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

A mirror that moves mid-photon could release a shower of new photons. https://arstechnica.com/science/2026/07/what-happens-when-you-try-to-chop-a-photon-in-half/?utm_brand=arstechnica&utm_social-type=owned&utm_source=mastodon&utm_medium=social