# Expectation value of an operator in matrix quantum mechanics

1. Oct 20, 2013

1. The problem statement, all variables and given/known data
Hey everyone.
Imma type this up in Word as usual:

http://imageshack.com/a/img577/3654/q9ey.jpg [Broken]

2. Relevant equations

http://imageshack.com/a/img22/3185/pfre.jpg [Broken]

3. The attempt at a solution
http://imageshack.com/a/img703/8571/xogb.jpg [Broken]

Last edited by a moderator: May 6, 2017
2. Oct 20, 2013

### vanhees71

There's a mistake in the last step. You've overlooked the imaginary units in the exponentials!

3. Oct 20, 2013

Ohhh yea it isnt $cosh$, it should be $cos$...but is the rest okay? I mean the matrix U and stuff?