Dipole-dipole interaction in a photonic crystal nanocavity

Abstract

Beijing National Laboratory for Condensed Matter Physics,Institute of Physics, Chinese Academy of Sciences, Beijing 100190 China(Dated: December 30, 2011)Dipole-dipole interaction between two two-level ‘atoms’ in photonic crystal nanocavity is investi-gated based on finite-difference time domain algorithm. This method includes both real and virtualphoton effects and can be applied for dipoles with different transition frequencies in both weak andstrong coupling regimes. Numerical validations have been made for dipoles in vacuum and in anideal planar microcavity. For dipoles located in photonic crystal nanocavity, it is found that thecooperative decay parameters and the dipole-dipole interaction potential strongly depend on the fol-lowing four factors: the atomic position, the atomic transition frequency, the resonance frequency,and the cavity quality factor. Properly arranging the positions of the two atoms, we can acquireequal value of the cooperative decay parameters and the local coupling strength. Large cooperativedecay parameters can be achieved when transition frequency is equal to the resonance frequency.For transition frequency varying in a domain of the cavity linewidth around the resonance frequency,dipole-dipole interaction potential changes continuously from attractive to repulsive case. Largervalue and sharper change of cooperative parameters and dipole-dipole interaction can be obtainedfor higher quality factor. Our results provide some manipulative approaches for dipole-dipole in-teraction with potential application in various fields such as quantum computation and quantuminformation processing based on solid state nanocavity and quantum dot system.