  A combined ferrite parametric amplifier and millimeter-wave homodyne
interferometer are proposed as an ambient temperature Bell Test. It is shown
that the non-linear magnetic susceptibility of the yttrium iron garnet (YIG)
ferrite, on account of its narrow line-width Larmor precessional resonance,
make it an ideal material for the creation of entangled photons. These can be
measured using a homodyne interferometer, as the much larger number of
thermally generated photons associated with ambient temperature emission can be
screened out. The proposed architecture may enable YIG quantum technology-based
sensors to be developed, mimicking in the millimeter-wave band the large number
of quantum optical experiments in the near-infrared and visible regions which
had been made possible by use of the nonlinear beta barium borate
ferroelectric, an analogue of YIG. It is illustrated here how the YIG
parametric amplifier can reproduce quantum optical Type I and Type II wave
interactions, which can be used to create entangled photons in the
millimeter-wave band. It is estimated that when half a cubic centimeter of YIG
crystal is placed in a magnetic field of a few Tesla and pumped with 5 Watts of
millimeter-wave radiation, approximately 0.5x10^12 entangled millimeter-wave
photon pairs per second are generated by the spin-wave interaction. This means
an integration time of only a few tens of seconds is needed for a successful
Bell Test. A successful demonstration of this will lead to novel architectures
of entanglement-based quantum technology room temperature sensors,
re-envisioning YIG as a modern quantum material.
