# Homework Help: Quantum State diagram for system of particles

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1. Oct 9, 2014

### SalfordPhysics

Question:
"Write the quantum state for the following system of particles distributed over evenly spaced energy levels"

The diagram (couldn't upload so hope its not too rough):

5 ----------------------
4 ----------------------
3 --------------X-------
2 ------X---X------X----
1 --X-------------------
0 ---------------------X
___(1) (2) (3) (4) (5) (6)

Answer:
I am assuming it means the quantum numbers, but don;t know how to deduce from energy level and particle number (which I am assuming are the axes).
An explanation rather than answer would be great.

2. Oct 14, 2014

### Staff: Admin

Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?

3. Oct 17, 2014

### SalfordPhysics

Sorry I've not really got any more information. I don;t know what "the quantum state" is :/

4. Oct 18, 2014

### BvU

A bit hard to help you along without knowing more of the context of this exercise (introduction to QM, relativistic quantum fields ?). Where are you in your curriculum ?

If you don't know what a quantum state is, things become a little awkward. But if you are supposed to know about energy levels as eigenvalues of the time-independent Schroedinger equation, we are better off.

Are you used to writing states as $\psi_E$ or are you into more advanced disguises like $|1,1,3,1,0,0>$ ?

5. Oct 18, 2014

### SalfordPhysics

We aren't even that far yet BvU, its to do with energy levels but eigenvalues haven't been introduced to the course. The course unit is statistical physics. Sorry I can't vive more information :(

6. Oct 18, 2014

### BvU

Makes sense. In statistical mechanics we want to count the number of ways a state with a given total energy can be brought about (usually with indistinguishable particles), so we need a way to describe individuals.

Doesn't help you, I'm afraid: you'll have to dig into your lecture material to find out what is meant at this stage. My best guess would be the already mentioned $|1,1,3,1,0,0>$, but I must admit it's a long shot. And it already has indistinguishability built in !

In fact, when I browse through my old Pathria, Statistical Mechanics (1972!), I don't see this bra-ket notation appearing anywhere (*). The term quantum states pops up here and there, but isn't really defined or outlined properly.

Can't help much further, but I hope you can get some other assistance, good luck !

(*)  Not correct: in chapter 5: quantum statistics... they do show up

Last edited: Oct 18, 2014
7. Oct 19, 2014

### SalfordPhysics

Thanks for your help BvU I will just have to go and interrogate the guy who wrote the tutorial!

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