Figure 1

(a) Sketch of the system under investigation: A quantum ring with average radius $R$, attached to input (left) and output (right) channels with the same width as the ring ($W=10$ $nm$), and to an extra horizontal channel of width $W_c$. (b) Contour plots of the transmission probabilities as a function of the extra channel width and ring radius. The solid, dashed, and dotted lines indicate seven minima that are discussed in the text. A zoom of the 4 $\text{nm}<W_c<16$ nm region with the logarithm of the transmission is shown in (c).Reuse & Permissions

Figure 2

Snapshot of the propagating wave function at $t=900$ fs for two values of the extra channel width: (a) 19 nm and (b) 20 nm.Reuse & Permissions

Figure 3

Probability density currents as a function of time, calculated (a) in the input lead and (b) in the extra channel, for different values of the extra channel width $W_c$, for wave packet energy $\epsilon =70$ meV.Reuse & Permissions

Figure 4

(a) Eigenstates of a finite quantum well as a function of its width. (b) Diagram representing the energy subbands in the input lead and in the extra channel. The horizontal dotted line is the average energy of the wave packet used in Figs. 1 and 3, and the shaded area in (a) illustrates the FWHM of the energy distribution of this wave packet.Reuse & Permissions

Figure 5

(a) Transmission probabilities as a function of the extra channel width in the vicinity of the minimum labeled as $M$ in Fig. 1a, for several values of the wave packet energy $\epsilon =70$ (bottom curve), $80,...,180$ meV (top curve). The curves were shifted 0.1 up from each other in order to help visualization. (b) Energy levels (solid) as a function of the channel width, plotted in a log scale, along with two fitting functions (dashed curves), for large ($f_1$) and small ($f_2$) values of the channel width. (c) Numerically obtained (symbols) positions of the $M$ minima as a function of the wave packet energy, along with the results (solid curve) of the analytical model, given by Eq. (5).Reuse & Permissions

Figure 6

Transmission probabilities for a $\epsilon =70$ meV wave packet scattered by two kinds of defects in the lead-ring junction: A Gaussian attractive potential of depth $V_G$ (solid, bottom axis) and width ${\sigma }_G=5$ nm, and a circular bump of radius $R_b$ (dashed, top axis), which are schematically illustrated in the lower and upper insets, respectively.Reuse & Permissions