Scattering approach to frequency-dependent current noise in Fabry-P\'erot graphene devices

TL;DR

This paper investigates finite-frequency quantum noise and photon-assisted transport in graphene devices, revealing interference effects, phase jumps, and oscillatory noise signatures related to electron-hole coherence and Fabry-Pérot interferences.

Contribution

It introduces a scattering approach to analyze frequency-dependent noise in graphene, highlighting interference patterns and energy scales unique to Dirac fermions.

Findings

Identification of interference patterns in noise spectra

Observation of phase jumps within interference patterns

Detection of oscillatory cross-correlation noise signatures

Abstract

We study finite-frequency quantum noise and photon-assisted electron transport through a wide and ballistic graphene sheet sandwiched between two metallic leads. The elementary excitations allow as to examine the differences between effects related to Fabry-P\'erot like interferences and signatures caused by correlations of coherently scattered particles in electron- and hole-like parts of the Dirac spectrum. We identify different features in the current-current auto- and cross-correlation spectra and trace them back to the interference patterns of the product of transmission- and reflection amplitudes which define the integrands of the involved correlators. At positive frequencies the correlator of the auto-terminal noise spectrum with final- and initial state associated to the measurement terminal is dominant. Phase jumps occur within the interference patterns of corresponding integrands, which also reveal the intrinsic energy scale of the two-terminal graphene setup. The excess noise spectra, as well as the cross-correlation ones, show large fluctuations between positive and negative values. Oscillatory signatures of the cross-correlation noise are due to an alternating behavior of the integrands.