Work done on a quantum state

Question

I have a Hamiltonian $H_{\lambda(t) }$, where $\lambda(t)$ characterizes a time dependent path in parameter space. The parameter is changed in finite time from $\lambda(t_i)$  to $\lambda(t_f)$ . At $t=t_i$ the system is in the initial state $|\psi>$. What is the work done on the system? Is it well defined?

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