A Quantum Dense Coding System. The system includes a source, a transmitter and a receiver. The source is capable of down-converting a pump photon into a signal photon and an idler photon and outputting probability amplitudes, the signal photon and the idler photon, wherein the signal photon and the idler photon have an equal probability of outputting to a transmission channel and a reception channel. The transmitter is capable of receiving probability amplitudes, signal photons and idler photons from the transmission channel; and selectively changing vertical and horizontal phases of probability amplitudes of signal photons and idler photons; and outputting probability amplitudes, signal photons and idler photons. The receiver is capable of receiving probability amplitudes, signal photons and idler photons from the reception channel and the transmitter; and identifying vertical and horizontal phase changes created by the transmitter. A method for the system is also described.