Controlling the delocalization-localization transition of light via electromagnetically induced transparency

TLDR: In this paper, the authors proposed a scheme to realize a transition from delocalization to localization of light waves via electromagnetically induced transparency, which is a resonant cold atomic ensemble having $N$ configuration, with a control field consisting of two pairs of laser beams with different cross angles.

Abstract: We propose a scheme to realize a transition from delocalization to localization of light waves via electromagnetically induced transparency. The system we suggested is a resonant cold atomic ensemble having $N$ configuration, with a control field consisting of two pairs of laser beams with different cross angles, which produce an electromagnetically induced quasiperiodic waveguide (EIQPW) for the propagation of a signal field. By appropriately tuning the incommensurate rate or relative modulation strength between the two pairs of control-field components, the signal field can exhibit the delocalization-localization transition as it transports inside the atomic ensemble. The delocalization-localization transition point is determined and the propagation property of the signal field is studied in detail. Our work provides a way of realizing wave localization via atomic coherence, which is quite different from the conventional, off-resonant mechanism-based Aubry-Andre model, and the great controllability of the EIQPW also allows an easy manipulation of the delocalization-localization transition.