Comparison of electromagnetically induced transparency schemes in semiconductor quantum dot structures: Impact of many-body interactions

We investigate the impact of many-body interactions on group-velocity slowdown achieved via electromagnetically induced transparency in quantum dots using three different coupling-probe schemes (ladder, $V$, and $\Lambda$, respectively). We find that for all schemes many-body interactions have an important impact on the slow light properties. In the case of the $\Lambda$ and $V$ schemes, the minimum required coupling power to achieve slow light is significantly reduced by many-body interactions. $V$ type schemes are found to be generally preferable due to a favorable redistribution of carriers in energy space.

Figure 1

Schematic quantum dot level structure and three EIT configurations. The frequency of the intense coupling field is denoted as ${\omega }_{\text{coup}}$ while the weak probe field is shown as ${\omega }_{\text{probe}}$. For illustrative purposes the figure has not been drawn to scale.

Figure 2

Ladder, $V$, and $\Lambda$ schemes using a coupling field intensity of $26\text{MW}/{\text{cm}}^2$: complex susceptibility vs probe energy. The dashed line corresponds to the atomic model, i.e., without many-body interactions, while the solid line is evaluated with many-body interactions. The energy is measured relative to the zero density excitonic resonances ${ϵ}_{e0,h0}^{\left(x\right)}$, ${ϵ}_{e5,h0}^{\left(x\right)}$, and ${ϵ}_{e0,h5}^{\left(x\right)}$, respectively. To facilitate a comparison between the two cases, the noninteracting spectra have been shifted accordingly.

Figure 3

(Color online) Maximum slowdown factor and corresponding absorption coefficient vs coupling intensity for various EIT schemes. The dashed curves are for the independent-particle (atomic) model while the solid curves include many-body interactions.

Figure 4

Temporal development of the Pauli probe blocking factors for $\Lambda$ and $V$ schemes at coupling intensity of $2.5\text{MW}/{\text{cm}}^2$. Shown in the figure are the Rabi oscillations of the populations at the onset of the coupling field and the relaxation toward their stationary value. Also shown is an illustration of the “turn on” of the coupling laser.