We demonstrate the selective coupling of a single quantum dot exciton spin state with the cavity mode in a quantum dot-micropillar cavity system. By tuning an external magnetic field, the Zeeman splitted exciton spin states coupled differently with the cavity due to field manipulated energy detuning. We found a 26 times increase in the emission intensity of spin-up exciton state with respect to spin-down exciton state at resonance due to Purcell effect, which gives rise to the selective enhancement of light emission with the circular polarization degree up to 93%. A four-level rate equation model is developed and quantitatively agrees well with our experimental data. Our results pave the way for the realization of future quantum light sources and the quantum information processing applications.
@article{arxiv.1008.1017,
title = {Spin Selective Purcell Effect in a Quantum Dot Microcavity System},
author = {Qijun Ren and Jian Lu and H. H. Tan and Shan Wu and Liaoxin Sun and Weihang Zhou and Wei Xie and Zheng Sun and Yongyuan Zhu and C. Jagadish and S. C. Shen and Zhanghai Chen},
journal= {arXiv preprint arXiv:1008.1017},
year = {2011}
}