Wide-band-limit approximation

To simplify the computation further, we consider an approximate scheme for Qa(r) based on the adiabatic wide-band-limit (AWBL) treatment for electrodes, as well as an adiabatic approximation for the memory effect. The scheme aims at simplifying the NEGF expression of Qq,(0 [42],... 

So far we have discussed noise-induced transitions only in the white noise limit. Naturally, the question arises if these noise-induced phenomena are robust. In other words, are essentially the same phenomena observed for cor small, but nonvanishing The answer is positive. Noise-induced transitions are HO-t an artifact of white noise they occur also for colored noise, i.e. for environments with nonzero correlation times. This has been established by various techniques, namely the wide band perturbation expansion [8,5], the approximate Fokker-Planck operator techniques [24], and approximate renormalized equations of evolution for Gaussian noise [25]. These methods are perturbation expansions and are limited to small T or order to ex-... 

Of the four procedures considered, the Egelstaff procedure P-4 (scaled) is clearly the best approximation to the exact quantum profile. It results in the almost exact quantum profile from the classical profile, even far in the wing where intensities have fallen off to a small fraction of the peak intensity. In other words, quantum corrections based on the ideal gas approximation are the leading ones. Next are the extremely simple procedures P-2 and P-3. The widely used procedure P-1, on the other hand, leads to rapidly deteriorating wings and should be avoided, unless limited to a narrow frequency band near the line center. 

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