講演情報
[16a-M_107-8]Direct Estimation of Density Matrix Time Evolution of Neutral Exciton Emission in a
Single Semiconductor Quantum Dot by Polarization-Time-Resolved Measurements
〇(M1)JOSEPHY VICTOR NJALA1, Yuta Yamamoto1, Reina Kaji1, Satoru Adachi1, Hirotaka Sasakura1 (1.Hokkaido Univ.)
キーワード：
Semiconductor Quantum dots、Quantum Tomography
We investigate the polarization dynamics of neutral excitons in a single InAlAs/AlGaAs quantum dot (QD). Time-resolved measurements were performed using a picosecond Ti:sapphire laser with 2LO-phonon resonant excitation in a reflection geometry. The excitation was left-circularly polarized, and single neutral exciton's emission were spectrally filtered using a 0.5-nm narrow bandpass filter before detection by single-photon detector. We measured the transient evolution of polarization-resolved emission via photon counting correlated with the laser mode-locked signal. We observed coherent oscillations from both left-circular and right circular polarization components. These oscillations reflect the coherent dynamics of a two-level system defined by the exciton fine-structure splitting, with the oscillation period consistent with the splitting energy determined from steady-state measurements. Additional measurements in the horizontal, vertical, diagonal, and anti-diagonal polarization bases allowed the reconstruction of the exciton s density matrix,
providing a direct estimation of its time-dependent evolution from the optically created initial state by circularly polarized excitation.
providing a direct estimation of its time-dependent evolution from the optically created initial state by circularly polarized excitation.