  Quarkonium at finite temperature is described as an open quantum system whose
dynamics are determined by a potential $V_R({\bf x})$ and drag coefficient
$\eta$, using a path integral with a non-local term. Path-integral Monte Carlo
calculations determine the Euclidean Green function for this system to an
accuracy greater than one part in a thousand and the maximum entropy method is
used to determine the spectral function; challenges facing any kind of
deconvolution are discussed in detail with the aim of developing intuition for
when deconvolution is possible. Significant changes to the quarkonium spectral
function in the $1S$ channel are found, suggesting that any description of
quarkonium at finite temperature, using a potential, must also carefully
consider the effect of dissipation.
