  We use gauge/string duality to investigate the free energy of two static
color sources (a heavy quark-antiquark pair) in a Yang-Mills theory in strongly
interacting matter, varying temperature and chemical potential. The dual space
geometry is Anti-de Sitter with a charged black-hole to describe finite
temperature and density in the boundary theory, and we also include a
background dilaton field to generate confinement. The resulting phase diagram
in the chemical potential-temperature $\mu-T$ plane is in a quite good
agreement with lattice results and effective models of QCD.
