Anomalous Fano resonance of massive Dirac particle through a time-dependent barrier

As is well known Fano resonance arises from the interference between a localized state and a continuum state. Using the standard Floquet theory and the scattering matrix method, we study theoretically the massive Dirac particle transmission over a quantum barrier with an oscillating field. It is found that the massive relativistic particles can generate not only normal Fano resonance in the transmission due to the interference between a localized state (bound state) and the continuum state, but also anomalous Fano resonance due to the interference between a delocalized state (extended state) and the continuum state. The dependence of line shapes on driving parameters for these two kinds of Fano resonances is quite different. For normal Fano resonance the asymmetry parameter is approximately proportional to a power law of the amplitude of the oscillating field, while for the anomalous Fano resonance the asymmetry parameters change slightly with different oscillation amplitudes. In practice, the anomalous Fano resonance can be identified by observing asymmetry parameters in experiment. Copyright (C) EPLA, 2015National Fundamental Research Program of China [2013CBA01502, 2011CB921503, 2013CB834100]; National Natural Science Foundation of China [11374040, 11274051, 11304281]; Zhejiang Education Department [Y201225191]SCI(E)ARTICLElbfu@iapcm.ac.cn611