Rosa edited untitled.tex  about 8 years ago

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\begin{equation}  G_{k\beta}^{h,t}(t,t') = \frac{-1}{\hbar} \sum_\beta\int dt_1 g_{k}^{h,t}(t,t_1) V_{\gamma k} G^{t}_{\gamma\beta}(t,t')  \end{equation}  Then, inserting the previous expression into the equation for $G_{kq}^{h,t}(t,t')$, $G_{qk}^{h,t}(t,t')$,  we obtain \begin{equation}  G_{kq}^{h,t}(t,t') G_{qk}^{h,t}(t,t')  = G_{kq}^{h,t}(t,t')\delta_{kq} G_{qk}^{h,t}(t,t')\delta_{kq}  + \sum_{\beta\gamma}\int \frac{-dt_1}{\hbar}\frac{-dt_2}{\hbar} g_{k}^{h,t}(t,t_1) g_{q}^{h,t}(t,t_1)  V_{\gamma k} q}  G^{t}_{\gamma\beta}(t_1,t_2)V_{\beta q}^* g_{q}^{h,t}(t_2,t') 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_{kq}^{h,t}(\omega) G_{qk}^{h,t}(\omega)  = g_{q}^{h,t}(\omega)\delta_{kq} + \sum_{\beta\gamma} g_{k}^{h,t}(\omega) g_{q}^{h,t}(\omega)  V_{\gamma k} q}  G^{t}_{\gamma\beta}(\omega)V_{\beta q}^* g_{q}^{h,t}(\omega)\,, k}^* g_{k}^{h,t}(\omega)\,,  \end{equation}  \begin{multline} 

Let us treat first the following term: $\sum_{k\beta,q\gamma} V_{\beta k} V_{\gamma q}^{*} [G^>_{\beta\gamma}(\epsilon) G^{h,<}_{qk}(\omega+\epsilon) - G^{>}_{\beta q}(\epsilon)G^{h,<}_{\gamma k}(\epsilon+\omega)]$  Then,  \begin{eqnarray}  &&G_{kq}^{h,<}(\omega+\epsilon) &&G_{qk}^{h,<}(\omega+\epsilon)  = g_{q}^{h,<}(\omega+\epsilon)\delta_{kq} + \sum_{\beta\gamma} [g_{k}^{h,r}(\omega+\epsilon) [g_{q}^{h,r}(\omega+\epsilon)  V_{\gamma k} q}  G^{r}_{\gamma\beta}(\omega+\epsilon)V_{\beta q}^* g_{q}^{h,<}(\omega)\nonumber k}^* g_{k}^{h,<}(\omega)\nonumber  \\  &&+g_{k}^{h,r}(\omega+\epsilon) &&+g_{q}^{h,r}(\omega+\epsilon)  V_{\gamma k} q}  G^{<}_{\gamma\beta}(\omega+\epsilon)V_{\beta q}^* g_{q}^{h,a}(\omega+\epsilon)+g_{k}^{h,<}(\omega+\epsilon) k}^* g_{k}^{h,a}(\omega+\epsilon)+g_{q}^{h,<}(\omega+\epsilon)  V_{\gamma k} q}  G^{a}_{\gamma\beta}(\omega+\epsilon)V_{\beta q}^* g_{q}^{h,a}(\omega+\epsilon)\,, 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} 

We need to compute the following product of Green functions: $G^>_{\beta\gamma}(\epsilon)G_{kq}^{h,<}(\omega+\epsilon)$  \begin{eqnarray}  &&G^>_{\beta\gamma}(\epsilon) G_{kq}^{h,<}(\omega+\epsilon) = \sum_{k\alpha\delta} 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} 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_{k}^{h,r}(\omega+\epsilon) [g_{q}^{h,r}(\omega+\epsilon)  V_{\gamma k} q}  G^{r}_{\gamma\beta}(\omega+\epsilon)V_{\beta q}^* g_{q}^{h,<}(\omega) k}^* g_{k}^{h,<}(\omega)  \nonumber \\  &&+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_{k}^{h,r}(\omega+\epsilon) [g_{q}^{h,r}(\omega+\epsilon)  V_{\gamma k} q}  G^{<}_{\gamma\beta}(\omega+\epsilon)V_{\beta q}^* g_{q}^{h,a}(\omega+\epsilon)]\\ k}^* g_{k}^{h,a}(\omega+\epsilon)]\\  \nonumber &&+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_{k}^{h,<}(\omega+\epsilon) \gamma}(\epsilon)[g_{q}^{h,<}(\omega+\epsilon)  V_{\gamma k} q}  G^{a}_{\gamma\beta}(\omega+\epsilon)V_{\beta q}^* g_{q}^{h,a}(\omega+\epsilon)]\,, k}^* g_{k}^{h,a}(\omega+\epsilon)]\,,  \end{eqnarray}  We now compute separately the different parts of the previous expression for the ac noise  \begin{eqnarray}  S^{>,1}(\omega)= \frac{e^2}{\hbar^2}\int_{-\infty}^\infty \frac{d\epsilon}{2\pi} \sum_{k,q,p\beta\gamma\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)[V_{\beta k} g_{q}^{h,<}(\omega+\epsilon)V^*_{\gamma q}\delta_{kq}  \end{eqnarray}  \begin{eqnarray}  S^{>,2}(\omega)= \frac{e^2}{\hbar^2} \int_{-\infty}^\infty \frac{d\epsilon}{2\pi} \sum_{k,q,p\beta\gamma\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) [V_{\beta k} g_{k}^{h,r}(\omega+\epsilon) [V^*_{\gamma q} g_{q}^{h,r}(\omega+\epsilon)  V_{\gamma q} G^{<}_{\gamma\beta}(\omega+\epsilon) V_{\beta  k} G^{<}_{\gamma\beta}(\omega+\epsilon)V_{\beta q}^* g_{q}^{h,a}(\omega+\epsilon)V^*_{\gamma q}] g_{k}^{h,a}(\omega+\epsilon)V^_{\beta k}]  \end{eqnarray}  \begin{eqnarray}  S^{>,3}(\omega)= \frac{e^2}{\hbar^2} \int_{-\infty}^\infty \sum_{k,q,p\beta\gamma\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) [V_{\beta k} g_{k}^{h,r}(\omega+\epsilon) V_{\gamma k} G^{<}_{\gamma\beta}(\omega+\epsilon)V_{\beta [V_{\gamma  q}^* g_{k}^{h,r}(\omega+\epsilon) V^*_{\gamma q} G^{<}_{\gamma\beta}(\omega+\epsilon)V_{\gamma q}  g_{q}^{h,a}(\omega+\epsilon) V^*_{\gamma q}] \end{eqnarray}  \begin{eqnarray}  S^{>,4}(\omega)= \frac{e^2}{\hbar^2} \int_{-\infty}^\infty \frac{d\epsilon}{2\pi} \sum_{k,q,p\beta\gamma\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)[V_{\beta k} g_{k}^{h,<}(\omega+\epsilon) V_{\gamma k} G^{a}_{\gamma\beta}(\omega+\epsilon)V_{\beta q}^* g_{q}^{h,a}(\omega+\epsilon)V^*_{\gamma q}]