Observation of exciton quantum beats by using a double-pulse pump-probe technique under higher temperatures

M. I. Shmiglyuk, A. I. Bobrysheva, V. Pavlov

The quantum beats (QB) in the time-dependent absorption intensity of the probe pulse and the spontaneous luminescence one in Cu2O crystal at the condition of double optical resonance are studied theoretically. It is assumed that the pump is performed by the CO2 laser pulse, which couples dynamically the 1s (Γ 5 + ) and 2p (Γ 4 - , Γ 5 - , Γ 3 - , Γ 2 - ) excitonic states and leads to their splitting into two or three quasienergy levels. The frequency of the probe pulse is in the region of the Γ 5 + exciton resonance. The respective intensities for different directions of the electric field E L of the pump, the polarization ξ of the probe pulse, and the observation q are obtained. The QB take place with the doubled Raby frequency, which at different E L , ξ, and q includes different sets of matrix elements of dipole transitions between 1s (Γ 5 + ) and 2p (Γ 4 - , Γ 5 - , Γ 3 - , Γ 2 - ) levels. These unknown matrix elements can be obtained, measuring the period of the QB.

Aoki, Svirko, Kuwata-Gonokami

Karl Leo, Ernst Otto Göbel, Theo C. Damen +6 more

Osamu Kojima, Kenta Kojima, Takashi Kita +1 more

We discuss the dephasing of quantum beat oscillation related to the intersubband transition between heavy-hole and light-hole excitons in a GaAs/AlAs multiple quantum well as measured by a pump-probe technique. We investigate the dependence of dephasing on temperature and pump energy. The analysis of the time-domain signals reveals that a strong quantum beat induces the rapid dephasing related to intersubband transition; the dependencies of the dephasing rate correspond to those of the amplitude. This implies that a quantum beat is useful in applications utilizing an ultrafast optical response.

Scot A. Hawkins, Eric J. Gansen, Martin J. Stevens +8 more

Time-integrated differential detection techniques are used to study quantum beats involving the light-hole and heavy-hole excitons in an optically thin InGaAs multiple quantum well. The contributions of the exciton-exciton correlations are separated from those of the intervalence-band Raman coherence and the interband (population) coherence by monitoring the signal in the probe direction and by taking advantage of the polarization selection rules for the excitonic transitions. Quantum beats are observed for pump and probe pulses with the same circular polarization, providing evidence for two-exciton correlations. A theoretical analysis based on the dynamics-controlled truncation formalism suggests that the beats for the same linear polarization arise from Raman, population, and two-exciton contributions.

K. Mizoguchi, T. Furuichi, Osamu Kojima +4 more