Two-stage Kondo effect in a four-electron artificial atom

An artificial atom with four electrons is driven through a singlet-triplet transition by varying the confining potential. In the triplet, a Kondo peak with a narrow dip at drain-source voltage V_ds=0 is observed. The low energy scale V_ds* characterizing the dip is consistent with predictions for the two-stage Kondo effect. The phenomenon is studied as a function of temperature T and magnetic field B, parallel to the two-dimensional electron gas. The low energy scales T* and B* are extracted from the behavior of the zero-bias conductance and are compared to the low energy scale V_ds* obtained from the differential conductance. Good agreement is found between kT* and |g|muB*, but eV_ds* is larger, perhaps because of nonequilibrium effects.Comment: 7 pages, 7 figures. Added labels on Fig. 3f and one referenc

The visibility study of S-T+_+ Landau-Zener-St\"uckelberg oscillations without applied initialization

Probabilities deduced from quantum information studies are usually based on averaging many identical experiments separated by an initialization step. Such initialization steps become experimentally more challenging to implement as the complexity of quantum circuits increases. To better understand the consequences of imperfect initialization on the deduced probabilities, we study the effect of not initializing the system between measurements. For this we utilize Landau-Zener-St\"uckelberg oscillations in a double quantum dot circuit. Experimental results are successfully compared to theoretical simulations.Comment: 8 pages, 5 figure

Detecting intraday periodicities with application to high frequency exchange rates

Many recent papers have documented periodicities in returns, return volatility, bid–ask spreads and trading volume, in both equity and foreign exchange markets. We propose and employ a new test for detecting subtle periodicities in time series data based on a signal coherence function. The technique is applied to a set of seven half-hourly exchange rate series. Overall, we find the signal coherence to be maximal at the 8-h and 12-h frequencies. Retaining only the most coherent frequencies for each series, we implement a trading rule that is based on these observed periodicities. Our results demonstrate in all cases except one that, in gross terms, the rules can generate returns that are considerably greater than those of a buy-and-hold strategy, although they cannot retain their profitability net of transactions costs. We conjecture that this methodology could constitute an important tool for financial market researchers which will enable them to detect, quantify and rank the various periodic components in financial data better

Quantum interference and phonon-mediated back-action in lateral quantum dot circuits

Spin qubits have been successfully realized in electrostatically defined, lateral few-electron quantum dot circuits. Qubit readout typically involves spin to charge information conversion, followed by a charge measurement made using a nearby biased quantum point contact. It is critical to understand the back-action disturbances resulting from such a measurement approach. Previous studies have indicated that quantum point contact detectors emit phonons which are then absorbed by nearby qubits. We report here the observation of a pronounced back-action effect in multiple dot circuits where the absorption of detector-generated phonons is strongly modified by a quantum interference effect, and show that the phenomenon is well described by a theory incorporating both the quantum point contact and coherent phonon absorption. Our combined experimental and theoretical results suggest strategies to suppress back-action during the qubit readout procedure.Comment: 25 pages, 8 figure

Community Outreach through Genomics Education Partnership

The J Craig Venter Institute (JCVI) has recently partnered with undergraduate university faculty to expand the scope of education and outreach program as part of the NIAID’s BRC initiative, by joining forces with faculty members participating in the Genomics Education Partnership (GEP). The goal of the GEP is to provide opportunities for undergraduate students to participate in genomics research and gain hands on experience. Faculty members trained on annotation methodologies and tools during the Prokaryotic Annotation Workshop conducted at JCVI, impart their knowledge in the classroom as part of the semester course. As a pilot project, we are currently collaborating with 3 groups lead by a faculty member, spread across 3 universities in the community curation of bacterial genomes. Each participating undergraduate group collectively annotates a specific bacterial genome that was sequenced at JCVI and run through the automatic annotation pipeline. Remote access to genome sequence data, pre-computed gene predictions, search results, automatic annotation and bioinformatics analysis is provided through our web-based manual annotation tool, MANATEE. The students log into JCVI genome databases with user specific ids and password and learn to annotate single genes, entire metabolic pathways leading to analysis of a question that may be unique to the genome being analyzed. Users of the genome data receive dedicated support and guidance from our in house annotation experts on the usage of JCVI’s tools and annotation methodologies. Through this exercise, the undergraduate students are introduced to concepts of genomics and bioinformatics and gain deeper understanding of the concepts of cellular metabolism and disease pathology, which may lead them to making scientific research their career path. Some groups are focusing on genome specific pathways and plan to conduct wet lab experiments to understand unique genome features. We are highly encouraged that this model of web based, remote access, community annotation has been successful and propose to leverage the community of annotators to update annotations of pathogen genomes in Pathema-BRC

Comparing Wireless Traffic Tracking with Regular Traffic Control Systems for the Detection of Congestions in Streets

Detecting congestions on streets is one of the main issues in the area of smart cities. Regular monitoring methods can supply information about the number of vehicles in transit and thus the saturation of the streets, but they are usually expensive and intrusive with respect to the road. In recent years a new trend in traffic detection has arisen, considering the Wireless signals emitted by ‘smart’ on-board devices for counting and tracking vehicles. In this paper, two traffic monitoring methods are compared: detections using a regular Inductive Loop Detector on the road and an own Wireless Tracking System based on Bluetooth detection called Mobywit. The correlation between the day of the week and the hour with the traffic flow in a metropolitan busy street has been analysed. Assuming that our system is not able to defect all the vehicles, but just only subset of them, it is expected a causality between the results obtained using the two methods. This means, that the Bluetooth-based system can detect the same variations in the traffic flow that the regular loop detector, but having two main advantages: the tracking possibilities and a much lower cost.This work has been supported in part by project MOSOS (reference PRY142/14), which has been granted by Fundación Pública Andaluza Centro de Estudios An- daluces in the call `IX Convocatoria de Proyectos de Investigación'. It also has been partially funded by national projects TIN2014-56494-C4-3-P and TEC2015- 68752 (Spanish Ministry of Economy and Competitiveness), PROY-PP2015-06 (Plan Propio 2015 UGR), and project CEI2015-MP-V17 of the Microprojects program 2015 from CEI BioTIC Granada

Macroeconometric Modelling with a Global Perspective

This paper provides a synthesis and further development of a global modelling approach introduced in Pesaran, Schuermann and Weiner (2004), where country specific models in the form of VARX* structures are estimated relating a vector of domestic variables to their foreign counterparts and then consistently combined to form a Global VAR (GVAR). It is shown that VARX* models can be derived as the solution to a dynamic stochastic general equilibrium (DSGE) model where over-identifying long-run theoretical relations can be tested and imposed if acceptable. Similarly, short-run over-identifying theoretical restrictions can be tested and imposed if accepted. The assumption of the weak exogeneity of the foreign variables for the long-run parameters can be tested, where foreign variables can be interpreted as proxies for global factors. Rather than using deviations from ad hoc statistical trends, the equilibrium values of the variables reflecting the long-run theory embodied in the model can be calculated

Influence of the amount of fine particles on rheological properties of uranium dioxide powders

International audienc