In a world’s first, researchers at the Kastler Brossel Laboratory in Paris and the U.S. National Institute of Standards and Technology (NIST) have performed a pioneering experiment demonstrating “hybrid” quantum networking. The approach, which unites two distinct methods of encoding information in particles of light called photons, could eventually allow for more capable and robust communications and computing.
Similar to how classical electronics can represent information as digital or analog signals, quantum systems can encode information as either discrete variables (DVs) in particles or continuous variables (CVs) in waves.
Systems leveraging quantum effects can take many forms, but they generally follow either a DV or CV architecture. Now these scientists have successfully united both techniques by establishing and distributing entanglement between DV- and CV-encoded states of light within a single quantum network.
Using a complicated assembly of optical components, the team successfully produced photons in two highly entangled states. One of them arose from splitting a single photon between two different paths. The other—a so-called hybrid-entangled state—emerged from entangling a DV optical qubit with a CV qubit, which was held in a superposition of two different phases of light. (Scientific American)