Photon-photon polaritons: the intriguing particles that emerge when two photons couple

Scientists at the University of Bath in the UK have found a way to bind together two photons of different colors, paving the way for important advancements in quantum-electrodynamics—the field of science that describes how light and matter interact. In time, the team’s findings are likely to impact developments in optical and quantum communication, and precision measurements of frequency, time and distances.