A two-photon process leading to coherent transitions between the two circularly polarized exciton states in a quantum dot is studied. It is shown that optical flipping of the exciton polarization is possible with picosecond laser pulses. The process is closely related to two-photon Rabi oscillations of a biexciton but it is much more stable against shifts of the laser frequency.

双光子过程导致两者之间的相干跃迁 研究了量子点中的圆偏振激子态。如图所示 激子偏振的光学翻转在皮秒内是可能的 激光脉冲。这一过程与双光子拉比振荡密切相关 它是一种双激子，但它对激光频率的变化更稳定。