  Significant progress has been made with multipartite entanglement of discrete
qubits, but continuous variable systems may provide a more scalable path toward
entanglement of large ensembles. We demonstrate multipartite entanglement in a
microwave frequency comb generated by a Josephson parametric amplifier subject
to a bichromatic pump. We find 64 correlated modes in the transmission line
using a multifrequency digital signal processing platform. Full inseparability
is verified in a subset of seven modes. Our method can be expanded to generate
even more entangled modes in the near future.
