Using this idea the secure key rate scales as , the same as for a single photon source.

The most obvious is to use a true single photon source instead of an attenuated laser.

This approach dates back to the late 1930s when photon sources were restricted to low-energy x-ray units (Mayneord 1937).

The researchers built independent but identical photon sources by mixing dye molecules into a polymer matrix, which was then cooled to near absolute zero.

His device scanned a plane of the brain by moving a high-energy photon source and a mechanically coupled detector around the head.

A large photon source results in more blurring in the final image and is worsened by an increase in image formation distance.

In reality, a perfect single photon source does not exist.

A single photon source emits one photon a time, at most.

According to them, this technology will help build new kinds of quantum emulators and other quantum information technologies such as massively parallel single photon sources.

If the probe is near a photon source, and the other assumptions above apply, the temperature of the probe will be higher.