“…Indeed, when driving the lowest excited state, the probability to gain a second quantum of energy is negligible. This scheme is often used in artificial atoms, such as in superconducting qubits [42,43]. In the case of the nanotorus, increasing the external magnetic field B allows one to produce an effective two-level system which spans the subspace S qb = {|l = 0, m = 0 , |l = 1, m = 0 }, with the main quantum number m = 0 and l = {0, 1}, see Fig.…”