  We outline a new class of continuous-variable graph states that can be useful
to describe entangle- ment, and also multimode squeezing, in an optical
frequency comb. We show that a particular case of such states coincides with
the squeezing of the carrier-envelope phase, or of the total intensity, of a
mode-locked laser. We then discuss the experimental issues related to measuring
the quantum noise of the carrier-envelope phase of a frequency comb and show
that this can be carried out by use of quantum heterodyne multiplexing, a
technique that may be useful to measure multipartite entanglement as well.
