Posted by **qwerty** on Sunday, February 24, 2013 at 6:42pm.

Suppose we have a qubit in the state |ψ>. We know that if we measure it in the standard basis, the probability of getting a 0 is 7/9. Now, if we instead first apply a Hadamard gate and then measure the resulting qubit H|ψ> in the sign basis, what is the probability of getting a +?