Do Intradot Electron-Electron Interactions Induce Dephasing?

We investigate the degree of coherence of electronic transport through a quantum dot (QD) in the presence of an intradot electron-electron interaction. By using an open multiterminal Aharonov-Bohm (AB) setup, we find that the intradot interaction does not induce any dephasing effect and the electron transport through the QD is fully coherent. We also observe that the asymmetric amplitude of the AB oscillation in the conductance through the two-terminal AB setup originates from the interplay between the confined structure and the electron-electron interaction. Thus, one cannot associate a dephasing process with this asymmetric amplitude, as has been done in previous studies.

Figure 1

Schematic diagram for an open multiterminal AB interferometer, containing a QD in its lower arm, penetrated by a magnetic flux $\Phi$, and four extra leads coupled.

Figure 2

(a) The total conductance $G$ vs the intradot level ${ϵ}_d$ at $U=5$, and (b) the flux-dependent conductance $\Delta G\equiv G(\varphi )-G(\varphi =0)$ of the three points specified in (a). (c)–(f) $G_d$ (dashed line), $G_1$ (solid line), and $r_G$ vs ${ϵ}_d$ for the case of $U=0$ and $\Delta {ϵ}_d=0$ (c), $U=5$ and $\Delta {ϵ}_d=0$ (d), $U=\infty$ and $\Delta {ϵ}_d=0$ (e), and $U=\infty$ and $\Delta {ϵ}_d=4$ (f). In (f), $r_{G\downarrow }$ and $r_{G\uparrow }$ are also plotted with ${ϵ}_{d\uparrow }={ϵ}_d$ and ${ϵ}_{d\downarrow }={ϵ}_d+\Delta {ϵ}_d$. The other parameters in (a)–(f) are $\Gamma /{\Gamma }^{sd}=5$ and $t_1=t_4=1$.

Figure 3

(a),(b) The coherence rates $r_G$ vs ${ϵ}_d$ for different couplings $\Gamma =10$, 50, 2, 0.5, and 0.1 from the up to down curves, with $U=0$ (a) and $\infty$ (b). (c),(d) $G_1$ vs ${ϵ}_d$ at $\Gamma =0.5$, with $U=0$ (c) and $\infty$ (d). The parameter $t_1=t_4=1$.