If you were trapped in a maze with another person, but never your paths never crossed, it is reasonable to say the paths you took were completely independent. This is not the case with photons though, according to researchers at the University of Copenhagen. Indeed two such photons will take interdependent paths, and this phenomenon could lead to new types of sensing techniques.
The researchers confirmed this odd occurrence by building a photonic nanostructure with randomly placed holes that will diffuse light. As the light source the researchers used a quantum dot which scattered its light in all directions. Studying the paths the light took revealed that the photons were sharing information with each other about the nanostructure. This result is not entirely surprising due to the dual nature of photons, as a particle and a wave, with the wave nature able to share information like this.
Potentially the researchers see this phenomenon as a way to gather spatial information on small objects, such as living cells. Thanks to the small scale of quantum dots, such a sensing technology would not harm the cell it is used on.