A truncated photon
arXiv:2510.21636 · doi:10.1103/94pm-hp34
Abstract
An elementary particle such as a photon cannot be cut in two pieces. Still it must be possible to truncate a photon with an optical shutter. The result is neither another photon nor a mix of a photon and a vacuum. Instead it is a superposition and mix of photon numbers up to infinity. This state is rather complicated, but nevertheless locally equivalent to a single photon or vacuum to the left and right, respectively, of a narrow transition region.
13 pages, 2 figures. Accepted for publication in Physical Review Letters