Schrodingers equation probability currents

golfingboy
Messages
3
Reaction score
0
Hi all,

I only have a real basic knowledge of quantum mechanics and I am finding a paper that I am taking quite challenging. If it is possible for someone to give me a hint or starting point on this folowing problem that would be great.

For problem - see attachment

Thanks.
 

Attachments

Physics news on Phys.org
I would start by writing \rho = |\psi|^2 = \psi^* \psi and differentiating with respect to time. You will get two pieces from the product rule. Try using Schrodinger's equation on each piece to write the time derivatives in terms of spatial derivatives. Hint: you may find it useful to take the complex conjugate of the Schrodinger equation.
 
golfingboy said:
Hi all,

I only have a real basic knowledge of quantum mechanics and I am finding a paper that I am taking quite challenging. If it is possible for someone to give me a hint or starting point on this folowing problem that would be great.

For problem - see attachment

Thanks.
Golfingboy,

we typically require that you show some effort on your part before we can help you. Please read the guidelines or the sticky thread at the top of this sub-forum.

As for your question, it looks like there's a typo in the first line, involving the integration variable (unless P is something other than the density).

Thirdly, I hope you've come across the continuity equation in fluid mechanics or in E&M. The question loses it's zing value if the solver can not appreciate the coneection to the above.
 
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