Multi-qubit quantum phase gates based on plasmonic nanospheres

The Dicke subradiance and superradiance resulting from the interaction between surface plasmons of nanospheres and an ensemble of quantum emitters have been investigated by using a Green's function approach. Based on such an investigation, we propose a scheme for a deterministic multi-qubit quantum phase gate. The case of single sphere has been compared with nanosphere cluster which possesses hot spots. The potential application of present phenomena to the quantum-information processing is anticipated.