Shot Noise Enhancement in Resonant Tunneling Structures in a Magnetic Field

TL;DR

This paper reports the observation of shot noise exceeding the classical limit in a resonant tunneling structure under a magnetic field, revealing complex quantum fluctuations in the device.

Contribution

It provides the first experimental evidence of shot noise enhancement beyond 2qI in a magnetic field, highlighting the role of density of states fluctuations in resonant tunneling.

Findings

Shot noise exceeds 2qI in the structure.

Noise enhancement correlates with negative differential conductance.

Maximum enhancement reaches up to 8qI.

Abstract

We have observed that the shot noise of tunnel current, I, in GaSb-AlSb-InAs-AlSb-GaSb double-barrier structure under a magnetic field can exceed 2qI. The measurements were done at T=4K in fields up to 5T parallel to the current. The noise enhancement occurred at each of the several negative-differential conductance regions induced by the tunneling of holes through Landau levels in the InAs quantum well. The amount of the enhancement increased with the strength of the negative conductance and reached values up to 8qI. These results are explained qualitatively by fluctuations of the density of states in the well, but point out the need for a detailed theory of shot noise enhancement in resonant tunneling devices.