Bad Qubits — Learn Quantum by Doing

Multiple choice

According to the threshold theorem for the surface code, what happens to the logical error rate when the per-operation physical error rate p is BELOW the threshold p_th and you increase the code distance d?

The logical error rate rises, since a larger code has more places to fail
The logical error rate falls exponentially in d
The logical error rate falls only linearly in d
The logical error rate is unchanged because it depends only on p