  We provide a brief survey of quantum statistical characterisations of order,
disorder and coherence in systems of many degrees of freedom. Here, order and
coherence are described in terms of symmetry breakdown, while disorder is
described in terms of entropy and algorithmic complexity, whose interconnection
has been recently extended from the classical to the quantum domain. We see
that, in the present physical context, the concepts of order and disorder are
not mutually antithetical, but bear an interrelationship similar to that
between signals and noise.
