title: Non-markovian dynamics of spectral narrowing for excitons in the layered semiconductor GaSe observed using optical four-wave mixing spectroscopy.
abstract: 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.
authors.affiliation: Department of Physics, Tokyo Institute of Technology, Oh-Okayama 2-12-1, Tokyo 152-8551, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tahara
authors.forename: Y
authors.initials: Y
authors.lastname: Ogawa
authors.forename: F
authors.initials: F
authors.lastname: Minami