Coherent light-matter interactions require that the wavefunction which describes the electronic state preserves its phase during the interaction with the optical field. For that reason, quantum phenomena are easily studied in systems that exhibit long coherence times, for example, in atomic vapors.
In semiconductors, the electronic wavefunction scatters rapidly due to many body interactions. Therefore, in semiconductors, coherent phenomena are usually observed at very low, cryogenic, temperatures.
In my PhD research I took a different avenue to study the quantum coherent interaction in semiconductors. Instead of operating at low cryogenic temperatures, I examined the interaction on very short time scales before the electronic wavefunction had the opportunity to dephase. This was achieved by constructing a very fast “oscilloscope” that could record the electrical field of the electromagnetic radiation in the time domain after the interaction took place.
Using this ultrafast “oscilloscope”, the temporal, femtosecond timescale, evolution of an effective wavefunction along the semiconductor optical amplifier was reconstructed in room temperature conditions. In this work, which saw light in [arXiv:1210.6803, (Phys. Rev. B 90, 045305)], the interaction was shown to take the form of Rabi oscillations.
Using the same experimental technique, in a later work [Nature Comm. 5, 5025] which was carried out as well under room-temperature conditions, we demonstrated a coherent control of the electronic wavefunction in a Ramsey analogous experiment.
Coherent light-matter interaction in room temperature semiconductors