Correlating the nanostructure of Al-oxide with deposition conditions and dielectric contributions of two-level systems in perspective of superconducting quantum circuits

This work is concerned with Al/Al-oxide(AlO$_{x}$)/Al-layer systems which are important for Josephson-junction-based superconducting devices such as quantum bits. The device performance is limited by noise, which has been to a large degree assigned to the presence and properties of two-level tunneling systems in the amorphous AlO$_{x}$ tunnel barrier. The study is focused on the correlation of the fabrication conditions, nanostructural and nanochemical properties and the occurrence of two-level tunneling systems with particular emphasis on the AlO$_{x}$-layer. Electron-beam evaporation with two different processes and sputter deposition were used for structure fabrication, and the effect of illumination by ultraviolet light during Al-oxide formation is elucidated. Characterization was performed by analytical transmission electron microscopy and low-temperature dielectric measurements. We show that the fabrication conditions have a strong impact on the nanostructural and nanochemical properties of the layer systems and the properties of two-level tunneling systems. Based on the understanding of the observed structural characteristics, routes are derived towards the fabrication of Al/AlO$_{x}$/Al-layers systems with improved properties.Comment: 28 pages, 4 figure

Cloud Chamber: A Performance with Real Time Two-Way Interaction between Subatomic Particles and Violinist

‘Cloud Chamber’ - a composition by Alexis Kirke, Antonino Chiaramonte, and Anna Troisi - is a live performance in which the invisible quantum world becomes visible as a violinist and subatomic particle tracks interact together. An electronic instrument was developed which can be “played” live by radioactive atomic particles. Electronic circuitry was developed enabling a violin to create a physical force field that directly affects the ions generated by cosmic radiation particles. This enabled the violinist and the ions to influence each other musically in real time. A glass cloud chamber was used onstage to make radioactivity visible in bright white tracks moving within, with the tracks projected onto a large screen

Antiferromagnetic phase of the gapless semiconductor V3Al

Discovering new antiferromagnetic compounds is at the forefront of developing future spintronic devices without fringing magnetic fields. The antiferromagnetic gapless semiconducting D03 phase of V3Al was successfully synthesized via arc-melting and annealing. The antiferromagnetic properties were established through synchrotron measurements of the atom-specific magnetic moments, where the magnetic dichroism reveals large and oppositely-oriented moments on individual V atoms. Density functional theory calculations confirmed the stability of a type G antiferromagnetism involving only two-third of the V atoms, while the remaining V atoms are nonmagnetic. Magnetization, x-ray diffraction and transport measurements also support the antiferromagnetism. This archetypal gapless semiconductor may be considered as a cornerstone for future spintronic devices containing antiferromagnetic elements.Comment: Accepted to Physics Review B on 02/23/1

Assessing the International Criminal Court

One of the most important issues surrounding international courts is whether they can further the dual causes of peace and justice. None has been more ambitious in this regard than the International Criminal Court (ICC). And yet the ICC has been the object of a good deal of criticism. Some people claim it has been an expensive use of resources that might have been directed to other purposes. Others claim that its accomplishments are meager because it has managed to try and convict so few people. And many commentators and researchers claim that the Court faces an inherent tension between the dual objectives of securing the peace and ending impunity for perpetrators of some of the most egregious crimes, including genocide, crimes against humanity, war crimes, and crimes of aggression. This chapter assesses the ability of the ICC to deter. In so doing, we follow the lead of the introduction and think not only about the Court’s performance in the narrow sense (e.g., how many people have been tried?) but rather think about the ways in which the ICC has contributed to a broader culture that refuses to tolerate impunity for violations of international criminal law. Because we must limit our topic to manageable proportions (and because we are social scientists and not lawyers) our focus is primarily on outcome performance rather than procedural performance. We focus on two outcomes alluded to in the introductory chapter: 1) reaching desired goals, and 2) deterring atrocities against civilians

Assessing the International Criminal Court

One of the most important issues surrounding international courts is whether they can further the dual causes of peace and justice. None has been more ambitious in this regard than the International Criminal Court (ICC). And yet the ICC has been the object of a good deal of criticism. Some people claim it has been an expensive use of resources that might have been directed to other purposes. Others claim that its accomplishments are meager because it has managed to try and convict so few people. And many commentators and researchers claim that the Court faces an inherent tension between the dual objectives of securing the peace and ending impunity for perpetrators of some of the most egregious crimes, including genocide, crimes against humanity, war crimes, and crimes of aggression. This chapter assesses the ability of the ICC to deter. In so doing, we follow the lead of the introduction and think not only about the Court’s performance in the narrow sense (e.g., how many people have been tried?) but rather think about the ways in which the ICC has contributed to a broader culture that refuses to tolerate impunity for violations of international criminal law. Because we must limit our topic to manageable proportions (and because we are social scientists and not lawyers) our focus is primarily on outcome performance rather than procedural performance. We focus on two outcomes alluded to in the introductory chapter: 1) reaching desired goals, and 2) deterring atrocities against civilians

