The Juridical Status of Privileged Combatants Under the Geneva Protocol of 1977 Concerning International Conflicts

Centralized control and coordination of the connections in a wireless network is not possible in practice. To keep the delay from measure-ment instants to actuating the decisions, distributed control is required. This paper focuses on the uplink (from mobiles to base stations) and dis-cusses distributing the decision of when and when not to transmit data (distributed scheduling) to the mobiles. The scheme, uplink transmission timing, utilizes mobile transmitter power control feedback from the base station receiver to determine whether the channel is favorable or not compared to the average channel condition. Thereby, the battery consumption and disturbing power to other connections are reduced. The algorithm can be described as a feedback control system. Some transient behaviors are analyzed using systems theory, and supported by wireless network simulations of a system with a WCDMA (Wideband Code Division Multiple Access) radio interface as in most 3G systems

Dielectric losses in multi-layer Josephson junction qubits

We have measured the excited state lifetimes in Josephson junction phase and transmon qubits, all of which were fabricated with the same scalable multi-layer process. We have compared the lifetimes of phase qubits before and after removal of the isolating dielectric, SiNx, and find a four-fold improvement of the relaxation time after the removal. Together with the results from the transmon qubit and measurements on coplanar waveguide resonators, these measurements indicate that the lifetimes are limited by losses from the dielectric constituents of the qubits. We have extracted the individual loss contributions from the dielectrics in the tunnel junction barrier, AlOx, the isolating dielectric, SiNx, and the substrate, Si/SiO2, by weighing the total loss with the parts of electric field over the different dielectric materials. Our results agree well and complement the findings from other studies, demonstrating that superconducting qubits can be used as a reliable tool for high-frequency characterization of dielectric materials. We conclude with a discussion of how changes in design and material choice could improve qubit lifetimes up to a factor of four.Comment: 10 pages, 4 figures,and 4 table

Traceable Coulomb Blockade Thermometry

We present a measurement and analysis scheme for determining traceable thermodynamic temperature at cryogenic temperatures using Coulomb blockade thermometry. The uncertainty of the electrical measurement is improved by utilizing two sampling digital voltmeters instead of the traditional lock-in technique. The remaining uncertainty is dominated by that of the numerical analysis of the measurement data. Two analysis methods are demonstrated: numerical fitting of the full conductance curve and measuring the height of the conductance dip. The complete uncertainty analysis shows that using either analysis method the relative combined standard uncertainty (k = 1) in determining the thermodynamic temperature in the temperature range from 20 mK to 200 mK is below 0.5 %. In this temperature range, both analysis methods produced temperature estimates that deviated from 0.39 % to 0.67 % from the reference temperatures provided by a superconducting reference point device calibrated against the Provisional Low Temperature Scale of 2000.Comment: 11 page

Vibronic spectroscopy of an artificial molecule

With advanced fabrication techniques it is possible to make nanoscale electronic structures that have discrete energy levels. Such structures are called artificial atoms because of analogy with true atoms. Examples of such atoms are quantum dots in semiconductor heterostructures and Josephson-junction qubits. It is also possible to have artificial atoms interacting with each other. This is an artificial molecule in the sense that the electronic states are analogous to the ones in a molecule. In this letter we present a different type of artificial molecule that, in addition to electronic states, also includes the analog of nuclear vibrations in a diatomic molecule. Some of the earlier experiments could be interpreted using this analogy, including qubits coupled to oscillators and qubits driven by an intense field. In our case the electronic states of the molecule are represented by a Josephson-junction qubit, and the nuclear separation corresponds to the magnetic flux in a loop containing the qubit and an LC oscillator. We probe the vibronic transitions, where both the electronic and vibrational states change simultaneously, and find that they are analogous to true molecules. The vibronic transitions could be used for sideband cooling of the oscillator, and we see damping up to sidebands of order 10.Comment: 5 pages, 4 figure

Enhancing Tc in field-doped Fullerenes by applying uniaxial stress

Capitalizing on the two-dimensional nature of superconductivity in field-effect doped C60, we show that it should be possible to increase the transition temperature Tc by applying uniaxial stress perpendicular to the gate electrode. This method not only holds the promise of substantially enhancing Tc (by about 30 K per GPa), but also provides a sensitive check of the current understanding of superconductivity in the doped Fullerenes.Comment: 3 pages RevTe

Integration techniques of pHEMTs and planar Gunn diodes on GaAs substrates

This work presents two different approaches for the implementation of pseudomorphic high electron mobility transistors (pHEMTs) and planar Gunn diodes on the same gallium arsenide substrate. In the first approach, a combined wafer is used where a buffer layer separates the active layers of the two devices. A second approach was also examined using a single wafer where the AlGaAs/InGaAs/GaAs heterostructures were designed for the realisation of pHEMTs. The comparison between the two techniques showed that the devices fabricated on the single pHEMT wafer presented superior performance over the combined wafer technique. The DC and small-signal characteristics of the pHEMTs on the single wafer were enhanced after the use of T-gates with 70 nm length. The maximum transconductance of the transistors was equal to 780 mS/mm with 200 GHz maximum frequency of oscillation (fmax). Planar Gunn diodes fabricated in the pHEMT wafer, with 1.3 μm anode-to-cathode separation (LAC) presented oscillations at 87.6 GHz with maximum power of oscillation equal to -40 dBm

Shot noise of a multiwalled carbon nanotube field effect transistor

We have investigated shot noise in a 6−nm-diameter, semiconducting multiwalled carbon nanotube field effect transistor at 4.2 K over the frequency range of 600–950 MHz. We find a transconductance of 3–3.5 μS for optimal positive and negative source-drain voltages V. For the gate referred input voltage noise, we obtain 0.2 and 0.3 μV/√Hz for V > 0 and V < 0, respectively. As effective charge noise, this corresponds to (2–3)×10 exp −5 e/√Hz.Peer reviewe

Temporal and Spatial Positioning of Service Crops in Cereals Affects Yield and Weed Control

Leguminous service crops (SCs) can provide multiple services to cropping systems, reducing the reliance on external resources if sufficient biomass is produced. However, rapid light and temperature reductions limit post-harvest cultivation of SCs in Northern Europe. A novel practice of intercropping SCs in two consecutive crops (spring-winter cereal) to extend the period of SCs growth, and hence improve yield and reduce weeds, was tested. Three spatial and temporal arrangements of SCs and cash crops were investigated, as well as three SC mixtures, characterized by their longevity and frost sensitivity. Compared to no SC, the best performing mixture, frost-tolerant annuals, increased grain and N yield of winter wheat by 10% and 19%, respectively, and reduced weed biomass by 15% and 26% in oats and winter wheat, respectively. These effects were attributed to high biomass production and winter survival. However, this SC reduced oat yields by 15% compared to no SC. Furthermore, SC growth and service provision varied largely between experiments, driven by the weather conditions. Extending the SC's growth period by intercropping in two consecutive cereal crops has potential, but locally adapted species choices and establishment strategies are needed to ensure SC vitality until termination