Dual barrier InAlN/AlGaN/GaN-on-silicon high-electron-mobility transistors with Pt and Ni based gate stacks

In this work, we report the performance of 3 μm gate length "dual barrier„ InAlN/AlGaN/GaN HEMTs on Si substrates with gate-drain contact separations in the range 4-26 μm. Devices with Pt and Ni based gates were studied and their leakage characteristics are compared. Maximum drain current IDS of 1 A/mm, maximum extrinsic transconductance gm ~203 mS/mm and on-resistance Ron 4.07 Ω mm for gate to drain distance LGD = 4 μm were achieved. Nearly ideal sub-threshold swing of 65.6 mV/dec was obtained for LGD = 14 μm. The use of Pt based gate metal stacks led to a two to three orders of magnitude gate leakage current decrease compared to Ni based gates. The influence of InAlN layer thickness on the transistor transfer characteristics is also discussed

Probing Gravity with Spacetime Sirens

A gravitational observatory such as LISA will detect coalescing pairs of massive black holes, accurately measure their luminosity distance and help identify a host galaxy or an electromagnetic counterpart. If dark energy is a manifestation of modified gravity on large scales, gravitational waves from cosmologically-distant spacetime sirens are direct probes of this new physics. For example, a gravitational Hubble diagram based on black hole pair luminosity distances and host galaxy redshifts could reveal a large distance extra-dimensional leakage of gravity. Various additional signatures may be expected in a gravitational signal propagated over cosmological scales.Comment: 11 pages, 1 figure, accepted for publication in ApJ Letter

Study on problems in detecting plural cracks by alternating flux leakage testing using 3D nonlinear eddy current analysis

The alternating magnetic flux leakage testing is used for the detection of cracks in a steel plate. A new technique of how to detect plural cracks, which are located at a very short distance from each other, using the parallel (x-) component of the leakage flux density is proposed. The behavior of leakage flux is examined using a three-dimensional edge-based hexahedral finite-element method. The effects of dimensions of search coils and cracks on the detection accuracy are illustrated. </p

A fast and robust approach to long-distance quantum communication with atomic ensembles

Quantum repeaters create long-distance entanglement between quantum systems while overcoming difficulties such as the attenuation of single photons in a fiber. Recently, an implementation of a repeater protocol based on single qubits in atomic ensembles and linear optics has been proposed [Nature 414, 413 (2001)]. Motivated by rapid experimental progress towards implementing that protocol, here we develop a more efficient scheme compatible with active purification of arbitrary errors. Using similar resources as the earlier protocol, our approach intrinsically purifies leakage out of the logical subspace and all errors within the logical subspace, leading to greatly improved performance in the presence of experimental inefficiencies. Our analysis indicates that our scheme could generate approximately one pair per 3 minutes over 1280 km distance with fidelity (F>78%) sufficient to violate Bell's inequality.Comment: 10 pages, 4 figures, 5 tables (Two appendixes are added to justify two claims used in the maintext.

Maximum Likelihood Decoding for Multilevel Channels With Gain and Offset Mismatch

Immink and Weber recently defined and studied a channel with both gain and offset mismatch, modeling the behavior of charge-leakage in flash memory. They proposed a decoding measure for this channel based on minimizing Pearson distance (a notion from cluster analysis). This paper derives a formula for maximum likelihood decoding for this channel, and also defines and justifies a notion of minimum distance of a code in this context

On the relation between Differential Privacy and Quantitative Information Flow

Differential privacy is a notion that has emerged in the community of statistical databases, as a response to the problem of protecting the privacy of the database's participants when performing statistical queries. The idea is that a randomized query satisfies differential privacy if the likelihood of obtaining a certain answer for a database $x$ is not too different from the likelihood of obtaining the same answer on adjacent databases, i.e. databases which differ from $x$ for only one individual. Information flow is an area of Security concerned with the problem of controlling the leakage of confidential information in programs and protocols. Nowadays, one of the most established approaches to quantify and to reason about leakage is based on the R\'enyi min entropy version of information theory. In this paper, we analyze critically the notion of differential privacy in light of the conceptual framework provided by the R\'enyi min information theory. We show that there is a close relation between differential privacy and leakage, due to the graph symmetries induced by the adjacency relation. Furthermore, we consider the utility of the randomized answer, which measures its expected degree of accuracy. We focus on certain kinds of utility functions called "binary", which have a close correspondence with the R\'enyi min mutual information. Again, it turns out that there can be a tight correspondence between differential privacy and utility, depending on the symmetries induced by the adjacency relation and by the query. Depending on these symmetries we can also build an optimal-utility randomization mechanism while preserving the required level of differential privacy. Our main contribution is a study of the kind of structures that can be induced by the adjacency relation and the query, and how to use them to derive bounds on the leakage and achieve the optimal utility