On Three "Anomalous" Measurements of Nonlinear QPC Conductance

TL;DR

This paper reviews three anomalous nonlinear conductance measurements in quantum point contacts, highlighting how advanced quantum kinetic models have explained two of them, while the third remains unresolved.

Contribution

It demonstrates the effectiveness of nonequilibrium quantum kinetic models in explaining anomalous QPC behaviors, advancing understanding beyond standard models.

Findings

Two anomalies explained by quantum kinetic models

Third anomaly remains theoretically unresolved

Highlights importance of correct boundary conditions

Abstract

Practical mesoscopic devices based on quantum point contacts (QPCs) must function at operating point involving large internal driving fields. Experimental evidence has accumulated to display anomalous nonlinear features of QPC response beyond the capacities of accepted tunnelling-based models of nonlinear quantum transport. Here we recall the physical setting of three anomalous QPC experiments and review how, for two of them, a microscopically based nonequilibrium quantum kinetic description (the correct physical boundary conditions being crucial) has already overcome the predictive limitations of standard nonequilibrium mesoscopic models. The third experiment remains a significant challenge to all theorists.