In Quantum Mechanics coherent states are defined as eigenstates to some annihilation operator. Afaik this notion is due to Roy Glauber.
Now, I just read that if you have a spin-state for example, then the coherence of the spin-state is measured by the off-diagonal elements of the density matrix. This meant that there is no coherence if the off-diagonal entries are zero, because then I have just spin-up or spin-down.
Are these two notions related to each other, cause I currently don't see it.
If anything is unclear, please let me know.