Can Quantum Mechanics Ket and Bra Methods Solve Scalar Equations?

  • Thread starter Thread starter Ugnius
  • Start date Start date
  • Tags Tags
    Quantum mechanics
Ugnius
Messages
54
Reaction score
10
Homework Statement
##\left|m\right\rangle = \frac{1}{\sqrt{A}}\binom{1-2i}{\alpha} , \left|n\right\rangle = \frac{1}{\sqrt{14}}\binom{-3+2i}{\beta}##
Relevant Equations
Find unknown constants A, α and β, we know that β is real positive integer , α has both real and imaginary parts
Not really even sure how to approach this problem , I would guess if we need scalar answer we would need to combine these two given equations together but I'm unfamiliar with such methods, in the book there is methods to make a ket to a bra and then matrix part transposes and multiplies with the original while constant squares like:
##\left\langle m \right|\left|m\right\rangle = ({\frac{1}{\sqrt{A}}}^2)*\binom{1-2i}{\alpha}*(1-2i ,\alpha)##

Would that be an approach?
 
Physics news on Phys.org
Ugnius said:
Homework Statement: ##\left|m\right\rangle = \frac{1}{\sqrt{A}}\binom{1-2i}{\alpha} , \left|n\right\rangle = \frac{1}{\sqrt{14}}\binom{-3+2i}{\beta}##
Relevant Equations: Find unknown constants A, α and β, we know that β is real positive integer , α has both real and imaginary parts

Not really even sure how to approach this problem , I would guess if we need scalar answer we would need to combine these two given equations together but I'm unfamiliar with such methods, in the book there is methods to make a ket to a bra and then matrix part transposes and multiplies with the original while constant squares like:
##\left\langle m \right|\left|m\right\rangle = ({\frac{1}{\sqrt{A}}}^2)*\binom{1-2i}{\alpha}*(1-2i ,\alpha)##

Would that be an approach?
If you normalize ##\mid n \rangle##, then yes, you can find ##\beta##. But you would write this as
##\langle n \mid n \rangle = \dfrac{1}{\sqrt{14}} \begin{pmatrix} -3-2i & \beta^* \end{pmatrix} \dfrac{1}{\sqrt{14}} \begin{pmatrix} -3+2i \\ \beta \end{pmatrix}##
(You wrote your bra and ket in the wrong order for ##\langle m \mid m \rangle## in your OP.)

We know that ##\beta## is real, so ##\beta^* = \beta##, and you can go from there.

To find A and ##\alpha## we need to know something about how ##\mid m \rangle## and ##\mid n \rangle## relate to each other. Are they orthogonal? ie. ##\langle n \mid m \rangle = 0##?

-Dan
 
Thank you.
They are orthogonal yes , I'm brute forcing the solution right now , I solved for \beta. Now I need to solve \langle n \mid m \rangle = 0 and i'll get back to you for confirmation if I did it correctly
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top