Department of Physics, Tokyo Institute of Technology, Oh-Okayama 2-12-1, Tokyo 152-8551, Japan.
Phys Rev Lett. 2011 Jul 15;107(3):037402. doi: 10.1103/PhysRevLett.107.037402. Epub 2011 Jul 11.
We have investigated non-markovian dephasing by using time-resolved and spectrally resolved four-wave mixing measurements in a layered semiconductor GaSe. When the time interval between the first and second excitation pulses is increased, photon echo spectra exhibit narrowing only in a regime of a few picoseconds. In the initial dephasing of these signals, fast damping is observed. The narrowing of the spectrally resolved signal is consistent with the Fourier transformation of the time-resolved signals. Spectral narrowing is crucial evidence of the transition from non-markovian to markovian dynamics. By comparing experimental data with calculation results based on the non-markovian theory, we have found that the correlation time of the exciton-phonon interaction is 1.1 ps.
我们通过在分层半导体 GaSe 中进行时间分辨和光谱分辨的四波混频测量来研究非马尔可夫退相。当第一个和第二个激发脉冲之间的时间间隔增加时，仅在几个皮秒的范围内，光子回波光谱才会出现变窄。在这些信号的初始退相过程中，观察到快速衰减。光谱分辨信号的变窄与时间分辨信号的傅里叶变换一致。光谱变窄是从非马尔可夫动力学向马尔可夫动力学转变的关键证据。通过将实验数据与基于非马尔可夫理论的计算结果进行比较，我们发现激子-声子相互作用的相关时间为 1.1 ps。
