Figure 1

Schematic of a one-dimensional lead-dot-lead system showing two leads, possibly maintained at a nonvanishing voltage difference, the quantum dot (filled circle, blue online), and a gate that screens the long-range part of the Coulomb interaction.Reuse & Permissions

Figure 2

Current-voltage characteristics of a broken Luttinger liquid (a) for $Y=0.9$ (representative of the presence of the excitonic interaction in a symmetric junction with nanotube leads) and (b) for $Y=1.1$ (representative of a dot with nanotube leads in the absence of the excitonic interaction), and different temperatures. We show results for a symmetrically applied bias voltage $\mathit{eV}={\mu }_L-{\mu }_R$ with the gate voltage set to zero. We assume that the renormalized and bare dot energies ${\mathrm{\varepsilon ̃}}_d$ and ${\varepsilon }_d$ are positive. Because our interest here is in the form of the threshold behavior we choose units such that in each panel the bias voltages $V$ and thermal energies $T$ are given in units of the corresponding on-site energy appropriate to that panel. The local Coulomb interaction is assumed to be twice as large as the on-site energy in both panels.Reuse & Permissions

Figure 3

Differential conductance $\mathit{dI}/\mathit{dV}$ (in units of its maximum value) as a function of bias voltage $V$ for different values of $Y$ calculated for voltages in the neighborhood of the higher bias step shown in Fig. 2 at temperature $T={\mathrm{\varepsilon ̃}}_d/30$ and other parameters identical to those used in Fig. 2.Reuse & Permissions

Figure 4

Color-scale plots of the current as a function of bias voltage $V$ and gate voltage $V_g$ (a) for $Y=0.9$ (representing the presence of the excitonic interaction) and (b) for $Y=1.1$ (representing the absence of the excitonic interaction). Voltages are given in units of the on-site energy. We assume $T={\varepsilon }_d/100$, $U=3{\varepsilon }_d$, and $\Delta ={\varepsilon }_d/2$ so that $\mathrm{Ũ}=2{\varepsilon }_d$.Reuse & Permissions

Figure 5

(a) Current-voltage characteristics and (b) transition rates for asymmetric excitonic dot-lead couplings, $Y_L=0.75$ and $Y_R=1.5$. We assume $T={\mathrm{\varepsilon ̃}}_d/100$ and $v_c\Lambda =15{\mathrm{\varepsilon ̃}}_d$, and as in Fig. 2 we choose $\mathrm{Ũ}=2{\mathrm{\varepsilon ̃}}_d$. Voltages are given in units of the on-site energy.Reuse & Permissions