Bad Qubits — Learn Quantum by Doing

Multiple choice

In each growth iteration of ADAPT-VQE, how does the algorithm decide which operator from the pool to append to the circuit next?

It adds every pool operator at once and then prunes those with small final parameters
It picks a pool operator uniformly at random and re-optimizes after each addition
It appends the pool operator with the smallest gate count to keep the circuit shallow
It scores every candidate operator A_m by the commutator gradient <[H, A_m]> on the current state and appends the one with the largest gradient magnitude