Rosa edited untitled.tex  about 8 years ago

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[G^t_{\beta\gamma}(t,t') G^{h,t}_{qk}(t',t) - G^{t}_{\beta q}(t,t')G^{h,t}_{\gamma k}(t',t)]\\ \nonumber  && + V_{\beta k}^{*}V_{\gamma q} [G^{h,t}_{kq}(t,t') G{t}_{\gamma\beta}(t',t) - G^{h,t}_{k\gamma}(t,t')G^{t}_{q \beta}(t',t)]  \end{eqnarray}  Finally, we employ the following relation to obtain $S^{<(>)(t,t')}$: $S^{<(>)}(t,t')$:  \begin{equation}  S(t,t') = A(t,t') B(t',t) \rightarrow S^{>(<)}(t,t') = A^{>(<)}(t,t') B^{<(>)}(t',t)   \end{equation} 

\end{equation}  Then, inserting the previous expression into the equation for $G_{qk}^{h,t}(t,t')$, we obtain  \begin{equation}  G_{qk}^{h,t}(t,t') = G_{qk}^{h,t}(t,t')\delta_{kq} + \sum_{\beta\gamma}\int \sum_{\tau\theta}\int  \frac{-dt_1}{\hbar}\frac{-dt_2}{\hbar} g_{q}^{h,t}(t,t_1) V_{\gamma V_{\tau  q} G^{t}_{\gamma\beta}(t_1,t_2)V_{\beta G^{t}_{\tau\theta}(t_1,t_2)V_{\theta  k}^* g_{k}^{h,t}(t_2,t') \end{equation}  The rest of equations for the Green functions that appear in the noise expression are already in J. S note.   Now we employ the following definition for the Fourier transform 

Now we enter the expression for $G_{kq}^{h,t}(t,t')$ in the frequency domain  \begin{equation}  G_{qk}^{h,t}(\omega) = g_{q}^{h,t}(\omega)\delta_{kq} + \sum_{\beta\gamma} \sum_{\tau\theta}  g_{q}^{h,t}(\omega) V_{\gamma V_{\tau  q} G^{t}_{\gamma\beta}(\omega)V_{\beta G^{t}_{\tau\theta}(\omega)V_{\theta  k}^* g_{k}^{h,t}(\omega)\,, \end{equation}  \begin{multline} 

