Figure 1

Conduction subbands of the asymmetric double quantum well in the bare state picture. The deep well ground state $|1⟩$ and the shallow well first excited state $|4⟩$ have energies $E_1=46.7\mathrm{meV}$ and $E_4=296.3\mathrm{meV}$, while the delocalized levels $|2⟩$ and $|3⟩$ have energies $E_2=174.8\mathrm{meV}$ and $E_3=183.5\mathrm{meV}$. The solid curves represent the corresponding wave functions. The growth sequence of the structure from left to right is as follows. A thick ${\mathrm{Al}}_{0.4}{\mathrm{Ga}}_{0.6}\mathrm{As}$ barrier is followed by a ${\mathrm{Al}}_{0.16}{\mathrm{Ga}}_{0.84}\mathrm{As}$ shallow well (6.8 nm). This shallow well is separated from the GaAs deep well (7.7 nm) on the right by a ${\mathrm{Al}}_{0.4}{\mathrm{Ga}}_{0.6}\mathrm{As}$ potential barrier (3.0 nm). Finally, a thin (1.5 nm) ${\mathrm{Al}}_{0.4}{\mathrm{Ga}}_{0.6}\mathrm{As}$ barrier separates the deep well from the last thick layer of ${\mathrm{Al}}_{0.16}{\mathrm{Ga}}_{0.84}\mathrm{As}$ on the right. Inset: in the presence of the switch field, subbands $|2⟩$ and $|3⟩$ couple with subband $|4⟩$ giving rise to the three dressed states $|+⟩$, $|0⟩$, and $|-⟩$.Reuse & Permissions

Figure 2

(a) Probe absorption spectra from Eq. (3) with ${\gamma }_{2d}=0.68\mathrm{meV}$ and ${\gamma }_{3d}=0.80\mathrm{meV}$ (solid line), with ${\gamma }_{2d}=1.36\mathrm{meV}$ and ${\gamma }_{3d}=1.60\mathrm{meV}$ (dashed line), and with ${\gamma }_{2d}=2.72\mathrm{meV}$ and ${\gamma }_{3d}=3.20\mathrm{meV}$ (dotted line). Other parameters are ${\gamma }_{2l}=3.47\mathrm{meV}$, ${\gamma }_{3l}=4.13\mathrm{meV}$, ${\Omega }_s={\Delta }_s=0$, and $\Delta =4.36\mathrm{meV}$. The black dots represent computational results [20] (see text). (b) Probe absorption spectra from Eq. (3) with ${\Omega }_s=0$ (solid line), ${\Omega }_s=1.0\mathrm{meV}$ (dashed line), and ${\Omega }_s=2.0\mathrm{meV}$ (dotted line). Other parameters are ${\gamma }_{2l}=3.47\mathrm{meV}$, ${\gamma }_{3l}=4.13\mathrm{meV}$, ${\gamma }_{4l}=0.80\mathrm{meV}$, ${\gamma }_{2d}=0.68\mathrm{meV}$, ${\gamma }_{3d}=0.80\mathrm{meV}$, ${\gamma }_{4d}=0.50\mathrm{meV}$, ${\Delta }_s=0$, and $\Delta =4.36\mathrm{meV}$. The black dots represent computational results [20] for ${\Omega }_s=2.0\mathrm{meV}$ (see text).Reuse & Permissions

Figure 3

Transmission spectra of the probe field for (a) $N{\sigma }_{2}z=5$ and (b) $N{\sigma }_{2}z=10$. Here ${\Omega }_s=0$ (solid line), ${\Omega }_s=1.0\mathrm{meV}$ (dashed line), and ${\Omega }_s=2.0\mathrm{meV}$ (dotted line) while other parameters are the same as in Fig. 2b.Reuse & Permissions

Figure 4

Time evolution of a cw probe field with ${\Delta }_p=0$, ${\Omega }_p=0.01\mathrm{meV}$, and $N{\sigma }_{2}z=10$. Here ${\Omega }_s=0.5\mathrm{meV}$ (solid line), ${\Omega }_s=1.0\mathrm{meV}$ (dashed line), and ${\Omega }_s=2.0\mathrm{meV}$ (dotted line) while other parameters are the same as in Fig. 2b. The cw switching field is turned on or off at a period of 10 ps. Inset: transient blowup showing switching and recovery times of about 1 ps.Reuse & Permissions