Efficient orthogonal control of tunnel couplings in a quantum dot array

Electrostatically-defined semiconductor quantum dot arrays offer a promising platform for quantum computation and quantum simulation. However, crosstalk of gate voltages to dot potentials and inter-dot tunnel couplings complicates the tuning of the device parameters. To date, crosstalk to the dot potentials is routinely and efficiently compensated using so-called virtual gates, which are specific linear combinations of physical gate voltages. However, due to exponential dependence of tunnel couplings on gate voltages, crosstalk to the tunnel barriers is currently compensated through a slow iterative process. In this work, we show that the crosstalk on tunnel barriers can be efficiently characterized and compensated for, using the fact that the same exponential dependence applies to all gates. We demonstrate efficient calibration of crosstalk in a quadruple quantum dot array and define a set of virtual barrier gates, with which we show orthogonal control of all inter-dot tunnel couplings. Our method marks a key step forward in the scalability of the tuning process of large-scale quantum dot arrays.Comment: 8 pages, 7 figure

A Study on Knowledge Sharing in Vietnamese Organizations

Knowledge sharing is very much a sign for the atmosphere of social interactions in the organizations, it depends on the quality of the conversation, formally or informally. In other words, for more effective knowledge sharing, communication competence is required in order to have appropriate conversation. During the past decades, most theories of communication competence have been developed on the basis of “western” conceptualization. This empirical research is conducted in order to study the organizational communication competence in a non-western country, Vietnam, and the effect of such competence to the employees’ knowledge sharing behavior respectively. Base on the data collected from 11 organizations, the effects of three culture dimensions, namely individualism, power distance, and uncertainty avoidance to the communication competence were statistically analyzed; then, stemming from the certain level of communication competence, the behavior of organizational members towards knowledge sharing was explaine

Collapsed 2-Dimensional Polymers on a Cylinder

Single partially confined collapsed polymers are studied in two dimensions. They are described by self-avoiding random walks with nearest-neighbour attractions below the $\Theta$-point, on the surface of an infinitely long cylinder. For the simulations we employ the pruned-enriched-Rosenbluth method (PERM). The same model had previously been studied for free polymers (infinite lattice, no boundaries) and for polymers on finite lattices with periodic boundary conditions. We verify the previous estimates of bulk densities, bulk free energies, and surface tensions. We find that the free energy of a polymer with fixed length $N$ has, for $N\to \infty$, a minimum at a finite cylinder radius $R^*$ which diverges as $T\to T_\theta$. Furthermore, the surface tension vanishes roughly as $(T_\theta-T)^\alpha$ for $T\to T_\theta$ with $\alpha\approx 1.7$. The density in the interior of a globule scales as $(T_\theta-T)^\beta$ with $\beta \approx 0.32$.Comment: 4 pages, 8 figure

Analysis of some localized boundary-domain integral equations for transmission problems with variable coefficients

This is the post-print version of the Article. The official published version can be found at the links below - Copyright @ 2011 Birkhäuser Boston.Some segregated systems of direct localized boundary-domain integral equations (LBDIEs) associated with several transmission problems for scalar PDEs with variable coefficients are formulated and analyzed for a bounded domain composed of two subdomains with a coefficient jump over the interface. The main results established in the paper are the LBDIE equivalence to the original transmission problems and the invertibility of the corresponding localized boundary-domain integral operators in corresponding Sobolev spaces function spaces.This research was supported by the EPSRC grant EP/H020497/1: ”Mathematical analysis of Localized Boundary-Domain Integral Equations for Variable-Coefficient Boundary Value Problems” and partly by the Georgian Technical University grant in the case of the third author