Multiple choice
In Wiesner's quantum money, each banknote qubit is prepared in one of the four BB84 states in a basis unknown to a forger, who can only guess a basis and measure. The lesson works out the probability that a single forged qubit passes the bank's verification as 1/2 + 1/4 = 3/4. What is the probability that an entire forged n-qubit note passes?