Systems and methods for multiplexing two or more channels of a quantum key distribution (QKD) system are disclosed. A method includes putting the optical public channel signal (SP1) in return-to-zero (RZ) format in a transmitter (T) in one QKD station (Alice) and amplifying this signal (thereby forming SP1*) just prior to this signal being detected with a detector (30) in a receiver (R) at the other QKD station (Bob). The method further includes precisely gating the detector via a gating element (40) and a coincident signal (PN1′) with pulses that coincide with the expected arrival times of the pulses in the detected (electrical) public channel signal (SP2). This allows for the public channel signal to have much less power, making it more amenable for multiplexing with the other QKD signals.