Geometric picture of quantum discord for two-qubit quantum states

Among various definitions of quantum correlations, quantum discord has attracted considerable attention. To find analytical expression of quantum discord is an intractable task. Exact results are known only for very special states, namely, two-qubit X-shaped states. We present in this paper a geometric viewpoint, from which two-qubit quantum discord can be described clearly. The known results about X state discord are restated in the directly perceivable geometric language. As a consequence, the dynamics of classical correlations and quantum discord for an X state in the presence of decoherence is endowed with geometric interpretation. More importantly, we extend the geometric method to the case of more general states, for which numerical as well as analytica results about quantum discord have not been found yet. Based on the support of numerical computations, some conjectures are proposed to help us establish geometric picture. We find that the geometric picture for these states has intimate relationship with that for X states. Thereby in some cases analytical expressions of classical correlations and quantum discord can be obtained.Comment: 9 figure

Otolith Microstructure in Young-of-the Year Dolly Varden, Salvelinus malma, from American and Asian Populations: Resolution of Comparative Life History Characteristics

Sigittal otoliths from young-of-the-year Dolly Varden, Salvelinus malma, captured from Cripple River, Alaska and Cha'atam River, Russia were prepared and observed with transmitted light microscopy. Distinct microstructure in samples from both locations indicated daily growth increments, hatching checks and first feeding checks that confirm literature findings in other salmonids. We used increment counts to estimate the ages of individual juveniles and calculated hatch dates and times of first feeding from those ages. Increments deposited before the first feeding mark were significantly smaller then those formed after this mark. Alaskan and Russian fish showed a significant difference in hatching times and the period of first feeding. Summer growth rates of the Russian population, calculated from length-at-the-age data, were faster (0.356 mm/day) than those of the Alaskan population (0.301 mm/day). However, when the average growth rate was calcualted with the formula GR=(Lcapture-Lhatching)/age, the values were higher for the Alaskan population (0.25 mm/day) than for the Russian population (0.20 mm/day). When otolith radius-fish size relationships were estimated, Alaskan otoliths were found to be larger for the same size fish, because wider increments were deposited in fish from Alaska. Increment width also was related to time of the year: wider increments were deposited during the warmer months. Otolith microstructure provided insights into the early life history of young-of-the-year Dolly Varden from American and Asian populations.Des sagittas provenant de Dolly Varden (Salvelinus malma) de l'année capturées dans la Cripple en Alaska et dans la Cha'atam en Russie ont été préparées et étudiées au microscope pour examen par transmission. Une microstructure distincte dans les échantillons provenant des deux sites révélait une croissance quotidienne, des repères de l'éclosion et des repères de la première phase alimentaire, qui confirment les résultats consignés dans la documentation sur d'autres salmonidés. On s'est servi du comptage des unités d'accroissement pour estimer l'âge des individus juvéniles et on a calculé la date d'éclosion et la date de la première phase alimentaire à partir de cet âge. Les unités d'accroissement formées avant le repère signalant le début de la phase alimentaire étaient nettement moindres que celles qui se sont formées après ce repère. Les poissons d'Alaska et ceux de Russie montraient une nette différence dans leurs dates d'éclosion et dans celles signalant le début de la phase alimentaire. Les taux de croissance estivaux de la population russe, calculés à partir des données sur la longueur à un âge précis, étaient plus rapides (0,356 mm/jour) que ceux de la population alaskienne (0,301 mm/jour). Cependant, quand on calculait le taux moyen de croissance à l'aide de la formule TC = (Lcapture - Léclosion)/âge, les valeurs étaient supérieures pour la population alaskienne (0,25 mm/jour) que pour la population russe (0,20 mm/jour). Lorsqu'on a estimé la relation entre le rayon de l'otolithe et la grosseur du poisson, on a trouvé que les otolithes alaskiennes étaient plus grosses pour la même taille de poisson, parce que les unités d'accroissement chez les poissons alaskiens étaient plus grandes. La taille des unités d'accroissement était aussi reliée à la période de l'année, le plus fort de l'augmentation ayant lieu durant les mois chauds. La microstructure des otolithes a permis de mieux comprendre la première étape de la vie de la Dolly Varden de l'année, venant de populations américaine et asiatique