4,712 research outputs found
The fast sampling algorithm for Lie-Trotter products
A fast algorithm for path sampling in path integral Monte Carlo simulations
is proposed. The algorithm utilizes the Levy-Ciesielski implementation of
Lie-Trotter products to achieve a mathematically proven computational cost of
n*log_2(n) with the number of time slices n, despite the fact that each path
variable is updated separately, for reasons of optimality. In this respect, we
demonstrate that updating a group of random variables simultaneously results in
loss of efficiency.Comment: 4 pages, 1 figure; fast rejection from Phys. Rev. Letts; transfered
to PRE as a Rapid Communication. Eq. 6 to 10 contained some inconsistencies
that have been repaired in the present version; A sample code implementing
the algorithm for LJ clusters is available from the author upon reques
Low-noise high-voltage DC power supply for nanopositioning applications
Nanopositioning techniques currently applied to characterize physical
properties of materials interesting for applications at the microscopic scale
rely on high-voltage electronic control circuits that should have the lowest
possible noise level. Here we introduce a simple, flexible, and custom-built
power supply circuit that can provide +375\,V with a noise level below 10\,ppm.
The flexibility of the circuit comes from its topology based on discrete MOSFET
components that can be suitable replaced in order to change the polarity as
well as the output voltage and current.Comment: 3 pages, 2 figure
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