Recent content by keen23

Thank you for your reply! Did I get it right, it's in general not possible to swap an operater and \rho? Indeed I want to take the trace, thanks for the hint of swapping "before" :) I will see later if this works for me (I am afraid, it won't, since U=U_A U_B. I was hoping to get rid of...

Hello all! I hope some of you are more proficient in juggling with bra-kets... I am wondering if/when the density operator commutes with other operators, especially with unitaries and observables. 1. My guess is, that it commutes with unitaries, but I am not sure if my thinking is correct...

At the moment I am reading about general measurements and POVMs. They say, that you can't definately distinguish two non-orthonormal states by a "normal" measurement, meaning by a projection onto the states (since each has an overlap with the other). (That's why you need the POVM to do that.)...

Hello! once again I got trouble with Dirac-notation: Homework Statement Given an non-orthonormal basis. Measurement via the projection operator should not give an definit answer, in which state the system was due to the overlap. Geometrical that's clear, but I'm unable to compute that...

Am I right that the + is actually an devided by? \bar{y}=\frac{1}{A} \int y\ dx dy = \frac{1}{A} \int 0.5\ y^2\ dx Is that ok?

Oh no! Yes, sure. that was my mistake. Thank you!

Hello all! I try to follow the computation in my textbook (nielsen, quantum computation) and miss a step. Homework Statement They say the following state |p\rangle=\frac{1}{2}\big[a (|0\rangle+|1\rangle)(|00\rangle+|11\rangle)+b(|0\rangle-|1\rangle)(|10\rangle+|01\rangle)\big] could be...

Thank you a lot! Now things got clear :)

Hello all!:smile: I am at the QM-basics, and now a little bit confused, but maybe someone can easily clarify. A QM-system can be described by a state that lives in a hilbertspace, this was introduced because superposition is essential. In the solutions of different problems polynomial...