Scalable photonic quantum computing with hybrid resource states

A system, comprising:

• a plurality of optical circuits configured to generate light having a plurality of output states via Gaussian Boson sampling (GBS);
• a plurality of photon number resolving detectors (PNRs) operatively coupled to the plurality of optical circuits, the plurality of PNRs configured to generate qubit clusters based on the plurality of output states;
• a multiplexer operatively coupled to the plurality of PNRs, the multiplexer configured to perform multiplexing of the qubit clusters and to replace empty modes with squeezed vacuum states, thereby configured to generate light having a plurality of hybrid resource states;
• and
• an integrated circuit operatively coupled to the multiplexer, the integrated circuit configured to entangle hybrid resource states from the plurality of hybrid resource states into a higher-dimensional cluster state that includes states for fault-tolerant quantum computation.

An apparatus, comprising:

• an integrated circuit including:
• a plurality of multi-mode sources;
• and
• a plurality of beamsplitters operatively coupled to the plurality of multi-mode sources, each beamsplitter from the plurality of beamsplitters connecting at least two multi-mode sources from the plurality of multi-mode sources,
• the integrated circuit configured, during operation, to sequentially energize subsets of multi-mode sources from the plurality of multi-mode sources and to generate a Raussendorf lattice based on interactions between multi-mode sources from the plurality of multi-mode sources and at least one homodyne measurement.

A method, comprising:

• receiving an input vector of homodyne measurements and a noise model;
• identifying, based on the input vector of homodyne measurements and the noise model, at least one direction having a noise level above a predetermined threshold;
• performing a change-of-basis on the input vector of homodyne measurements, based on the identified at least one direction, to generate a first modified vector;
• applying a transformation to the first modified vector, the transformation including a binning operation and a rounding operation, to generate a second modified vector;
• undoing the change-of-basis based on the second modified vector, to return a candidate lattice point;
• and
• generating a binary string based on the candidate lattice point, the binary string representing an interpreted qubit measurement outcome.