Preparation of entangled states of two photons in several spatial modes
Preparation of entangled states of two photons in several spatial modes
We describe a protocol capable of preparing an arbitrary state of two photons in several spatial modes using pairs of photons generated by spontaneous parametric down conversion, linear optical elements, and single-photon detectors or postselection. The protocol involves unitary and nonunitary transformations realizable by beam splitters and phase shifters. Nonunitary …