Physicists have theoretically explored what happens when a photon, the fundamental particle of light, is "chopped" in half. Normally, photons cannot be divided. However, if a photon is in the process of reflecting off a mirror and the mirror is suddenly removed, a complex phenomenon occurs.

This event, described by Norwegian physicists, is not a linear interaction but a nonlinear one. When a photon hits a partially reflective mirror, it enters a superposition of being both reflected and transmitted. If the mirror is removed mid-reflection, the photon's electromagnetic field undergoes sharp transitions. The abrupt cessation of reflection and the sudden appearance of transmission require a broader spectrum of frequencies than the original photon possessed.

This "cutting" of a photon, according to the researchers, generates a multitude of new photons. These new photons are in a superposition of both reflected and transmitted states, potentially allowing both to be measured simultaneously. While the experiment is challenging, requiring precise timing and materials like semiconductors that can switch reflectivity rapidly, evidence suggests this phenomenon occurs when shortening ultrashort pulses. The researchers anticipate observing this with single photons within about a year.