  We have experimentally confirmed the presence of long-memory correlations in
the wandering of a thin Gaussian laser beam over a screen after propagating
through a turbulent medium. A laboratory-controlled experiment was conducted in
which coordinate fluctuations of the laser beam were recorded at a sufficiently
high sampling rate for a wide range of turbulent conditions. Horizontal and
vertical displacements of the laser beam centroid were subsequently analyzed by
implementing detrended fluctuation analysis. This is a very well-known and
widely used methodology to unveil memory effects from time series. Results
obtained from this experimental analysis allow us to confirm that both
coordinates behave as highly persistent signals for strong turbulent
intensities. This finding is relevant for a better comprehension and modeling
of the turbulence effects in free-space optical communication systems and other
applications related to propagation of optical signals in the atmosphere.
