Superconductivity — a phenomenon in which electrons can travel through certain materials with zero resistance — has revolutionized parts of medicine, travel and science. Now, an intriguing experiment has seen the same behaviour that underlies superconductivity — but in particles of light. The finding has left physicists wondering how far the comparison might reach.
“This is really exciting work,” says Nick Vamivakas, a quantum physicist at the University of Rochester, New York, who was not involved with the research. “It’s a beautiful connection between light scattering, condensed-matter physics and quantum optics.”
Conventional superconductivity relies on the formation of ‘Cooper pairs’ of electrons, which stabilize each other’s path and allow electricity to flow without resistance. Its discovery led to the development of powerful superconducting magnets, which are now used in medical scanners, particle accelerators, wind turbines and magnetically levitated trains.
Physicists in Brazil have now seen evidence of photons of light forming similar pairs. The process occurs at room temperature when light passes through a range of transparent liquids, including water, although it is very difficult to observe. “Not only is this formation of pairs possible, but it is everywhere,” says André Saraiva, a theoretical physicist at the Federal University of Rio de Janeiro (UFRJ) and co-author of a paper that has been accepted for publication in Physical Review Letters.