I have troubles with modern terminology in the field of quantum information technologies. There are a lot of new terms that everyone is using and no-one takes time to explain, even though modern textbooks did not catch up to these yet. Two of them are optical coherence lifetime vs spin coherence lifetime in the context of atomic clocks and quantum information storage/processing: definitions are needed.
Please, notice that I am not asking for a classical definition of coherence. I am rather asking about two very specific terms, listed above in the given context.
The title was given this way to attract attention and because in the given context the term "coherence" is overloaded and it is a known in the community fact (quantum, optical, quantum information coherence, to name a few).
Thanks to Harry Levine: helpful link