Exploring qubit-qubit entanglement mediated by one-dimensional plasmonic   nanowaveguides
  We exploit the qubit-qubit coupling induced by plasmon-polariton modes in a one-dimensional nanowaveguide to obtain various two-qubit entanglement situations. Firstly, we observe three phenomena occurring when preparing the initial state of the system and leaving it freely relax: spontaneous formation of entanglement, sudden birth and revival. Then, we show that plugging a laser to each of the qubit, the system arrives to an steady state which, depending on their inter-qubit distance, can also be entangled. For this situation, we also characterize the quantum state of the system showing the entanglement-purity- diagram typical for two-qubit systems. 
A. Gonzalez-Tudela, D. Martin-Cano, E. Moreno, L. Martin-Moreno, F.J.   Garcia-Vidal and C. Tejedor
cond-mat.mtrl-sci quant-ph