V_{\beta k} V_{\gamma q}^{*} [G^>_{\beta\gamma}(\epsilon) G^{h,<}_{qk}(\omega+\epsilon) - G^{>}_{\beta q}(\epsilon)G^{h,<}_{\gamma k}(\epsilon+\omega)]  + V_{\beta k}^{*}V_{\gamma q} [G^{>,h}_{kq}(\epsilon_1) G^{<}_{\gamma\beta}(\epsilon+\omega) - G^{h,>}_{k\gamma}(\epsilon)G^{<}_{q \beta}(\epsilon+\omega)]\Biggr\}\,,  \end{multline}  Let us treat first the following term: $\sum_{k\beta,q\gamma} $e^2/\hbar^2\sum_{k\beta,q\gamma}  V_{\beta k} V_{\gamma q}^{*} [G^>_{\beta\gamma}(\epsilon) G^{h,<}_{qk}(\omega+\epsilon) - G^{>}_{\beta q}(\epsilon)G^{h,<}_{\gamma k}(\epsilon+\omega)]$ G^{h,<}_{qk}(\omega+\epsilon)]$  Then,  \begin{eqnarray}  &&G_{qk}^{h,<}(\omega+\epsilon) = g_{q}^{h,<}(\omega+\epsilon)\delta_{kq} + \sum_{\beta\gamma} \sum_{\tau\theta}  [g_{q}^{h,r}(\omega+\epsilon) V_{\gamma V_{\tau  q} G^{r}_{\gamma\beta}(\omega+\epsilon)V_{\beta G^{r}_{\tau\theta}(\omega+\epsilon)V_{\theta  k}^* g_{k}^{h,<}(\omega)\nonumber \\  &&+g_{q}^{h,r}(\omega+\epsilon) V_{\gamma V_{\tau  q} G^{<}_{\gamma\beta}(\omega+\epsilon)V_{\beta G^{<}_{\tau\theta}(\omega+\epsilon)V_{\theta  k}^* g_{k}^{h,a}(\omega+\epsilon)+g_{q}^{h,<}(\omega+\epsilon) V_{\gamma V_{\tau  q} G^{a}_{\gamma\beta}(\omega+\epsilon)V_{\beta G^{a}_{\tau\theta}(\omega+\epsilon)V_{\theta  k}^* g_{k}^{h,a}(\omega+\epsilon)\,, \end{eqnarray}  On the other hand we have for $G^>_{\beta\gamma}(\epsilon)$ (accordingly with J.S note)  \begin{eqnarray}  G^>_{\beta\gamma}(\epsilon) = \sum_{k\alpha\delta} \sum_{p\alpha\delta}  G^r_{\beta \alpha}(\epsilon) [V^*_{\alpha k} g^<_{k}(\epsilon)V_{\delta k} p} g^>_{p}(\epsilon)V_{\delta p}  + V_{\alpha k} g^{h,<}_{k}(\epsilon) p} g^{h,>}_{p}(\epsilon)  V^*_{\delta k}]G^a_{\delta p}]G^a_{\delta  \gamma}(\epsilon) \end{eqnarray}  We need to compute the following product of Green functions: $P^>(t,t')=G^>_{\beta\gamma}(\epsilon)G_{kq}^{h,<}(\omega+\epsilon)$ $P^>(t,t')=e^2/\hbar^2\sum_{k\beta,q\gamma} G^>_{\beta\gamma}(\epsilon)G_{kq}^{h,<}(\omega+\epsilon)$  \begin{eqnarray}  &&G^>_{\beta\gamma}(\epsilon) &&\sum_{k\alpha\delta} V_{\gamma q}^* V_{\beta k} G^>_{\beta\gamma}(\epsilon)  G_{kq}^{h,<}(\omega+\epsilon) = \sum_{k\alpha\delta} V_{\gamma q}^* V_{\beta k}\Biggr\{  G^r_{\beta \alpha}(\epsilon) [V^*_{k\alpha} g^>_{k}(\omega)V_{\delta k} + V_{\alpha k} g^{h,>}_{k}(\omega) V^*_{\delta k}]G^a_{\delta \gamma}(\epsilon) g_{q}^{h,<}(\omega+\epsilon)\delta_{kq} \\ \nonumber &+& \sum_{p\beta\gamma\alpha\gamma} \sum_{p \alpha\delta}  G^r_{\beta \alpha}(\epsilon) [V^*_{\alpha p} g^>_{p}(\epsilon)V_{ \delta}p + V_{\alpha p} g^{h,>}_{p}(\epsilon) V^*_{\delta p}]G^a_{\delta \gamma}(\epsilon) [g_{q}^{h,r}(\omega+\epsilon) [  V_{\gamma q}^* g_{q}^{h,r}(\omega+\epsilon) V_{\tau  q} G^{r}_{\gamma\beta}(\omega+\epsilon)V_{\beta G^{r}_{\tau\theta}(\omega+\epsilon)V_{\theta  k}^* g_{k}^{h,<}(\omega) V_{\beta k}  \nonumber \\  &&+G^r_{\beta &&\sum_{p \alpha\delta} G^r_{\beta  \alpha}(\epsilon) [V^*_{\alpha p} g^>_{p}(\epsilon)V_{ \delta}p + V_{\alpha p} g^{h,>}_{p}(\epsilon) V^*_{\delta p}]G^a_{\delta \gamma}(\epsilon) [g_{q}^{h,r}(\omega+\epsilon) [  V_{\gamma q}^* g_{q}^{h,r}(\omega+\epsilon) V_{\tau  q} G^{<}_{\gamma\beta}(\omega+\epsilon)V_{\beta G^{<}_{\tau\theta}(\omega+\epsilon)V_{\theta  k}^* g_{k}^{h,a}(\omega+\epsilon)]\\ g_{k}^{h,a}(\omega) V_{\beta k}  \nonumber &&+G^r_{\beta \\  &&+ \sum_{p \alpha\delta} G^r_{\beta  \alpha}(\epsilon) [V^*_{\alpha p} g^>_{p}(\epsilon)V_{ \delta}p + V_{\alpha p} g^{h,>}_{p}(\epsilon) V^*_{\delta p}]G^a_{\delta \gamma}(\epsilon)[g_{q}^{h,<}(\omega+\epsilon) \gamma}(\epsilon) [  V_{\gamma q}^* g_{q}^{h,<}(\omega+\epsilon) V_{\tau  q} G^{a}_{\gamma\beta}(\omega+\epsilon)V_{\beta G^{a}_{\tau\theta}(\omega+\epsilon)V_{\theta  k}^* g_{k}^{h,a}(\omega+\epsilon)]\,, g_{k}^{h,a}(\omega) V_{\beta k} \Biggr\}  \,,  \end{eqnarray}  We now compute separately the different parts of the previous expression for the ac noise  \begin{eqnarray}