Quantum analysis of shot noise suppression in a series of tunnel barriers

TL;DR

This paper uses a quantum-mechanical model to analyze shot noise suppression in cascaded tunneling barriers, revealing localization effects that challenge semiclassical predictions and align with experimental observations.

Contribution

It introduces a quantum analysis showing localization effects in 1D disordered tunneling structures, contrasting with semiclassical models predicting a fixed Fano factor limit.

Findings

Localization causes deviations from semiclassical shot noise predictions.

Fano factor behavior differs from the 1/3 limit in quantum models.

Experimental evidence supports the presence of localization in practical structures.

Abstract

We report the results of an analysis, based on a straightforward quantum-mechanical model, of shot noise suppression in a structure containing cascaded tunneling barriers. Our results exhibit a behavior that is in sharp contrast with existing semiclassical models for this particular type of structure, which predict a limit of 1/3 for the Fano factor as the number of barriers is increased. The origin of this discrepancy is investigated and attributed to the presence of localization on the length scale of the mean free path, as a consequence of the strictly 1-dimensional nature of disorder, which does not create mode mixing, while no localization appears in common semiclassical models. We expect localization to be indeed present in practical situations with prevalent 1-D disorder, and the existing experimental evidence appears to be consistent with such a prediction.