Fix the Detection state

[Mengjia He]

Hi, Prof. Kuprov,

Regards fixing the coil in calculating FID, we usually extract the evolution of -1 quantum coherence, this lead to coil = L-, according to the forluma FID = trace(coil' * rho).

So I am confused why you fixed the coil as L+ in many examples.

[kuprov]

It's entirely up to the user of course! Detect what you like - it's a simple matter of frequency sign convention: the conjugate observable turns the other way.