Two-mode squeezing generation in hybrid chains of superconducting resonators and nitrogen-vacancy-center ensembles

We consider a hybrid quantum system consisting of two independent chains of nearest-neighbor linearly interacting superconducting transmission-line resonators, each of which a nitrogenvacancy-center ensemble (NVE) is magnetically coupled to. In addition, the first-beginning pair of the resonators is locally driven by a two-mode microwave squeezed bath. We show that in the steady state a series of NVE pairs in the up and down chains is in a two-mode spin squeezed state. In the low excitation limit, collective excitation modes of the up-and down-NVE pairs are in the two-mode squeezed state of the driven field, i.e., realizing a perfect squeezed state replication.