Where is the Shot Noise of a Quantum Point Contact?

TL;DR

This paper explores the fundamental connection between conservation principles, gauge invariance, and compressibility in mesoscopic transport, explaining the anomalous noise peak observed in quantum point contacts.

Contribution

It reveals the deep link between conservation laws and mesoscopic behavior, providing a theoretical explanation for the observed noise anomalies in quantum point contacts.

Findings

Identifies gauge invariance and compressibility as key to understanding noise.

Links experimental observations to fundamental conservation principles.

Highlights the universal role of these principles in mesoscopic transport.

Abstract

Reznikov et al. (Phys. Rev. Lett. 75, 3340 (1995)) have presented definitive observations of nonequilibrium noise in a quantum point contact. Especially puzzling is the "anomalous" peak structure of the excess noise measured at constant current; to date it remains unexplained. We show that their experiment directly reveals the deep link between conservation principles in the electron gas and its low-dimensional, mesoscopic behavior. Key to that connection are gauge invariance and the compressibility sum rule. These are central not only to the experiment of Reznikov et al. but to the very nature of all mesoscopic transport.