High speed removal of bias of a homodyne detector using a clone local oscillator

A receiver comprising:

• a local oscillator (LO) configured to produce pulses comprising
• a train of primary pulses synchronized to a train of reference pulses transmitted by a transmitter over a quantum communication channel, and
• a train of secondary pulses, each secondary pulse being a clone LO pulse, wherein each primary pulse corresponds to one or more clone LO pulses from the train of secondary pulses, where the one or more clone LO pulses are timed to split a duty cycle of the train of primary pulses in an even number of equal time intervals;
• a homodyne detector configured to
• receive the reference pulses from the transmitter over the quantum communication channel,
• mix each reference pulse with a corresponding primary pulse, and
• output measurement signals comprising (i) reference measurements acquired with the primary pulses mixed with the references pulses, respectively and (ii) bias measurements acquired with respective one or more clone LO pulses for a primary pulse;
• and
• processing circuitry configured to remove bias from the reference measurements by subtracting from the reference measurements corresponding bias measurements.