Bad Qubits — Learn Quantum by Doing

Multiple choice

For H = A + B, the symmetric (second-order) Suzuki-Trotter formula is S2(tau) = e^(-iA*tau/2) e^(-iB*tau) e^(-iA*tau/2). Compared with first-order Trotter, what global error does it achieve after r steps for total time t?

O(t^3 / r^2), an improvement over the first-order O(t^2 / r)
O(t^2 / r), exactly the same as first order
Zero error, because the formula is exact for any non-commuting A and B
O(t / r), linear improvement only