2023 Exam - Problem 1c

2023 Exam - Problem 1c

by Yago Pérez Pérez -
Number of replies: 2

Hey

I computed the probability in a similar manner as to what is seen in the solution, except I ignored the "Charlie bit" since we just apply the identity to it, however I end up with a probability of 1, instead of 1/2. What exactly is wrong with my method? Do we really need to worry about Charlie's part too?


In reply to Yago Pérez Pérez

Re: 2023 Exam - Problem 1c

by Nicolas Macris -
Yes you need to worry about charlie’s part too. There will be no cross term in the expansion of the square norm equ (12) because the states 0 and 1 of charlie are orthogonal! Then you find (13) with no double product cross term! Which eventually leads to 1/2 in (14).
In your handwritten calculation i dont ser the bits of Charlie, hence this calculation is probably wrong.