Alice, who does not have any sophisticated quantum technology, delegates her
quantum computing to Bob, who has a fully-fledged quantum computer. Can she
check whether the computation Bob performs for her is correct? She cannot
recalculate the result by herself, since she does not have any quantum
computer. A recent experiment with photonic qubits suggests she can. Here, I
explain the basic idea of the result, and recent developments about secure
cloud quantum computing.