What happens when you try to chop a photon in half?

A single photon, normally indivisible and lacking a fixed location, is explored in a theoretical experiment where a mirror is removed mid-reflection. This action, unusual in photon behavior, could cause the photon to split, generating a multitude of new photons across various frequencies, effectively creating a rainbow from a single light source. While technically complex, similar phenomena of pulse shortening already provide evidence for this effect, with researchers anticipating direct observation in single photons within a year.

• Photons are typically indivisible particles of light, but they also lack a specific location, existing as extended objects.
• An experiment is proposed where a mirror is removed while a photon is reflecting, potentially dividing the photon.
• This division is a nonlinear process that requires specific conditions, such as a changing medium or high-intensity light.
• Removing the mirror mid-reflection creates sharp transitions in the electromagnetic field, requiring a broader frequency spectrum than the original photon possessed.
• The photon is hypothesized to enter a superposition state of both reflected and transmitted light, and the division could generate multiple new photons, leading to a rainbow effect.
• Performing this experiment requires specialized equipment, including single-photon sources and materials that can switch reflectivity extremely rapidly, like semiconductors activated by ultrafast lasers.
• Evidence for similar phenomena exists in the shortening of ultrashort pulses, where reflected pulses gain more frequencies, implying new photon generation.
  Continue reading https://arstechnica.com/science/2026/07/what-happens-when-you-try-to-chop-a-photon-in-half/