Particles can sometimes act like waves, and photons (particles of light) are no exception. Just as waves create an interference pattern, like ripples on a pond, so do photons. Physicists from the National Institute of Standards and Technology (NIST) and their colleagues have achieved a major new feat—creating a bizarre “quantum” interference between two photons of markedly different colors, originating from different buildings on the University of Maryland campus.
Source:
https://phys.org/news/2019-12-scientists-photon-pairs.html