Extending the time of coherent optical response in ensemble of singly-charged InGaAs quantum dots

Multiple Rabi rotations of trions in InGaAs quantum dots observed by photon echo spectroscopy with spatially shaped laser pulses

“…The excellent agreement of the experimental data and the modeling allows us to conclude that the coupling to acoustic phonons is the dominant mechanism for the loss of optical coherence inherent to a single dot. For the used pulse durations of 3.8 ps, the largest pulse areas in our experiment ∼ 5π feature a mean Rabi frequency of roughly 4.1 THz, which is close to the maximum of the phonon spectral density (6) with the found parameters. Consequently, the loss of coherence acts very efficient in the regime of large pulse areas.…”

“…In this context, excitonic complexes in semiconductor quantum dots (QDs) represent outstanding systems as they typically combine a large ratio between inhomogeneous and homogeneous linewidths with the possibility for sub-picosecond optical initialization, which makes them advantageous over atomic vapors [3,4]. As recently demonstrated, the relatively short excitation lifetimes of QDs, that limit potential storage times, can be extended from the picosecond to the nanosecond timescale by transfer between optical and spin coherence [5,6]. However, the use of high optical powers for a complete inversion of the ensemble leads to an irreversible loss of microscopical coherence due to the interaction between the QDs and acoustic phonons [7].…”