Abstract:
Intraexciton transitions in semiconductor quantum wells are modulated by strong and tunable few-cycle
terahertz pulses. Time-resolved terahertz-pump and optical-probe measurements demonstrate that the
1s heavy-hole and light-hole exciton resonances undergo large-amplitude spectral modulations when the
terahertz radiation is tuned near the 1s–2p intraexciton transition. The strong nonlinear optical transients
exhibit the characteristics of Rabi sidebands. The spectral features also reveal the dephasing properties of
the optically dark 2p states. A microscopic theory shows that the 2p-dephasing rate is three times that of
the 1s-state. The ultrafast nonlinear optical effects and their quantum nature suggest promising applications
to ultrahigh-speed optical signal processing and quantum information processing in the THz region.
