Photonic circuits in which stateful components are coupled via guidedelectromagnetic fields are natural candidates for native implementation ofiterative stochastic algorithms based on propagation of information around agraph. Conversely, such message passing algorithms suggest novel circuitarchitectures for signal processing and computation that are well matched tonanophotonic device physics. Here we construct and analyze a quantum opticalmodel of a photonic circuit for iterative decoding of a class of low-densityparity-check (LDPC) codes called expander codes. Our circuit can be understoodas an open quantum system whose autonomous dynamics map straightforwardly ontothe subroutines of an LDPC decoding scheme, with several attractive features:it can operate in the ultra-low power regime of photonics in which quantumfluctuations become significant, is robust to noise and componentimperfections, achieves comparable performance to known iterative algorithmsfor this class of codes, and provides an instructive example of hownanophotonic cavity quantum electrodynamic components can enable useful newinformation technology even if the solid-state qubits on which they are basedare heavily dephased and cannot support large-scale entanglement.
展开▼
