Quantum phase flip gate based on plasmonic double-bar resonators.

We demonstrate a quantum phase flip gate between two QDs that resonantly couple to plasmonic double-bar resonators with asymmetric coupling strengths. Large coupling strengths can be achieved due to the deep subwavelength mode volumes of the optical modes in plasmonic double-bar resonators. High fidelity (~98%) and high success probability of the phase gate operation have been obtained when the coupling strength ratio (g2/g1) and resonant mode decay rate (κ/g1) are optimized. The subwavelength-scale plasmonic structures provide tremendous potential for solid-state quantum information processing.