Public exhibit for demonstrating the quantum of electrical conductance

We present a new robust setup that explains and demonstrates the quantum of electrical conductance for a general audience and which is continuously available in a public space. The setup allows users to manually thin a gold wire of several atoms in diameter while monitoring its conductance in real time. During the experiment, a characteristic step-like conductance decrease due to rearrangements of atoms in the cross-section of the wire is observed. Just before the wire breaks, a contact consisting of a single atom with a characteristic conductance close to the quantum of conductance can be maintained up to several seconds. The setup is operated full-time, needs practically no maintenance and is used on different educational levels

How Different Medical School Selection Processes Call upon Different Personality Characteristics

BACKGROUND:Research indicates that certain personality traits relate to performance in the medical profession. Yet, personality testing during selection seems ineffective. In this study, we examine the extent to which different medical school selection processes call upon desirable personality characteristics in applicants. METHODS:1019 of all 1055 students who entered the Dutch Bachelor of Medicine at University of Groningen, the Netherlands in 2009, 2010 and 2011 were included in this study. Students were admitted based on either top pre-university grades (n = 139), acceptance in a voluntary multifaceted selection process (n = 286), or lottery weighted for pre-university GPA. Within the lottery group, we distinguished between students who had not participated (n = 284) and students who were initially rejected (n = 310) in the voluntary selection process. Two months after admission, personality was assessed with the NEO-FFI, a measure of the five factor model of personality. We performed ANCOVA modelling with gender as a covariate to examine personality differences between the four groups. RESULTS:The multifaceted selection group scored higher on extraversion than all other groups(p<0.01), higher on conscientiousness than both lottery-admitted groups(p<0.01), and lower on neuroticism than the lottery-admitted group that had not participated in the voluntary selection process. The latter group scored lower on conscientiousness than all other groups(p<0.05) and lower on agreeableness than the multifaceted selection group and the top pre-university group(p<0.01). CONCLUSIONS:Differences between the four admission groups, though statistically significant, were relatively small. Personality scores in the group admitted through the voluntary multifaceted selection process seemed most fit for the medical profession. Personality scores in the lottery-admitted group that had not participated in this process seemed least fit for the medical profession. It seems that in order to select applicants with suitable personalities, an admission process that calls upon desirable personality characteristics is beneficial

Manipulation of a single charge in a double quantum dot

We manipulate a single electron in a fully tunable double quantum dot using microwave excitation. Under resonant conditions, microwaves drive transitions between the (1,0) and (0,1) charge states of the double dot. Local quantum point contact charge detectors enable a direct measurement of the photon-induced change in occupancy of the charge states. From charge sensing measurements, we find T1~16 ns and a lower bound estimate for T2* of 400 ps for the charge two-level system.Comment: related articles at http://marcuslab.harvard.ed

Entanglement between charge qubits induced by a common dissipative environment

We study entanglement generation between two charge qubits due to the strong coupling with a common bosonic environment (Ohmic bath). The coupling to the boson bath is a source of both quantum noise (leading to decoherence) and an indirect interaction between qubits. As a result, two effects compete as a function of the coupling strength with the bath: entanglement generation and charge localization induced by the bath. These two competing effects lead to a non-monotonic behavior of the concurrence as a function of the coupling strength with the bath. As an application, we present results for charge qubits based on double quantum dots.Comment: 9 pages, 7 figure

Electromagnetically Induced Transparency with an Ensemble of Donor-Bound Electron Spins in a Semiconductor

We present measurements of electromagnetically induced transparency with an ensemble of donor- bound electrons in low-doped n-GaAs. We used optical transitions from the Zeeman-split electron spin states to a bound trion state in samples with optical densities of 0.3 and 1.0. The electron spin dephasing time T* \approx 2 ns was limited by hyperfine coupling to fluctuating nuclear spins. We also observe signatures of dynamical nuclear polarization, but find these effects to be much weaker than in experiments that use electron spin resonance and related experiments with quantum dots.Comment: 4 pages, 4 figures; Improved analysis of data in Fig. 3, corrected factors of 2 and p

The conceptual design of SeamFrame

This project deliverable provides the underlying architecture of a concept for linking models and databases and it provides the design of SeamFrame, delivering its architecture to provide an integration framework for models and simulation algorithms, supported by procedures for data handling and spatial representation, quality control, output visualization and documentatio

Partitioning of melt energy and meltwater fluxes in the ablation zone of the west Greenland ice sheet

We present four years (August 2003–August 2007) of surface mass balance data from the ablation zone of the west Greenland ice sheet along the 67&amp;deg; N latitude circle. Sonic height rangers and automatic weather stations continuously measured accumulation/ablation and near-surface climate at distances of 6, 38 and 88 km from the ice sheet margin at elevations of 490, 1020 and 1520 m a.s.l. Using a melt model and reasonable assumptions about snow density and percolation characteristics, these data are used to quantify the partitioning of energy and mass fluxes during melt episodes. The lowest site receives very little winter accumulation, and ice melting is nearly continuous in June, July and August. Due to the lack of snow accumulation, little refreezing occurs and virtually all melt energy is invested in runoff. Higher up the ice sheet, the ice sheet surface freezes up during the night, making summer melting intermittent. At the intermediate site, refreezing in snow consumes about 10% of the melt energy, increasing to 40% at the highest site. The sum of these effects is that total melt and runoff increase exponentially towards the ice sheet margin, each time doubling between the stations. At the two lower sites, we estimate that radiation penetration causes 20–30% of the ice melt to occur below the surface

Evaluation of Hoof Circumference to Predict Birth Weight

Records from 81 calves showed that hoof circumference is an unreliable predictor of birth weight. A hoof tape predicted only 25.9% of birth weights within 2 Ib of actual birth weight. For 29.6% of the calves the error in predicting birth weight was over 10 Ib