Detuning-determined qubit-qubit entanglement mediated by plasmons: An effective model for dissipative systems

We theoretically investigate a general scheme for determining quantum entanglement of two detuned quantum dots (QDs) mediated by plasmon nanoparticle for weakly driven dissipative systems. By adiabatically eliminating the field operators, an effective model is proposed to find the underlying mechanism for this determination. Two specific hybrid systems composed of two QDs and a metallic nanoparticle (MNP) are considered. In the QD-MNP-QD system, the concurrence maxima generated by the detunings are several times larger than those in the resonance condition because of the robust superposition between the two separated entangled states. However, in the MNP-QD-QD system, the detunings generally reduce entanglement because the dipole-dipole interaction strongly suppresses the superposition of the entangled states. Moreover, the plateau of large concurrence exists for a broad range of parameters in both cases. The scheme is robust to dissipative systems and paves the way to improve entanglement in quantum information devices at the nanoscale. Published by AIP Publishing.National Key Basic Research Program [2013CB328700]; National Natural Science Foundation of China [11525414, 11374025, 91221304]SCI(E)ARTICLE2012