktlinjer som baseras på tre teman och i vår slutsats presenteras tydlighet och konsekvens som två återkommande begrepp och ses som uppsatsen bidrag till den akademiska världen. Anledningen till detta är att begreppen tror vi är viktiga för att kunna tackla övervakningssystemens komplexitet och stora mängd information som presenteras

Medium-term hydro-thermal coordination via hydro and thermal subsystem decomposition

Short-Term Hydro-Thermal Coordination, Unit Commitment, Hydro Scheduling, Decomposition, Linear Programming, Relaxation,

Dispersion and self-orientation of gold nanoparticles in sol–gel hybrid silica – optical transmission properties

International audienceSilica-based hybrid materials doped with gold nanoparticles (AuNPs) of different shapes were prepared with an adapted sol–gel technology (using MTEOS) and polished to high optical quality. Both spherical (23 and 45 nm in diameter) and bipyramidal (36, 50 and 78 nm in length) AuNPs were prepared and used as dopants. The AuNPs were functionalized with a novel silicone polymer for compatibilization with the sol–gel medium. The glass materials showed well defined localized surface plasmon resonance (SPR) absorbance from the visible to NIR. No redshifts in the spectra, due to the increase in doping concentration, were observed in the glasses, proving that no or very small SPR coupling effects occur. Spectroscopic Muller Matrix Ellipsometry showed that the shorter bipyramidal AuNPs (36 and 50 nm in length) have a clear preferred orientation in the MTEOS matrix, i.e. a tendency to be oriented with their long axis in the plane parallel to the glass surfaces. Dispersions of AuNPs have proven to be good optical power limiters that depend on particle size and geometry. The solid-state glass materials showed good optical power limiting at 532 nm for nanosecond pulses, which did not depend on the size or geometry of the AuNPs. In contrast to the observation at 532 nm, at 600 nm no optical limiting effect was observed. In these solids, as for dispersions of AuNPs, the optical limiting response is caused by scattering