4 research outputs found
A Scanning Electron Microscope for Ultracold Atoms
We propose a new technique for the detection of single atoms in ultracold
quantum gases. The technique is based on scanning electron microscopy and
employs the electron impact ionization of trapped atoms with a focussed
electron probe. Subsequent detection of the resulting ions allows for the
reconstruction of the atoms position. This technique is expected to achieve a
much better spatial resolution compared to any optical detection method. In
combination with the sensitivity to single atoms, it makes new in situ
measurements of atomic correlations possible. The detection principle is also
well suited for the addressing of individual sites in optical lattices.Comment: 5 pages, 2 figure
Markov Properties of Electrical Discharge Current Fluctuations in Plasma
Using the Markovian method, we study the stochastic nature of electrical
discharge current fluctuations in the Helium plasma. Sinusoidal trends are
extracted from the data set by the Fourier-Detrended Fluctuation analysis and
consequently cleaned data is retrieved. We determine the Markov time scale of
the detrended data set by using likelihood analysis. We also estimate the
Kramers-Moyal's coefficients of the discharge current fluctuations and derive
the corresponding Fokker-Planck equation. In addition, the obtained Langevin
equation enables us to reconstruct discharge time series with similar
statistical properties compared with the observed in the experiment. We also
provide an exact decomposition of temporal correlation function by using
Kramers-Moyal's coefficients. We show that for the stationary time series, the
two point temporal correlation function has an exponential decaying behavior
with a characteristic correlation time scale. Our results confirm that, there
is no definite relation between correlation and Markov time scales. However
both of them behave as monotonic increasing function of discharge current
intensity. Finally to complete our analysis, the multifractal behavior of
reconstructed time series using its Keramers-Moyal's coefficients and original
data set are investigated. Extended self similarity analysis demonstrates that
fluctuations in our experimental setup deviates from Kolmogorov (K41) theory
for fully developed turbulence regime.Comment: 25 pages, 9 figures and 4 tables. V3: Added comments, references,
figures and major correction