- #1
noamriemer
- 50
- 0
Hello!
There is something I can't understand...
[itex]\psi(0)= \frac {1}{\sqrt 5}|1>+ \frac {2i}{\sqrt 5}|2>
[/itex]
I need to find [itex]<H> for \rightarrow \psi(t)[/itex]
For
[itex]E_n= \hbar \omega (n + \frac {1}{2})[/itex] , [itex]\hat {H} =(a^\dagger a+1/2)[/itex]
These make me understand that this problem is one dimensional. (+1/2 in the Hemiltonian)
Finding the time dependence is easy. But now there is a thing I don't understand:
I was told I could relate to the wave function as a vector:
[itex] \psi= \frac {1}{\sqrt 5} \begin{pmatrix}
e^{-it/\hbar}\\ 2ie^{-2it/\hbar}
\end{pmatrix} [/itex]
And that means :
[itex]|1>=\begin{pmatrix}
1\\0
\end{pmatrix} [/itex]
[itex]|2>=\begin{pmatrix}
0\\1
\end{pmatrix} [/itex]
But now, when I use a on |1> , for instance- I receive |0>.
What does that mean?
I also receive- |3>. according to what I think- I should have defined:
[itex]|0>=\begin{pmatrix}
1\\0
\\ 0
\\0
\end{pmatrix}
[/itex]
, |1>=\begin{pmatrix}
0\\1
\\ 0
\\0
\end{pmatrix}[/itex]
Because I have four base vectors, and should have 4 dimensions. But the problem refers to 1 dim...
What am I not getting here?
How are dimension related?
Thank you!
There is something I can't understand...
[itex]\psi(0)= \frac {1}{\sqrt 5}|1>+ \frac {2i}{\sqrt 5}|2>
[/itex]
I need to find [itex]<H> for \rightarrow \psi(t)[/itex]
For
[itex]E_n= \hbar \omega (n + \frac {1}{2})[/itex] , [itex]\hat {H} =(a^\dagger a+1/2)[/itex]
These make me understand that this problem is one dimensional. (+1/2 in the Hemiltonian)
Finding the time dependence is easy. But now there is a thing I don't understand:
I was told I could relate to the wave function as a vector:
[itex] \psi= \frac {1}{\sqrt 5} \begin{pmatrix}
e^{-it/\hbar}\\ 2ie^{-2it/\hbar}
\end{pmatrix} [/itex]
And that means :
[itex]|1>=\begin{pmatrix}
1\\0
\end{pmatrix} [/itex]
[itex]|2>=\begin{pmatrix}
0\\1
\end{pmatrix} [/itex]
But now, when I use a on |1> , for instance- I receive |0>.
What does that mean?
I also receive- |3>. according to what I think- I should have defined:
[itex]|0>=\begin{pmatrix}
1\\0
\\ 0
\\0
\end{pmatrix}
[/itex]
, |1>=\begin{pmatrix}
0\\1
\\ 0
\\0
\end{pmatrix}[/itex]
Because I have four base vectors, and should have 4 dimensions. But the problem refers to 1 dim...
What am I not getting here?
How are dimension related?
Thank you!
Last edited: