Rasterized qubit delivery in photonic circuits

A system comprising:

• a qubit delivery circuit configured to selectably deliver a photonic qubit on an active delivery path selected from a plurality of delivery paths, the plurality of delivery paths including a first subset of delivery paths having a number (R) of delivery paths and a second subset of delivery paths having the number R of delivery paths, wherein R is at least 2;
• and
• a plurality of downstream circuits, each downstream circuit having a first input port and a second input port;
• a first optical switching circuit having a set of R input paths coupled to the first subset of the delivery paths and a plurality of output paths coupled to the first input ports of the downstream circuits via delay circuits that introduce different amounts of delay;
• a second optical switching circuit having a set of R input paths coupled to the second subset of the delivery paths and a plurality of output paths coupled to the second input ports of the downstream circuits;
• and
• control logic circuitry coupled to the qubit delivery circuit, the first optical switching circuit, and the second optical switching circuit and configured to:
• control the qubit delivery circuit such that, during a rastering period consisting of 2R consecutive time bins, each output path in the first subset of delivery paths and each output path in the second subset of delivery paths is selected as the active delivery path according to a fixed order;
• and
• control the first optical switching circuit and the second optical switching circuit such that a first photonic qubit output on one of the first subset of delivery paths of the qubit delivery circuit and a second photonic qubit output on one of the second subset of delivery paths arrive in temporal alignment at the first and second input ports of one of the downstream circuits.