Electromagnetically induced transparency in an inverted Y-type four-level system

TL;DR

This paper theoretically explores electromagnetically induced transparency in an inverted Y-type four-level atomic system, demonstrating controllable transparency windows and group velocities, with potential quantum information applications.

Contribution

It introduces a new four-level atomic configuration showing controllable EIT windows and group velocities, advancing quantum control techniques.

Findings

Single or double EIT windows depend on coupling laser parameters.

Group velocity of probe can be switched from superluminal to subluminal.

Potential for experimental observation in $^{87}Rb$ atoms.

Abstract

The interaction of a weak probe laser with an inverted-Y type four-level atomic system driven by two additional coherent fields is investigated theoretically. Under the influence of the coherent coupling fields, the steady-state linear susceptibility of the probe laser shows that the system can have single or double electromagnetically induced transparency windows depending on the amplitude and the detuning of the coupling lasers. The corresponding index of refraction associated with the group velocity of the probe laser can be controlled at both transparency windows by the coupling fields. The propagation of the probe field can be switched from superluminal near the resonance to subluminal on resonance within the single transparency window when two coupling lasers are on resonance. This provides a potential application in quantum information processing. We propose an atomic $^{87}Rb$ system for experimental observation.