# Quantum Mechanics: Deducing observables?

1. Jan 29, 2017

### iharuyuki

1. The problem statement, all variables and given/known data

I have a question on my homework set and I'm not sure the principle behind it:
1. Alice measured an observable F (a matrix) and passed the measured system immediately to another experimentalist, Bob, who is going to measure another observable G. Alice claims that she can deduce the experiment outcome of Bob without Bob telling her what his outcome is. Can she really do that?

2. Given the observables F and G, suppose Alice measures an observable G first then passes the measured system to Bob, who then measures F. Can Alice deduce Bob's outcome? Can Bob's deduce Alice's?

F=
1 0 0
0 1 0
0 0 4

G=
1 0 0
0 5 0
0 0 6

I apologize for the poorly formatted matrices. I'm not sure how to put them in LaTeX.

2. Relevant equations

3. The attempt at a solution
1. I believe Alice cannot deduce the outcome of Bob's experiment (Question: what does "deduce" imply in this context?) because upon measurement the system will collapse into one of its eigenstates which each have a probability of occuring. Thus Alice will not be able to deduce with certainty the result that Bob measured.

2. I believe the same principle applies and neither of them can deduce each other's outcome.

Are my answers correct? Thank you.