Quantum Interference in Semiconductor Quantum Wells

We present a review of theoretical and experimental evidence for quantum interference in intersub- band transitions of coupled semiconductor quantum wells. Intersubband absorption spectra are calculated using semiconductor Bloch equations to include the Coulomb interaction between the conduction band electrons. We demonstrate that the absorption spectra must be viewed as collective excitations. In a configuration analogous to electromagnetically induced transparency (EIT) in atomic systems, we show that quantum interference occurs between the levels of these collective intersubband excitations rather than single electronic states. Exper- iments which demonstrate quantum interference in coupled quantum wells due to tunneling induced transpar- ency (TIT) are presented. The design issues for such samples are reviewed, and the effects of monolayer growth fluctuations on the spectra are simulated. Finally, we discuss the temperature dependence of TIT and demon- strate that the quantum interference persists at room temperature.