  LiOsO$_3$ has been recently identified as the first unambiguous
"ferroelectric metal", experimentally realizing a prediction from 1965 by
Anderson and Blount. In this work, we investigate the metallic state in
LiOsO$_3$ by means of infrared spectroscopy supplemented by Density Functional
Theory and Dynamical Mean Field Theory calculations. Our measurements and
theoretical calculations clearly show that LiOsO$_3$ is a very bad metal with a
small quasiparticle weight, close to a Mott-Hubbard localization transition.
The agreement between experiments and theory allows us to ascribe all the
relevant features in the optical conductivity to strong electron-electron
correlations within the $t_{2g}$ manifold of the osmium atoms.

Strongly Correlated Electrons