Light can act as either a particle or a wave. Researchers at nanjing university have created a controllable quantum superposition of the two complementary states. The research extends the experimental capabilities of quantum optics and could help develop quantum technology in the future. The paper was published online Sept. 2 in nature photonics.

       Whether light is made up of particles or travels in a medium as a wave has been a subject of debate in the history of science. In the 20th century, people realized that light could be a particle and a wave, but not both. However, the nature of light has always challenged people's understanding and intuition.