In this screenshot of a paper I am reading, I have the following question:
1.What is a $SU(1,1)$ group and how do we find its generators?
2.From the expression for the Hamiltonian $\hat{H}$, how do we infer the form of the operator $\hat{U}(t,0)$ as in the equation $6$?
3.How can I write a similar definition of $\hat{U}$ for time $t_0$ to $t$ rather than $0$ to $t$?