Entangling continuous variables with a qubit array. (arXiv:1903.06285v1 [quant-ph])

We show that an array of qubits embedded in a waveguide can emit entangled
pairs of microwave photon beams. The quadratures obtained from a homodyne
detection of these outputs beams form a pair of correlated continuous variables
similarly to the EPR experiment. The photon pairs are produced by the decay of
plasmon-like collective excitations in the qubit array. The maximum intensity
of the resulting beams is only bounded by the number of emitters. We calculate
the excitation decay rate both into a continuum of photon state and into a
one-mode cavity. We also determine the frequency of Rabi-like oscillations
resulting from a detuning.