Revisiting quantum feedback control: disentangling the feedback‐induced phase from the corresponding amplitude

Coherent time‐delayed feedback allows the control of a quantum system and its partial stabilization against noise and decoherence. The crucial and externally accessible parameters in such control setups are the round‐trip‐induced delay time τ and the frequencies ω of the involved optical transitions which are typically controllable via global parameters like temperature, bias, or strain. They influence the dynamics via the amplitude and the phase= of the feedback signal. These quantities are, however, not independent. Here, the aim is to control the feedback phase via a microwave pump field. Using the example of a Λ‐type three‐level system, it is shown that the Rabi frequency of the pump field induces phase shifts on demand and therefore increases the applicability of coherent quantum feedback control protocols.DFG, 163436311, SFB 910: Kontrolle selbstorganisierender nichtlinearer Systeme: Theoretische Methoden und AnwendungskonzepteEC/H2020/734690/EU/Localized Surface Plasmon Resonance in doped semiconductor nanocrystals/SONARTU Berlin, Open-Access-Mittel - 201

<p class="FrontMatter">OXIDATION OF SILICON AND GERMANIUM BY ATOMIC AND MOLECULAR OXYGEN</p>

Space vehicles residing in the low Earth orbit (LEO) are exposed to a harsh environment that rapidly degrades their materials. The LEO ranges from 200-700km in altitude from the Earth’s surface, and the temperature varies between 200 and 400K. The most hazardous species in LEO is atomic oxygen (AO) containing 5eV kinetic energy due to the high velocity of the spacecrafts (8km/s). The goal of this research is the elucidation of the fundamental mechanisms of semiconductor degradation and passivation in LEO conditions by comparing the structural differences in the oxide films created by exposure to AO and molecular oxygen (MO). Silicon is the base material for solar cells used in LEO whereas Ge and SiOx films are common coatings to protect polymer materials that are used as structural materials in spacecrafts.  Hyperthermal AO was created by the laser detonation of MO within a high vacuum (HV) chamber, that produces a high flux of AO. A variety of nano-characterization techniques, including high resolution transmission electron microscopy (HREM), and electron energy loss spectroscopy (EELS) were used to determine the microstructure and local chemistry of the oxide and the oxide/semiconductor interface. For Si, the amorphous silica formed by AO was nearly twice as thick, more ordered, and more homogeneous in composition, than the oxide formed by MO. The Si/SiOx interface formed by AO was atomically abrupt, with no suboxides detected near the interface or throughout the oxide. The oxide scale formed by MO on Si(100) consisted of transitional oxidation states. The oxide film formed on Ge(100) due to exposure to 5eV AO, is 2-3 times thicker and similarly to the Si/SiOx interfaces, the Ge/GeOx interface was found to be atomically abrupt.  The oxidation kinetics of Si and Ge were monitored in situ using a research quartz crystal microbalance (RQCM) that was incorporated into the AO source. The oxidation kinetics in hyperthermal AO did not follow the standard linear to parabolic Deal-Grove kinetics. A novel oxidation model, based on the oxide structure continually changing during AO exposure, is proposed to explain the unusual power law oxidation kinetics.  </p

Influence of Defects on Critical Parameters in High Temperature Superconductors

Bismuth cuprate high temperature superconductors are currently the only ceramic material that can be successfully processed in kilometer length wires. Bismuth cuprates form three compositions that can be represented with the generic formula Bi2Sr2CanCun+1O8+d n = 0, 1, 2 (with critical temperatures Tc = 20K, 85-94K and 110K respectively). With critical temperatures above 77K (liquid nitrogen boiling point) the only property inhibiting a widespread use is the infield performance, that is, insufficient critical current densities in high magnetic fields. The infield critical current is intimately related to the pinning of the flux vortices that form under the influence of a magnetic field. The intrinsic pinning of flux vortices, is still not well understood in these quaternary systems. The influence of SrCuO2 second phase additions as well as internal cation nonstoichiometry was investigated as a viable way to control the flux pinning properties in the Bi2Sr2CaCu2O8+d (Bi-2212) system. The compositions of Bi2Sr2+xCaCu2+xO8+y (x = 0.0001-0.6) as well as Nd substituted Ca samples were prepared via freeze-drying. Phase pure stoichiometric Bi-2212 was synthesized via freeze-drying in a reduced oxygen atmosphere. It was further determined that up to 20mol% additions of SrCuO2 can be accommodated in the Bi-2212 structure and that the additions increase critical current. The incorporation of SrCuO2 into Bi-2212 results in change of both lattice parameters and modulation vector

Turkey’s COVID-19 strategy: “the West is jealous of us”

Populist nationalist attacks on health and human rights have been increasing throughout the COVID-19 pandemic. These attacks may be used to divert attention from the government’s inability to control the virus, to deflect blame, or even to consolidate power. Authoritarian governments have increased the rhetoric of nationalism, created bogus enemies and alternative narratives, increased the authority of security forces, and banned democratic demonstrations. In this article, we discuss how the Turkish government has hidden the truth about the extent of the disease, spent considerable effort on polishing its own image, promoted the notion of Western jealousy, and fabricated a host of scapegoats to blame for its own failure to protect its people from the ravages of this crippling epidemic.publishedVersio

