99 research outputs found
Effects of Disorder on Electron Transport in Arrays of Quantum Dots
We investigate the zero-temperature transport of electrons in a model of
quantum dot arrays with a disordered background potential. One effect of the
disorder is that conduction through the array is possible only for voltages
across the array that exceed a critical voltage . We investigate the
behavior of arrays in three voltage regimes: below, at and above the critical
voltage. For voltages less than , we find that the features of the
invasion of charge onto the array depend on whether the dots have uniform or
varying capacitances. We compute the first conduction path at voltages just
above using a transfer-matrix style algorithm. It can be used to
elucidate the important energy and length scales. We find that the geometrical
structure of the first conducting path is essentially unaffected by the
addition of capacitive or tunneling resistance disorder. We also investigate
the effects of this added disorder to transport further above the threshold. We
use finite size scaling analysis to explore the nonlinear current-voltage
relationship near . The scaling of the current near ,
, gives similar values for the effective exponent
for all varieties of tunneling and capacitive disorder, when the current is
computed for voltages within a few percent of threshold. We do note that the
value of near the transition is not converged at this distance from
threshold and difficulties in obtaining its value in the limit
Understanding ML driven HPC: Applications and Infrastructure
We recently outlined the vision of "Learning Everywhere" which captures the
possibility and impact of how learning methods and traditional HPC methods can
be coupled together. A primary driver of such coupling is the promise that
Machine Learning (ML) will give major performance improvements for traditional
HPC simulations. Motivated by this potential, the ML around HPC class of
integration is of particular significance. In a related follow-up paper, we
provided an initial taxonomy for integrating learning around HPC methods. In
this paper, which is part of the Learning Everywhere series, we discuss "how"
learning methods and HPC simulations are being integrated to enhance effective
performance of computations. This paper identifies several modes ---
substitution, assimilation, and control, in which learning methods integrate
with HPC simulations and provide representative applications in each mode. This
paper discusses some open research questions and we hope will motivate and
clear the ground for MLaroundHPC benchmarks.Comment: Invited talk to "Visionary Track" at IEEE eScience 2019. arXiv admin
note: text overlap with arXiv:1806.04731 by other author
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