Hartman effect and non-locality in quantum networks

We study the phase time for various quantum mechanical networks having potential barriers in its arms to find the generic presence of Hartman effect. In such systems it is possible to control the `super arrival' time in one of the arms by changing parameters on another, spatially separated from it. This is yet another quantum nonlocal effect. Negative time delays (time advancement) and `ultra Hartman effect' with negative saturation times have been observed in some parameter regimes.