Photonic Quantum Computing

Abstract Photonic quantum computation (QC) refers to QC that uses photons as the physical system for doing the QC. The field is largely divided between discrete-variable (DV) and continuous-variable (CV) photonic QC. In the former, quantum information is represented by one or more modal properties (e.g., polarization) that take on distinct values from a finite set. Quantum information is processed via operations on these modal properties (e.g., waveplates in the case of polarization) and eventually measured using single-photon detectors. In CV photonic QC, quantum information is represented by properties of the electromagnetic field that take on any value in an interval (e.g., position). Both CV and DV implementations have been realized experimentally; each has a unique set of challenges that need to be overcome to achieve scalable universal photonic QC. It is possible to combine both DV and CV in a hybrid CV–DV fashion to overcome the limitations of either approach.