You can separate a photon from light.
A photn is a The quantum of electromagnetic energy, regarded as a discrete particle having zero mass, no electric charge, and an indefinitely long lifetime.
And light (I assume you know what that is) is comprised of photons.
Now assuming it would be possible to separate a photon from light you couldnt make a device to measure it or a mirror that could contain it, OK.Becasue that is not enough to contain a photon.
Even if it were super astronomically possible to separate a photon and place it in a device wher it is contained and no other light is there you cant measure exactly at what speed it moves and also the exact position so you couldnt keep track of the photon.
Are you sure your not confusing a photon with a proton?