Can the channel capacity of a light-wave communication system be increased by the use of photon-number–squeezed light?

The channel capacity C of a light-wave communication system based on photoevent point process observations cannot be increased by use of photon-number–squeezed light. Under a constraint of maximum photon rate ${\lambda }_{\max }$, the channel capacity C=${\lambda }_{\max /\mathrm{e}}$ is achieved with a Poisson process. On the other hand, the channel capacity of a communication system based on photon counting can be increased by use of photon-number–squeezed light. The improvement vanishes in the limit of very small mean counts.