Mechanical control of spin-orbit splitting in GaAs and InGaAs epilayers

Time-resolved Kerr rotation spectroscopy as a function of pump-probe distance, voltage and magnetic field is used to measure the momentum-dependent spin splitting energies in GaAs and InGaAs epilayers. The strain of the samples can be reproducibly controlled in the cryostat using three- and four-point bending applied with a mechanical vise. We find that the magnitude of the spin splitting increases linearly with applied tension and voltage. A strain-drift diffusion model is used to relate the magnitude of the measured spin-orbit splitting to the amount of strain in the sample.Comment: 4 pages, 5 figure

Pinning a Domain Wall in (Ga,Mn)As with Focused Ion Beam Lithography

We utilize a focused beam of Ga+ ions to define magnetization pinning sites in a ferromagnetic epilayer of (Ga,Mn)As. The nonmagnetic defects locally increase the magneto-crystalline anisotropy energies, by which a domain wall is pinned at a given position. We demonstrate techniques for manipulating domain walls at these pinning sites as probed with the giant planar Hall effect (GPHE). By varying the magnetic field angle relative to the crystal axes, an upper limit is placed on the local effective anisotropy energy.Comment: 13 pages, 3 figure

Introducing v0.5 of the AI Safety Benchmark from MLCommons

This paper introduces v0.5 of the AI Safety Benchmark, which has been created by the MLCommons AI Safety Working Group. The AI Safety Benchmark has been designed to assess the safety risks of AI systems that use chat-tuned language models. We introduce a principled approach to specifying and constructing the benchmark, which for v0.5 covers only a single use case (an adult chatting to a general-purpose assistant in English), and a limited set of personas (i.e., typical users, malicious users, and vulnerable users). We created a new taxonomy of 13 hazard categories, of which 7 have tests in the v0.5 benchmark. We plan to release version 1.0 of the AI Safety Benchmark by the end of 2024. The v1.0 benchmark will provide meaningful insights into the safety of AI systems. However, the v0.5 benchmark should not be used to assess the safety of AI systems. We have sought to fully document the limitations, flaws, and challenges of v0.5. This release of v0.5 of the AI Safety Benchmark includes (1) a principled approach to specifying and constructing the benchmark, which comprises use cases, types of systems under test (SUTs), language and context, personas, tests, and test items; (2) a taxonomy of 13 hazard categories with definitions and subcategories; (3) tests for seven of the hazard categories, each comprising a unique set of test items, i.e., prompts. There are 43,090 test items in total, which we created with templates; (4) a grading system for AI systems against the benchmark; (5) an openly available platform, and downloadable tool, called ModelBench that can be used to evaluate the safety of AI systems on the benchmark; (6) an example evaluation report which benchmarks the performance of over a dozen openly available chat-tuned language models; (7) a test specification for the benchmark

Introducing v0.5 of the AI Safety Benchmark from MLCommons

This paper introduces v0.5 of the AI Safety Benchmark, which has been created by the MLCommons AI Safety Working Group. The AI Safety Benchmark has been designed to assess the safety risks of AI systems that use chat-tuned language models. We introduce a principled approach to specifying and constructing the benchmark, which for v0.5 covers only a single use case (an adult chatting to a general-purpose assistant in English), and a limited set of personas (i.e., typical users, malicious users, and vulnerable users). We created a new taxonomy of 13 hazard categories, of which 7 have tests in the v0.5 benchmark. We plan to release version 1.0 of the AI Safety Benchmark by the end of 2024. The v1.0 benchmark will provide meaningful insights into the safety of AI systems. However, the v0.5 benchmark should not be used to assess the safety of AI systems. We have sought to fully document the limitations, flaws, and challenges of v0.5. This release of v0.5 of the AI Safety Benchmark includes (1) a principled approach to specifying and constructing the benchmark, which comprises use cases, types of systems under test (SUTs), language and context, personas, tests, and test items; (2) a taxonomy of 13 hazard categories with definitions and subcategories; (3) tests for seven of the hazard categories, each comprising a unique set of test items, i.e., prompts. There are 43,090 test items in total, which we created with templates; (4) a grading system for AI systems against the benchmark; (5) an openly available platform, and downloadable tool, called ModelBench that can be used to evaluate the safety of AI systems on the benchmark; (6) an example evaluation report which benchmarks the performance of over a dozen openly available chat-tuned language models; (7) a test specification for the benchmark

