Bad Qubits — Learn Quantum by Doing

Multiple choice

On a line, how does the standard deviation

\sigma

of the walker's position after

t

steps scale for a classical random walk versus a discrete-time quantum walk?

Both scale as $\sqrt{t}$ ; the quantum walk only changes the shape, not the rate
Classical $\sigma \sim t$ ; quantum $\sigma \sim \sqrt{t}$
Classical $\sigma \sim \sqrt{t}$ (diffusive); quantum $\sigma \sim t$ (ballistic, linear in $t$ )
Classical $\sigma \sim t^2$ ; quantum $\sigma \sim t$