Computing expectation values

[AdrianPerezSalinas]

Hi all,

I have a question for you: how are numerically computed the expectation values of a Hamiltonian?

I assume that this computation is exact, and we have some state, some matrix, and we just do the bra - H - ket sandwich. However, I would like to know whether there is an option to compute this expectation value using samples, that is, we obtain some string of (0,1) and extract its energy.

I understand this is less efficient than the direct calculation, but it allows us to perform some algorithms such as this one https://quantum-journal.org/papers/q-2020-04-20-256/pdf/

Is it possible to compute hamiltonians in this way?