A Russian-U.K. research team has proposed a theoretical description for the new effect of quantum wave mixing involving classical and nonclassical states of microwave radiation. This effect, which previously lacked a rigorous mathematical description, could be of use to quantum computer scientists and fundamental physicists probing light-matter interactions. The study came out in Physical Review A.
"We have formulated a mathematical language for handling the unconventional and intriguing phenomenon of wave mixing of classical light - coherent electromagnetic radiation - and rather exotic forms of nonclassical light, in particular, squeezed light and a superposition of one photon and zero photons, which effectively contains 'one half of a photon,' if you will. The study builds on our prior work, where we first designed a single-photon microwave source and then used it to create a quantum superposition between one and zero photons in a pulse, producing in effect a half-photon state," explains the study's PI Oleg Astafiev, of Skoltech, MIPT, the University of London, and U.K.'s National Physical Laboratory.