Partially dark optical molecule via phase control
  We study the tunable photonic distribution in an optical molecule consisting of two linearly coupled single-mode cavities. With the inter-cavity coupling and two driving fields, the energy levels of the optical-molecule system form a closed cyclic energy-level diagram, and the phase difference between the driving fields serves as a sensitive controller on the dynamics of the system. Due to the quantum interference effect, we can realize a partially dark optical molecule, where the steady-state mean photon number in one of the cavities achieves zero even under the external driving. And the dark cavity can be changed from one of the cavities to the other by only adjusting the phase difference. Furthermore, we show that when one of the cavities couples with an atomic ensemble, it will be dark under the same condition as that without atoms, but the condition for the other cavity to be dark is modified. 
Z. H. Wang and Y. Li
quant-ph