Full Counting Statistics for a Single-Electron Transistor: Nonequilibrium Effects at Intermediate Conductance

We evaluate the current distribution for a single-electron transistor with intermediate strength tunnel conductance. Using the Schwinger-Keldysh approach and the drone (Majorana) fermion representation, we account for the renormalization of system parameters. Nonequilibrium effects induce a lifetime broadening of the charge-state levels, which suppress large current fluctuations.

Figure 1

Current distribution $P$ of a symmetric SET [$T=0$ and $eV/E_C=0.2$]. (a) Solid lines are plots of $P$ for various values of ${\Delta }_0$ [Eq. (10)]. The dashed lines represent the orthodox theory [Eq. (12)], and the dotted-dashed line represents the cotunneling expansion [Eq. (15)]. The inset shows the average current for the same parameters. (b) Plot of $P$ at ${\Delta }_0=0$ for various values of the conductance versus the current normalized to $V/2(R_L+R_R)$; inset: the same distribution normalized to the average current $⟨I⟩$. (c) The skewness and (d) kurtosis for various conductances derived from Eq. (10) (solid lines) and the sum of Eqs. (12, 14) (dashed lines).