Question

When is Fermi golden rule exact?

Answer 1

 In a generic problem, it should not be exact. I mean, the transition probability p(t)p(t)should be a linear function of time for tc1<t<tc2tc1<t<tc2, where tc1tc1 and tc2tc2 are two characteristic times, but the slope is not that predicted by Fermi golden rule.

Answer 2

Explanation:

Fermi's golden rule describes a system which begins in an eigenstate, , of an unperturbed Hamiltonian, H0 and considers the effect of