Surface plasmon polariton induced strong coherent superposition

A strong coherent superposition is shown to be induced between the energy states of a two-level emitter immersed in a surface plasmon polariton evanescently confined to a small metallic ring. It turns out that there is nearly equal chance for the two-level emitter to be found either in the upper or lower energy level at steady state even for a weaker surface plasmon driving strength. This indicates that it is possible to create a qubit that is robust against emitter spontaneous damping rate, which can be applicable in designing a device that can perform certain quantum information processing tasks. In support of this proposal, the photon statistics of the emitted radiation is found to exhibit significant nonclassical features.