Exciton fine structure in coupled quantum dots

We have developed a theoretical treatment of exciton fine structure effects in coupled quantum dots. We find that the dominant contributions giving mixing of optically bright and dark states and anticrossings between them are (i) an anisotropic Zeeman interaction for the hole and (ii) the electron spin-orbit interaction at nonzero magnetic field. Detailed calculations are given for vertically coupled InAs/GaAs dots that give a framework for the interpretation of recent experimental results. We find that anticrossings arise from deviations from axial symmetry in these systems.