Quantum-limited shot noise in graphene

TL;DR

This paper calculates shot noise and conductance in ideal graphene strips, revealing a universal Fano factor of 1/3 at the Dirac point, similar to disordered metals, despite ballistic dynamics.

Contribution

It provides an analytical calculation of mode-dependent transmission and shot noise in ideal graphene, showing universal noise characteristics at the Dirac point.

Findings

Fano factor at Dirac point equals 1/3 for short, wide strips

Minimum conductivity is of order e^2/h at the Dirac point

Shot noise behavior resembles that of disordered metals

Abstract

We calculate the mode-dependent transmission probability of massless Dirac fermions through an ideal strip of graphene (length L, width W, no impurities or defects), to obtain the conductance and shot noise as a function of Fermi energy. We find that the minimum conductivity of order e^2/h at the Dirac point (when the electron and hole excitations are degenerate) is associated with a maximum of the Fano factor (the ratio of noise power and mean current). For short and wide graphene strips the Fano factor at the Dirac point equals 1/3, three times smaller than for a Poisson process. This is the same value as for a disordered metal, which is remarkable since the classical dynamics of the Dirac fermions is ballistic.