QM - Spin operator conjugate question

AI Thread Summary
The discussion centers on the properties of the conjugate of a wave function represented as a 2x1 matrix, specifically whether the conjugate results in a 1x2 matrix with imaginary components negated. The user is attempting to solve a problem involving the spin operator Sx and its application to the state vector v. They express confusion about the dimensionality of the resulting matrices after operations, noting that multiplying Sx by v yields a 2x1 matrix rather than a 2x2 matrix. The user also mentions that the conjugate of v should be a transpose matrix with altered imaginary components. The thread highlights the complexities of matrix operations in quantum mechanics, particularly regarding conjugation and dimensionality.
QMQuestions2
Messages
2
Reaction score
0

Homework Statement



Okay so I've got a question I really need answered first up! If I have a 2x1 matrix for Psi, is Psi* a 1x2 matrix with all the 'i's turned to '-i's?

Now onto the actual question - http://imgur.com/3ucb4" - part b only

Homework Equations



http://imgur.com/bcEm3"

(Sorry to URL everything)

The Attempt at a Solution



http://imgur.com/FW0dP"

What did I do wrong?
 
Last edited by a moderator:
Physics news on Phys.org
Simply have the 2 x 2 matrix of Sx operate on the state v, then multiply your new 2 x 2 matrix with the conjugate of v.

And yes the conjugate of v is a transpose matrix with the i's all different.
 
Isn't that what I did? v is a 2x1 matrix. When I multiply Sx with v I'm left with a 2x1 matrix, not a 2x2.

Sx times v = v

v* times v = 2

Integral = infinity
 
Thread 'Help with Time-Independent Perturbation Theory "Good" States Proof'
(Disclaimer: this is not a HW question. I am self-studying, and this felt like the type of question I've seen in this forum. If there is somewhere better for me to share this doubt, please let me know and I'll transfer it right away.) I am currently reviewing Chapter 7 of Introduction to QM by Griffiths. I have been stuck for an hour or so trying to understand the last paragraph of this proof (pls check the attached file). It claims that we can express Ψ_{γ}(0) as a linear combination of...
Back
Top