Hybrid communication assisted by coherent oscillator using resonant excitation of Nitrogen–vacancy center in diamond

We propose the multi-channel hybrid communication assisted by a coherent oscillator, by configuring the diamond Nitrogen–vacancy center using spontaneous parametric four-wave mixing. For one-channel hybrid communication, composite signal of fluorescence (information) and Stokes (carrier) is sent to the receiver; information is recovered by subtracting intensities of composite signal and reference coherent signal (from coherent oscillator) at demodulator. Further, we achieved two-channel and three-channel hybrid communication through two-mode and three-mode intensity–noise correlation, respectively. Two-mode correlation of hybrid signal (produced through photon subtraction) and anti-Stokes demonstrates the nonclassical behavior by violating Cauchy–Schwarz inequality, verified through corresponding squeezing (−5 dB). Such phenomenon of non-classical behavior was also verified by non-Gaussian negativity of Wigner function. Our hybrid communication model is based on temporal width- and coherence time-contrast, which can be controlled by wavelength (power) of input beams. The coherence time-contrast is about 90%.