Researchers at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) have theoretically demonstrated that photons trapped inside an optical cavity carry detailed information about a material placed within it. By measuring the properties of the photons leaking out of the cavity, researchers can probe how an optical cavity modifies the properties of the embedded materials.

This insight opens new possibilities for experimental techniques to explore entangled light-matter systems. Their work has been published in Physical Review Letters.

According to basic quantum mechanics, empty space is not truly empty—it’s filled with particles that constantly pop in and out of existence, a phenomenon known as vacuum fluctuations. This process is somewhat analogous to atoms at the surface of boiling water, which continually jump in and out of the liquid.