Control of non-Markovian effects in the dynamics of polaritons in semiconductor microcavities

We report on time-resolved photoluminescence from semiconductor microcavities showing that an optically controllable mechanism exists to turn on and off memory effects in a polariton system. By increasing the laser pumping pulse intensity resonantly exciting the upper polariton branch, we observe revivals of the decaying time-resolved photoluminescence signal, a manifestly non-Markovian behavior of the optically active lower branch polaritons. Based on an open quantum system approach we perform a comprehensive analytical and numerical study of the optically active polaritons to confirm the origin of the observed features. Our findings show that negative detunings and strong excitation should occur simultaneously for memory effects to take place.