Silicon oxidation by atomic and molecular oxygen

Atomic oxygen is the most hazardous species of molecules present in the Low Earth Orbit causing failure of the material in space. This study was undertaken to examine the differences in the oxidation of silicon by molecular and atomic oxygen. Hypotheses about the effects of reactive atomic oxygen on the oxidation mechanism of silicon and formed oxide microstructure are presented. The oxides created with atomic and molecular oxygen were studied via Rutherford Backscattering (RBS), High-Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction (SAED), Electron-Energy Loss Spectroscopy (EELS), X-ray Photoelectron Scattering (XPS) and Atomic Force Microscopy (AFM).The results obtained in the experiments are discussed and the possible effects of atomic oxygen on the oxidation mechanism and microstructure formation are inferred. An oxidation model based on thermionic emission is presented as a model for the oxidation by atomic oxygen

The Skills of Principals to Manage the Generational Differences: A Scale Development Study

The aim of this study is to develop a valid and reliable data collection tool that teachers can evaluate the ability of principals to manage generational differences in the schools. The study was conducted with 380 teachers who work in Nigde. In this context, item pool was created and presented to the experts. According to expert’s opinions and pre-application, the last version of scale was created and applied to 380 teachers. Based on the KMO and Bartlett values, the data set was found suitable for Exploratory Factor Analysis. The number of factors was determined as one, based on eigenvalues and scree plot. According to the factor loadings of the items, values ranged from ,871 to ,722. As a result, a structure consisting of 19 items and one factor. Based on the fit indices obtained from Confirmatory Factor Analysis, the model was found perfectly compatible with the model. The structure found with EFA was confirmed by CFA. The Cronbach alpha value calculated as ,971 which indicates that the scale is reliable. As a result, it can be said that “Managing Generational Differences in Schools Scale” which composed of 19 items and one dimension is a valid and reliable data collection tool

Digital Television: Has the Revolution Stalled?

When digital television technology first hit the scene it garnered great excitement, with its promise of movie theater picture and sound on a fraction of the bandwidth of analog. A plan was implemented to transition from the current analog broadcasting system to a digital system effective December 23, 2006. As we reach the half point of this plan, the furor begins to die as the realities of the difficult change sink in

Deutsche Telekom and Voicestream Merger: Charting a New Regulatory Course

On July 24, 2000, the German telecommunications giant Deutsche Telekom AG (Deutche Telekom) agreed to purchase the Bellvue, Washington based VoiceStream Wireless Corporation (VoiceStream) for over $50 billion. Although the merger may ultimately fall through, the response generated by the proposed merger indicates the future for deals between US and foreign-owned telecommunications companies. With the increasing globalization of the world\u27s telecommunications markets, the Deutche Telekom deal represents the first time that a company dominated by a foreign government has attempted to purchase an American corporation. The signatories of the Basic Telecommunications Agreement, an agreement among World Trade Organization (WTO) members to open their telecom markets to foreign competition, are closely watching the US response. The stance that the US government takes in reviewing this merger can be seen as a sign of things to come as the world\u27s single largest telecommunications market opens up to the world

Global injury morbidity and mortality from 1990 to 2017: results from the Global Burden of Disease Study 2017

Background: Past research in population health trends has shown that injuries form a substantial burden of population health loss. Regular updates to injury burden assessments are critical. We report Global Burden of Disease (GBD) 2017 Study estimates on morbidity and mortality for all injuries. Methods: We reviewed results for injuries from the GBD 2017 study. GBD 2017 measured injury-specific mortality and years of life lost (YLLs) using the Cause of Death Ensemble model. To measure non-fatal injuries, GBD 2017 modelled injury-specific incidence and converted this to prevalence and years lived with disability (YLDs). YLLs and YLDs were summed to calculate disability-adjusted life years (DALYs). Findings: In 1990, there were 4 260 493 (4 085 700 to 4 396 138) injury deaths, which increased to 4 484 722 (4 332 010 to 4 585 554) deaths in 2017, while age-standardised mortality decreased from 1079 (1073 to 1086) to 738 (730 to 745) per 100 000. In 1990, there were 354 064 302 (95% uncertainty interval: 338 174 876 to 371 610 802) new cases of injury globally, which increased to 520 710 288 (493 430 247 to 547 988 635) new cases in 2017. During this time, age-standardised incidence decreased non-significantly from 6824 (6534 to 7147) to 6763 (6412 to 7118) per 100 000. Between 1990 and 2017, age-standardised DALYs decreased from 4947 (4655 to 5233) per 100 000 to 3267 (3058 to 3505). Interpretation: Injuries are an important cause of health loss globally, though mortality has declined between 1990 and 2017. Future research in injury burden should focus on prevention in high-burden populations, improving data collection and ensuring access to medical care.publishedVersio

Adolescent transport and unintentional injuries: a systematic analysis using the Global Burden of Disease Study 2019

Bill & Melinda Gates FoundationpublishedVersio