I'm given a one-dimensional potential with two wells, one local minimum at some higher energy and one deep global minimum next to it, separated by a barrier of own shape and height (phase qubit). I used a WKB approx. in conjunction with a harmonic approximation of the barrier to find the tunneling probability, i.e. the transmission coefficient T.
Now, I'm asked to estimate the tunneling lifetime of the metastable levels in the elevated well. How do you relate the tunneling probability to the lifetime?