Coherent switching by detuning a side-coupled quantum-dot system

We investigate phase-coherent electronic transport in an open quantum system, which consists of quantum dots side coupled to a nanowire. It is demonstrated that coherent switching can be characterized by adjusting the electronic energy. A comparative analysis of quantum coherence effects in side-coupled quantum-dot systems is presented. Our results demonstrate the relevance of electronic nanodevices based on coherent switching by appropriately detuning the side-coupled quantum dots that are located at variable distance along a wire.

Figure 1

Schematic of a scattering region in a nanowire connected to electronic reservoirs.

Figure 2

(Color online) Diagram of the system under investigation. (a) Double quantum dots side coupled to a nanowire. (b) Transverse potential profile at $x=x_1$ for the double quantum dots side coupled to a nanowire (solid-red curve) in comparison with the unperturbed nanowire (dashed-green curve).

Figure 3

(Color online) (a) Conductance as a function of the parameter $X_E$ for the cases of double side-coupled quantum dots (solid-red curve), single side-coupled quantum dot (dashed-blue curve), and unperturbed nanowire (dotted-green curve). The conductance curves exhibiting Fano resonances are emphasized in (b).

Figure 4

(Color online) Square root of probability densities of the scattering states for the case of single-dot system corresponding to the Fano resonance dip marked by $\mathit{a}$ in Fig. 3 for the electrons occupying the incident subband (a) $n=0$ and (b) 1.

Figure 5

(Color online) Square root of probability densities of the scattering states for the case of double-dot system corresponding to the Fano resonance dip marked by $\mathit{b}$ in Fig. 3 for the electrons occupying the incident subband (a) $n=0$ and (b) 1.

Figure 6

(Color online) Conductance as a function of the parameter $X_E$ and detuning parameter $\Delta V_{2a}$ for the case of double side-coupled quantum dots: (a) top and (b) three-dimensional (3D) views.

Figure 7

(Color online) Conductance as a function of the parameter $X_E$ of the double side-coupled quantum dots for the cases with detuning $\Delta V_{2a}=-0.14{\epsilon }_0$ (solid-red curve) and with no detuning $\Delta V_{2a}=0.0{\epsilon }_0$ (dashed-blue curve).

Figure 8

(Color online) Square root of probability densities of the scattering states at the dip structure in conductance marked by $\mathit{e}$ in Fig. 7 for the case of $\Delta V_{2a}=-0.14{\epsilon }_0$ with incident subband (a) $n=0$ and (b) 1.

Figure 9

(Color online) Square root of the probability densities of the scattering states marked by $\mathit{f}$ in Fig. 7 for the case of $\Delta V_{2a}=-0.14{\epsilon }_0$ with incident subband (a) $n=0$ and (b) 1.

Figure 10

(Color online) Square root of the probability densities of the scattering states at the dip structure in conductance marked by $\mathit{g}$ in Fig. 7 for the case of $\Delta V_{2a}=-0.14{\epsilon }_0$ with incident subband (a) $n=0$ and (b) 1.

Figure 11

(Color online) (a) Conductance as a function of the parameter $X_E$ in a nanowire with double side-coupled quantum dots for the cases with detuning $\Delta V_{2a}=-0.055{\epsilon }_0$ (solid-red curve) and with no detuning $\Delta V_{2a}=0.0{\epsilon }_0$ (dashed-blue curve). The small blip structure marked by $\mathit{j}$ in (a) is emphasized in (b).

Figure 12

(Color online) Square root of the probability densities of the scattering states at the small blip in conductance marked by $\mathit{j}$ in Fig. 11 with detuning parameter $\Delta V_{2a}=-0.055{\epsilon }_0$ for the cases of incident subband (a) $n=0$ and (b) 1.

Figure 13

(Color online) Square root of the probability densities of the scattering states marked by $\mathit{k}$ in Fig. 11 with detuning parameter $\Delta V_{2a}=-0.055{\epsilon }_0$ for the cases of incident subband (a) $n=0$ and (b) 1.

Figure 14

(Color online) Square root of the probability densities of the scattering states at the dip marked by $\mathit{l}$ in Fig. 11 with detuning parameter $\Delta V_{2a}=-0.055{\epsilon }_0$ for the cases of incident subband (a) $n=0$ (b) 1.