Mechanical control of spin-orbit splitting in GaAs and In0.04Ga0.96As epilayers

Time-resolved Kerr rotation spectroscopy as a function of pump-probe distance, voltage, and magnetic field is used to measure the momentum-dependent spin splitting energies in GaAs and InGaAs epilayers. The strain of the samples can be reproducibly controlled in the cryostat using three- and four-point bending applied with a mechanical vise. We find that the magnitude of the spin splitting increases linearly with applied tension and voltage. A strain-drift-diffusion model is used to determine the value of the spin-strain coupling coefficient for a strained GaAs epilayer

Implementation of Prototype Building Blocks for Value Added Services (VAS) in a Digital Broadcasting Standard Final report

DDB (Digital Data Broadcasting) is an extension of the already existing progressive DAB broadcasting system. It is based on the standard, which has been elaborated within the europroject EUREKA147 and it opens up a wide range of value added data services. New services, which have not been possible in previous broadcasting systems, are to increase the acceptance of the new system in order to make possible a wide introduction of DAB in the future. Therefore it is essential to make DAB receivers available both at high quantities and at reasonable prices. The realization of combined audio-data receivers is only practicable by use of highly integrated, application specific, monolithically integrated circuits (ASICs). This is due to the fact that the DAD/DDB techniques apply highly sophisticated real time algorithms. Furthermore the tasks which have to be done within the project are of such extent and of such various kind, that they are only practicable in a consortium project. Within this consortium project the already manufactured test ASICs have been developed on with regard to even higher functionality, realized, and tested. In the analog part of the receiver the integrated bipolar circuits have been extended by additional functionality. Investigations with regard to an integration by use of gallium arsenide technology gave promising results. The digital signal processing algorithms have been accelerated by means of new architectures and extensions of the circuitry and have been adopted to the required higher data rates. The implementation of the data decoder as a program running on a signalprocessor offers high flexibility with respect to adaptation and expansion. Regarding the transmitter, investigations and computer simulations for the linearization of power amplifiers have been carried out in order to reach optimal usage of the limited frequency resources. The work carried out and its results are one step more paving the way to realize small size and low power DAB receivers. (orig.)Available from TIB Hannover: F98B90+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Implementation of prototype building blocks for a DAB standard Final report

DAB (Digital Audio Broadcasting) is a basically new development of a broadcasting system to be based on the standard elaborated within the Europroject EUREKA 147. With regard to a future wide introduction of DAB it is essential that DAB-receivers have to be made available as mass products at low unit costs. The DAB-technique applies highly sophisticated algorithms to be processed in real time. Therefore, the realization of such receivers is only feasible by means of highly integrated application specific monolitically integrated circuits (ASICs). Furthermore the problems to be solved are so extensive and of different kind that they can only be treated useful in an consortium project. Within the consortium project a set of test-ASICs has been developed, realized, and tryed which are the key components of the receiver (and partially also of the transmitter). Integrated bipolar circuits for the analog part of the receiver have been realized as prototypes which are characterized by high dynamic range, good noise properties, and low power consumption. The digital signal processing algorithms were processed by means of two highly integrated CMOS-circuits in combination with a signal processor. Based on these key components the realization of DAB-receivers having a volume of three litres and a power consumption of about 50 Watts was possible. Multimedia components will become more and more important in future, that is why a further reduction of volume and power consumption becomes esssential. (orig.)SIGLEAvailable from TIB Hannover: F97B1461+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman