Mesoscopic Fluctuations of Nonlinear Conductance of Chaotic Quantum Dots

The nonlinear dc conductance of a two-terminal chaotic cavity is investigated. The fluctuations of the conductance (anti)symmetric with respect to magnetic-flux inversion through multichannel cavities are found analytically for arbitrary temperature, magnetic field, and interaction strength. For few-channel dots the effect of dephasing is investigated numerically. A comparison with recent experimental data is provided.

Figure 1

(Left) Quantum dot with magnetic field $B$ and dc bias voltages $V_{1,2}$ at the contacts and $V_0$ at the gates with capacitance $C$; an additional lead $\varphi$ models dephasing. (Right) Normalized fluctuation of the (anti)symmetric component $({\mathcal{G}}_a){\mathcal{G}}_s$ of the second order nonlinear conductance for a coherent dot as a function of flux $\Phi /{\Phi }_c$. Importantly, a crossover occurs at ${\Phi }_c\ll {\Phi }_0=eh/c$, because of the long time an electron spends in the dot.

Figure 2

var ${\mathcal{G}}_a$, normalized by $(\pi /16\Delta {)}^2$, as a function of dephasing ${\gamma }_{\phi }$ for $N=2$, $N_l=1$ for $N_{\phi }=1$, 3, 10, 20.