Formal integration of Heissenberg equation?

[climbon]

Hi,

I am reading a paper and can't get the same answer they do, they have;

<br /> H= -i\hbar \sum_{\lambda} \int dK (a_{(k,\lambda)} g_{(1;K,\lambda)} \sigma_{1}^{+} e^{-i(\omega_{k}- \omega)t} - H.C )<br />

Then states they do a formal integration of the Heissenberg equation for a_{k,\lambda}(t) using the above Hamiltonian, they get;

<br /> a_{k,\lambda}(t) = a_{k,\lambda}(t_{0}) + \int_{t_{0}}^{t} dt^{&#039;} g^{*} \sigma_{1}^{-}(t^{&#039;}) e^{-i(\omega_{k}- \omega)t^{&#039;}}<br />


Could anyone help me as to how they get this answer from the Heissenberg equation...you be greatly appreciated!

Thanks.

 

[Einj]

Does a_{(k,\lambda)} and a^\dagger_{(k,\lambda)} follow some kind of orthogonality relation?
In fact, you get the correct result if a_{(k,\lambda)}\cdot a_{(q,\lambda&#039;)}=0 and a_{(k,\lambda)}\cdot a^\dagger_{(q,\lambda&#039;)}=\delta(k-q)\delta_{\lambda\lambda&#039;}.

However, I'm just guessing.

 

[vanhees71]

It would be much easier to help you, if you'd give the reference to the paper!