AC driven strongly correlated quantum circuits and Hall edge states: Unified photo-assisted noise and revisited minimal excitations

TL;DR

This paper investigates photo-assisted noise in strongly correlated quantum systems, revealing universal super-poissonian behavior, revisiting minimal excitations, and proposing improved methods for fractional charge detection in quantum Hall regimes.

Contribution

It extends fluctuation relations to correlated systems, characterizes minimal excitations via noise, and proposes advanced shot noise spectroscopy techniques for fractional charge measurement.

Findings

Photo-assisted noise obeys a non-equilibrium fluctuation relation.

Photo-assisted noise is universally super-poissonian.

New methods for fractional charge detection are proposed.

Abstract

We study the photo-assisted noise generated by time-dependent or random sources and transmission amplitudes. We show that it obeys a perturbative non-equilibrium fluctuation relation that fully extends the lateral-band transmission picture in terms of many-body correlated states. This relation holds in non-equilibrium strongly correlated systems such as the integer or fractional quantum Hall regime as well as in quantum circuits formed by a normal or Josephson junctions strongly coupled to an electromagnetic environment, with a possible temperature bias. We then show that the photo-assisted noise is universally super-poissonian, giving an alternative to a theorem by L. Levitov {\it et al} which states that an ac voltage increases the noise. Restricted to a linear dc current, we show that the latter does not apply to a non-linear superconducting junction. Then we characterize minimal excitations in non-linear conductors by ensuring a poissonian photo-assisted noise, and show that these can carry a non-trivial charge value in the fractional quantum Hall regime. We also propose methods for shot noise spectroscopy and for a robust determination of the fractional charge which is more advantageous than those we have proposed previously and implemented experimentally.