Noise in an ac biased junction. Non-stationary Aharonov-Bohm effect

TL;DR

This paper investigates excess noise in a quantum conductor under combined constant and alternating voltages, revealing phase-sensitive singularities and flux-dependent oscillations in noise characteristics.

Contribution

It introduces a novel analysis of phase-sensitive noise effects in ac biased quantum conductors, highlighting singular dependencies and flux-induced oscillations.

Findings

Noise exhibits cusplike singularities at specific voltage and frequency ratios.

Phase sensitivity causes oscillations in noise with flux amplitude.

Zero-temperature noise dependence on dc voltage and ac frequency is characterized.

Abstract

We study excess noise in a quantum conductor in the presence of constant voltage and alternating external field. Due to a two particle interference effect caused by Fermi correlations the noise is sensitive to the phase of the time dependent transmission amplitude. We compute spectral density and show that at T=0 the noise has singular dependence on the {\rm dc} voltage $V$ and the {\rm ac} frequency $\Omega$ with cusplike singularities at integer $eV/\hbar\Omega$. For a metallic loop with an alternating flux the phase sensitivity leads to an oscillating dependence of the strengths of the cusps on the flux amplitude.