Abstract: A communication linker includes: a classical encoder; an optical transmitter; a receiver; a local oscillator in communication with the receiver and that: receives a feedback signal; and produces a displacement frequency, based on the feedback signal; a single photon detector in communication with the receiver and that: receives an optical signal from the receiver; and produces a single photon detector signal, based on the optical signal; a signal processor in communication with the single photon detector and that: receives the single photon detector signal from the single photon detector; produces the feedback signal, based on the single photon detector signal; and produces a decoded signal, based on the single photon detector signal, the decoded signal comprising a frequency of the feedback signal.