  We study the Dicke phase transition in a disordered system of emitters
coupled to the plasmonic modes of a graphene monolayer. This system has unique
properties associated with the tunable, dissipative and broadband characters of
the graphene surface plasmons, as well as the disorder due to the random
spatial distribution and the inhomogeneous line-width broadening of the
emitters. We apply the Keldysh functional-integral approach, and identify a
normal phase, a superradiant phase and a spin-glass phase of the system. The
conditions for these phases and their experimental signatures are discussed.
